Hip and knee replacement as a proxy measure for lower limb osteoarthritis in Scottish military veterans

Introduction: Physical activity is an important component of military training. Although injuries and musculoskeletal disorders are the most common cause of medical retirement from the Armed Forces, the long-term risk of lower limb osteoarthritis in veterans is unknown. We used data on hip and knee replacement in Scottish military veterans as a proxy measure.

Methods: Retrospective cohort study of 78 000 veterans born between 1945 and 1995 and a comparison group of 253 000 non-veterans, matched for age, sex and area of residence, followed up for up to 37 years, using survival analysis to examine the risk of hip and knee replacement.

Results: Veterans were significantly less likely to undergo hip replacement than non-veterans, Cox proportional HR 0.87, 95% CI 0.80 to 0.95, p<0.001. There was no significant difference between veterans and non-veterans in respect of knee replacement, HR 1.02, 95% CI 0.94 to 1.11, p=0.643, and there was no difference in the ages at which veterans and non-veterans underwent joint replacement. People who had served for longest in the military had similar risk to those with the shortest service.

Conclusions: Based on the likelihood of undergoing joint replacement surgery in later life, we found no evidence of a positive association between military service and an increased risk of lower limb osteoarthritis.