# Dysbaric Osteonecrosis in Divers: A Narrative Review With a Systematic Literature Search of Pathophysiology, Prevalence, Clinical Features, and Screening

## TL;DR

This review explores dysbaric osteonecrosis in divers, highlighting its causes, prevalence, and diagnostic challenges, emphasizing the need for better screening and prevention.

## Contribution

The paper provides a systematic review of dysbaric osteonecrosis in divers, identifying research gaps and diagnostic challenges.

## Key findings

- DON prevalence is higher in unregulated divers (up to 76.9%) compared to regulated ones (0%-3.125%).
- MRI is more effective for diagnosing DON than plain radiography due to higher sensitivity.
- Type A lesions are more symptomatic than incidental Type B lesions.

## Abstract

Dysbaric osteonecrosis (DON) is a form of bone injury that occurs when nitrogen bubbles form during rapid decompression, leading to impaired blood flow and subsequent bone necrosis. Although DON was first described more than a century ago, it remains underdiagnosed, particularly among unregulated diving populations. This review aims to summarize available data on the prevalence, anatomical distribution, clinical presentation, and diagnostic methods of DON in divers, while also identifying research gaps and evaluating proposed pathophysiological mechanisms. A literature search was conducted across Google Scholar, PubMed, Embase, and Scopus. Twelve studies (seven prevalence studies and five case-based reports) were included based on relevance and sample size. Reported prevalence varied widely, with unregulated artisanal divers showing markedly higher rates (up to 76.9%) compared with regulated populations, such as military divers (0%-3.125%). Plain radiography and magnetic resonance imaging (MRI) were the most commonly used diagnostic modalities. DON predominantly involved long bones, particularly the humeral and femoral heads, likely reflecting their terminal blood supply and susceptibility to ischemia. Type B (diaphyseal) lesions were typically incidental, whereas Type A (subchondral) lesions were more often symptomatic. Proposed pathophysiological mechanisms include thrombus formation secondary to adipocyte rupture and direct vascular obstruction by nitrogen bubbles. Although the role of prophylactic anticoagulation remains uncertain, elevated plasminogen activator inhibitor-1 (PAI-1) levels in some cases suggest a coagulative component. Studies relying primarily on radiography reported higher prevalence rates, likely reflecting detection bias rather than true disease burden, given the low sensitivity of X-ray imaging for early DON. MRI, considered the diagnostic gold standard, was predominantly used in controlled or regulated settings. DON is a preventable complication of decompression exposure. Adherence to established diving protocols and early screening using sensitive imaging modalities are essential. Further prospective studies and evaluation of emerging diagnostic tools, such as computed tomography (CT), are needed to improve detection, prevention, and overall diving safety.