Chapman’s Orthopaedic Surgery
3rd Edition

CHAPTER 174
CONGENITAL LOWER LIMB DEFICIENCY
William L. Oppenheim
Hugh G. Watts
Robert M. Bernstein
Yoshio Setoguchi
W. L. Oppenheim: Division of Pediatric Orthopedics, University of California–Los Angeles School of Medicine; Shriners’ Hospital, Los Angeles, California, 90095.
H. G. Watts: Shriners’ Hospital; Department of Orthopedics, University of California–Los Angeles School of Medicine, Los Angeles, California, 90020.
R. M. Bernstein: Shriners’ Hospital; Department of Orthopedics, University of California–Los Angeles School of Medicine, Los Angeles, California, 90020.
Y. Setoguchi: Shriners’ Hospital; Department of Pediatrics, University of California–Los Angeles School of Medicine, Los Angeles, California, 90020.
This chapter focuses on a group of diverse congenital anomalies affecting the lower extremities of children. Many involve a failure of formation of various tissues, as well as leg-length discrepancy. The general approach to these patients is to evaluate their limbs in terms of potential function, to estimate the projected leg-length discrepancy at maturity, and then to address the situation either by standard leg-length equalization techniques or through the use of a prosthesis that can be adjusted in length as the child grows. When amputation is indicated as part of
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the overall solution, one must identify a key joint for salvage and then convert the tissue distal to that joint into a usable weight-bearing organ. The key joint is the most distal joint with sufficient function to power a prosthesis. Complicating the technical problems are psychological feelings of helplessness, anxiety, and frustration among parents and physicians alike.
The concept of sacrificing a body part to facilitate prosthetic fitting is initially poorly accepted by most parents, particularly if the part proposed for sacrifice appears quite normal. The parents rightly question why modern technology cannot be called upon to salvage their child’s limb. Physicians faced with this scenario must improvise based on their combined expertise in prosthetics and reconstructive surgery. Although some of the procedures may initially appear radical to parents, with education and counseling the child and parents can accept them as simply reconstructive. Experience has shown that it is frequently preferable to convert a limb to a logical prosthetic level rather than embark on a prolonged operative reconstruction that, even when modestly successful, frequently precludes participation in normal childhood activities (41). Treatment thus requires an understanding of the natural history of the specific defect as well as a thorough knowledge of any associated abnormalities.
Because of the complicated nature of these conditions, evaluation and treatment are best carried out at special clinics where appropriate psychological, social, and pediatric support is available. Surgical procedures are not easily undertaken and rely on the parents’ informed judgment based on a balanced medical presentation and the experience gained through the consultation process. An opportunity to associate with other families in similar circumstances who have already gone through the process is a reassuring influence and should be part of the family’s decision-making process.
ETIOLOGY
The period during which a developing embryo is most susceptible to malformations being perpetuated in subsequent cell lines is between the fourth and eighth weeks postfertilization, the so-called period of organogenesis. Both the axial and appendicular skeletons form at this time. A single cell gives rise to billions of descendants, so the surprising thing is not that congenital anomalies occur, but that they do not occur even more frequently. Some conditions have a familial origin and hence a preordained genetic derivation. For example, congenital dislocation of the knee may occur sporadically or in association with Larsen’s syndrome, an autosomal dominant condition in which dislocations of other joints and anomalies of the cervical spine also occur. Whatever the cause, once a defect is present, with the limb bud developing in a proximal to distal progression, areas “downstream” from the initial insult may also be affected. For example, proximal femoral focal deficiency is frequently associated with a more distal fibula deficiency, and absence of the fibula in turn may be associated with absence of lateral foot rays.
Because other organ systems also differentiate during this gestational period, limb defects frequently are seen in the presence of anomalies exclusive of the musculoskeletal system. The VACTERLS syndrome refers to the association of vertebral, anal, cardiac, tracheoesophageal, renal or radial flaws, associated with limb defects and a single umbilical artery. In the amniotic band syndrome, the insult is thought to take place after limb bud development during the fetal period of gestation. Multiple bands may be present, predisposing to autoamputations. From this brief discussion, it is clear that limb reduction defects often present as part of a more general syndrome.
DIFFERENCES BETWEEN CHILD AND ADULT AMPUTEES
Amputation surgery in children differs from that in adults. In adults, amputation is frequently related to peripheral vascular disease or diabetes; healing is delayed and rehabilitation is difficult and prolonged. Adults are concerned about their body image, time lost from work, and their livelihood in general. Children, on the other hand, usually heal promptly and completely; conversion to an amputation at an early age is not ordinarily difficult or prolonged, and potential employability is not an immediate concern (see Chapter 175). Phantom pain and neuromas, which can significantly impact on the results in adults, do not appear as clinically significant in children and present only an occasional problem in adolescents. Gait training takes place spontaneously under the guidance of a prosthetist or physical therapist, and psychological acceptance of the limb is natural and not elaborate.
However, one problem peculiar to growing children is frequent overgrowth following transdiaphyseal amputations, particularly in the humerus, tibia, and fibula. This can result in a need for serial surgical revisions throughout growth (see section on Terminal Overgrowth at the end of this chapter). Where possible, perform amputation through an adjacent joint to avoid this problem, but this consideration must in turn be tempered by the concomitant goal of maintaining length. Through-joint amputations not only preserve length, but, by preservation of the adjacent growth plate, add to the length throughout childhood, preventing an initial adequate length from becoming a proportionately shorter stump as adult stature is attained.
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ASSESSMENT AND GOAL SETTING
When assessing an infant with a limb deficiency, identify possible etiologic factors. Consider the influence of teratogenic agents such as thalidomide, maternal risk factors such as diabetes, and environmental factors such as radiation exposure. A genetics consultation is recommended to assess the risks for additional pregnancies and to offer counseling. Despite the gravity of the situation, the professional staff should maintain an optimistic demeanor. Nearly all children with lower extremity anomalies gain functional mobility, attend regular school, and lead quality lives, participating in sports such as swimming, skiing, tennis, and horseback riding. Schools may restrict participation in contact sports such as football and hockey because of the risk of injury to other children from prosthetic parts. The role of the parents and grandparents cannot be underestimated. Acceptance of the child as he is and the avoidance of overprotection, which can lead to an overly dependent and submissive personality, facilitates the child’s development, sense of self worth, and eventual integration into the workplace.
CONGENITAL DEFICIENCY OF THE FIBULA
Congenital malformations of the fibula usually are not associated with classic modes of genetic transmission and thus likely result from embryonic insults occurring during the development of the limb bud. The severity ranges from simple hypoplasia to total absence of the fibula. Experimental evidence suggests that the earlier the insult occurs in embryonic development, the more likely is concurrent involvement of the proximal femur. Later insults involve the fibula and foot to a greater degree (46). Fibular deficiency thus may be accompanied by proximal femoral focal deficiency, shortening and/or bowing of the tibia, general limb growth retardation, delayed epiphyseal ossification, absence of rays, tarsal coalitions, residual fibrous bands, deficiencies of various muscles, genu valgum, and loss of ankle integrity (2,18,30,31,59,68). Upper extremity anomalies are also seen in some cases. Although rare compared to diseases such as developmental dysplasia of the hip or clubfeet, the fibula is the most common congenitally absent long bone (18).
Clinically, the most important issues are the stability and function of the ankle and foot and the overall length of the limb. To better characterize the variability, Achterman and Kalamchi (2) refined a classification originally utilized by Coventry and Johnson (18) (Fig. 174.1). In type IA, the entire fibula is present but shortened, leaving the proximal fibular epiphysis distal to the upper physis of the tibia, and the distal fibular physis proximal to the dome of the talus. In type IB, there is a partial absence of the upper fibula, and the lower fibular epiphysis is likewise elevated above the talar dome and thus not buttressing the ankle. In type I deformities, the foot usually remains plantigrade but may be associated with a ball and socket ankle joint, and either equinovalgus or equinovarus may be present. In type II, by contrast, the entire fibula is absent, tibial bowing is frequent, and ankle instability is the rule. A residual lateral fibrous band may contribute to the type II deformity.
Figure 174.1. Achterman-Kalamchi classification of fibula hemimelia. See text for explanation.
