Sheehy P, Burdett R G, Irrgang J J, VanSwearingen J
WestArm Therapy Services, Lower Burrell, PA, USA.
J Orthop Sports Phys Ther. 1998 Jun;27(6):423-9. doi: 10.2519/jospt.1998.27.6.423.
Imbalances in the firing pattern and contraction intensity of the vastus medialis oblique (VMO) and the vastus lateralis (VL) have been considered important factors contributing to patellofemoral joint dysfunction. Vastus medialis oblique and vastus lateralis electromyographic (EMG) activity were measured for 15 individuals without patellofemoral pain (asymptomatic group) and 13 subjects with patellofemoral pain (symptomatic group) while ascending and descending steps. The peak VMO/VL ratios of EMG activity and the difference in peak VMO and VL onset times were measured. Two-way mixed-model analyses of variance (ANOVA) were used to determine the main effects of group (asymptomatic and symptomatic), phase (concentric phase ascending and two eccentric phases descending stairs), and the interaction between group and phase. The ANOVAs indicated no difference between groups for the peak VMO/VL EMG ratio or for the onset timing between peak VMO and VL muscle activity. Combining groups, the peak VMO/VL EMG ratio was less for the eccentric weight acceptance phase of descent compared with the concentric phase of ascent. These findings suggest no differences between asymptomatic and symptomatic individuals, but differences may exist between concentric and eccentric VMO/VL ratios. Further research is needed to determine if VMO and VL muscle imbalances contribute to patellofemoral dysfunction.
股内侧斜肌（VMO）和股外侧肌（VL）的放电模式及收缩强度失衡被认为是导致髌股关节功能障碍的重要因素。在15名无髌股疼痛的个体（无症状组）和13名有髌股疼痛的受试者（有症状组）上下楼梯时，测量了股内侧斜肌和股外侧肌的肌电图（EMG）活动。测量了EMG活动的VMO/VL峰值比率以及VMO和VL峰值起始时间的差异。采用双向混合模型方差分析（ANOVA）来确定组（无症状组和有症状组）、阶段（上楼梯的向心阶段和下楼梯的两个离心阶段）的主要影响，以及组和阶段之间的相互作用。方差分析表明，两组之间在VMO/VL EMG峰值比率或VMO和VL肌肉活动峰值的起始时间方面没有差异。将两组合并后，与上楼梯的向心阶段相比，下楼梯的离心负重接受阶段的VMO/VL EMG峰值比率更低。这些发现表明无症状个体和有症状个体之间没有差异，但向心和离心VMO/VL比率之间可能存在差异。需要进一步研究以确定VMO和VL肌肉失衡是否导致髌股功能障碍。
