Trends and risk factors for spinal cord injury-induced heterotopic ossification: A retrospective population-based...

Heterotopic ossification (HO), the abnormal formation of bone in soft tissue, is a known complication of spinal cord injury (SCI). Prior studies have identified several associated factors but are limited by small sample sizes and provide little insight into the burden on the healthcare system. This study will assesses national trends in hospitalizations for SCI-induced HO in the U.S. from 2016 to 2021 and identifies demographic and clinical factors associated with HO in hospitalized SCI patients.

Retrospective, population-based cross-sectional study.

Healthcare Cost and Utilization Project's National Inpatient Sample (NIS) from 2016 to 2021.

A total of 380,928 hospitalizations with SCI, with or without HO, were identified.

Hospitalizations with a primary or secondary SCI diagnosis, with or without HO complication, were identified using ICD-10 codes. Survey-weighted logistic regression models assessed associations between SCI-induced HO and demographic and clinical factors. Interaction analyses evaluated potential effect modification.

Of 380,928 SCI hospitalizations, 181 (0.048%) included an HO diagnosis. Younger age, male sex, hip-pelvic trauma, pressure ulcers, spasticity, thoracic trauma, and thromboembolism were associated with increased odds of HO; lung injury and pneumonia/pneumonitis were associated with decreased odds. Thoracic and complete SCI were independently associated with HO, and a significant interaction was observed between SCI level and completeness (P<0.0001).

Hospitalized SCI patients with these risk factors should be closely monitored for HO prevention, early detection, and treatment. The inverse association between HO and lung injury or pneumonia warrants further investigation.