Risk of post-traumatic knee osteoarthritis after knee injury in military service members

Purpose: The aims of the present study were: (a) to identify the incidence of osteoarthritis (OA) after a traumatic knee injury; (b) identify the risk of post-traumatic osteoarthritis (PTOA) based on the type of injury; and (c) identify the time from injury to OA diagnosis. Patients and methods: The Expeditionary Medical Encounter Database, containing healthcare utilization for all deployment injuries sustained by military service members, was queried for traumatic knee injuries between 2001 and 2016. Subsequent diagnosis of knee OA was identified, defined as PTOA. Time to knee PTOA diagnosis was determined and logistic regression was used to obtain odds ratios (ORs) (95% confidence interval [CI]) between knee injury type and development of PTOA. Results: A total of 345 (9.57%) of the 3,605 subjects were diagnosed with PTOA. The median time to diagnosis was 4.10 years. Four primary diagnoses remained significantly associated with PTOA after adjusting for age and injury severity score: fracture (adjusted OR [aOR] = 1.36; 95% CI 1.02, 1.82), sprain (aOR = 1.59; 95% CI 1.23, 2.06), dislocation (aOR = 3.70; 95% CI 2.09, 6.55) and derangement (aOR = 2.38; 95% CI 1.33, 4.28). Subjects were significantly less likely to develop PTOA after a soft-tissue injury (aOR = 0.44; 95% CI 0.41, 0.75). Conclusions: A substantial number of individuals with a traumatic knee injury developed early PTOA (9.6%). Certain knee injuries have a greater association with PTOA. Future studies should implement longer surveillance periods and identify other healthcare variables associated with the risk of developing PTOA, to include appropriate and timely interventions.