The bone turnover marker procollagen type I N-terminal propeptide is associated with 12-week neurogenic heterotopic ossification after traumatic brain injury

Neurogenic heterotopic ossification (NHO) after traumatic brain injury may involve osteogenic synthesis of a type I collagen-rich matrix. Procollagen type I N-terminal propeptide (P1NP) reflects type I collagen formation. This single-center retrospective cohort study examined whether baseline P1NP was associated with radiographic NHO within 12 weeks after traumatic brain injury. We reviewed 124 adults transferred to physical and rehabilitation medicine within 21 days after injury who completed 26-34 days of inpatient rehabilitation and had 12-week follow-up. The primary Firth penalized logistic regression model included P1NP per 50 ng/ml, acute care length of stay per 5 days, overall Modified Ashworth Scale score per 5 points, and neutrophil-to-lymphocyte ratio. Twelve-week NHO occurred in 19 (15.3%) patients. Higher P1NP was associated with NHO in the primary model (odds ratio: 6.11, 95% confidence interval: 1.34-33.97; P = 0.013). Longer acute care length of stay, higher overall Modified Ashworth Scale score, and higher neutrophil-to-lymphocyte ratio were also associated with NHO. In a supplementary model replacing acute care length of stay with the Disability Rating Scale, P1NP did not reach statistical significance (odds ratio: 4.63, 95% confidence interval: 0.85-30.18; P = 0.062). In adults with traumatic brain injury undergoing early inpatient rehabilitation, higher baseline P1NP was associated with 12-week NHO in the primary model. Prospective studies with standardized imaging and serial sampling are needed to confirm its predictive value.