后上肩袖损伤后肩袖肌肉功能与肩关节外展功能关系的动态生物力学研究

Relationship between rotator cuff muscle function and shoulder abduction function in patients with posterior superior rotator cuff tear:a dynamic biomechanical study

目的探讨后上肩袖损伤后肩袖肌肉功能与肩关节外展功能关系。方法通过自主研发的动态肩关节生物力学检测平台, 对7具尸体肩关节标本分别在以下4种状态模拟肩关节90°外展动作:(1)肩袖完整、施力(正常肩袖组);(2)后上肩袖损伤、施力(后上肩袖损伤施力组);(3)后上肩袖损伤、后上肩袖不施力(后上肩袖损伤无力组);(4)肱骨头旋转中心上方无肩袖组织、不施力(广泛性肩袖损伤组)。通过中三角肌施力峰值和稳定值来评估不同肩袖损伤情况下肩关节外展过程中的生物力学状态。通过肩峰下压强峰值、肩峰下压强平均值、肩峰下接触面积和肩峰下压力评估不同肩袖损伤情况下肩峰的受压情况。通过盂肱关节内压力/中三角肌施力峰值和稳定值比率评估不同肩袖损伤情况下肩关节的稳定情况。结果在90°动态外展时, 正常肩袖组中三角肌施力峰值和稳定值分别为(42.1±8.7)N、(29.9±7.4)N, 后上肩袖损伤施力组分别为(45.7±10.3)N、(30.5±7.2)N, 后上肩袖损伤无力组分别为(48.4±13.4)N、(29.9±4.8)N(P均>0.05), 而广泛性肩袖损伤组中三角肌施力峰值和稳定值分别为(69.7±9.7)N、(53.7±8.9)N, 较前三组显著升高(P均<0.05)。中三角肌施力的增加会同时增加肱骨头与肩峰压力。正常肩袖组肩峰下压强峰值、肩峰下压强平均值、肩峰下接触面积和肩峰下压力分别为(0.40±0.05)MPa、(0.22±0.03)MPa、(7.71±5.09)mm^(2)、(1.66±1.06)N, 后上肩袖损伤施力组分别为(0.41±0.05)MPa、(0.26±0.07)MPa、(12.71±11.35)mm^(2)、(2.93±2.46)N, 后上肩袖损伤无力组分别为(0.50±0.12)MPa、(0.26±0.07)MPa、(17.29±9.11)mm^(2)、(4.09±1.46)N(P均>0.05), 而广泛性肩袖损伤组肩峰下压强峰值、肩峰下压强平均值、肩峰下接触面积和肩峰下压力分别为(3.64±1.70)MPa、(0.98±0.49)MPa、(47.63±11.91)mm^(2)、(45.48±23.86)N, 较前三组显著升高(P均<0.05)。正常肩袖组盂肱关节内压力/中三角肌峰值和稳定值比率分别为2.24±0.30、2.46±0.13, 后上肩袖损伤施力组分别为2.21±0.19、2.52±0.08, 后上肩袖损伤无力组分别为2.03±0.14、2.42±0.16(P均>0.05), 而广泛性肩袖损伤组盂肱关节内压力/中三角肌施力峰值和稳定值比率分别为1.40±0.14、1.52±0.41, 较前三组显著降低(P均<0.05)。以上指标后上肩袖损伤施力组和后上肩袖损伤无力组与正常肩袖组比较, 差异无统计学意义(P均>0.05)。结论后上肩袖损伤后肩袖肌肉的功能不影响肩关节的整体外展功能。当肩袖损伤大小累及整个肱骨头旋转中心上方时, 肩关节正常外展功能会显著受限。

Objective To evaluate the relationship of rotator cuff muscle function with shoulder abduction function after posterior superior rotator cuff tear via dynamic biomechanical study.Methods By using the customized dynamic shoulder biomechanical testing system,seven freshly frozen cadaveric shoulders were used to stimulate shoulder abduction at 90°under four statuses:(1)intact rotator cuff with activation(normal rotator cuff group);(2)posterior superior rotator cuff tear with activation(posterior superior rotator cuff tear with activation group);(3)posterior superior rotator cuff tear with posterior superior rotator cuff deactivation(posterior superior rotator cuff tear with deactivation group);(4)none rotator cuff tissue above the geometric rotation center of the humeral head with deactivation(global tear group).The peak and stable value of middle deltoid force were used to evaluate biomechanical status in different rotator cuff tear conditions during shoulder abduction procedure.The peak subacromial pressure,average subacromial pressure,subacromial contact area,and subacromial force were used to evaluate subacromial pressed conditions under different rotator cuff tear conditions.The peak and stable ratio of glenohumeral contact force/middle deltoid force were used to evaluate shoulder stability under different rotator cuff tear conditions.Results During dynamic abduction at 90°,the peak and stable value of middle deltoid force were(42.1±8.7)N and(29.9±7.4)N in normal rotator cuff group,(45.7±10.3)N and(30.5±7.2)N in posterior superior rotator cuff tear with activation group,and(48.4±13.4)N and(29.9±4.8)N in posterior superior rotator cuff tear with deactivation group(all P>0.05).But the peak and stable value of middle deltoid force were(69.7±9.7)N and(53.7±8.9)N in global tear group,significantly increased compared with other three groups(all P<0.05).The elevated middle deltoid force increased the subacromial contact pressure between glenohumeral head and acromion.The peak subacromial pressure,average subacromial pressure,subacromial contact area,and subacromial force were(0.40±0.05)MPa,(0.22±0.03)MPa,(7.71±5.09)mm2,and(1.66±1.06)N respectively in normal rotator cuff group,(0.41±0.05)MPa,(0.26±0.07)MPa,(12.71±11.35)mm2,and(2.93±2.46)N respectively in posterior superior rotator cuff tear with activation group,and(0.50±0.12)MPa,(0.26±0.07)MPa,(17.29±9.11)mm2,and(4.09±1.46)N respectively in posterior superior rotator cuff tear with deactivation group(all P>0.05).However,the peak subacromial pressure,average subacromial pressure,subacromial contact area,and subacromial force were(3.64±1.70)MPa,(0.98±0.49)MPa,(47.63±11.91)mm2,and(45.48±23.86)N respectively in global tear group,significantly higher than those in other three groups(all P<0.05).The peak and stable ratio of glenohumeral contact force/middle deltoid force were 2.24±0.30 and 2.46±0.13 in normal rotator cuff group,2.21±0.19 and 2.52±0.08 in posterior superior rotator cuff tear with activation group,and 2.03±0.14 and 2.42±0.16 in posterior superior rotator cuff tear with deactivation group(all P>0.05).However,the peak and stable ratio of glenohumeral contact force/middle deltoid force were 1.40±0.14 and 1.52±0.41 in global tear group,significantly higher than those in other three groups(all P<0.05).No significant differences of the above parameters were observed in posterior superior rotator cuff tear with activation group,posterior superior rotator cuff tear with deactivation group and global tear group(all P>0.05).Conclusions After posterior superior rotator cuff tear,rotator cuff muscle function does not affect the whole abduction function of shoulder.When the size of rotator cuff tear involves the whole superior humeral head rotation center,the normal abduction function of shoulder will be significantly impaired.