Biceps Tendon- Superior Capsule Reconstruction and Acellular Dermal Matrix Augmentation for Large to Massive Incompletely Repairable Rotator Cuff Tears

Large-to-Massive rotator cuff tears of the shoulder with poor tendon and muscle quality often cannot be fully repaired back to its footprint, and they have a high risk of re-tear. This study evaluates a combined technique for these tears. During surgery, the torn rotator cuff is repaired as far as possible, the long head of the biceps tendon is transposed (rerouted) and fixed to the top of the humeral head, and the repair is augmented with an acellular dermal matrix graft (MegaDerm Plus, L\&C Bio, Republic of Korea). All participants receive the same operation and the same structured rehabilitation program; there is no comparison group. Forty adults aged 40 to 75 years treated at Tam Anh General Hospital, Ho Chi Minh City, Vietnam, will be followed for at least 12 months after surgery. The main outcome is the rate of tendon retear on MRI at 12 months. Pain, shoulder function scores (Constant, ASES, UCLA), range of motion, muscle strength, X-ray findings and complications, including graft-related complications, will also be recorded.

Inclusion Criteria: * Preoperative: * Age 40 to 75 years * Large posterosuperior rotator cuff tear (supraspinatus and/or infraspinatus) confirmed clinically and on MRI * Tear size greater than 3 cm on preoperative MRI * At least one risk factor for retear: severe muscle atrophy (occupation ratio \< 40%) or positive tangent sign; supraspinatus fatty infiltration Goutallier grade III or higher, or infraspinatus Goutallier grade II-III; or Rotator Cuff Healing Index (RoHI) \< 7 * Tendon retraction Patte stage II or higher on MRI * No MRI evidence of complete rupture of the long head of the biceps tendon * Written informed consent * Intraoperative (all required for inclusion in the analysis): * Arthroscopically confirmed full-thickness tear of the supraspinatus and/or infraspinatus * Tear size greater than 3 cm in both anteroposterior and mediolateral dimensions, measured with a 5-mm graduated probe * Incomplete footprint coverage after maximal repair (less than 50% of the footprint) or Yoo type II-III * Long head of the biceps tendon Lafosse grade 0-II, suitable for transposition Exclusion Criteria: * Preoperative: * Glenohumeral arthritis / cuff tear arthropathy Hamada grade IV or higher * Subscapularis tear Lafosse type V (complete tear with humeral head decentering and Goutallier grade 3-4) * Previous surgery of the affected shoulder or shoulder deformity * Axillary nerve palsy or cervical nerve root injury * Shoulder joint infection * Neuromuscular conditions affecting postoperative rehabilitation (Parkinson disease, stroke with motor sequelae, severe dementia) * Refusal to participate or inability to comply with follow-up * Intraoperative: * Posterosuperior tear that cannot be repaired to the footprint to any degree after maximal release (irreparable) * Subscapularis tear of any Lafosse type that cannot be repaired to the footprint after maximal release * Long head of the biceps tendon Lafosse grade III, completely ruptured, or not suitable for transposition Participants who consented but meet an intraoperative exclusion criterion receive the most appropriate alternative procedure, are informed after surgery, and are not included in the analysis.