Some surgeons have used the absence of rays to predict ankle stability (e.g., a four-toed foot can be salvaged, but a three-toed foot should be sacrificed), but we have found that stability can be directly assessed and that a three-toed foot can often be serviceable. The degree of tibial shortening increases with advanced stages, although associated femoral shortening is maximal in type I. Children with type I feet will not require conversion to an amputation, but conversion is usually performed for the majority of children with type II deformities.
The literature abounds with ankle stabilization procedures for the treatment of type II deformities, but the test of time has not supported this approach (4,7,11,15). Stabilization by arthrodesis is complicated by delayed ossification of the epiphyses, as well as by potential inadvertent injury to the distal tibial physis. Kruger and Talbott (41) have pointed out that whereas the goal of preserving the foot might be laudable, in fact many children who undergo repetitive operations eventually undergo amputation, and that upon honest review there is good evidence that conversion should have been offered as a primary treatment rather than a secondary salvage procedure. In addition, we have found a higher incidence of complications when Syme amputation was performed as a salvage
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procedure in multiply operated limbs rather than as a primary procedure (6). In areas where cultural concerns do not allow amputation, or in lesser developed areas where surgery is not available, it is feasible to fit a prosthesis around the foot.
In instances where the ankle is relatively stable and the overall length can be made acceptable, leg lengthening using Ilizarov techniques, in which the ankle is stabilized during lengthening, is an acceptable approach.
INDICATIONS FOR ANKLE DISARTICULATION IN CHILDREN
The indications for conversion to a below-knee amputation are (a) a deformity of the foot so severe that any surgery to make the foot plantigrade and functional is likely to fail (70) and (b) an estimated leg-length discrepancy at maturity of 7.5 cm or more (60). The value of 7.5 cm is arbitrary and tends to vary among physicians (46,59,60). We now base our decision more on the stability of the ankle than the leg-length discrepancy, per se, provided the overall limb-length discrepancy at maturity is not projected to exceed 12 cm.
TECHNIQUE OF SYME’S AMPUTATION
  • Begin the procedure of Syme’s ankle disarticulation (Fig. 174.2) by making a fish-mouth incision with anterior and posterior skin flaps. The apex begins 1 cm distal to the medial malleolus and parallels the anterior ankle joint to a point estimated to be the level where the fibular tip would ordinarily be palpable.
    Figure 174.2. Syme’s ankle disarticulation as performed in children. Make skin incisions from a point 1 cm distal to the medial malleolus to the tip of what would have been the fibula malleolus, as illustrated. A: Schematic of the anatomy posterior to the medial malleolus. B: Divide the collateral ligaments to facilitate hyper plantarflexion of the ankle. C: Location of the flexor hallucis longus posterior to the talus. D: Protect the neurovascular bundle by retraction of the flexor hallucis longus muscle tendon. E: Divide the Achilles tendon, taking care to include excision of the apophysis of the calcaneus. F: Preserve the neurovascular bundle to the end of the flap; avoid injury to the bundle at the level of the ankle joint. G: Close the wound over a drain, and stabilize the heel pad with a stout K-wire or smooth Steinmann pin inserted into the tibia from the plantar aspect of the heel.
  • Carry the dissection down through the subcutaneous tissue to the level of the medial and lateral collateral ligaments of the ankle, ligating larger vessels and controlling smaller ones with electrocautery.
  • Identify the nerves. Gently tension, sharply divide, and allow the nerves to retract away from potential subcutaneous positioning.
  • Divide the collateral ligaments so that the talar dome can be pulled forward away from the distal tibia.
  • In the interval between the talus and tibia, identify the flexor hallucis longus tendon. It is the key to locating and protecting the neurovascular bundle posteromedially. By protecting this tendon and drawing it medially with a retractor, the dissection can be continued with the neurovascular bundle shielded so that the actual division of the posterior tibial artery will be at the most distal portion of the posterior flap.
  • Excise the calcaneus from the heel pad in a subperiosteal fashion so that the periosteum remains intact, maintaining the structural integrity of the fat pad, which has a hydraulic-like function during weight bearing. Be sure that the entire calcaneal apophysis is excised so that it will not form a persistent ossicle later (Fig. 174.3). Two centimeters of the distal Achilles tendon can be resected to ensure there will be no tendency to reattach and pull the heel pad posteriorly. Shave the distal tibia only in older children, because smoothing and remodeling occur spontaneously in younger children once the talus no longer occupies the mortise.
    Figure 174.3. In performing Syme’s amputation, be certain to excise the entire apophysis, otherwise it will persist and complicate later prosthetic fitting. This one required removal during adolescence.
  • Finally, stabilize the heel pad underneath the tibia by inserting a stout Kirschner wire (K-wire) through the pad into the tibia, and close the skin over a Penrose drain with absorbable subcutaneous sutures and interrupted nylon sutures for the skin. In approximating the heel pad to the tibia, take care to avoid crimping the posterior tibial artery.
After skin repair, apply Xeroform (Sherwood Medical, Markham, Ontario) gauze, fluffs, sterile cast padding, and a spica cast for short stumps (as when the amputation is combined with a knee fusion for proximal femoral focal deficiency). A long-leg cast can be applied when the knee can be effectively flexed to prevent the cast from sliding off. Remove the drain at 2 days and allow 6 weeks for soft-tissue healing in the cast. An elastic wrap is occasionally necessary for several additional weeks to control any residual
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stump edema. The stump is ready for prosthetic fitting between the tenth and twelfth weeks.
Associated tibial bowing ordinarily corrects spontaneously after a Syme’s amputation, but in those cases accompanied by bowing in excess of 30°, perform a tibial osteotomy simultaneously, and extend the K-wire to act as intramedullary fixation.
TECHNIQUE OF BOYD AMPUTATION
Some authors have reported problems with stabilization of the heel pad in the Syme’s amputation and thus prefer the Boyd amputation, in which the calcaneus is displaced anteriorly in an effort to fuse it into the distal tibia or at least to stabilize it under the tibial plafond (8,10,70). Modest additional length can also be maintained by this approach. Alternatively, the distal tibial physis can be excised at the time of calcaneal tibial fusion, so that the bulbous self-suspending stump gradually “ascends” to the level of the opposite calf. In deformities with severely displaced equinus hind feet, repositioning of the calcaneus under the tibia may not be possible, and Syme’s procedure is preferred. No shaping of the malleoli is necessary in young children in either the Boyd or the Syme ankle conversion. Without the talus occupying the mortise, the malleoli remodel to a satisfactory shape. Either procedure yields a pleasing stump because the prominent malleoli atrophy after talar excision.
  • Boyd amputation (8) utilizes an approach similar to the Syme procedure just described. However, excise only the talus and forefoot, leaving the calcaneus attached to the fat pad (Fig. 174.4).
    Figure 174.4. Boyd’s amputation. A: Scheme of bony resection. B: Final position, emphasizing anterior displacement of the calcaneus to provide a rounded stump.
  • Carefully shave the articular cartilage of the distal tibia with a knife until the ossific nucleus is encountered; take care to breech neither the distal tibial physis nor its surrounding perichondrium, unless shortening of the stump is desired.
  • Osteotomize the anterior portion of the calcaneus, if necessary, just distal to the peroneal tubercle; shave the superior surface flat, allowing it to sit congruously under the prepared distal tibia.
  • Divide the Achilles tendon through the space left by the enucleation of the talus. When performed properly, the heel pad can be positioned in its normal weight-bearing attitude but slightly displaced anteriorly.
  • Use a smooth Steinmann pin to secure the final position, extending it through the calcaneus across the distal tibial physis into the medullary canal of the tibia.
  • Close the skin over a drain.
The postoperative management is similar to that described for the Syme’s amputation.
RESULTS OF ANKLE DISARTICULATION
With the exception of one patient who died of unrelated causes, in our series of 61 patients with Syme amputations (6), all were ambulatory, and patient satisfaction was excellent. Patients participated in sports activities, including bicycling, swimming, football, soccer, and roller skating.
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Although some did report occasional problems, such as calluses and rashes, on closer inspection these problems seemed to be related to prosthetic fit rather than to the stump per se, and they were easily addressed with minor prosthetic accommodations in the socket. Posterior heel pad migration was commonly encountered, although it rarely required surgical intervention. Hypertrophy of the skin over the distal tibia and prosthetic adjustment were usually enough to compensate for changes in heel pad position. Of these patients, 40% felt that they had no functional restriction at all, and all of the adults reviewed were employed.
