棘上筋腱関節面不全断裂に対するdebridementが応力分布に与える影響

―2次元有限要素法による解析―

抄録

In the surgical treatment of joint side incomplete rotator cuff tears, the role of the arthroscopic debridement has not been fully clarified yet. The purposes of this study were : 1. To clarify the stress distribution at the insertion in the supraspinatus tendon with joint side tears. 2. To clarify whether the stress distribution at the tendon insertion changes after debridement or not. A 2D finite element model of the normal supraspinatus tendon was used for this study. Three different sized joint side tears were created on the model (I-models). Moreover, models simulating state after the debridement were also created (D-models). Using the software, MARC 2001, a tensile load was applied at the proximal end of tendon and the stress distribution was analyzed. Then, both the pattern of the stress distribution and the maximum value of the von Mises stress in I-models were compared to those in D-models. In I-models, the von Mises stress concentrated at the site of incomplete tears. In D-models, the highest concentration of the von Mises stress was seen at the bottom of incomplete tears. From this site, the area of high stress concentration continued to the bursal side. In D-models, the pattern of the stress distribution was almost identical to that in the I-models. Moreover, the highest value of the stress concentration did not change significantly after debridement. These results were just identical irrespective the size of the incomplete tears. Biomechanical stress has been suggested as one of the pathogenetic factors for the rotator cuff tearing. Thus, it is desirable that the stress at the tendon insertion would decrease after debridement. However, our study revealed that the debridement of incomplete supraspinatus tendon tears did not improve the stress concentration at this site.