腰大肌收縮厚度變化之動態超音波研究—比較單側下背痛與健康族群之差異

Abstract

研究背景: 腰大肌為人體上唯一一條由腰椎連結到下肢的肌肉，生物力學和解剖相關研究都顯示當此肌肉收縮時，可以提供腰椎在矢狀面上的曲度(curvature)的控制，並且透過正向壓力增進腰椎的穩定性。下背痛族群在坐姿時腰椎曲度的控制、軀幹肌肉的神經肌肉控制皆和健康族群有所不同，另外先前研究也指出在單側下背痛的病人族群中，其疼痛側的腰大肌截面積顯著小於健康側，因此，對於單側下背痛族群中的腰大肌對於腰椎曲度控制的功能探討則顯得重要，然而，由於此肌肉位於人體較深層的位置，對於腰大肌的研究目前多為靜態時的核磁共振影像(MRI)與靜態針極肌電圖(Needle Electromyography)來研究腰大肌的截面積改變或是活化程度，使用動態影像量測且非侵入性的研究仍十分有限。 研究目的: 此研究有兩個研究目的，第一個為比較單側下背痛病人與健康族群之間在執行腰椎前凸任務下(lumbar lordosis maneuver)於腰大肌厚度變化量與豎脊肌活化程度的差異。另外，探討單側下背痛病人疼痛側、非疼痛測在執行腰椎前凸任務下於腰大肌厚度變化量和豎脊肌活化程度的差異。 研究方法：本計畫研究族群年齡介於20-45 歲之健康男性，以及三個月內有單側下背痛之症狀男性。此計畫研究為橫斷式(cross-section)分析，除了基本柔軟度、疼痛量表紀錄外，將以表面肌電圖和超音波影像來量化受試者在執行腰椎前凸任務時軀幹肌肉豎脊肌活化程度和腰大肌的厚度變化量。此計畫研究將使用無母數分析統計方法之一-曼－惠特尼U考驗法(Mann-whitney u test)分析比較兩組別(健康組、疼痛組)在不同腰椎前凸壓力下腰大肌厚度變化量和豎脊肌活化程度，另外使用魏克生符號檢定(Wilcoxon Signed Rank test)分析比較兩側(疼痛側、非疼痛側)之差異。所有分析統計上顯著差異設定為α<.05。 研究結果: 本研究共招募二十三位受試者(健康組:13; 下背痛組:10)，兩組在年齡(健康: 21.4 ± 2.5 年; 下背痛: 25.4 ± 4.1 年)、身體質量指數有顯著差異(健康: 21.3 ± 0.5 Kg/m2 下背痛: 23.5 ± 1.1 Kg/m2)。兩組在下肢柔軟度、腰大肌收縮形變上有顯著的差異。柔軟度部分，下背痛組別在髖伸肌、湯瑪士測試皆較健康組來的受限。在腰大肌厚度變化量上，下背痛組在於較大收縮程度的腰椎前凸動作下顯著低於健康組別。(40-25mmHg: 健康: 23.2 ± 14.6 %;下背痛:11.1 ± 4.1 %, p=0.006; 40-20mmHg: 健康: 29.2 ± 15.7 %; 下背痛:12.2 ± 6.5 %, p=0.001). 兩組在豎脊肌活化程度則沒有顯著差異。統計結果顯示在單側下背痛組別中，疼痛側和非疼痛側在腰大肌厚度變化量、豎脊肌活化程度並無顯著差異。 結論: 使用超音波動態影像可以發現單側下背痛組在執行腰椎前凸任務時腰大肌厚度變化量顯著低於健康組別。腰大肌可提供腰椎曲度穩定，單側下背痛組別在腰大肌收縮上和健康人有所差異，此研究結果提供往後針對此肌肉訓練和評估的可能性。

Background Psoas major (PM) is the only muscle that attaches to both lumbar spine and hip joint. Anatomical and biomechanical studies revealed that PM contraction could increase segmental compressive force that leads to an increase in lumbar stability and also controls lumbar lordosis. Patients with low back pain (LBP) had different lumbar curvatures and neuromuscular recruitment strategies in sitting positions. Several studies indicated that patients with unilateral LBP showed significant reductions in PM cross-sectional areas at their symptomatic sides of their backs but most of them are static MRI approaches. Therefore, it is warranted to investigate whether PM thickness changes differently during dynamic lumbar lordosis maneuver between patients with unilateral LBP and healthy populations using a dynamic imaging approach. Purpose There are two purposes of this study. First, to investigate whether the neuromuscular control of PM and erector spinae muscle during lumbar lordosis maneuver are different between unilateral LBP and healthy individuals. Second, to investigate whether the neuromuscular control of PM and erector spinae during lumbar lordosis maneuver are different between painful side and non-painful side in the LBP population. Methods Both LBP patients and healthy subjects were recruited in this study, and patients with unilateral LBP were recruited from National Taiwan University hospital. Besides recording basic data, PM and erector spinae muscle were measured by ultrasonography and surface electromyography respectively during lumbar lordosis maneuver simultaneously in different contraction levels for each subjects. Data were analyzed using SPSS18.0 version, and were presented as means ± standard deviations and percentages. Mann-whitney u test were used to analyze the ratios of thickness changes in PM, erector spinae EMG magnitudes between groups (unilateral LBP, healthy) and Wilcoxon Signed Rank test were used to analyze outcome measures between sides (painful side, non-painful side) during different contraction levels. The significance level was set at α< 0.05. Results: A total of twenty-three participants enrolled in this study. (Healthy:13; LBP:10) Significant group differences in age (Healthy: 21.4 ± 2.5 y/o; LBP: 25.4 ± 4.1 y/o) and BMI (Healthy: 21.3 ± 0.5 Kg/m2; LBP: 23.5 ± 1.1 Kg/m2) were detected. Mann-Whitney U test revealed that there were significant group differences in ratios of PM thickness changes in higher contraction levels (40-25mmHg: Healthy: 23.2± 14.6 %; LBP:11.1 ± 4.1 %, p=0.006; 40-20mmHg: Healthy: 29.2 ± 15.7 %; LBP:12.2 ± 6.5 %, p=0.001). There were no significant group differences in erector spinae muscle activities in all contraction levels. Within unilateral LBP group, there were no side to side differences in ratios of PM thickness changes and erector spinae muscle activities in all contraction levels. Conclusion: There was a significant reduction in ratios of PM thickness changes during dynamic lumbar lordosis maneuver in persons with unilateral LBP when compared to healthy controls. Furthermore, ultrasound can be a feasible tool in clinical practice to examine PM thickness changes in a non-invasive, dynamic approach.