Chapman’s Orthopaedic Surgery
3rd Edition

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.

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.

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 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.

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

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.

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,
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.

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).

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

(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).

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).

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).

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.

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).

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°.

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.

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.