Radiation Therapy for Heterotopic Ossification: A Systematic Review

Abstract

Heterotopic Ossification (HO) is a benign disorder characterized by ectopic bone formation in soft tissues that can lead to functional loss in patients. We conducted a systematic review of the evidence on the use of Radiation Therapy (RT) for the prevention or treatment of HO. Literature searches were conducted using Medline (via PubMed), Embase, and ClinicalTrials.gov to April 1, 2023. Medical Subject Headings (MeSH) and free text terms relevant to HO and radiation therapy were used. In brief, eligible study participants were ≥18 years of age with heterotopic ossification and were treated with low-dose, external RT. Two reviewers selected relevant abstracts and abstracted full text data for analysis. The review followed the PRISMA guidelines. Ten studies evaluating the effect of RT for either the prevention or treatment of heterotopic ossification met the inclusion for evidence synthesis. Nine RCTs did not clearly report their methods and had medium risk of bias. The studies were conducted between 1988 and 2008 with follow-up ranging on average from three to 59 months post treatment. A total of 1530 participants were analyzed, and 566 were treated with RT following fracture fixation, total hip arthroplasty (THA), or total hip replacement (THR). In pooled data from eight RCTs, there was a non-significant but clinically meaningful reduction in the presence of heterotopic ossification at follow-up for patients who received RT vs. comparators (pooled OR = 0.47, 95% CI [0.19, 1.17]. There was minimal evidence of adverse events. This systematic review found a clinically, but not statistically, significant benefit of prophylactic RT for HO at follow up. These findings are tempered by a moderate risk of bias. While practice patterns vary, RT for HO prophylaxis, in high-risk patients, may have benefits that outweigh the risks.