Electromyographic patterns suggest changes in motor unit physiology associated with early osteoarthritis of the knee

被引:45
作者
Ling, S. M.
Conwit, R. A.
Talbot, L.
Shermack, M.
Wood, J. E.
Dredge, E. M.
Weeks, M. J.
Abernethy, D. R.
Metter, E. J.
机构
[1] NIA, Clin Res Branch, IRP, NIH, Baltimore, MD 21225 USA
[2] NINDS, Extramural Res Program, Bethesda, MD 20894 USA
[3] Uniformed Serv Univ Hlth Sci, Bethesda, MD 20894 USA
[4] Johns Hopkins Med Inst, Baltimore, MD 21224 USA
[5] Harbor Hosp, Dept Orthoped Surg, Baltimore, MD 21225 USA
[6] NIA, IRP, Clin Invest Lab, Baltimore, MD 21224 USA
关键词
knee osteoarthritis; quadriceps muscle; motor unit; electromyography; mobility;
D O I
10.1016/j.joca.2007.03.024
中图分类号
R826.8 [整形外科学]; R782.2 [口腔颌面部整形外科学]; R726.2 [小儿整形外科学]; R62 [整形外科学(修复外科学)];
学科分类号
摘要
Objective: To assess characteristics of active motor units (MUs) during volitional vastus medialis (VM) activation in adults with symptomatic knee osteoarthritis (OA) across the spectrum of radiographic severity and age-comparable healthy control volunteers. Methods: We evaluated 39 participants (age 65 3 years) in whom weight-bearing knee X-rays were assigned a Kellgren & Lawrence (KL) grade (18 with KL grade = 0; four each with KL grades = 1, 2 and 4; nine with grade 3). Electromyography (EMG) signals were simultaneously acquired using surface [surface EMG (S-EMG)] and intramuscular needle electrodes, and analyzed by decomposition-enhanced spike-triggered averaging to obtain estimates of size [surface-represented MU action potentials (S-MUAP) area], number [MU recruitment index (MURI)] and firing rates [MU firing rates (mFR)] of active MUs at 10%, 20%, 30% and 50% effort relative to maximum voluntary force [maximal voluntary isometric contraction (MVIC)] during isometric knee extension. Results: Knee extensor MVIC was lower in CA participants, especially at higher KL grades (P = 0.05). Taking the observed force differences into account, OA was also associated with activation of larger MUs (S-MUAP area/MVIC x %effort; P < 0.0001). In contrast, the estimated number of active units (MURI/MVIC x %effort) changed differently as effort increased from 10% to 50% and was higher with advanced CA (KIL = 3, 4) than controls (P = 0.0002). Conclusion: VM activation changes at the level of the MU with symptomatic knee OA, and this change is influenced by radiographic severity. Poor muscle quality may explain the pattern observed with higher KIL grades, but alternative factors (e.g., nerve or joint injury, physical inactivity or muscle composition changes) should be examined in early OA. (C) 2007 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码:1134 / 1140
页数:7
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