Pain therapy following joint replacement.A randomized study of patient-controlled analgesia versus conventional pain therapy.

A prospective randomized trial in 42 patients undergoing elective total hip or knee arthroplasty under general anaesthesia was carried out to evaluate the efficacy of patient-controlled analgesia (PCA) versus demanded conventional pain therapy (CPT) for controlling postoperative pain. Four patients had to be excluded from the study (2 postoperative confusion, 1 elevated piritramid dosage caused by chronic pain therapy, 1 stressed by PCA pump handling). PCA group (n = 19) received piritramid via PCA pump, CPT group (n = 19) received tramadol (oral or intramuscularly) or piritramid intravenously. PCA or CPT was started in the intensive care unit. Pain was measured with a standard 100 mm visual analogue scale (VAS) for 60 h postoperatively. Over this period of time, no significant differences were found in the pain score of both groups, nor did the incidence of side-effects differ significantly. The PCA group required on average twice as much piritramid-equivalent than the CPT group (P < 0.001). Patient satisfaction was good in both groups, but significantly better in the PCA group (P < 0.01), although the measured postoperative individual pain scores were above the preoperatively determined individual subjective pain threshold in the majority of both groups. From these results we draw the conclusion that even if the patients feel satisfied by the pain therapy administered, the majority are objectively treated below their individual subjective pain threshold.