<i>In vitro</i> experiments were conducted using apoptotic muscle satellite cells (MuSCs) conditioning medium to evaluate its effects on FAP activation and adipogenic differentiation.<h4>Results</h4>Preoperative muscle fat infiltration (MFI), C-reactive protein (CRP) level, and concurrent meniscus repair were independent predictors of quadriceps atrophy at 3 months post-ACLR. The gene discussed is FAP; the disease is medical procedure.