Bursal acromial resurfacing improves shoulder biomechanics in a cadaveric model of massive rotator cuff tear.

ABSTRACT

PURPOSE: To investigate the effectiveness of bursal acromial resurfacing (acromiograft) on acromiohumeral distance, subacromial contact area, and pressure in a cadaveric model of massive rotator cuff tear. METHODS: Eight fresh-frozen cadaveric shoulders were tested using a customized shoulder testing system. Humeral head translation, subacromial contact pressure, and the subacromial contact area were evaluated across four conditions (1) intact shoulder; (2) simulated massive rotator cuff tear; (3) 3-mm acromiograft condition; (4) 6-mm acromiograft condition. The acromiografts were simulated using Teflon and a reported technique. The values were measured at 0°, 20°, and 40° abduction and 0°, 30°, 60°, and 90° external rotation (ER) for each abduction status. RESULTS: Compared with a massive cuff tear, the 6-mm acromiograft significantly reduced the superior translation of the humeral head at all abduction/ER angles (P<0.05). The 3-mm acromiograft also decreased superior translation of the humeral head compared to massive cuff tear, but not all differences were significant. The 3- and 6-mm acromiografts significantly decreased the subacromial contact pressure and increased the subacromial contact area in almost all positions (P<0.05). The 3-mm acromiograft maintained biomechanical properties similar to the intact condition, whereas the 6-mm acromiograft increased the contact area. CONCLUSIONS: This biomechanical study demonstrated that both 3- and 6- mm acromiografts using Teflon in a cadaveric model of a massive cuff tear resulted in recentering of the superiorly migrated humeral head, increased the subacromial contact area, and decreased the subacromial contact pressure. The 3- mm graft was sufficient for achieving the intended therapeutic effects. CLINICAL RELEVANCE The acromiograft can normalize altered biomechanics and may aid the treatment of massive cuff tears. As grafting the acromion's undersurface is new with limited clinical outcomes, further observation is crucial. Using Teflon instead of ADM allograft for bursal acromial resurfacing could yield different results, requiring careful interpretation.