BACKGROUND: Sarcopenia, an age-related loss of muscle mass and function, has been previously linked to an increased risk of morbidity, mortality, and infection after a variety of surgical procedures. This study is the first to evaluate the impact of the psoas-lumbar vertebral index (PLVI), a validated marker for central sarcopenia, on determining post-arthroplasty infection status. METHODS: This is a case-control, retrospective review of 30 patients with prosthetic joint infection (PJI) diagnosed by the Musculoskeletal Infection Society criteria compared to 69 control patients who underwent a total hip or knee arthroplasty. All patients had a recent computed tomography scan of the abdomen/pelvis to calculate the PLVI. PLVI was evaluated alongside age, gender, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists score, and smoking status to determine the predictive value for infection. RESULTS: Notably, the infected group had a large, significant difference in their average PLVI (0.736 vs 0.963, P < .001). The patient's PLVI was a predictor of infection status, with a higher PLVI being protective against infection (odds ratio [OR] 0.28, 95% confidence interval [CI] 0.109-0.715, P = .008). Additional predictors of infection status were higher American Society of Anesthesiologists score (OR 10.634, 95% CI 3.112-36.345, P < .001) and Charlson Comorbidity Index (OR 1.438, 95% CI 1.155-1.791, P = .001). Multivariate, binary logistic regression analysis confirmed that PLVI was a significant independent predictor of infection status (B = -0.685, P = .039). CONCLUSION: PLVI, a marker for central sarcopenia, was demonstrated to be a risk factor for PJI. Further research and consideration of sarcopenia as a screening and optimizable risk factor for total joint arthroplasty must be explored.