Interlimb muscle and fat comparisons in persons with lower-limb amputation.

Abstract

To investigate differences in muscle and fat tissue between amputated and intact limbs in subjects with transfemoral and transtibial amputations and to determine the effect of amputation level on limb differences. We hypothesized that the amputated limb would have a higher relative amount of fat than the intact limb, and transfemoral amputees would have greater limb differences in muscle size than transtibial amputees. Cross-sectional, repeated-measures design. Laboratory. Subjects included persons with unilateral transfemoral (TF) (n=5) and transtibial (TT) (n=7) amputations and age- and sex-matched nonamputation controls (n=12). Not applicable. Muscle cross-sectional areas and fat cross-sectional areas of the end of residual limbs were compared with similar cross-sectional sites of the intact limb by using peripheral quantitative computed tomography scans. Thigh and lower-leg fat mass (FM) and bone-free lean body mass were measured by dual-energy x-ray absorptiometry. There was a 93% to 117% difference between limbs in muscle cross-sectional areas for TF and TT. TT had a between-limb difference of 39% for fat cross-sectional areas. Thigh bone-free lean body masses and FM were significantly (P<.05) lower for the amputated limb for both TF and TT. Thigh percent fat was significantly (P<.05) higher in the amputated thigh for TF and TT, but limb differences were greater in TF. Muscle atrophy was prevalent in the residual limb with larger relative amounts of fat in the thighs, especially in TF subjects.