Anatomic TSA for B2 glenoids treated with asymmetric reaming has equivalent survivorship and patient outcomes compared to type A glenoids at mean 9 years follow-up.

BACKGROUND: Walch B2 glenoids can present a challenge to shoulder arthroplasty surgeons. Short-term studies have demonstrated that corrective reaming to 10° of retroversion in anatomic total shoulder arthroplasty (aTSA) can result in good outcomes, however there is little data reporting the long-term outcomes in this cohort. B2 glenoids treated with high-side reaming present a theoretical risk of early glenoid component failure as one may ream into the subchondral bone. This study aimed to demonstrate that 1) B2 glenoids treated with corrective reaming have durable results and 2) offer similar results to Walch A1/2 in long-term follow-up.

METHODS: Patients who underwent aTSA by a single surgeon (E.L.F.) were identified from a shoulder arthroplasty registry. Inclusion criteria included Walch A1, A2 or B2 glenoid, a diagnosis of primary shoulder osteoarthritis, and a minimum radiographic and clinical follow-up of 5 years. 43 patients with B2 glenoids were compared to a cohort of 42 patients with A1 or A2 glenoids. Preoperative computed tomography (CT) and radiographs were utilized to assess deformity, glenoid version, and posterior subluxation of the humeral head. Postoperatively, patients were assessed with radiographs and patient-reported outcome measures including American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST) score, and Visual Analog Scale (VAS).

RESULTS: 85 shoulders (82 patients, 42 B2 and 43 A1/A2 glenoids) with an average follow-up of 9.4 years were included. In the B2 cohort, the average retroversion was 21.1° and posterior subluxation was 69.4% compared with 10.6°(p<0.001) and 57.5% (p<0.001) in the A1 or A2 cohort. The cohort demographics were similar except for male sex (B2 69.8% vs A1 or A2 37.2%, p=0.008). There was no difference between the cohorts in their improvement in ASES (p=0.807), SST (p=0.586), or VAS (p=0.930) scores. There was no difference in lateral humeral offset (p=0.889) or acromial humeral interval (p=0.468) between initial postoperative and final follow-up visits. Survivorship for B2 glenoids was 97.6%, 94.1% and 73.3% at 5, 10 and 15 years, respectively compared to 97.6%, 91.9% and 83.5% in type A glenoids. The revision rate was similar between the two groups (p=0.432). Lazarus score (p=0.682) and rates of humeral radiolucency (p=0.366) and humeral osteolysis (p=0.194) were similar between the two cohorts at final follow-up.

CONCLUSION: Asymmetric reaming of patients with B2 glenoids is a reliable method of glenoid preparation with excellent mid- to long-term clinical results, patient reported outcomes, and low revision rates similar to their A1 and A2 counterparts.