In an alternate study evaluating the physical and psychological function in young patients after Syme’s amputation, the results documented a surprisingly easy adjustment process (6). The age of amputation may be important, and it seemed preferable that the procedure be performed prior to the age of 18 months to 2 years, because at this time the infant has an incompletely developed body image and adapts to the new physical status quite quickly. It seems that a missing foot compensated by a functional prosthesis is more acceptable to a child or teenager than a significantly deformed foot that compromises activities and gait.
COMPLICATIONS OF ANKLE DISARTICULATION
Posterior heel pad migration, wound sloughs, and damage to the distal tibial physis are seen in both the Boyd and the Syme conversions. In addition, an occult retained calcaneal apophysis and later pencilling of the distal tibia may complicate Syme’s amputation. Careful attention to the indications and surgical details will limit the problems encountered. Displacement of the heel pad, although frequent, is rarely an indication for reoperation.
PROCEDURES TO STABILIZE THE ANKLE
In the past, many attempts have been made to create a lateral buttress to replace the fibula. The Bardenhauer procedure (7) involved inserting the talus into a sagittal split in the tibia, clearly breaching the growth plate. The Albee procedure (4) involved buttressing by autogenous bone grafted into the tibial metaphysis in an effort to replace the fibular malleolus. Lacking a growth plate, the buttress would quickly rise above the level of the ankle, mitigating its effectiveness.
More recent attempts at ankle stabilization have centered on the Gruca procedure (28,54). In a review of this technique by Thomas and Williams (60) at the Royal Children’s Hospital in Melbourne, patients were considered for the procedure only if they exhibited minimal shortening of the tibia and had a foot that comfortably reached the ground with no gross deformity. Of seven attempts reported, three had been converted to an amputation, three were awaiting amputation, and the remaining patient had embarked on a program of leg-length equalization. Thus, this procedure is not definitive for most patients and can be regarded only as an interim procedure to be followed by an amputation beause of the progressive leg-length inequality that develops. With rare exception, it appears that Syme’s or Boyd’s amputations are the preferred primary treatment for type II (complete) fibular deficiencies.
WILTSE OSTEOTOMY
While stabilization procedures in the absence of a fibula have not been very successful, for specific cases of partial absence resulting in a mild leg-length discrepancy and a valgus but stable ankle, Wiltse (69) proposed a supramalleolar osteotomy designed to minimize the prominence of the medial malleolus. The osteotomy is performed toward the end of growth through an anterior approach to the ankle (Fig. 174.5).
Figure 174.5. The Wiltse osteotomy reduces the medial prominence of the ankle following correction of a residual valgus ankle deformity, as might accompany lesser degrees of fibula deficiency. A: Plan of wedge resection. B: After closure and fixation of the osteotomy.
CONGENITAL DEFICIENCY OF THE TIBIA
Unlike most other longitudinal deficiencies, congenital deficiency of the tibia, the rarest form of lower extremity deficiency, may be sporadic or inherited. Both autosomal dominant and recessive patterns have been reported. The anomaly is frequently associated with other system deficits such as herniae, gonadal malformations, hypospadias,
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cleft palate, imperforate anus, and congenital heart disease. Associated vascular abnormalities may underlie the malformations (32). Always search for absent or duplicated rays, ipsilateral proximal femoral focal deficiency (PFFD), contralateral clubfoot, hemivertebra, hip dysplasia, coxa valga, syndactyly, and lobster claw deformities (53). In contrast to fibular deficiencies, the foot is in a varus position, and the knee may be unstable due to an associated absence of collateral or cruciate ligaments.
There are two classification systems available in the literature. The Kalamchi classification is perhaps simpler and more straightforward (Fig. 174.6), but the classification of Jones et al. (35) is the most widely accepted. It separates the deficiencies radiographically into five types: 1a, 1b, 2, 3, and 4 (Table 174.1). Both classifications are helpful in formulating treatment.
Figure 174.6. The Kalamchi classification for congenital tibial deficiency. Type I, no tibial anlage. Type II, tibial anlage present. Type III, tibial fibula diastasis.
Table 174.1. Jones Classification of Tibial Dysplasia
The distinction is whether a proximal portion of the tibia remains, and whether this portion is meaningfully powered by a quadriceps mechanism. Usually the fragment is palpable, and active knee extension is easily discerned. However, this is not always a simple distinction in a chubby uncooperative infant, so the cartilaginous remnant may need to be sought by arthrography, ultrasonography, magnetic resonance imaging (MRI), or direct observation during surgery. Radiographically, a marked reduction in width and delayed ossification of the distal femur are also suggestive of an absent or nonfunctional proximal segment. When this tibial fragment is present and powered, surgery is warranted to fuse the fibula into the fragment and then to perform a Syme’s amputation, which produces a functional below-knee amputation (Fig. 174.7). When the proximal fragment is absent (Jones type 1a), knee disarticulation is warranted, resulting in a functional above-knee amputee. Try to avoid above-knee amputation in treating congenital tibial deficiency because of problems with bony overgrowth, skin problems associated with the residual limb, not to mention the loss of the major growth physis of the femur and resultant shortening (36).
Figure 174.7. A: Transfer of the fibular into the tibial anlage in Kalamchi type II deformities of the tibia. B: Side-to-side fixation of the fibula into the tibia after resection of the upper portion of the fibula.
The Brown procedure (12,13) (described in the following section), which centralizes the fibula under the femur, is an alternative that allows the child to function as a below-knee prosthetic user rather than as an above-knee amputee. Most authors report disappointing results, in part because of recurring knee flexion contractures, which result from an imbalance between the hamstrings and a weak, albeit present, quadriceps musculature (35,42,58). The Brown procedure (12) may nevertheless be offered if a functioning quadriceps mechanism of grade 3 strength or better is present, because some patients can achieve a functional below-knee stump that allows active knee flexion and extension, according to Simmons et al. (55). Residual ligamentous laxity following Brown centralization can be controlled by an appropriately designed prosthetic socket. Keep in mind that if the Brown procedure proves unsuccessful, the limb may be salvaged and a perfectly acceptable result obtained by performing a knee disarticulation, which would have been the alternative operation anyway. In some severe cases of concomitant femoral shortening, fusion of the fibula into the femur may be desirable to add length to an otherwise short above-knee stump. Unfortunately, 20% to 30% of tibial deficiencies occur bilaterally with an additional compromise of the final functional ability of the patient, regardless of the treatment approach.
When the proximal tibial anlage is present and powered (Jones types 1b and 2), surgery is warranted to fuse the fibula into the fragment when it is sufficiently ossified. Simultaneously, Syme’s amputation is performed and the result is a functional below-knee amputee.
De Sanctis et al. (22) presented another strategy and reported three cases treated with Jones type 2 deformities
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(tibial anlage present) by correction of the foot deformity shortly after birth through a combination of casting and soft-tissue release followed by fibulotibial diaphyseal reconstruction, alignment of the axis of the leg with the foot (talofibular arthrodesis), and leg-length equalization by the Ilizarov method. In a preliminary report, two of the patients achieved satisfactory ambulation, whereas the other sustained recurrence of deformity during the lengthening process.
The Jones type 3 tibial deficiency, characterized by a deficiency of the proximal tibia with a distal, abnormally formed tibial remnant, is extremely rare. This has been adequately treated with a Syme’s or Chopart’s amputation. The Jones type 4 deformity, with diastasis of the distal tibia and fibula, may be treated by Syme’s amputation, or an ankle reconstruction may be attempted (53).
TOTAL ABSENCE OF THE TIBIA
Brown Fibula Centralization
  • Create an anterior U-shaped incision that parallels the distal femoral condyles (Fig. 174.8A), and develop a skin flap proximally that allows access to the quadriceps expansion.
    Figure 174.8. The Brown procedure. A: Incision utilized for the Brown procedure. B: Release of fibular tethering; note roundness of distal femur. C: Cross K-wire fixation. If the fibula cannot be relocated distally under the femur, a segmental resection of the upper part of the fibula may help.
  • Make a lateral parapatellar longitudinal incision through the expansion that, based on the radiograph, will allow exposure of the upper fibula, which is displaced proximally from its normal position. Now incise and excise the tissue between the upper fibula and the femoral epiphysis as necessary to allow transposition of the fibular head to a point under the midportion of the femoral epiphysis (Fig. 174.8B). Brown excised the upper 3/8 inch of the fibula to provide a flat surface to oppose to the distal femur.
