Bone Mineral Density and Associated Factors in Individuals with Traumatic Unilateral Transfemoral Amputation

Introduction/background: Lower extremity amputations, particularly at more proximal levels such as transfemoral amputations (TFA)s, negatively affect bone mineral density (BMD). The aim of this study was to determine the relationship between muscle strength, residual limb length (RLL), and BMD on the amputated side in individuals with traumatic unilateral TFA and to investigate other potentially related factors.

Methodology: This is a retrospective, cross-sectional study. The study included 39 individuals with TFA. Demographic and clinical data of the individuals were recorded. RLL was determined by measuring the distance from the trochanter major to the most distal end point of the stump. Hip flexor and extensor muscle strengths were assessed by determining peak torque at an angular velocity of 60°/s using an isokinetic system. Dual-energy X-ray absorptiometry (DXA) imaging T-scores of the femoral neck and lumbar spine on the amputee side were evaluated.

Results: There was a statistically significant relationship between peak hip flexion torque and RLL with the femoral neck BMD T-score (r = 0.327*, p = 0.045; r = 0.432*, p = 0.006, respectively). RLL and peak hip flexion torque were identified as determinants of femoral neck BMD T-score (p = 0.004, p = 0.031, respectively). It was found that for every 1 cm increase in RLL, the femoral neck BMD T-score increased by approximately 0.09. A one-unit increase in peak hip flexion torque was associated with an approximate increase of 0.04 in the ipsilateral femoral neck BMD T-score.

Conclusions: In the rehabilitation program of individuals with unilateral TFA, it may be important to plan hip flexor muscle strengthening interventions that may affect BMD. Performing amputation surgeries while preserving RLL at the longest possible length may be beneficial in terms of BMD results on the amputated side.