The factors associated with prosthetic joint infection for 126 patients in a case-control study were as follows: bacteremia during the previous year (odds ratio [OR], 4.25 [95% confidence interval {CI}, 1.3–3.8]), nonsurgical trauma to the prosthetic joint (OR, 21.5 [95% CI, 2.6–175.2]), and surgical site infection (OR, 5.25 [95% CI, 1.7–16.7]).