  • Fix the fibula in position with cross K-wires (Fig. 174.8C) and leave intact the insertion of the patella ligament; reattachment to the fibula itself is not necessary. If the fibula is too high to be brought distally, remove a segment of bone from the upper third of the fibula to facilitate positioning under the femur.
  • Fix the reconstituted fibula with a smooth Steinmann pin placed intramedullary. A Syme’s or Boyd’s ankle disarticulation can be done simultaneously or at a later time.
  • Close the skin over a hemovac drain, and immobilize the limb from toe to groin in a maximal, but comfortable, degree of extension.
Change the cast at monthly intervals up to the third or fourth month, at which time remove the K-wires and immediately apply a prosthesis. We prefer to attempt the operation at the age of walking, between 1 and 2 years of age, rather than keeping the patient in a cast until the time when a prosthesis can be applied.
Complications include ligamentous instability, dislocation or subluxation of the fibula from under the femur, stiffness, and recurrent knee flexion contracture. The latter can be treated by hamstring release, but after one or two attempts at making this procedure work, consider knee disarticulation or tibial fibula fusion.
Knee Disarticulation
The mainstay of treatment for Kalamchi type I tibial deformity, in which there is no meaningful tibial remnant, is a knee disarticulation with prosthetic fitting as an above-knee amputee. The distal femoral growth plate is preserved by this technique and therefore considerable growth potential is salvaged. Take care during the procedure not to inadvertently breech the growth plate or the surrounding perichondrium. The following description assumes a nonfunctional tibial anlage, so the usual structures are described. In the actual situation, modifications may be necessary depending on what is actually encountered.
  • With the patient in a supine position and under tourniquet control, make an anterior transverse skin incision commencing 1–2 cm distal to the tibial tubercle (or where it should be), sloping upward medially and laterally toward the joint line to a point slightly posterior to the mid-coronal plane (Fig. 174.9). Carry the incision posteriorly 2–3 cm distal to the popliteal crease. Any extraneous flap tissue can always be trimmed later, but too short a flap may necessitate shortening the femur, potentially injuring the physis.
    Figure 174.9. Knee disarticulation for severe tibial deficiency. A: Expose the distal femur through a transverse incision. The patellar and tibial anlage shown here for clarity are usually absent in those cases requiring knee disarticulation. B: Divide the collateral ligaments, ligate the neurovascular bundle, and divide the peroneal nerve. We routinely resect the patella to prevent later chrondromalacia.
  • Incise the deep fascia in line with the fish-mouth skin incision. If present, divide the patellar ligament and excise the patella to prevent later chondromalacia.
  • With the knee flexed to 90°, divide the medial and lateral collateral ligaments and anterior and posterior cruciate ligaments as distally as feasible.
  • Isolate and ligate the popliteal artery and accompanying veins individually.
  • Gently pull the posterior tibial nerve distally and divide it proximally; if it is accompanied by large veins, ligate these before they are allowed to retract proximally. Treat the peroneal nerve similarly.
  • Next, divide the sartorius, gracilis, semimembranosus, and semitendinosus tendons at their insertions into the tibia, and the biceps femoris at its fibular insertion. Section the iliotibial band transverse to its fibers, and incise the capsule of the knee at the joint line, eventually circumferentially.
  • Finally, divide the gastrocnemius muscle heads at their origins on the femur, and pass the leg off the table.
  • Close by approximating the hamstring tendons and the patellar ligament to the cruciate ligaments, trimming any excess skin and closing the skin flaps over a drain.
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    It is unnecessary and meddlesome to trim the femoral condyles, as might be attempted for an adult.
  • Apply a rigid plaster dressing that will remain for 4–6 weeks; in small children, a single hip spica may be necessary to keep the cast in position.
PARTIAL ABSENCE OF THE TIBIA
Transfer of the Fibula into the Proximal Tibial Anlage
The transfer of the fibula into the proximal tibial anlage can be done in an end-to-end fashion with intramedullary pins, or by side-to-side approximation with interfragmentary screw fixation. Fusion must await the development of a bony tibial diaphysis, if it is not initially present.
  • Make a longitudinal anterior incision centered over the distal portion of the tibial remnant (Fig. 174.7).
  • Approach the fibula through a separate lateral incision and dissect the peroneal nerve free where it crosses the fibula.
  • Transect the fibula at the level of the distal tibial anlage, and excise the proximal portion. Transpose the distal fibula by incising intervening tissue as necessary. Align the distal transected fibula with the tibial anlage and secure the final alignment with the tibia with a K-wire or smooth intramedullary Steinmann pin.
  • Alternatively, if the anlage is very short, a side-to-side fusion may be performed by fixation with small screws or cross K-wires. Apply a long-leg or single-hip spica cast until healing is assured (2–3 months).
Perform prosthetic fitting shortly after cast removal. At
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times, the union can appear tenuous, especially if considerable residual cartilage was encountered in the tibial anlage, but progressive ossification of the fibrous union does mature over time. A simultaneous Syme’s amputation is usually performed, although some surgeons continue to attempt preservation of the foot by tibiofibular fusion. The Ilizarov apparatus can be used to align and fuse the foot, but the results of such an approach are thus far unreported.
CONGENITAL DISLOCATION OF THE KNEE
Congenital dislocation of the knee (CDK) is a rare condition encompassing a continuum from mild subluxation to frank dislocation. According to Parsch (48), Koptis reported a frequency of about 1.7 per 100,000 live births. Breech presentation occurs in 30% to 40% (44). CDK is easily recognized in the neonatal period, with the knee fixed in hyperextension. The femoral condyles may be palpable in the popliteal region. The patella may not be easily located, often being displaced laterally.
Table 174.2 presents the associated anomalies and syndromes of CDK. Accompanying musculoskeletal anomalies occur in more than 50% of cases, the most common being dislocated hips and clubfeet (37). In association with Larsen’s syndrome, abnormalities of the cervical spine are frequent and should be sought (9).
Table 174.2. Congenital Dislocation of the Knee: Associated Anomalies and Syndromes
Thus, CDK might better be characterized as a syndrome rather than an isolated entity. Pathologic findings at surgery include quadriceps fibrosis, ablation of the suprapatellar pouch, anterior dislocation of the hamstring tendons, femoral and tibial articular surface dysplasia, and anterior cruciate elongation and attenuation (19). Children seen in the first few months of life can be treated with biweekly casting or traction until reduction is obtained or progress toward reduction is deemed to have failed. Parsch (48) found conservative treatment to be successful in two thirds of patients.
Should conservative treatment fail, open reduction is necessary. A failure is defined by persistent subluxation of the tibia on the femur, as visualized on a lateral radiograph, or the inability to obtain 45° of flexion after a trial of closed reduction and serial casting. Obliteration of the suprapatellar pouch may be seen when arthrography is performed in nonresponsive patients. Accompanying congenital hip dislocation can be difficult to treat by conventional closed methods until the knee deformity has been controlled. This is due to a tight quadriceps becoming even tighter with knee reduction and in turn precluding reduction of the hip. The Pavlik harness in such cases, aside from being difficult to apply, may actually be counterproductive unless knee flexion has been obtained prior to application. Some authors have reported its successful use in such instances (33,45).
OPEN REDUCTION
Given the pathologic findings in CDK, direct surgery toward lengthening the contracted quadriceps mechanism by V-Y advancement or Z-plasty, and releasing the tight medial and lateral capsular structures; after that, reduction can be accomplished (Fig. 174.10). Anterior cruciate ligament augmentation or advancement, meniscectomy, and posterior capsule reefing are rarely necessary.
Figure 174.10. Open reduction of congenital dislocation of the knee. A: Visualize the pathology through a lateral approach. The iliotibial band and quadriceps tendon are usually contracted, the hamstring tendons may be subluxed anterior to the femoral epicondyles, and the anterior cruciate often is attenuated, stretched, or absent. B: A condensation of fibrous tissue may connect the distal quadriceps expansion to the distal femur and should be released. C: Perform a V-Y quadriceps plasty. D: With the quadriceps divided, flexion of the knee promotes spontaneous reduction and the anterior cruciate can be inspected. Do not repair the cruciate, even if attenuated. E: Repair the quadriceps with the knee located. F: Position of immobilization postoperatively. G,H: Result at 3-year follow-up. From Johnson EJ, Audell R, Oppenheim WL. Congenital Dislocation of the Knee. J Pediatr Orthop 1987;7:194, with permission.
