Lower limb joint reaction forces during sit-to-stand and stand-to-sit movements in stroke patients with spastic hemiplegia

Objective: We investigated the characteristics of hip, knee, and ankle joint reaction forces (JRFs) in stroke patients with spastic hemiplegia during sit-to-stand (Si-St) and stand-to-sit (St-Si) movements and explored the relationship between JRFs and joint moments. Methods: Thirteen stroke patients with spastic hemiplegia and thirteen age-matched healthy subjects were recruited in this study. Three-dimensional motion capture system and force plates were employed to collect kinematic data and ground reaction forces during Si-St and St-Si tasks. Musculoskeletal modeling was used to calculate JRFs and joint moments of the hip, knee and ankle joints during these movements. Results: Those stroke patients exhibited higher JRFs (ranging from 13.49 N/kg to 43.18 N/kg) compared to the healthy group (ranging from 15.81 N/kg to 23.00 N/kg) in hip and knee joints. Furthermore, hip and ankle JRFs exhibited positive correlations with their joint moment in stroke patients during Si-St and St-Si movements. Conclusion: Early rehabilitation strategies should focus on correcting weight distribution and enhancing symmetry in joint loading. Interventions focused on reducing joint moment, particularly for hip and ankle joints, may prove effective in mitigating lower extremity JRFs in stroke patients with spastic hemiplegia during Si-St and St-Si movements.