Individual joint contribution to body weight support in the affected lower limb during walking in post-stroke hemiplegia.

OBJECTIVE: Patients with post-stroke hemiplegia have difficulty with body weight support during walking. However, it is unclear which intra-limb strategy for body weight support tends to predominate, and how the intra-limb strategy is related to gait function. Support moment and individual joint contribution to support moment are the parameters that reflect intra-limb strategy for body weight supporting. The aim of this study was to test whether support moment and individual joint contributions differed between post-stroke subjects with different gait function.

METHOD: Laboratory gait analysis was performed for 14 non-hemiplegic elderly (NE) and 12 post-stroke hemiplegic elderly walking without cane (HNC) and 11 walking with a cane (HWC). Data were obtained for the vertical ground reaction force (vGRF) curve, 1st peak and 2nd peak of vGRF and corresponding temporal occurrences. Support moment (Ms) was numerical sum of hip extension, knee extension, and ankle plantar flexion moment. Individual joint contribution was calculated as the ratio of each joint moment to support moment. At temporal occurrences of vGRF peaks, Ms and individual joint contribution to Ms were calculated. Ms and individual joint contribution to Ms were compared among NE, HNC and HWC groups. Each subject's characteristics of individual joint contribution to Ms were explored.

RESULTS: At the 1st peak of vGRF, support moments were similar among the three groups. However, the hip contributions were significantly greater in the NE group than in the other two groups, the ankle contributions were significantly greater in the HNC group than in the NE group. Notably, some of the subjects with post-stroke hemiplegia showed atypical characteristics that did not correspond to the group characteristics.

CONCLUSION: Observing support moment and individual joint contribution is helpful to ascertain not only group characteristics, but also individual characteristics of intra-limb strategy for weight support in patients with post-stroke hemiplegia.