Osteoporosis and body composition in old patients with amputated lower limbs

The study aim was to investigate bone mineral density (BMD) and body composition in old patients with amputated lower limbs. Materials and methods . This work is a cross-sectional study, which enrolled 31 patients, who underwent amputation of one of the lower extremities. The mean age of the study patients was 73.4±9.0 years, ranging from 60 to 101 years. The majority of study patients were men (77.4%). 41.4% of patients underwent amputation of the left lower limb, 58.6% – right. The time from amputation to enrollment in the study ranged from 4 to 444 months, with a median of 30 months. Bone mineral density in the lumbar spine and proximal femurs was analyzed by dual energy x-ray absorptiometry. Results. Osteoporosis in the proximal part of the left femur was registered in 51.7% of patients, osteopenia – in 17.2%, normal BMD – in 31.1% of cases. Osteoporosis in the proximal part of the right femur was observed in 64.0% of patients. In the lumbar spine, osteoporosis was found only in 6.9% of patients. The mean T-score in the lumbar spine reached +0.38 SD, in the proximal left femur – -1.5 SD, in the left femur neck – -2.1 SD, in the proximal right femur – -2.0 SD, in the right femur neck – -2.1 SD. In the case of amputation of the left lower limb, the left femur BMD averaged 710.8±239 mg/cm3, the left femur T-score – -2.6±1.6SD, the T-score in the left femur neck – –3.0±1.3 SD, with the intact left leg – 980.1±194 mg/cm3,–0.8±1.5SD,–1.5±1.2SD, respectively (p=0.002, p=0.005 and p=0.006). In case of amputation of the right lower limb, the right femur BMD reached 743.8±268 mg/cm3, right femur T-score – -2.4±1.7SD, the T-score in the right femur neck – -2.4±1.7SD, with the intact right leg – 909.9±211.0 mg/cm3, -1.2±1.5SD, -1.5±1.5SD, respectively (p=0.09, p=0.06 and p=0.1). The likelihood of developing osteoporosis in the left femur with amputation of the left leg increased by 9.8 times, compared with patients who had a preserved left lower limb (odds ratio=9.8; 95% CI=1.1–93.5; p=0.02). In patients with amputation of the left leg, inverse correlation was registered between bone mineral density and the time from the moment of amputation to inclusion in the study (r= -0.65, p=0.03). Conclusion. Preliminary results of this study demonstrate a decrease in bone mineral density in the proximal femur of the amputated limb. Further studies are needed to study BMD in amputees and to elucidate the pathogenetic basis of the relationship between BMD and other clinical and laboratory parameters in this group of patients.