  • Use an anterior midline incision curving distally and laterally. Enter the joint through a parapatellar approach. If the iliotibial band is tight anteriorly to the lateral femoral condyle, release it with a diagonal incision that can later be reapproximated in a lengthened position.
  • The quadriceps tendon must be lengthened. Employ a V-Y technique (Fig. 174.10E). This release allows inspection of the joint prior to repair of the quadriceps, so that any remaining adhesions in the suprapatellar pouch area can be released, and reduction can then be obtained and secured by flexion of the knee.
  • The collateral ligaments of the knee may need to be carefully released to facilitate knee flexion. The hamstring tendons ordinarily spontaneously retreat from an anterior position to one posterior to the femoral epicondyles.
  • After quadriceps repair and closure, immobilize the knee in a long-leg cast flexed to 45° for 6–8 weeks.
Most children spontaneously move their knees following cast removal without the need for formal physical therapy. The goal is 90° of active flexion. Bilateral cases, however, do not seem to recover as much motion as unilateral cases (34).
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CONGENITAL DISLOCATION OF THE PATELLA
Congenital dislocation of the patella (CDP) presents a challenge to the orthopedist. Not only is the patella small and misshapen, but the femoral groove is often shallow, and the entire quadriceps musculature is displaced laterally and contracted. In longstanding cases, the tibia may be laterally rotated, subluxated, and in mild valgus because of the abnormal pull of the quadriceps. The tibial tubercle appears lateral to its usual position, resulting in an increased Q angle. The diagnosis can be made by direct palpation and confirmed by radiography, ultrasonography, or MRI. Keep in mind that the patella does not normally ossify until 4–6 years of age. It is thus easy to miss the diagnosis if relying on radiography alone. The keys to diagnosis are a high level of suspicion in addition to the clinical findings of a knee flexion contracture associated with an external rotation deformity of the tibia, lack of full extension, and weakness. Because of this, the diagnosis is rarely made before the age of walking.
Congenital dislocation of the patella may be familial, occur sporadically, or be associated with Down syndrome or arthrogryposis. It frequently occurs bilaterally. The natural history of untreated patellar dislocation is early degenerative arthritis, pain, and disability. Conservative therapy is futile; surgery is indicated once the diagnosis becomes clear. Most operative techniques have stressed a soft-tissue release of the quadriceps associated with a V-Y-plasty of the quadriceps tendon, with realignment of the patellar ligament insertion. The operative technique must not breach the tibial physis in skeletally immature individuals, but realignment of the patellar ligament can be performed utilizing the Roux Goldthwait procedure (split patellar tendon transfer), or alternatively, the patellar ligament, in its entirety, can be medially transposed into the periosteum over the proximal tibia. We routinely perform a Galleazzi semitendinosus tenodesis of the patella. In skeletally mature individuals, the tibial tubercle itself may be translocated medially.
TECHNIQUE OF REDUCTION
There are several techniques to correct a congenitally dislocated patella (26,27,56). We prefer the following technique.
  • Begin with a straight lateral incision at the junction of the middle and upper thirds of the thigh and extend it distally lateral to the dislocated patella across the femoral condyle, and then swing medially across but 2 cm distal to the tibial tubercle (Fig. 174.11).
    Figure 174.11. Congenital dislocation of the patella. Plan of incision. A: Release the iliotibial tract. B: Raise the medial capsular flap. C: Develop the lateral half of the patellar ligament for transfer. D: Transfer the lateral patellar ligament to the medial aspect of the tibia. E: Repair the medial capsular flap over the patella and advance the vastus medialis insertion. The resulting lateral capsular defect may be patched with a piece of harvested fascia lata.
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  • Dissect down to the iliotibial band, and divide it obliquely so it may later be repaired in a lengthened position if necessary. Follow the band posteriorly to its insertion on the femur by separating it from the adherent fibers of the vastus lateralis; this portion of the band is known as the lateral intermuscular septum.
  • Elevate the quadriceps extraperiosteally off the femur and up the lateral aspect of the femur to the proximal one-quarter.
  • Lateral to the patella, make an incision through the capsule and connect it to the main release along the vastus lateralis.
  • On the medial side of the patella, incise the large flap of attenuated capsule for later plication, and separate the vastus medialis from the quadriceps expansion distally.
  • Relocate the patella in the femoral groove. If flexion cannot be accomplished to 90° with the patella in the groove, lengthen the quadriceps in a V-Y fashion and/or release any fibrotic bands.
  • Now sew the semicircular flap over the patella and anchor it to the tissue along its lateral aspect. Advance the vastus medialis as necessary to produce stable tracking of the patella. Flex the knee at each stage to see if the patella is becoming more stable in the femoral groove; if not, adjust the tension of the suturing accordingly.
  • The patellar ligament almost always appears to be attached too laterally on the tibia, so split the patellar ligament longitudinally and detach the lateral portion just proximal to its insertion. Then transfer this detached free stump under the medial portion of the ligament and suture it into the periosteum along the medial aspect of the tibia near the insertion of the tibial collateral ligament. Take care not to make the attachment so tight that the patella becomes rotated around its longitudinal axis. A piece of tensor fascia lata may be used to close the lateral capsular defect, if desired, although we do not routinely do this.
GALLEAZZI PROCEDURE
As mentioned, we routinely perform the Galleazzi semitendinosus transfer procedure to keep the patella relocated.
  • First, identify the semitendinosus tendon at its insertion into the pes anserinus. Through the main incision or through a separate incision, release the tendon at its musculotendinous junction and free the tendon to its distal insertion into the pes anserina, which can be partially released to allow the insertion of the tendon to move more medially on the tibia.
  • Make an oblique drill hole from inferomedially to superolaterally through the lower medial patella, parallel to the articular surface.
  • Then pass the semitendinosus stump through the drill hole and suture it to itself or to the dorsal periosteum of the patella to complete the tenodesis.
  • After wound closure, apply a long-leg cast for 4–6 weeks.
Commence active and passive exercises of the knee when the cast is removed if the child does not exhibit spontaneous motion and improvement. In older children, the hamstrings may occasionally need to be lengthened to
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correct a residual fixed flexion deformity. We have not employed prolonged bracing following cast removal.
CONGENITAL COXA VARA
Congenital or developmental coxa vara occurs perinatally and is characterized by a decreased femoral neck shaft angle in association with a primary femoral neck defect. This defect involves both the inferior portion of the capital physis and the adjacent metaphysis. Histologically, it represents a defect in enchondral ossification (16,51). Some authors have commented on a hereditary tendency, but there is no predilection for sex or race (5,16,46,67). Radiographs confirm the decreased neck shaft angle as well as a shallow acetabulum and widened teardrop. Because of the varus, the center–edge angle may appear to be normal, which can cause the examiner to underestimate the true dysplasia of the acetabulum.
Although the etiology is unknown, studies of the natural history suggest the early onset of degenerative arthritis and increasing disability for those cases that progress (5). Because of this, the mainstay of treatment has been proximal valgus osteotomy. Most cases are diagnosed because of a limp or waddling gait in children 3–12 years of age. Only a few children present with leg or back pain. Coxa vara can also present in association with syndromes such as coxa vara with femoral shortening, coxa vara as part of PFFD, multiple epiphyseal dysplasia, cleidocranial dysostosis, achondroplasia, or hypothyroidism. In addition, coxa vara can be acquired as a sequella of Legg-Perthes disease, infection, trauma, or as a complication of treatment for developmental hip dysplasia or other diseases. For the true developmental or congenital cases with only mild shortening or femoral bowing, Weinstein et al. (67) utilized Hilgenreiner’s epiphyseal angle to help define treatment indications. This is the angle formed between Hilgenreiner’s line and a line drawn on the anteroposterior (AP) radiographic projection parallel to the capital physis. In the study by Weinstein et al., when the angle was in excess of 60°, progression was the rule; if it was less than 45°, the deformities spontaneously corrected. In the 46° to 59° range, the natural history was not predictable so the patients were observed for signs of progression prior to undergoing surgery. The goal of surgical correction was to restore the Hilgenreiner epiphyseal angle to less than 45° (Fig. 174.12).
Figure 174.12. The Hilgenreiner epiphyseal angle. This measurement is helpful in predicting which cases of coxa vara should be observed and which should be operated on.
