重度変形性膝関節症患者における歩行時の疼痛と膝関節周囲筋筋活動との関係

Relationship between Pain and Muscle Activities of the Knee Joint during Walking in Patients with Severe Knee Osteoarthritis

要旨

目的：重度変形性膝関節症（膝OA）患者における，歩行時の膝関節周囲筋の筋活動と拮抗筋の同時収縮指数（co-contraction index：CCI）の特徴について解析を行い，膝関節の疼痛との関係について検討した．

方法：膝OA患者11名のKellgren-Lawrence分類でⅢまたはⅣ度である13膝を対象とした．快適歩行における内側広筋，外側広筋，半腱様筋，大腿二頭筋の平均筋活動とCCIを算出した．膝関節の疼痛は，numerical rating scale（NRS）を用いて測定を行った．平均筋活動，膝関節内側および外側の平均CCIとNRSとの関係を，Spearmanの順位相関係数により検定した．

結果：NRSと立脚後期での大腿二頭筋の平均筋活動（r＝−0.61，p＜0.05），外側平均CCI（r＝−0.582，p＜0.05），内側平均CCI（r＝−0.596，p＜0.05）にそれぞれ負の相関を認めた．

結論：歩行時の膝OA患者に特徴的な膝関節周囲筋のCCIの増大は，歩行時の疼痛と負の相関関係があった．

Objective：To investigate the relationship between clinical assessment of pain and muscle activity during walking in patients with severe knee osteoarthritis (OA)．

Methods：Eleven patients diagnosed as having severe knee OA (13 knees) were evaluated with electromyography and numerical rating scale (NRS) of pain during walking. Electromyography was recorded from the vastus medialis (VM), semitendinosus (ST), vastus lateralis (VL), and biceps femoris (BF) muscles. Co-contraction indexes (CCIs) for the extensor and flexor muscles of the knee joint were calculated as follows：using the VM and ST data for CCI at the medial aspect of the knee and the VL and BF data for CCI at the lateral aspect. Spearman's rank correlation coefficients between the average individual muscle activities or CCI and pain were calculated.

Results：During the terminal stance of walking, NRS significantly correlated with the activation patterns of BF (r ＝−0.61, p＜0.05), the CCI of VL-BF (r ＝−0.582, p＜0.05), and the CCI of VM-ST (r ＝−0.596, p＜0.05)．

Conclusion：This study suggests that pain severity is reflected in increasing CCI at the medial and lateral aspects during the terminal stance phase in severe knee OA.