[Translated article] Influence of prosthetic lateralization on tuberosity healing in reverse shoulder arthroplasty for proximal humerus fractures

INTRODUCTION: To evaluate the effect of prosthetic lateralization on tuberosity healing following reverse shoulder arthroplasty (RSA) for proximal humerus fractures (PHFs) in older adults. MATERIAL AND METHODS: This single-center retrospective study included patients aged > 65 years with displaced Neer 3- or 4-part PHFs treated with RSA within four weeks of injury. Patients were allocated according to the global lateralization of the prosthesis: Very Highly Lateralized (VHL; 21.4 mm, Arrow®, n = 53) and Lateralized (L; 14.7 mm, Unique®, n = 20). Tuberosity healing was assessed radiographically and classified as anatomic, non-anatomic, or failed consolidation. Statistical analysis was performed using Student's t-test or Mann-Whitney U test for continuous variables, and Chi-square or Fisher's exact test for categorical variables. RESULTS: The final cohort consisted of 73 patients (62 women, 11 men) with a mean age of 76.2 ± 6.9 years. Overall tuberosity healing occurred in 60 patients (82.2%), while 13 (17.8%) demonstrated failed consolidation. The L group showed a significantly higher overall healing rate (100%) compared with the VHL group (75.5%; P = .020). Anatomic healing was achieved in 55% of the L group and 28% of the VHL group (P = .020). All failures occurred exclusively in the VHL cohort (24.5%). The overall complication rate was 6.8%, with no significant differences between groups. CONCLUSION: Very high prosthetic lateralization (> 20 mm) is associated with reduced rates of anatomic tuberosity healing and a higher incidence of failed consolidation, likely due to increased mechanical tension that compromises osteointegration in osteoporotic bone.