The purpose of this study is to investigate the outcome of one-stage and two-stage exchange arthroplasty for the management of patients with chronic PJI. The hypothesis of this study is that one-stage exchange arthroplasty, if performed in the appropriate patient population, carries a similar success rate for the treatment of chronic PJI as two-stage exchange arthroplasty and avoids many of the problems associated with two-stage exchange arthroplasty.