Gait Analysis During Level and Uphill Walking After Lengthening Osteotomy of the Lateral Column

A common surgical treatment for posterior tibial tendon dysfunction (and the resulting flat foot) is the correction through a calcaneal lengthening osteotomy of the lateral column (LLC). Clinical studies showed pain relief and functional improvements through different scores. However, according to clinical experience, some patients complain about a limited ankle dorsiflexion after LLC surgery. Several joints of the foot (talocrural, subtalar, talonavicular, calcaneocuboid) contribute to the overall range of motion in foot plantarflexion/dorsiflexion and pronation/supination. Changes in the range of motion in one joint can affect all the other joints. For instance, it was shown that a fusion of the talonavicular joint removes most of the residual hindfoot motion in plantarflexion/dorsiflexion and pronation/supination. Because the lengthening of the lateral column presumably decreases the mobility of the medial column and thus of the talonavicular joint, this surgery can influence the range of motion of the other joints, and hence contribute to the reported decreased ankle dorsiflexion motion. Patients after LLC have less plantarflexion of the first metatarsal throughout stance of level walking and less inversion of the hindfoot during push-off compared to healthy subjects. Uphill walking requires more ankle plantarflexion and dorsiflexion than level walking. A limitation of the ankle joint mobility especially in dorsiflexion could therefore lead to additional or greater changes in gait patterns (hindfoot and forefoot kinematics) during uphill walking. The primary objective is: • To compare differences in hindfoot and forefoot kinematics between level and uphill treadmill walking in relation to passive range of motion The secondary objectives are: * To compare lower leg muscle activation during level and uphill treadmill walking between patients after LLC and healthy subjects * To test the association between muscle strength, muscle activation patterns and hindfo