Peltz Cathryn D, Dourte Leann M, Kuntz Andrew F, Sarver Joseph J, Kim Soung-Yon, Williams Gerald R, Soslowsky Louis J
McKay Orthopaedic Research Laboratory, University of Pennsylvania, 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA 19104,USA.
J Bone Joint Surg Am. 2009 Oct;91(10):2421-9. doi: 10.2106/JBJS.H.01121.
Surgical repairs of torn rotator cuff tendons frequently fail. Immobilization has been shown to improve tissue mechanical properties in an animal model of rotator cuff repair, and passive motion has been shown to improve joint mechanics in animal models of flexor tendon repair. Our objective was to determine if daily passive motion would improve joint mechanics in comparison with continuous immobilization in a rat rotator cuff repair model. We hypothesized that daily passive motion would result in improved passive shoulder joint mechanics in comparison with continuous immobilization initially and that there would be no differences in passive joint mechanics or insertion site mechanical properties after four weeks of remobilization.
A supraspinatus injury was created and was surgically repaired in sixty-five Sprague-Dawley rats. Rats were separated into three postoperative groups (continuous immobilization, passive motion protocol 1, and passive motion protocol 2) for two weeks before all underwent a remobilization protocol for four weeks. Serial measurements of passive shoulder mechanics (internal and external range of motion and joint stiffness) were made before surgery and at two and six weeks after surgery. After the animals were killed, collagen organization and mechanical properties of the tendon-to-bone insertion site were determined.
Total range of motion for both passive motion groups (49% and 45% of the pre-injury values) was less than that for the continuous immobilization group (59% of the pre-injury value) at two weeks and remained significantly less following four weeks of remobilization exercise. Joint stiffness at two weeks was increased for both passive motion groups in comparison with the continuous immobilization group. At both two and six weeks after repair, internal range of motion was significantly decreased whereas external range of motion was not. There were no differences between the groups in terms of collagen organization or mechanical properties.
In this model, immediate postoperative passive motion was found to be detrimental to passive shoulder mechanics. We speculate that passive motion results in increased scar formation in the subacromial space, thereby resulting in decreased range of motion and increased joint stiffness. Passive motion had no effect on collagen organization or tendon mechanical properties measured six weeks after surgery.
肩袖肌腱撕裂的手术修复常常失败。在肩袖修复的动物模型中，制动已被证明可改善组织力学性能，而在屈肌腱修复的动物模型中，被动运动已被证明可改善关节力学。我们的目的是确定在大鼠肩袖修复模型中，与持续制动相比，每日被动运动是否会改善关节力学。我们假设，与最初的持续制动相比，每日被动运动将改善被动肩关节力学，并且在重新活动四周后，被动关节力学或植入部位力学性能不会有差异。
在65只Sprague-Dawley大鼠中造成冈上肌损伤并进行手术修复。大鼠术后被分为三组（持续制动、被动运动方案1和被动运动方案2），持续两周，之后全部进行四周的重新活动方案。在手术前以及术后两周和六周对被动肩部力学（内、外活动范围和关节僵硬程度）进行系列测量。在动物处死之后，测定肌腱-骨植入部位的胶原组织和力学性能。
在两周时，两个被动运动组的总活动范围（分别为损伤前值的49%和45%）小于持续制动组（损伤前值的59%），并且在重新活动锻炼四周后仍显著较小。与持续制动组相比，两个被动运动组在两周时的关节僵硬程度增加。在修复后的两周和六周时，内活动范围均显著减小，而外活动范围则未减小。各组之间在胶原组织或力学性能方面没有差异。
在该模型中，发现术后立即进行被动运动对被动肩部力学有害。我们推测，被动运动导致肩峰下间隙瘢痕形成增加，从而导致活动范围减小和关节僵硬程度增加。被动运动对术后六周时测量的胶原组织或肌腱力学性能没有影响。
