Impact of Unilateral Transfemoral Amputation on Lumbar Bone and Muscle Quality.

Objective: The aim of the study was to examine the long-term perioperative changes in lumbar bone density, muscle size and fatty atrophy, and facet degeneration after transfemoral amputation.

Methods: All patients who underwent transfemoral amputation at an academic center between 2002-2022 were retrospectively identified. Patients were required to have preoperative and postoperative computed tomography (>1 yr) and regularly utilize a prosthesis. Preoperative to postoperative changes in lumbar and muscular vertebral Hounsfield units, facet degeneration, and bilateral psoas, quadratus lumborum, multifidus, and erector spinae cross-sectional area were determined.

Results: A total of 42 patients met the inclusion criteria. There were significant preoperative to postoperative decreases in Hounsfield units in the L1 and L3 vertebral bodies were -17.69 and -25.35, respectively. There were significant preoperative to postoperative increases in L4-5 and L5-S1 facet degeneration grade. There were significant preoperative to postoperative decreases in amputated side psoas Hounsfield unit and cross-sectional area. There were also significant preoperative to postoperative Hounsfield unit decreases in the bilateral multifidus and erector spinae muscles, where the changes were more pronounced on the contralateral side.

Conclusions: Transfemoral amputation was associated with progression of lumbar facet degeneration, small scale decreases in lumbar bone quality, amputated side psoas atrophy, and bilateral fatty infiltration of the multifidus and erector spinae.