A Biological Spacer to Treat Irreparable Rotator Cuff Tears: A Biomechanical Study Utilizing a Secured Versus Unsecured Tensor Fascia Lata Graft

Abstract

Background: Designed to help treat pain and loss of function after rotator cuff repair, allograft spacer procedures utilize a graft to act as a spacer in the subacromial space, decreasing pain from impingement of the greater tuberosity on the acromion at the extremes of overhead motion. Purpose: To evaluate the biomechanical characteristics of secured versus unsecured tensor fascia lata allografts used in an allograft spacer procedure. Study Design: Controlled laboratory study. Methods: A total of 8 fresh-frozen cadaveric shoulder specimens were used. There were 4 conditions tested: (1) intact rotator cuff, (2) stage III rotator cuff tear (complete supraspinatus tendon and superior one-half of the infraspinatus tendon), (3) unsecured tensor fascia lata graft, and (4) secured tensor fascia lata graft. Both superior and posterior translation of the humeral head were calculated in each condition. A 4-cm × 5-cm × 6-mm tensor fascia lata graft was used in the subacromial space to act as a spacer. Grafts were secured at the lateral edge of the native rotator cuff footprint with 2 knotless anchors. Results: With unbalanced loading, both secured and unsecured grafts varied in their ability to limit superior and posterior translation at various rotation angles back to levels seen with intact rotator cuffs at 0° and 20° of abduction. During balanced loading, both unsecured and secured grafts limited superior and posterior translation more than those seen in the rotator cuff–deficient condition (P < .01) and similar to those seen in the intact condition (P > .05). The secured and unsecured grafts allowed similar amounts of translation at every position with both unbalanced and balanced loading (P > .05). Finally, total graft motion was <7 mm in all positions. Conclusion: Unsecured tensor fascia lata grafts were biomechanically equivalent to secured grafts when used during allograft spacer procedures. Clinical Relevance: While both grafts were successful at limiting superior and posterior translation of the humeral head during early range of motion, the unsecured graft represents a cheaper, easier option to utilize during allograft spacer procedures.