Patient-specific BIO-RSA (bony increased-offset reverse shoulder arthroplasty) for glenoid dysplasia (type C) osteoarthritis

Glenoid dysplasia (Walch type-C) is characterized by a retroversion > 25&#xb0; and predisposes the shoulder to degenerative osteoarthritis. Our purpose is to report the mid- to long-term clinical and radiologic outcomes of reverse shoulder arthroplasty (RSA) with a patient-specific structural humeral head autograft (bony increased-offset RSA [BIO-RSA] technique) for the treatment of glenoid dysplasia (Walch type C) osteoarthritis (OA). This is a retrospective single-center case series of 45 shoulders (37 patients; mean age 76 &#xb1; 9 years) with type C glenoid OA (retroversion >25&#xb0;) treated using a patient-specific BIO-RSA technique between 2012 and 2022. The cancellous bone graft was harvested from the proximal humerus using a bell saw. A wedge-shaped bone graft (12-25 mm) was crafted based on preoperative 3D planning (Blueprint; Tornier) and fixed to the native glenoid using a long (&#x2265;25-mm) central baseplate (Tornier Aequalis Reversed II)-either pegged (35 cases) or screwed (10 cases)-along with 4 peripheral screws. At least 10 mm of the central peg or screw was anchored in the native glenoid. Outcome measures included prosthesis survival, functional and subjective results, bone graft healing, and correction of glenoid retroversion and inclination. The mean follow-up was 6.5 years (range, 2-14 years). At the final follow-up, no reoperations or revisions were required, and no glenoid loosening or complications were observed. The mean retroversion correction was 30&#xb0; &#xb1; 10&#xb0; (from 37&#xb0; &#xb1; 8&#xb0; to 7&#xb0; &#xb1; 7&#xb0;), and the mean RSA angle improved from 13&#xb0; &#xb1; 11&#xb0; to 0&#xb0; &#xb1; 5&#xb0; (P < .001). Computed tomography scan evaluation demonstrated complete bone graft healing in 95% (43/45) of shoulders; partial graft lysis was observed in 2 cases. Graft size (>20-mm) did not influence healing. Incomplete retroversion correction (>10&#xb0;) did not significantly impact functional outcomes, and the use of patient-specific guides (27% of cases) was not associated with improved correction. Constant-Murley scores and Subjective Shoulder Value improved from 40 &#xb1; 10 to 80 &#xb1; 12, and from 38% &#xb1; 13% to 91% &#xb1; 9%, respectively (P < .001). All patients reported being satisfied or very satisfied with the procedure. Our data demonstrate that patient-specific BIO-RSA is a safe, effective, and durable technique for reconstructing severe posterior erosion seen in type C glenoid OA, including cases with severe retroversion (>45&#xb0;) requiring thick bone grafts (>20-mm). The procedure provides excellent functional and subjective outcome, and the structural humeral autograft predictably heals the native glenoid, even in elderly patients (>80 years).