Humeral Head Morphology Influences Outcomes of Arthroscopic Interposition Glenoid Patch Allograft for Glenohumeral Arthritis

PURPOSE: To determine short- to midterm patient-reported outcomes of arthroscopic soft-tissue interposition arthroplasty using acellular dermal allograft with a minimum follow-up of 1 year and to assess outcomes in patients with and without flattening of the humeral head. METHODS: Patients with a diagnosis of primary glenohumeral arthritis who underwent arthroscopic soft-tissue interposition arthroplasty with an acellular dermal allograft from July 2010 to November 2019 were retrospectively enrolled. Inclusion criteria were a primary diagnosis of glenohumeral arthritis and Outerbridge 4 full-thickness cartilage loss of ≥50% of the glenoid articular surface. Patients underwent arthroscopic debridement, microfracture, and biological arthroscopic soft-tissue interposition arthroplasty with an acellular dermal matrix. Postoperative outcomes included American Shoulder and Elbow Surgeon (ASES) score, Single Assessment Numeric Evaluation (SANE) score, Penn Shoulder Score (PSS), numeric rating scale (NRS) pain score, analgesic use, and conversion to total shoulder arthroplasty (TSA). Results were stratified according to humeral head morphology on preoperative radiographs. RESULTS: A total of 25 patients were included, with a mean age of 56.0 years (range 19.2 to 74.8) and a mean follow-up of 3.36 years (range 1.03 to 8.98). The mean postoperative ASES score was 64.1 (range 11.7 to 100.0), SANE score was 62% (range 5% to 100%), and PSS was 61.2 (range 10.6 to 97.9). Additionally, 56% of patients rated their shoulder function as improved or much improved, and 36% of patients converted to TSA at a mean of 2.35 years. Patients with and without humeral flattening had similar postoperative ASES scores (P = .44), SANE scores (P = .90), PSS (P = .73), and conversions to TSA (P = .83). Patients with humeral flattening were more likely to have shoulder pain at night (83.3% versus 28.6%, P = .02). CONCLUSION: Arthroscopic soft-tissue interposition arthroplasty with an acellular dermal allograft resulted in satisfactory short- to mid-term postoperative outcomes for younger patients with glenohumeral arthritis but demonstrated a TSA conversion rate of 36%. Patients with humeral head flattening also had satisfactory shoulder function but were more likely to experience shoulder pain at night. LEVEL OF EVIDENCE: Level IV, therapeutic case series