Schmitt Laura C, Rudolph Katherine S
University of Cincinnati College of Medicine, Sports Medicine Biodynamics Center, Occupational Therapy and Physical Therapy Department, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
J Orthop Res. 2008 Sep;26(9):1180-5. doi: 10.1002/jor.20619.
The sensation of knee instability (shifting, buckling. and giving way) is common in people with medial knee osteoarthritis (OA). Its influence on knee stabilization strategies is unknown. This study investigated the influence of knee instability on muscle activation during walking when knee stability was challenged. Twenty people with medial knee OA participated and were grouped as OA Stable (OAS) (n = 10) and OA Unstable (OAU) (n = 10) based on self-reported knee instability during daily activities. Quadriceps strength, passive knee laxity, and varus alignment were assessed and related to knee instability and muscle cocontraction during walking when the support surface translated laterally. Few differences in knee joint kinematics between the groups were seen; however, there were pronounced differences in muscle activation. The OAU group used greater medial muscle cocontraction before, during, and following the lateral translation. Self-reported knee instability predicted medial muscle cocontraction, but medial laxity and limb alignment did not. The higher muscle cocontraction used by the OAU subjects appears to be an ineffective strategy to stabilize the knee. Instability and high cocontraction can be detrimental to joint integrity, and should be the focus of future research.
膝关节不稳定感（移位、屈曲和打软腿）在膝关节内侧骨关节炎（OA）患者中很常见。其对膝关节稳定策略的影响尚不清楚。本研究调查了在行走过程中当膝关节稳定性受到挑战时，膝关节不稳定对肌肉激活的影响。20名膝关节内侧OA患者参与研究，根据日常活动中自我报告的膝关节不稳定情况分为OA稳定组（OAS）（n = 10）和OA不稳定组（OAU）（n = 10）。评估了股四头肌力量、被动膝关节松弛度和内翻对线情况，并将其与行走过程中支撑面横向平移时的膝关节不稳定和肌肉共同收缩相关联。两组之间膝关节运动学差异不大；然而，肌肉激活存在明显差异。OAU组在横向平移之前、期间和之后使用了更大的内侧肌肉共同收缩。自我报告的膝关节不稳定可预测内侧肌肉共同收缩，但内侧松弛度和肢体对线情况则不能。OAU受试者使用的较高肌肉共同收缩似乎是一种无效的膝关节稳定策略。不稳定和高共同收缩可能对关节完整性有害，应成为未来研究的重点。
