正常人與退化性膝關節患者於行走跨越障礙物時之生物力學分析

Abstract

因跨越障礙物而絆倒是老人跌倒的主要原因之一，且其可能造成嚴重後果。一個完整的下肢運動學與力動學分析，將有助於設計預測或預防跌倒之方法。本研究利用一包括七台紅外線攝影機之動作份析系統量測跨越三種高度障礙物（10，20及30％腳長）之運動學，並利用兩塊測力板量測地面反作用力。我們先建立年輕人跨越不同高度時之下肢動力學資料，以此為基礎進一步探討健康及退化性膝關節老年人跨越不同高度障礙物時之下肢生物力學，瞭解老化對行走跨越障礙物之影響。根據結果，我們發現老人會藉由增加髖關節彎曲角度達到跨越瞬間跨越腳與障礙物之垂直距離大於年輕人的結果，基於安全考量，當前腳跨越時，老人採用將身體質量中心留在離站立腳較近且較久之策略，但其會增加站立腳膝關節伸展力矩並減少髖關節屈曲力矩。於前腳及後腳跨越時，為了控制身體質量中心內外側方向之運動，健康老人需要較大之髖、膝關節外展力矩。退化性膝關節炎老人之跨越策略會改變，站立早期時，其膝關節外展力矩會增加，在跨越瞬間及跨越後，此一力矩會藉增加骨盆傾斜角度及足偏角而降低。為了減少膝關節負荷及相關之疼痛，退化性膝關節炎老人會將骨盆前傾使膝關節伸展力矩降低，但其髖關節伸展力矩則會隨之增加以代償此一改變。因此，我們知道在跨越障礙物時，老人基於安全考量，會採用一較保守之策略，退化性膝關節炎會改變老人跨越障礙物時之正常步態，此一改變會增加跌倒發生的危險。

Falls are a common problem leading to physical injuries among the elderly, resulting in individual costs such as pain and impairment of locomotion, as well as financial costs related to treatment and rehabilitation. From the literature review, it was suggested that investigating kinematics and kinetics of the locomotor system during obstacle crossing may help in devising strategies to predict and prevent trip-related falls in the elderly. In the present study, young, older and knee osteoarthritic subjects were recruited to investigate the influence of aging and aging-related disease on the biomechanics of obstacle crossing using motion analysis techniques. Compared to the baseline data in the young group, a higher leading toe clearance was adopted in the older group achieved by a swing hip flexion strategy. During the crossing of the leading limb, the older group kept the COM more posterior and longer on the trailing stance limb with increased knee extensor and decreased hip flexor crossing moments. For both leading and trailing stance limbs, bigger abductor moments of the hip and knee were needed in controlling the medial-lateral COM motion. Knee OA seemed to increase peak knee abductor moments for both limbs in the early stance. The corresponding moments were reduced around and after crossing the obstacle through pelvis list and toe-out gait. For reducing knee joint loading and associated pain, bigger hip extensor moments were needed to compensate by anterior tilt of the pelvis. It was suggested that the older group used a more conservative strategy for obstacle-crossing due to the safety considerations. Knee OA altered normal gait pattern during obstacle crossing, which may increase the risk of trip-related falls in the elderly.