WORKUP	Section 5 of 11
Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Pictures Bibliography

Imaging Studies:

• Judicious use of appropriate imaging studies is necessary to fully evaluate and treat postaxial hypoplasia of the lower extremity. Some of the more pertinent radiographic studies are listed below.

• A long-leg standing series shows the overall picture of the affected lower extremity and permits use of the contralateral side as a control. Limb-length discrepancies and alignment can be measured. Abnormalities involving specific parts of the lower extremity can be seen and, if necessary, imaged further with the use of specific views.

• A pelvis and/or hip series is useful in evaluating acetabular dysplasia, PFFD, and the location and amount of any varus deformity. Changing the rotation of the femur can sometimes help show version and varus/valgus deformity more clearly.

• A knee series is useful for evaluating distal femur valgus, hypoplasia of the lateral femoral condyle, and flattening of the tibial eminence. The patella may be small and/or high riding, and the femoral sulcus may be shallow.

• A tibia/fibula series provides information about the tibia. In several studies, a small percentage of patients showed anteromedial bowing of the tibia. This imaging series is also useful for classifying the disorder. The Achterman and Kalamchi classification system is based on fibular morphology as follows:
  • Type IA: The proximal fibular epiphysis is distal to the level of the tibial growth plate with the distal fibular epiphysis proximal to the talar dome.

  • Type IB: The proximal fibula is absent for 30-50% of its length. The distal fibula is present but does not adequately support the ankle.

  • Type II: The fibula is completely absent.

• An ankle/foot series is useful for determining the ankle morphology, the fibular contribution to the mortise, the distal tibial epiphyseal morphology, the presence of tibiotalar valgus, the presence of a ball-and-socket ankle, the presence of a tarsal coalition, and the number of rays.

• The factors just described can be used to classify the fibular hemimelia by using the following system introduced by Stanitski and Stanitski:
  • Fibula
    • I - Nearly normal
    • II - Small or miniature fibula, regardless of its position in the limb
      
    • III - Complete absence of the fibula

  • Tibiotalar joint and distal tibial epiphyseal morphology
    • H - Horizontal
    • V - Valgus (triangular distal tibial epiphysis)
      
    • S - Spherical (ball and socket ankle)

  • Presence of a tarsal coalition (denoted with a lowercase c)

  • Number of foot rays, medial to lateral - Denoted 1-5

• A pattern type is constructed to describe the condition. For example, a patient with a hypoplastic fibula, a horizontal ankle, tarsal coalition, and a 5-ray foot is classified as having a type IIHc5 fibular hemimelia. This system should lead to better communication regarding this condition.

	TREATMENT	Section 6 of 11
Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Pictures Bibliography

Medical therapy: No specific medical therapies can correct the underlying abnormalities. However, for mild deformities, observation and/or nonoperative management may be useful.

As with limb-length discrepancies resulting from other causes, no treatment or the use of heel lifts may be adequate, particularly in discrepancies less than 2 cm. However, although the relative percentage of shortening generally remains constant at 10-20% relative to the contralateral side, the absolute discrepancy may be progressive with growth, and it must be followed up until skeletal maturity is achieved.

Similarly, observation may be adequate for hip varus, genu valgum, tibial kyphosis, and patellar instability. Although an absent anterior cruciate ligament (ACL) with a positive Lachman test result is frequently observed, clinical signs of instability are rare, and nonoperative management is appropriate. In mild cases, ankle valgus may be managed with a University of California-Berkeley (UCB) orthosis, but as with limb-length discrepancy, the patient must be monitored through his or her continued growth because the fibular portion of the mortise may be progressively compromised.

Surgical therapy: Several issues must be addressed before any procedure is performed for postaxial hypoplasia of the lower extremity. The ultimate goal is to achieve symmetrical, stable, and well-aligned joints with the minimal number of surgical procedures. No one set of operations should always be performed, but individual procedures addressing the specific abnormalities for each patient should be planned. Finally, realistic guidelines of what is involved regarding the timing, the duration of recovery, and the ultimate outcome must be communicated to the patient and to his or her family.

For limb-length discrepancy, Birch et al recommend amputation in patients with a nonfunctional foot, regardless of length, unless the upper extremities also are nonfunctional. In patients with a functional foot, the surgical procedure recommendations generally fall into 1 of the following 3 groups:

• The first group involves patients with a discrepancy less than 10%. There is little disagreement that these patients can benefit from lengthening procedures or contralateral epiphysiodesis.

• The second group for which there is little disagreement on the recommended treatment involves patients with a discrepancy more than 30%. Amputation is recommended for these patients.

• The third group, which involves patients a discrepancy of 10-30%, represents the greatest challenge. Lengthening more than 10 cm in a limb with associated knee, ankle, and foot abnormalities is difficult. At maturity, an average lower-extremity length is often 80-110 cm. A 10% discrepancy for this limb is 8-11 cm. Although parents have hopes for a normal limb as opposed to an amputated limb, they must be helped to understand the problems associated with lengthening in cases of severe deficiencies. Lengthening with a contralateral epiphysiodesis may also be considered as an alternative to multiple lengthening procedures.

If an amputation is determined to be the most appropriate procedure for an individual, the Syme amputation is generally recommended. In the past, transtibial amputation was more commonly performed because of cosmetic concerns for a bulky ankle. However, in subsequent observations, the ankle did not enlarge with growth, and the Syme amputation allowed for weight bearing on the residual limb. Boyd described a modification to the Syme amputation in which the talus is removed, but the retained calcaneus is fused to the tibia to help prevent posterior migration of the heel pad. In this modification, the heel pad grows with the patient. However, the procedure is associated with more wound problems, nonunion, and malpositioning of the calcaneus. In general, a Syme amputation is recommended.

When a Syme amputation is performed in children, trimming the condyles is not necessary. As opposed to adults, children have small condyles that do not grow to a normal size.