Healing Rate and Clinical Outcomes of Lesser Tuberosity Osteotomy for Anatomic Shoulder Arthroplasty.

Abstract

Background:Several techniques are available for subscapularis management during total shoulder arthroplasty (TSA). Lesser tuberosity osteotomy (LTO) is advocated owing to improved biomechanical strength and high rates of healing. However, displacement or nonunion of the LTO could theoretically cause functional deficits for the affected shoulder. The purpose of this study is to examine the healing rate and clinical outcomes of LTO in patients undergoing anatomic TSA.Methods:A retrospective review of our institution's prospectively enrolled TSA registry was performed. Patients undergoing primary TSA who had an LTO performed and radiographs at a minimum of 3 months postoperatively were included. Two fellowship-trained shoulder and elbow surgeons reviewed all radiographs and categorized LTO healing into three groups: healed, nondisplaced nonunion, or displaced nonunion. Physical examination data and patient-reported outcome scores including American Shoulder and Elbow Score, Single Assessment Numeric Evaluation scores, and the Veteran Rand mental and physical component scores were obtained at a median of 1 year after surgery. Comparative statistical analysis was performed on the healed versus nondisplaced nonunion groups.Results:We included 142 shoulders in 130 patients who met the inclusion criteria with an average age of 65.2 years (SD: 10.3). Radiographic evaluation at a median of 1.0 years postoperatively (range: 6 months to 2.2 years) revealed 124 (87%) healed LTO, 12 (8%) nondisplaced nonunions, and six (5%) displaced nonunions. The median American Shoulder and Elbow Score total score was 89.2 (IQR: 72.2, 98.3) in the healed LTO group versus 96.7 (30, 98.3) in the LTO nondisplaced nonunion group (P = 0.9637). The median Veteran Rand mental component was 55.1 (IQR: 43.4, 61.0) in the healed LTO group versus 54.6 (38.8, 58.2) in the LTO nondisplaced nonunion group (P = 0.5679). The median Single Assessment Numeric Evaluation score was 85.0 (IQR: 70.0, 95.0) in the LTO-healed group versus 75.1 (35.0, 97.1) in the LTO nondisplaced nonunion group (P = 0.7699). There were no significant differences in revision surgery occurrence between the groups to address subscapularis instability: one patient in the LTO-healed group underwent revision surgery for subscapularis repair 3 months after primary surgery because of continued pain and weakness, and no patients in the other LTO groups underwent revision surgery.Conclusion:Although there is a risk of nonunion and displacement using the LTO technique in TSA, the overall clinical outcomes and radiographic union rates are high with a very low risk of revision surgery. In addition, radiographic evidence of nonunion does not significantly correlate with clinical outcomes.