McMaster University, Hamilton, Ontario, Canada.
Arthritis Care Res (Hoboken). 2014 May;66(5):687-94. doi: 10.1002/acr.22223.
To determine the extent to which knee extensor strength and power explain variance in knee adduction moment (KAM) peak and impulse in clinical knee osteoarthritis (OA).
Fifty-three adults (mean ± SD age 61.6 ± 6.3 years, 11 men) with clinical knee OA participated. The KAM waveform was calculated from motion and force data and ensemble averaged from 5 walking trials. The KAM peak was normalized to body mass (Nm/kg). The mean KAM impulse reflected the mean total medial knee load during stride (Nm × seconds). For strength, the maximum knee extensor moment attained from maximal voluntary isometric contractions (MVIC) was normalized to body mass (Nm/kg). For power, the maximum knee extensor power during isotonic contractions, with the resistance set at 25% of MVIC, was normalized to body mass (W/kg). Covariates included age, sex, knee pain on the Knee Injury and Osteoarthritis Outcome Score, gait speed, and body mass index (BMI). Relationships of the KAM peak and impulse with strength and power were examined using sequential stepwise forward linear regressions.
Covariates did not explain variance in the KAM peak. While extensor strength did not, peak knee extensor power explained 8% of the variance in the KAM peak (P = 0.02). Sex and BMI explained 24% of the variance in the KAM impulse (P < 0.05). Sex, BMI, and knee extensor power explained 31% of the variance in the KAM impulse (P = 0.02), with power contributing 7% (P < 0.05).
Knee extensor power was more important than isometric knee strength in understanding medial knee loads during gait.
确定膝关节伸肌力量和功率在多大程度上解释了临床膝关节骨关节炎（OA）中膝关节内收力矩（KAM）峰值和冲量的变化。
53 名成年人（平均±标准差年龄 61.6±6.3 岁，男性 11 人）患有临床膝关节 OA。从运动和力数据中计算出 KAM 波形，并从 5 次步行试验中进行整体平均。KAM 峰值被标准化为体重（Nm/kg）。平均 KAM 冲量反映了步幅中内侧膝关节总负荷的平均值（Nm×秒）。对于力量，从最大等长收缩（MVIC）中获得的最大膝关节伸肌力矩被标准化为体重（Nm/kg）。对于功率，在等速收缩期间，将阻力设置为 MVIC 的 25%，最大膝关节伸肌功率被标准化为体重（W/kg）。协变量包括年龄、性别、膝关节损伤和骨关节炎结果评分中的膝关节疼痛、步态速度和体重指数（BMI）。使用逐步向前线性回归检查 KAM 峰值和冲量与力量和功率的关系。
协变量不能解释 KAM 峰值的变化。虽然伸肌力量不能解释 KAM 峰值的变化，但峰值膝关节伸肌功率解释了 KAM 峰值变化的 8%（P=0.02）。性别和 BMI 解释了 KAM 冲量变化的 24%（P<0.05）。性别、BMI 和膝关节伸肌功率解释了 KAM 冲量变化的 31%（P=0.02），其中功率贡献了 7%（P<0.05）。
在理解步态中内侧膝关节负荷时，膝关节伸肌功率比等长膝关节力量更重要。
