PROXIMAL TIBIOFIBULAR-BIFURCATION SYNOSTOSIS FOR THE MANAGEMENT OF LONGITUDINAL DEFICIENCY OF THE TIBIA

Three adults with severe longitudinal deficiency of the tibia (LDT), i n which an unossified proximal tibial anlage was present, who had been treated with proximal tibiofibular bifurcation synostosis (PTFBS) in early childhood, were evaluated between 20 and 31 years after the inde x procedure. All three were found to be functioning well as below-the- knee (BK) amputees. Mediolateral stability and anteroposterior instabi lity of the knee mere present In all eases. Instrumented motion analys is revealed diminished loading characteristics of the prosthetic limb, similar to that described for BK amputees in general. The most signif icant gait deviations at the knee unique to this study group were a qu adriceps-avoidance gait pattern and an increased dynamic varus alignme nt. Instrumented muscle testing suggested that these deviations were a consequence of ligamentous instability. This study supports the conce pt that the presence of a proximal tibial anlage in severe LDT is indi cation for a surgical strategy that preserves the biological knee join t. The PTFBS maintains the integrity of the knee-extensor mechanism, t he fibular collateral ligament, the tibiofemoral joint capsule, and th e medial collateral ligament, enhancing the long-term stability and fu nction of the knee joint.