RESUMEN
Objectives:To investigate the effects of different plantarflexion resistance of an ankle foot orthosis (AFO) on the motion of the thorax and pelvis during the gait of stroke patients. Methods:From June, 2020 to January, 2021, 26 stroke inpatients in Beijing Bo'ai Hospital wore AFO with oil damper (OD) ankle hinge, and measured thorax and pelvis during stroke gait under three plantarflexion resistance (OD1, OD2.5, OD4) of the AFO with a three-dimensional motion capture system. The main parameters were pelvic (P) and thoracic (T) angles at the following time or phases: initial contact (IC), contralateral foot off (CFO), contralateral initial contact (CIC), foot off (FO); the change of thoracic angle in gait cycle (Tcyclex), the change of thoracic angle in stance phase (TSTx) and the change of thoracic angle in single stance phase (TSSx). Thoracic and pelvic motions were defined on three coordinate axes: forward/backward tilt (x), oblique (y) and rotation (z). Results:The loading response times were significant different among different plantarflexion resistance conditions (χ2 = 7.923, P = 0.019), as well as between OD2.5 and in OD4 (P = 0.017). PCFOx, PCFOz, PCICx and PFox; TCFOx, TCFOy, TCFOz and TFOx; relative angle of thorax to pelvis TPICx, TPCFOx and TPCICx; and TSSx were significant different among three resistance conditions (χ2 > 6.077, P < 0.05). Forward tilt of pelvis decreased in condition OD2.5 and increased in condition OD4 during each timing. When CFO, the thoracic forward/backward tilt angle was less in OD2.5 than in OD4 (P < 0.05), the thoracic rotation angle was less in OD1 than in OD4 (P < 0.05). Conclusion:Plantarflexion resistance has a significant effect on the motion of the thorax and pelvis in the gait of stroke patients. Under the middle magnitude of resistance, the pelvic and thoracic posture becomes more upright, the oblique angle is reduced, showing the improvement of the upright posture. On the contrary, the pelvic forward tilt and thoracic oblique are increased when resistance become low or high, compensation of rotational motion appeared in high resistance, posture getting worse.