Background: Mesenchymal stem cells can be differentiated into muscle satellite cells. Testosterone replacement therapy (TRT) promotes the differentiation of satellite cells into muscle cells.
Case report: A 31-year-old male with a T4 complete chronic spinal cord injury (SCI) had fixation for a mid-shaft fracture of the left femur. The participant received transdermal testosterone patches (4 mg/day) daily for 16 weeks. Skeletal muscle and yellow bone marrow adiposity cross-sectional areas (CSAs) of both thighs were measured using magnetic resonance imaging.
Clinical rehabilitation impact: The yellow bone marrow CSA was 67-69% lower in the left femur compared to the right femur. Following intervention, a discrepancy was noted between the whole skeletal muscle CSAs of the right (+13%) and left (+6%) thighs. The right knee extensor CSA increased by 7% with no changes in the left CSA. Disruption in bone marrow fat may attenuate the systemic effects of TRT on muscle size.