A biomechanical cadaveric study of patellar tendon allograft as an alternative graft material for superior capsule reconstruction

Hypothesis: In a cadaveric irreparable rotator cuff tear model, patellar tendon allograft-superior capsule reconstruction (PT-SCR) will restore glenohumeral stability and reduce subacromial contact pressures without significant graft deformation during testing. Methods: Eight cadaveric shoulders were tested in a custom shoulder testing system. Rotational range of motion (ROM), superior translation, and subacromial contact pressure were measured in the following experimental conditions: intact rotator cuff, irreparable supraspinatus tear (massive cuff tear [MCT]), and PT-SCR. Results: MCT and PT-SCR resulted in significantly increased total ROM at all degrees of abduction compared with the intact state (P < .001). In both 0 degrees and 30 degrees of glenohumeral abduction, MCT showed a significant increase in superior translation compared with the intact state (P <.001). Application of the PT-SCR resulted in a decrease of superior translation compared with MCT (P < .001). At 0 degrees abduction/60 degrees external rotation and 0 degrees abduction/90 degrees external rotation, MCT showed significantly greater peak subacromial contact pressure compared with the intact state (P < .006). At both of these positions, PT-SCR was able to reduce peak pressure to lower than or no significant difference from the intact state. There was no statistically significant change in graft thickness, length, or width after testing. Conclusion: PT-SCR was able to reduce superior translation of the humeral head and peak subacromial contact pressure without restricting ROM. Furthermore, there was no significant graft deformation during testing. PT-SCR in this validated cadaveric model demonstrates favorable biomechanical properties and is a viable source of graft material for SCR. (C) 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.