In our practice, we simply utilize the neck–shaft angle on standing AP radiographs with both knees in the same position and pointing as anteriorly as possible. Deformities associated with a neck–shaft angle of 110° or better are followed with the expectation of resolution. Those less than 100° are operated early to avoid continued shear stress on the physis. The group between 100° and 110° are observed for 6 months to 1 year to see whether they will spontaneously resolve.
The goal of surgery is to restore a normal neck–shaft angle while avoiding damage to the capital physis and greater trochanteric apophysis. However, Schmidt and Kalamchi (52) have noted premature closure of the capital physis in 90% of operated case, even when direct injury was avoided. In addition, they carefully studied the acetabular development, noted it to be deficient, and concluded that unless correction to 140° or better was achieved at surgery, the acetabular dysplasia did not improve. Thus the goal is correction of the neck–shaft angle to at least 140°.
VALGUS OSTEOTOMY
Determine the amount of correction to be obtained on the preoperative radiograph. Use an image intensifier prior to commencing the actual surgery to obtain a final check on the true neck–shaft angle. Rotate the hip until the femoral neck appears the longest, and then measure the neck–shaft angle on that particular projection. If necessary, perform a percutaneous adductor tenotomy to facilitate later closure of the bony osteotomy. Because of the incidence of premature physeal closure of the capital physis, and the possibility that this may be related to tight musculature, consider lengthening the iliopsoas as well.
  • Approach the hip laterally through a longitudinal skin incision and split the iliotibial band. Elevate the vastus lateralis subperiosteally from the proximal femur. Use a pediatric osteotomy screw (or, alternatively, a pediatric blade plate and matching instrument set) (Fig. 174.13).
    Figure 174.13. Valgus osteotomy for congenital coxa vara. A: Make a standard lateral exposure to the upper lateral femur through the iliotibial tract, dividing the posterior portion of vastus lateralis and reflecting it anteriorly. B: Guide wire placement and overreaming short of the capital physis. C: Insertion of cannulated pretapped screw and removal of lateral wedge of bone. D: Application of sideplate.
  • Place a guide wire along the front of the femoral neck to locate its axis, and introduce a guide pin through the lateral cortex up to but not through the capital physis.
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  • Ream over this wire, then tap the hole under image intensifier control, and finally introduce a screw of appropriate length. Attach the spanner to the femoral neck screw to control the proximal portion while removing with an oscillating saw a wedge of bone based laterally at the level of the lesser trochanter.
  • Now close the osteotomy and apply a two-hole side plate bent with the bending irons to accommodate the new shape of the lateral cortex.
  • Check the position with the image intensifier or plain radigraphs, and then secure the plate to the proximal femoral shaft using 4.5 mm screws.
  • Then irrigate the wound and close it over a hemovac drain, which is removed at 48 hours.
Immobilize the child in a one-and-one-half hip spica cast for 6 weeks or until the osteotomy is radiographically united. Treat residual leg-length discrepancy by a lift and, if necessary, by an appropriately planned epiphysiodesis of the opposite femur.
Complications include continued acetabular dysplasia, premature closure of the capital physis, overgrowth of the greater trochanteric, leg-length discrepancy, recurrence of varus, malunion, nonunion, failure of fixation, avascular necrosis, and infection. These problems may be treated as necessary by techniques described in Chapter 29, Chapter 166, Chapter 170, Chapter 171, and Chapter 173. Repeat valgus osteotomy is sometimes required if the enchondral neck defect has not healed within a year.
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CONGENITAL DEFICIENCIES OF THE FEMUR
Congenital deficiencies of the femur form a continuum from simple hypoplasia to total absence. The deficiencies may be diffuse or limited to the upper or lower portions, and they are often associated with other limb deficits and other organ anomalies. Many classification schemes have been proposed to aid in selecting proper treatment. Most focus on PFFD. Some include congenital short femur as the least affected category in the spectrum. However, a child with a congenital short femur is most frequently amenable to lengthening, whereas few with PFFD are. Hence, we prefer to think of these deformities as separate entities.
Treatment can range from observation to amputation and fitting with a prosthesis, so a general treatment protocol is not easy to describe. Subtleties of hip, knee, or ankle strength and motion, along with the wishes of the family regarding cosmesis, may play pivotal roles in the final plan, and no one treatment will ever be correct for every child.
CONGENITAL SHORT FEMUR
For children with congenital shortness of the femur who have a stable hip and knee (including those instances in which a stable knee and hip have resulted through surgical intervention), limb lengthening may be indicated. Children whose limbs are predicted to have a discrepancy at maturity in the range of 5–15 cm can be considered for lengthening. We prefer to lengthen using Ilizarov’s biology (i.e., lengthening of a healing callus) while utilizing a unilateral half-pin fixator (such as the Wagner) (64) for its safety and convenience. For less than 5 cm of predicted leg-length discrepancy, we perform percutaneous epiphysiodesis.
Leg equalization of up to 5 cm can usually be gained by epiphysiodesis. For example, a child with a predicted discrepancy of 7.5 cm would be left with a 2.5 cm discrepancy after epiphysiodesis. The parents need to decide whether the potential complications associated with lengthening are worth it to correct the remaining discrepancy.
Keep in mind that the need to equalize the length of the extremities does not have to be accomplished by a single technique. A difference of 10 cm could, for example, be made up with an acceptance of a 2 cm difference, the addition of a 1 cm lift inside the shoe, and an epiphysiodesis of 7 cm, resulting in a final lengthening of 10 cm. A lengthening of 10 cm is within reason, whereas a lengthening of 20 cm would be beyond the margin of current practice. For discrepancies predicted to be in excess of 20 cm, seriously consider amputation and prosthetic fitting.
In general, the milder forms of femoral dysplasia are associated with coxa vara, whereas the more serious forms, normally classified under the banner of PFFD, are associated with subtrochanteric bowing. Subtrochanteric bowing may be corrected prior to consideration of limb-length equalization. However, coxa vara can help stabilize the hip joint during femoral lengthening and is better corrected after the lengthening is complete.
PROXIMAL FEMORAL FOCAL DEFICIENCY
The management of children with PFFD has been confused by an array of classification systems that have focused on the radiographic appearance of the hip. The major decisions in caring for a child with PFFD concern primarily the marked limb shortening and depend very little on the anatomy of the hip.
Classification
Clearly, children with PFFD are not all the same. Classification systems can be used to organize clinical material for presentation in the medical literature, or they can be used to help the orthopedic surgeon make clinical decisions for an individual child; sometimes they serve both functions. Aitken’s (3) classification of PFFD is an example of the first use. It focuses entirely on the radiographic appearance of the bones of the upper end of the femur and the pelvis (Fig. 174.14). This classification plays a moderately small role in the overall decision making. The classifications of Pappas (47), Fixen (24), and Amstutz (5) are similarly constrained. By contrast, the classification by Torode and Gillespie (62) is concise and practical: “short” (i.e., lengthenable) or “very short” (extend with a prosthesis). This useful classification scheme focuses on the real problem—the marked limb shortening.
Figure 174.14. The Aitken classification for proximal femoral focal deficiency. Types A and B generally have a well-developed acetabulum and by implication a femoral head anlage, even when not initially visualized. Types C and D are usually shorter and the acetabular landmarks are ill defined. Types B and C are characterized on early radiographs by a tufted appearance of the upper femur, which most likely is an ossified portion of femur above a nonossified area.
Clinical Decision Issues
Initially, help the family decide whether their child has a useful extremity that can be lengthened, or whether lengthening is unrealistic and the leg needs to be shortened and the difference to the ground made up with a prosthesis.
Amstutz (5) made a significant contribution by pointing out that the length of the short leg compared to the normal leg at infancy remains in the same proportion at maturity. This allows prediction, while the child is still an infant, of what the ultimate leg-length difference will be at the end of growth. The parents can become accustomed to the problems that need to be faced, which usually makes their decisions easier. Orthopedic surgeons have differed between stating leg-length differences as absolute numbers of centimeters versus percentages of the bone length. There is no agreement currently. An average male femur at maturity is approximately 46 cm, and an average female femur is 43 cm. A leg-length difference anticipated to be
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greater than 40% to 50% of the normal length at maturity will not likely leave a child with a good functioning extremity even if lengthened.
