Two techniques of postoperative analgesia for primary total knee arthroplasty were compared retrospectively. Twenty-four patients received a femoral nerve catheter with continuous infusion of ropivacaine (FNC group), whereas 26 patients received intravenous (IV) opioids (IV opioid group). Pain and rehabilitation scores and hospital length of stay (LOS) were compared. On the first postoperative day, both groups reported similar pain scores. After 4 sessions of twice-daily rehabilitation, the FNC group used less IV patient-controlled opioids (29.1% vs 84.5%, P = .0001) and demonstrated better performance with knee flexion and mobility. Hospital LOS was significantly less in the FNC group (3.6 vs 4.2 days, P = .034). Femoral nerve catheters with continuous infusion of ropivacaine provide satisfactory analgesia, improve rehabilitation, and shorten hospital LOS.