Incidence, Risk Factors, and Clinical Outcomes of Heterotropic Ossification Following Reverse Shoulder Arthroplasty

Introduction: Heterotropic ossification (HO) is the pathologic formation of bone in soft tissue, often following trauma or surgery. HO is a common radiographic finding after reverse shoulder arthroplasty (RSA), yet its incidence, risk factors, and clinical significance remains under-explored. Despite the relatively high incidence, the etiology, risk factors, and functional outcomes are not understood. Methods: This is a literature review to understand the incidence, risk factors, and clinical outcomes of HO following RSA. Pubmed, Embase, and Web of Science were the databases used to review nine peer-reviewed sources. No restrictions were placed on publication date due to the sparsity of literature, but all articles were published in 2009 or later. The search term strategy used was: (osteophyte OR "bone spur" OR "bony spur" OR "heterotropic ossification" OR ossificans) AND ("arthroplasty, replacement, shoulder" OR "reverse shoulder replacement" OR "reverse shoulder arthroplasty" OR “reverse total shoulder”). Results: The incidence of HO ranges from 10% to 61.6%, with an average of 31.9% across all included studies. The earliest it has been identified is at three months postoperatively. Identified risk factors include male sex, revision surgery, iatrogenic injury. Prosthesis design and surgical approach may play a factor in development of HO. Conclusion: HO is a frequent finding in RSA, typically non-progressive and asymptomatic. However, it may impact function in severe cases. Several factors play a role in the incidence and location of HO, such as the prosthesis design and implant placement.