Association between combat-related traumatic injury and skeletal health: bone mineral density loss is localised and relates to altered loading in amputees – The ADVANCE Study

Louise McMenemy, Behan FP, Kaufmann J, Cain D, Bennett AN, Boos C, Fear NT, Cullinan P, Bull AMJ, Phillips ATM, McGregor AH

Academic Department of Military Trauma and Surgery, Birmingham

A disproportionate number of young lower-limb amputees are diagnosed with osteopenia/osteoporosis, increasing lifetime risk of fragility fracture and challenging traditional osteoporosis treatment paradigms. The association between traumatic injury, amputation, and bone health is uncertain. The aim was to test the hypothesis that trauma results in a systemic reduction in Bone Mineral Density (BMD), as well as a localised BMD reduction in the amputated limb of lower limb amputees, that is progressively greater with higher level amputations.

Cross-sectional analysis of a cohort study comprising 579 male adult UK military personnel with combat related traumatic injury (CRTI) (including 153 lower limb amputees) and 565 frequency-matched uninjured men. BMD was assessed using DEXA scanning of the hips and lumbar spine.

Femoral neck BMD was lower in the CRTI than the uninjured group (T-score -0.08 vs -0.42 p=0.000). Subgroup analysis revealed this reduction was significant only at the femoral neck of the amputated limb of amputees (p=0.000), where the reduction was greater for above knee amputees than below knee amputees (p=0.037). There were no differences in spine BMD.

Changes in bone health appear to be mechanically driven rather than systemic and are only evident in those with lower limb amputation. This may arise from altered joint and muscle loading creating a reduced mechanical stimulus to the femur which we propose is an unloading osteopenia. This diagnostic distinction may prevent inappropriate use of systemic treatment and will, we hope, drive research into the ideal loading environment to potentially reverse BMD changes.