臀中肌與闊筋膜張肌肌肉徵召型態於髕股關節疼痛症候群病人之研究

Abstract

背景：近年來，對於髕股關節疼痛症候群的研究發現這類病人有髋外展肌群無力的現象。髖外展肌群的主要肌肉是臀中肌，Janda在1983年提出，當臀中肌無力時，會導致闊筋膜張肌運動單位元（motor unit）提早徵召且過度活化（over activity）來代償，進而造成腸脛带柔軟度不佳。但並未有進ㄧ步的肌電圖研究來佐證，是否髕股關節疼痛症候群的病人會出現此代償現象，這樣的代償現象是否與髋外展肌群肌力及腸脛带柔軟度不佳有關。 研究目的：本研究的目的是以肌電圖訊號觀察健康人與髕股關節疼痛症候群的患者，在次強度的等長肌肉收縮（submaximal isometric contraction）動作中，臀中肌與闊筋膜張肌之肌肉收縮型態（muscle activity pattern）是否有差異。若此肌肉收縮型態在健康人與患者之間是有差異的，則進ㄧ步探討此肌肉收縮形態是否與髖外展肌群肌力及腸脛帶柔軟度有相關性。 研究方法：受測者為健康人及髕股關節疼痛症候群的患者各30名。使用肌電圖偵測器（BIOPAC MP100WSW system）記錄臀中肌與闊筋膜張肌的反應時間及肌肉活化強度。測試動作是在受測者側躺的姿勢之下，請受測者主動做出髖外展的動作到水平的位置，維持八秒鐘。使用Cybex 6000等速肌力測試儀（Cybex 6000,Cybex International Inc）量測受測者在每秒30度的角速度下，髖外展肌群的肌力。並以骨盆固定架及電子水平儀測量腸脛帶柔軟度。以獨立樣本t檢定，比較健康控制組與患者在各項實驗變數上是否有差異，以皮爾森相關係數檢測臀中肌與闊筋膜張肌反應時間及肌肉活化強度與髖外展肌群肌力、髁脛束柔軟度是否有相關。 結果：髕股關節疼痛症候群的患者，臀中肌有反應延遲的現象(p=.035)；臀中肌的肌肉活化強度較控制組高（p=.004），闊筋膜張肌的肌肉活化強度較控制組低（p=.027）。與控制組相比，患者腸脛带柔軟度較差(p<.000)且髋外展肌群顯著較無力 (p=.014)。此肌肉收縮形態與腸脛帶柔軟度有低度相關，但與髖關節肌群肌力沒有顯著相關。 結論：本研究發現髕股關節疼痛患者有髖外展肌群神經肌肉失能的情形，雖與患者之腸脛带柔軟度有低度相關性；但在本實驗中，並無觀察到臀中肌無力所導致闊筋膜張肌運動單位元提早徵召且過度活化，進而造成腸脛带柔軟度不佳的現象。

Background：Previous literature reported that patients with patellofemoral pain syndrome (PFPS) have impaired hip abductors. Gluteus medius(Gm) is the major component of hip abductors muscle group. Janda V. stated in 1983 that weakness in the Gm leads to early firing, overactivation, and tightness of the tensor fascia lata (TFL) and iliotibial band(ITB). There are no electromyography studies of Gm and TFL in patients with PFPS, and no studies about the relationship between strength of hip abductors, flexibility of ITB and muscle activity patterns of Gm and TFL in this population. Purposes：To investigate the muscle activity patterns of Gm and TFL in a healthy control group and a group of patients with PFPS in submaximal isometric muscle contraction. If the results of the investigation show a difference, then a second phase of research will be conducted to identify the relationship between strength of hip abductors, flexibility of ITB and muscle activity patterns of Gm and TFL. Methods and Measurements：The experimental group was comprised of thirty patients with PFPF, while the control group for this study was composed of thirty gender- and age- matched healthy subjects. The study examined electromyography（BIOPAC MP100WSW system）firing patterns, including pre-motor time and muscle firing amplitude in gluteus medius and tensor fascia lata during eight second submaximal isometric muscle contraction while patients lied on their sides. Isokinetic muscle strength of hip abductors was tested using Cybex 6000 with the speed set at 30 degrees per second. ITB flexibility was measured with the Ober test using electro-inclinometer and pelvic stabilizer. Independent tests were performed on all variables between the two groups. Pearson correlation coefficient was used to identify the relationship between strength of hip abductors, flexibility of ITB and muscle activity pattern of Gm and TFL. Results：In the PFPS group, Gm demonstrated delayed onset (p=.035) and higher muscle firing amplitude（p=.004）; TFL demonstrated lower muscle firing amplitude（p=.027）than the control group . The PFPS group had weak hip abductors(p=.014) and tightness of ITB(p<.000) . Muscle activity pattern of Gm and TFL only correlated with flexibility of ITB, not with strength of hip abductors. Conclusion：Patients with PFPS had significant neuromuscular dysfunction, including pre-motor time and muscle firing amplitude, in Gm and TFL compared with the healthy control group. But the hypothesis that weakness in the Gm leads to early firing, overactivation, and tightness of the tensor fascia lata (TFL) and iliotibial band(ITB) was not observed in this study.