Background Occupation is a key determinant for the risk of developing musculoskeletal injuries (MSKI). The aim of this study was to investigate the lifelong, cumulative effects of occupational physical loading as a risk factor for hip pain in UK military personnel.

Methods This was a population-based case-control study. Cases (N=104) with physician diagnosed intra-articular hip pain were age-matched (1:1) with healthy controls (N=104). Participants were serving (male) UK military personnel (age range 19-50 yrs). Participants completed the Military Physical Loading Questionnaire (MPLQ) enquiring about lifetime exposure to 18 occupational & 18 operational physical tasks. Based on MPLQ responses participants were categorized into high, medium or low exposure groups for each task. Logistic regression analysis adjusting for baseline predictor variables was used to estimate the odds ratios (OR) & occupational risk for incident hip pain.

Results A univariate logistic regression showed high cumulative exposure to the occupational tasks ‘road driving for at least 4-hours’ (OR 3.4, 95% CI, 1.70 – 6.72) & ‘driving over rough terrain’ (OR 2.3, 95% CI, 1.15 – 4.54) were significantly associated with hip pain. Two further driving tasks, ‘driving over rough, uneven terrain’ (OR 3.6, 95% CI, 1.55 – 8.26) & ‘mounted vehicle movements’ (OR 3.3, 95% CI, 1.43 – 7.75) presented the highest risk on deployed operations. Results of the multivariate logistic regression adjusted for predictor variables showed the strongest independent risk factor associated with hip pain was the occupational task ‘road driving for 4-hours’ (OR 4.5, 95% CI, 0.54 – 3.50).

Conclusions Occupational factors during military service are associated with a risk of developing hip pain. Prolonged exposure to driving & vehicle mounted tasks may present the highest risk. Since the future pattern of combat movement for UK troops is more likely to be mounted than dismounted, programmes should be developed aimed at preventing MSK disorders caused by prolonged vehicle movements.