Malleolus externus plasty for joint reconstruction in fibular aplasia: preliminary report of a new technique.

The instability of the upper and the lower ankle joint represents a serious problem in patients with fibular aplasia. None of the previous techniques demonstrated at least sufficient results. In this report we present a new technique of malleolus externus plasty applied in a 5 1/2-year-old boy with fibular aplasia (type II according to Coventry and Johnson or type Ib according to Achtermann and Kalamchi) with a 6 cm length deficiency of the lower leg and 1 cm of the upper leg. Furthermore, he showed a tibial antecurvation deformity of 20 degrees, a fourth ray foot with adduction deformity of the hindfoot, cutane syndactyly D 2-4, and a hallux varus. This new technique works on the following principle. A triangular iliac crest transplant is implanted with an apophysis and the annexing fascia glutealis, including the osseous part of the transplant, in the lateral distal tibia in a way that the growing apophyseal part lays distally covering the lateral talus. Gluteal fascia annexed to the apophysis was used for the reconstruction of a lateral tendon. Using a ring fixator the transplant is fixed and coincidentally the lower leg lengthened and the axis corrected. The axis deformity and the leg-length deficiency of 7 cm were equalized. The fixator could be removed after 6 months. Radiologically, an entire integration of the iliac crest transplant was found. Magnetic resonance imaging showed it had sufficient circulation. The reexamination 2.5 years later demonstrated a simultaneous growth of the malleolus externus and the distal tibia and stable ankle joints with sufficient mobility and full weight-bearing capability. For support of the foot the boy uses ready-made shoes with curved arch supports. In conclusion, using this new technique an individually adapted lateral malleolus with growth-potential can be constructed that stabilizes the foot and the ankle joints. Thus, reluxations of the foot specifically in relation to lengthening of lower legs can be avoided with concurrent preservation of the range of movement of the ankle joint.