Biceps Box Configuration for Superior Capsule Reconstruction of the Glenohumeral Joint Decreases Superior Translation but Not to Native Levels in a Biomechanical Study

Abstract

Purpose: To quantitatively biomechanically assess superior stability, subacromial contact pressures, and glenohumeral kinematics of an in situ biceps tenodesis and a box-shaped long head of the biceps tendon (LHBT) superior capsule reconstruction (SCR) in a superior massive rotator cuff tear (MCT) model. Methods: Eight cadaveric shoulders (mean age, 62 years; range, 46-70 years) were tested with a custom testing system used to evaluate range of motion, superior translation, and subacromial contact pressure at 0 , 20 , and 40 of abduction. Conditions tested included native state, MCT (complete supraspinatus and one-half of the infraspinatus), a box-shaped LHBT SCR, and an in situ biceps tenodesis. The box-shaped SCR was performed by maintaining the biceps origin, securing 2 corners to the greater tuberosity, and one corner to the posterior glenoid. The in situ tenodesis was performed anatomically at the top of the articular margin in the same shoulder after take-down of the box SCR. Results: Range of motion was not impaired with either repair construct (P > .05). The box SCR decreased superior translation by approximately 2 mm compared with the MCT at 0 , but translation remained greater compared with the intact state in nearly every testing position. The in situ tenodesis had no effect on superior translation. Peak subacromial contact pressure was increased in the MCT at 0 and 20 abduction compared with the native state but not different between the native and box SCR at the same positions. Conclusions: A box-shaped SCR using the native biceps tendon partially restores increased superior translation and peak subacromial contact pressure due to MCT. The technique may have a role in augmentation of an irreparable MCT. Clinical Relevance: The box-shaped LHBT SCR technique may have a role in augmentation of an irreparable MCT.T he superior capsule of the glenohumeral joint is a distinct anatomical structure that plays a vital biomechanical role in the shoulder. 1,2 In the setting of a massive irreparable rotator cuff repair, stability of the glenohumeral joint is disrupted. An absent superior capsule allows for passive superior translation and hence an impaired fulcrum for glenohumeral abduction. Superior capsule reconstruction (SCR) has been shown biomechanically to restore superior stability and is supported with clinical outcomes up to 5 years after surgery. 3,4 A variety of graft sources have been proposed for SCR. Initially, Mihata et al. 5 reported the use of tensor

Biomechanical outcomes of superior capsular reconstruction for irreparable rotator cuff tears by different graft materials-a systematic review and meta-analysis

“…Superior translation of humeral head was reported in 15 studies ( 15 , 17 , 21 , 27 , 38 , 40 , 41 , 43 – 45 , 50 , 55 , 58 – 60 ). In 14 studies, a significant increase was found in superior translation of the humeral head after establishing an irreparable rotator cuff tear, except in the Han study ( 27 ).…”

“…Subacromial contact pressure was significantly reduced after SCR and nearly returned to its original level. With these two enhancements, SCR for IRCT could improve the functional outcomes and restore the biomechanical outcomes, as seen in the clinical studies (39,45,58,59).…”

“…The loading conditions were not properly displayed in the other six experiments ( 46 – 48 , 51 , 53 , 56 ). Therefore, only 20 studies were involved in the quantitative research ( 8 , 15 , 17 , 21 , 27 , 38 – 45 , 50 , 54 , 55 , 57 – 60 ).…”

“…In 14 studies, a significant increase was found in superior translation of the humeral head after establishing an irreparable rotator cuff tear, except in the Han study ( 27 ). In addition, 13 studies—all except the Denard study ( 45 )— found a significant improvement in the superior translation of the humeral head following SCR. Of these, 10 studies reported that superior translation could be restored to intact rotator cuff by SCR ( 15 , 17 , 21 , 27 , 40 , 41 , 44 , 55 , 58 , 60 ).…”

“…Subacromial peak contact pressure was reported in 12 studies ( 21 , 27 , 38 – 41 , 44 , 45 , 55 , 58 – 60 ). Of these, six studies noted a marked increase in subacromial peak contact pressure following the appearance of the irreparable rotator cuff tear ( 21 , 39 – 41 , 59 , 60 ).…”