INTRAARTICULAR INJECTION OF BUPIVACAINE IN KNEE-REPLACEMENT OPERATIONS - RESULTS OF USE FOR ANALGESIA AND FOR PREEMPTIVE BLOCKADE

The effectiveness of an intra-articular injection of bupivacaine, admi nistered before the incision or after closure of the wound, was studie d in an effort to decrease the need for postoperative narcotics and to improve analgesia for patients who have elective knee replacement. Ei ghty-two patients received two intra-articular injections in a random, double-blind fashion. Twenty-eight of them received thirty milliliter s of 0.5 per cent bupivacaine and 1:200,000 epinephrine in saline solu tion before the incision and an injection of thirty milliliters of pla in saline solution after closure of the wound (Group 1). Twenty-seven patients received an injection of thirty milliliters of plain saline s olution before the incision and thirty milliliters of 0.5 per cent bup ivacaine and 1:200,000 epinephrine in saline solution after closure of the wound (Group 2). Twenty-seven patients were given thirty millilit ers of plain saline solution (a placebo) for both injections (Group 3) , The patients who had received bupivacaine after closure of the wound (Group 2) used less morphine from the patient-controlled analgesia pu mps than the patients who had received bupivacaine before the incision (Group 1) and the patients who had received the placebo (Group 3). In the first twenty-four hours after the operation, the administration o f morphine (mean and standard deviation) was 59 +/- 27 milligrams for Group 2 compared with 68 +/- 30 milligrams for Group 1 (p = 0.26) and 81 +/- 30 milligrams for Group 3 (p = 0.006). At the time of discharge from the hospital, the patients in Group 2 also had a significantly g reater mean range of motion (85.2 +/- 8.0 degrees) compared with that of the patients in Groups 1 (80.6 +/- 6.8 degrees, p = 0.02) and 3 (80 .1 +/- 6.2 degrees, p = 0.009). However, there was no difference among the groups with respect to the effectiveness of the analgesia, as mea sured with use of either the visual-analog or the verbal pain-rating s cale, or in the prevalence of side effects, including somnolence, urin ary retention, nausea and vomiting, or pruritus, Serum concentrations of bupivacaine were well below toxic levels. It was our conclusion tha t that an intra-articular injection of thirty milliliters of 0.5 per c ent bupivacaine and 1:200,000 epinephrine in saline solution after clo sure of the wound decreases the need for narcotics and increases the r ange of motion after an elective knee replacement. The clinical import ance of the amount of increased motion is questionable and needs longe r-term monitoring.