Intraarticular vs. extraarticular ropivacaine infusion following high-dose local infiltration analgesia after total knee arthroplasty: a randomized double-blind study

Background and purpose

Ropivacaine infusion following high-volume local infiltration analgesia has been shown to be effective after total knee arthroplasty, but the optimum site of administration of ropivacaine has not been evaluated. We compared the effects of intraarticular and extraarticular adminstration of the local anesthetic for postoperative supplementation of high-volume local infiltration analgesia.

Patients and methods

In this double-blind study, 36 rheumatic patients aged 51–78 years with physical status ASA 2–3 who were scheduled for total knee arthroplasty were randomized into 2 groups. All patients received wound infiltration at the end of surgery with 300 mg ropivacaine, 30 mg ketorolac, and 0.5 mg epinephrine (total volume 156 mL). A tunneled catheter was randomly placed either extraarticularly or intraarticularly. Continuous infusion of ropivacain (0.5%, 2 mL/h) was started immediately and was maintained during the next 48 h. Pain intensity at rest, on movement, and with mobilization was estimated by the patients and the physiotherapist; rescue morphine consumption was recorded.

Results

As estimated by the patients, ropivacaine administered intraarticularly did not improve analgesia relative to extraarticular infusion, but improved the first mobilization. The incidence of high intensity of pain (VAS 7–10) was less in the group with intraarticular infusion. Analgesic requirements were similar in the 2 groups (47 mg and 49 mg morphine). No complications of postoperative wound healing were seen and there were no toxic side effects.

Interpretation

Continuous infusion of ropivacaine intraarticulary did not improve postoperative analgesia at rest relative to extraarticular administration, but it appeared to reduce the incidence of high pain intensity during first exercises, and could therefore be expected to improve mobilization up to 24 h after total knee arthroplasty.Pain after total knee arthroplasty is severe in two-thirds of patients (Bonica 1984, Beattie et al. 1997). The pain may be a result of trauma to the bone or soft tissues or a result of hyperperfusion after tourniquet release (Estebe et al. 1995). The optimal form of pain relief is one that is applied preoperatively, perioperatively, and postoperatively to avoid the establishment of pain hypersensitivity (Badner et al. 1996). Good pain relief allows effective postoperative rehabilitation (Shoji et al. 1990). In contrast to epidural analgesia and femoral block, an alternative method to achieve good postoperative pain relief is local infiltration combined with single-shot injection or continuous infusion of local anesthetics into the surgical site. Local anesthetic infiltration is helpful in the management of postoperative pain after several orthopedic procedures (De Andres et al. 1993). The use of intraarticular analgesia to limit postoperative pain following knee arthroplasty has been investigated, with different results (Smith et al. 1991, Allen et al. 1993, Osborne and Keene 1993, Badner et al. 1996, Mauerhan et al. 1997, Ritter et al. 1999).A local infiltration analgesia (LIA) technique was developed by Kerr and Kohan in Sydney, Australia (Rostlund and Kehlet 2007, Kerr and Kohan 2008). With this technique, the long-acting local anesthetic ropivacaine, a non-steroidal anti-inflammatory drug (ketorolac), and epinephrine are infiltrated periarticulary during surgery. An alternative technique that might have widespread applicability is the insertion of catheters to allow continuous infusion of local anesthetics into the surgical wound at the end of the procedure. There is a need for detailed systematic studies to evaluate the optimal site of administration of local anaesthetics. In this randomized, double-blind study, we compared the analgesic effects of continuous infusion of local anesthetics either intraarticulary or extraarticulary after TKA using the LIA technique.