# The Prevalence of Chronic Interosseous Membrane Lesions Following Mason II and III Radial Head Fractures in Complex Elbow Instability—A Retrospective Observational Cohort Study

## TL;DR

This study found that chronic injuries to the interosseous membrane are rare after certain elbow fractures and that proper treatment leads to good outcomes.

## Contribution

The study challenges previous assumptions about poor healing of the interosseous membrane after radial head fractures.

## Key findings

- Chronic cbIOM lesions were very rare in patients with complex elbow instability.
- Five patients showed increased cbIOM laxity but had excellent clinical outcomes.
- The study suggests the interosseous membrane may heal better than previously believed with proper treatment.

## Abstract

Purpose: The primary aim of the present study was to assess the prevalence of chronic lesions of the central band of the interosseous membrane (cbIOM) in complex elbow instability (CEI) in a consecutive series of patients who had previously undergone surgical treatment for Mason II and III radial head (RH) fractures. The secondary aim was to define its clinical significance. Methods: We performed a retrospective study on a prospective database. Our study population comprised 93 patients affected by CEI with type II or III RH fractures according to Mason’s classification who were analyzed in the chronic setting. All patients were treated according to the current therapeutic algorithms. At the last follow-up, the “muscular hernia sign” was investigated by means of a bilateral ultrasonographic examination to assess any chronic cbIOM lesions; the Mayo Elbow Performance Score (MEPS) was used to evaluate the clinical significance of these lesions. Results: All 93 patients were assessed after a mean time of 7.3 years (range: 2–12). No positive “hernia signs” were found, while five patients (5.4%) displayed an increased laxity of the cbIOM when compared with the contralateral side despite a negative “hernia sign”. The clinical outcome in all five patients was excellent with a mean MEPS of 96 (range, 90–100). Conclusions: Chronic cbIOM lesions are very rare in CEI with RH fractures. No patients in this large sample displayed a cbIOM complete lesion; in cases with increased laxity, satisfactory mid-term clinical results were observed. Considering that previous studies reported (1) a high prevalence of cbIOM lesions in patients with Mason II and III RH fractures and (2) the current expert opinion about the scarce healing potential of the cbIOM, this study also suggests that the IOM may heal better than previously believed when RH fractures are treated appropriately in the acute setting.