Prosthesis alignment and knee valgus in individual with fibula hemimelia: Study case.

OBJECTIVE: Fibula hemimelia is a congenital malformation of the lower limbs that is associated to aplasia or hypoplasia of the fibula. This condition is characterized by knee valgus which tends to increase over years in children walking with a below knee prosthesis. However, few recommendations are available regarding the optimal prosthesis alignment for amputated children with fibula hemimelia. The aim of this case study was to compare different prosthesis alignments and to assess their impact on knee joint moment in the frontal plane during walking.

PATIENTS AND METHODS: Gait analysis was performed on a 17 years old participant with fibula hemimelia who used trans-tibial prosthesis on the left leg to walk. Kinematic and kinetic data were collected. Prosthesis alignments were adjusted below the socket on the proximal and distal parts of the shank. Gait was evaluated with the following adjustments: (1) initial alignment, (2) distal alignment with higher varus (5°), (3) proximal alignment with higher varus (5°).

RESULTS: Knee varus external moment was lightly reduced and ankle eversion external moment was increased with alignment (2) and (3) compared to alignment (1). No differences were observed between alignment (2) and (3).

DISCUSSION/CONCLUSION: These results suggest an inadequate modification of varus alignment to significantly influence knee moments. It could be interesting to evaluate the effect of higher than 5° varus alignment and to adjust the foot with a higher eversion to reduce ankle moment caused by knee varus.