The options for making up for the marked leg-length difference are to (a) lengthen; (b) remove the foot and fit the child as a below-knee amputee, accepting the huge difference in knee heights; (c) remove the foot, fuse the knee, and shorten the limb so that the child can be fitted as an above-knee amputee; or (d) perform a Van Nes rotationplasty.
Lengthen the Short Bone
If children with a congenitally short femur are excluded from the category of PFFD, relatively few children with a PFFD would have limbs that can be equalized by lengthening.
The hip needs to be stable before lengthening can proceed, although rarely the proximal arm of the lengthening device can be fixed to the pelvis.
Even though the diagnosis is described as a proximal femoral deficiency, most children have deformity in the distal femoral condyles and the ligaments about the knee, as well as deficiencies of the fibula and foot. Lengthening a femur that has a congenital deficiency is much more likely to result in anterior subluxation of the femur on the tibia, ultimately resulting in poor knee function. Lengthening should not be performed by surgeons who do not do it on a frequent basis.
Fit as a Below-Knee Amputee
Remove the foot by Syme’s or Boyd’s amputation (discussed previously) and use an extra-long below-knee prosthesis. This is a simple solution, but it is cosmetically unappealing due to the great difference in knee heights, which is especially obvious when the child is sitting. This choice is less frequently taken now than in years past.
Shorten and Fit at the Above-Knee Level
If lengthening is not a realistically practical option, consider shortening the limb sufficiently that the child will be able to function well as an above-knee amputee. King (38) initially suggested the concept of a single skeletal lever, and he fused the knee joint in an effort to improve hip function and to facilitate prosthetic fitting. As a part of this procedure, the foot must be removed. This can be done either as Syme’s or as Boyd’s amputation. Many surgeons favor Syme’s amputation because of its simplicity. However, Syme’s amputation done in infancy has more of a tendency to “pencil-point thinning” of the distal tibia. The worries about heel-pad migration are probably overstated, because the skin of children will modify to the pressures applied, as witnessed in children with untreated clubfeet who are able to walk on the dorsum of their feet without skin breakdown. However, there is not good scientific evidence to enable an informed choice between these two procedures, so the choice tends to be one of personal preference of the surgeon.
Ultimately, the end of the stump on the deficient side should be sufficiently short to allow room for a standard mechanical knee joint in the prosthesis to be at the level of the opposite, normal knee. Although orthopedic surgeons have often focused on the end of the bony stump as seen on a scanogram, remember that there is soft tissue beyond that as well as room needed for the socket padding and the thickness of the socket itself—a total of almost 3 cm. An ideal to aim for is that the end of the bone of the stump be 10 cm proximal to the knee joint on the opposite side.
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Most children with PFFD have a tibia on the short side that is approximately 90% or more of the normal length (i.e., in boys about 37 cm and in girls about 35 cm, or about 10 cm shorter than the average normal femur). This means that if the tibia is left intact and there is any segment of femur remaining, the probability is overwhelming that the stump will be excessively long. There should therefore be plans to either excise one or both physes around the knee if considering a knee fusion or, alternatively, be a plan for epiphysiodesis at the appropriate time.
Knee Fusion
Most children with PFFD live with the anatomic knee held in flexion. They will often sit on the thigh section of their prosthesis. This gives decreased control and power over the prosthesis and aligns the vertical axis of the prosthesis lateral to the center of gravity, producing a lateral lurch in the stance phase of gait. Function can be greatly enhanced if the femur is fused to the tibia. When this is done, the fusion must be done with the knee in full extension. Initially, there may be enough of a hip flexion contracture that the residual extremity will not come to neutral at the hip, but this stretches out in short order (38). In the past, this procedure was not frequently performed, but it is now routine. Delay knee fusion until the proximal tibial center of ossification is easily visualized by plain radiography, usually between 18 months and 2 years of age.
  • Use an anterolateral approach. Section the patellar ligament and remove the patella along with the menisci and cruciate ligaments. Perform the femoral resection just proximal to the distal physis; divide the gastrocnemius at the level of the insertions to the posterior femoral condyles. Protect the peroneal nerve and posterior neurovascular bundle throughout the resection.
  • Use a knife or micro–air saw to resect the articular cartilage of the tibia, carefully exposing the ossification nucleus to its widest diameter.
  • Introduce a Rush rod retrograde through the intercondylar notch of the femur, exiting along the lateral aspect of the proximal femur. Then withdraw it and drive it antegrade across the knee to fix the fusion in good alignment. The Rush rod should be centralized in the proximal tibial physis as much as possible. We have not observed growth arrest, but cross K-wire fixation above the tibial physis is an alternative method of fixation.
  • Use the resected distal femur for supplemental bone graft, if needed.
  • Close the wound over suction drainage.
Syme’s amputation may be performed at the same time, although some surgeons delay this stage for 6 weeks.
Van Nes Procedure
An alternative to the knee fusion just described and the fitting as an above-knee amputee is the Van Nes rotationplasty (63), in which the leg is rotated 180° so that the ankle functions as a substitute for the knee (25,29,39,40,63) (Fig. 174.15). A special prosthesis is used that uses the ankle as the knee and the foot as the leg, similar to a standard below-knee prosthesis. (The socket usually has an additional thigh support attached with outside hinges.) For this to be successful, there are three requirements:
Figure 174.15. The Van Nes turnaround procedure. A: Area of bony resection. B: Plan for derotation. The removal of bone leads to soft-tissue redundancy and the ability to rotate without injuring the muscle or neurovascular bundles. C: After derotation, the ankle is 180° from its usual orientation. D,E: Preoperative clinical appearance. F: Radiographs show the knee fusion and the tibial turnaround osteotomy. G: Radiographs show the knee fusion and the tibial turnaround osteotomy. H,I: Postoperative clinical appearance.
  • The length must be appropriate. Ultimately, the reversed ankle should be at approximately the level of the opposite knee joint. Plantar flexion and dorsiflexion of the foot is a composite of the motion at the ankle and the subtalar joints. The axis of rotation for the purposes of prosthetic fitting is at the tip of the lateral malleolus. The limb can be shortened an appropriate amount at the time of rotation and/or knee fusion. It is rare to have the extremity too short, because that would be due to a considerable deformity in the tibia and would probably be associated with an inadequately functioning ankle joint.
  • The ankle must be sufficiently normal to function as a substitute knee. It must have an appropriate range of motion and sufficient strength to power a prosthesis. A foot with all five rays usually has these requirements, but not invariably.
  • The psychological acceptance of the procedure needs to be within the tolerable limits of the patient, the family, and the medical personnel looking after the child. Concerns may vary from age to age and culture to culture. In medical centers where the Van Nes procedure is frequently performed, there are usually other children and families who can act as models and counsel potential patients and their parents. The psychology of the medical staff cannot be ignored. If the medical personnel feel that such procedures are bizarre, it is clear that they will not be offered, or they will be presented in such a manner that no patient would accept the choice. As a consequence, some centers in the United States have moderately large numbers of children who have had the procedure and other centers have none.
Additionally, prosthetic facilities must be considered. The prosthesis that is required following a Van Nes procedure is difficult to fit. If good prosthetic facilities are not available, avoid this operation.
  • Perform the knee fusion as previously described, but use the soft-tissue redundancy obtained from the femoral resection to derotate the limb.
  • Secure the knee derotation with an oblique K-wire across the fusion site, supplementing the Rush rod fixation (61).
  • Either extend the knee wound along the tibial crest or use an additional incision over the mid tibia. Incise the periosteum and resect and discard at least 1 inch of the tibia.
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  • Further rotate the limb laterally until the ankle is repositioned 180° with respect to the hip.
  • Fix the tibia with a four-hole semitubular AO plate, or use a long enough intramedullary Rush rod to fix both the knee and the hip, and another oblique K-wire to secure rotation.
  • Perform an anterior compartment release prior to closure, and use a spica cast until radiographic consolidation of the osteotomies, which usually requires 6–8 weeks.
Complications
Late fractures at the end of the intramedullary fixation device occurred in two of our patients but healed uneventfully in a spica cast. Although Hall and Bochman (29) have stated that the procedure should not be performed until maturity because remodeling and derotation of the limb require further surgery, we perform the procedure at about 2 years of age. We are content with rerotating the limb as necessary. In our experience, approximately half the patients required one repeat surgery to rerotate the limb, but only one patient of 13 required a third surgery.
