CONGENITAL TIBIAL APLASIA WITH PREAXIAL POLYDACTYLY - A CASE-REPORT

An anatomical study of a left lower limb with congenital tibial aplasi a and preaxial polydactyly amputated at 10 months of age was carried o ut. The tibia was replaced by a fibrous band (a band of connective tis sue) and there were four cuneiforms, six metatarsal bones and seven to es. The second metatarsal bone showed characteristics of the hallux. A n intermuscular septum which showed an orifice for the anterior tibial artery was found on the medial side of the leg and foot. All the musc les of the leg and foot were present except for the tibialis posterior muscle, which was replaced by two atypical muscles. No muscular attac hments reached the fibrous band. Several intertendinous connection ban ds were found. Also, an accessory muscular belly split from the tibial is anterior tendon and attached to the common flexor tendinous sheet o f the foot. An unusual motor branch of the deep peroneal nerve ran tog ether with this belly to supply the intrinsic muscles of the hallux, W e also observed other minor anomalies of the nerve pattern. The arteri al pattern was complete, except for some arteries which showed both an anomalous origin and course. The findings of this study suggest that the development of the skeletal elements plays an important role in th e differentiation of the muscles, tendons, arteries and nerves. We pos tulate that a dysmorphogenic event involving the development of the ti bial field of the limb could give rise to both defective histodifferen tiation of the tibia and defective programmed cell death in the pre-ha llucial anlage. These anomalies would determine secondary adaptations of muscles, tendons, vessels and nerves of the limb