Other Issues
Length of the Stump
As discussed, most children who have had conversion of their PFFD extremity to an above-knee amputation end up with a stump that is too long. At the time of knee fusion, consider excision of the distal femoral and/or the proximal tibial physis. Some orthopaedic surgeons are wary of doing this for fear that the extremity will be much too short; however, proper application of growth data using the Green-Anderson-Mesner charts (see Chapter 170) can alleviate that fear. Moseley’s straight line graph (see Chapter 170) does not differentiate between the femur and the tibia and does not provide the answer for this calculation.
Before the Definitive Surgery
Regardless of what the decision is for ultimate management, there is a period when the difference in leg lengths can be considerable, yet it is too early to do anything definitive surgically. Lifts greater than 5 cm in height tend to lead to ankle sprains, but ankle–foot prostheses can be used to decrease this likelihood. However, when the difference gets to 8 or 9 cm, an extension prosthesis (sometimes called an extension orthosis or even a prosthosis) can be made that has a hole in the front of the prosthesis distally through which the forefoot extends. If tried at too young an age, when the length difference is less than 5 cm, however, there is not room enough below the socket to fit a foot on the end of such a prosthesis.
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Reconstruction of the Hip Joint
In the past, there has been a great deal of focus on the radiograph of the upper end of the femur. What is seen by the radiograph, however, is only the bone. What is going on with the cartilage, let alone the muscles, is not seen. If there is absolutely no acetabulum, the decisions regarding the management of limb length given in this chapter apply. If, on the other hand, the acetabulum is satisfactorily formed and there is some element of a femoral head in the acetabulum and some segment of upper femur that are not joined, consider surgery. Wait until there is sufficient ossification of the two fragments that they can be fused together, bone to bone. There is certainly no rush to do this, and more complications occur from proceeding too soon, before there is adequate bone stock.
Fusion of the Distal Femur to the Pelvis
The distal femur can be fused to the pelvis in order to use the knee joint as a replacement for the hip joint (Fig. 174.16). This has the theoretical advantage of providing a stable hip. However, the knee joint does not allow reasonable rotation. Once it is fused to the pelvis, the distal femur has some capacity to grow, and the hip joint will grow to a point that is mechanically disadvantageous, depending on the orientation of the distal femur at the time of fusion to the pelvis. Although there have been a small number of reports of such cases (24,57), most surgeons feel that this is not an advantageous procedure and avoid it (23,25).
Figure 174.16. In rare cases, the knee can be used as a surrogate hip in conjunction with a Chiari osteotomy combined with fusion of the femoral remnant into the pelvis.
MISCELLANEOUS ITEMS
TERMINAL OVERGROWTH
“Overgrowth” of amputation stumps in children has always been a problem and can occur even in congenital amputees. It is particularly a problem in the humerus, the fibula, and the tibia. Pellicore et al. (1,49) found that 15% of their juvenile patients who had amputations before 12 years of age required revision, whereas none did if the amputations were done at a later age. Yet, if children required stump revisions and they were older than 12 years, overgrowth could still occur.
This overgrowth is not a result of stimulation of the physis proximally but of the development of appositional new bone on the end of the stump (see Chapter 175). The easiest way to manage the problem is to avoid it by performing amputations through a joint, where possible, so that the end of the bone is covered by its normal cartilage. If this is not possible, a number of maneuvers have been used with varying success. Silastic end pieces (either as a stemmed plug that fits into the medullary cavity or as a cap that fits over the end of the diaphyseal bone) have been tried, but frequent breakage and dislodgement of the plug or cap have led to their abandonment. Surgical procedures that provide a smooth periosteal surface around the end of the bone appear to be successful in many cases. The Marquardt method (50) (Fig. 174.17) introduced the use of autogenons epiphyseal caps. Davids et al. (21) recently reviewed their patients. Apophyseal cartilage from the iliac crest can be used. Our preference is to use the proximal fibula and invert its diaphysis into the tibial or humeral medullary canal. This cartilage cap is not expected to grow but only to provide a smooth nonosseous surface to prevent osteoblastic reaction. This has been very effective. Keep this technique in mind for situations in which transosseous amputations are required. It may be possible to salvage an epiphysial cap from part of the discarded specimen (e.g., the first metatarsal head, the talar head, or the os calcis), which could then be attached to the end of the cut bone.
Figure 174.17. Modified Marquardt method of capping bony overgrowth in a transdiaphyseal amputation in a growing child. A: Preoperative radiograph showing terminal overgrowth of an above-elbow amputation. B: Postoperative appearance after transfer of a epiphyseal cartilage graft onto the revised distal humerus.
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In children who have had amputations for tumors and who receive postoperative chemotherapy, bone protrusion at the end of the stump may be caused by soft-tissue retraction rather than terminal overgrowth. In such children, the chemotherapy adversely influences the healing of the fascia, so that the muscles draw proximally, leaving the bone protruding subcutaneously. If a stump revision is done while the child is still receiving chemotherapy, the complication is likely to recur. Several revisions may lead to an unfortunately short stump. It is better to wait until 3–6 months after the cessation of the chemotherapy to do a definitive procedure.
CONSERVATION OF PARTS FOR TOE-TO-THUMB TRANSFER
Not infrequently in treating lower extremity defects, there are concurrent hand abnormalities. Toe-to-hand transfers are now well-established procedures, so before any lower extremity parts are discarded, search for possible uses for the reconstruction of the upper extremities. We have assisted the hand surgeon with harvesting the parts prior to Syme’s or Boyd’s amputation, with very gratifying results.
LENGTHENING OF SHORT AMPUTATION STUMPS
For children who have amputation stumps that are very short (acquired or congenital), the gain of even a small amount of length may provide an adequate lever to use a more functional prosthesis. The advantages are decreased energy consumption, improved prosthetic control, decreased heat retention, increased comfort from the lesser weight of the prosthesis, and fewer components requiring repairs, as well as decreased cost.
Children with loss of an upper extremity, especially if the loss is congenital, frequently choose not to wear prostheses. However, longer residual limbs may allow for grasping objects in the midline between the stumps for “bimanual” activity without a prosthesis. Additionally, a longer distal segment can permit objects to be grasped between a lengthened humeral stump and the chest, or between a lengthened forearm and the upper arm.
Watts (66) reported lengthening 32 short amputation stumps in 27 patients. All were lengthened by gradual distraction using Ilizarov techniques (see Chapter 32 and Chapter 171). The 16 children who completed lengthening of their femurs or tibias achieved sufficient length to be fitted with a prosthesis at one level more distal than previously possible (Fig. 174.18). Children who underwent lengthening of their upper extremities were more difficult to assess. Three patients were lengthened with the anticipation that a prosthesis would not be used after lengthening. All became “users,” in that they became able to grasp objects between the lengthened stump and trunk. Of the remaining patients—all with upper extremity lengthenings—all
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but one are “wearers” of their prostheses but not constantly.
Figure 174.18. AP (A) and lateral (B) radiographs of a short, below-knee stump prior to lengthening. Lengthening in progress with an Ilizarov device (C). AP (D) and lateral (E) radiographs showing the result of lengthening the stump. The patient was converted from a functional above-knee prosthesis to a below-knee prosthesis.
A WORD ABOUT PROSTHESES
Modern prosthetic methods help make the surgeon look good. Of less importance today than previously is the exact placement of the surgical scar, the nature of the skin, or even such complications as a displaced fat pad. Further enhancing the activities of these amputees are recent advances in prosthetic feet utilizing newer space-age energy-storing materials that have the ability to absorb and store energy at the beginning of stance, only to redeliver the energy at toe-off (14,43,65). This results in a livelier feel to the limb, and it may enhance certain activities such as running. Amputees now compete in athletic activities previously felt to be beyond their capabilities. A cottage industry has arisen that caters to amputees who are high-grade athletes in such sports as running, swimming, and skiing. Young children growing up with such conversions have a better chance than ever to enjoy an enhanced physical and psychological environment (6,21).
AUTHORS’ PERSPECTIVE
This is a very rewarding group of patients to treat surgically. Patients with these complex problems are frequently beyond the capabilities of most community orthopaedic surgeons and hospitals and are cared for at specialized centers. The long-term physician–patient relationship that develops is gratifying. The children are otherwise healthy and their zest for living and full participation in life is admirable. Early medical intervention is important for them to develop early independence and to reach their maximal potential. It is a privilege to care for them.
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