Local anaesthetic infiltration added intraoperatively to standard care provides significant improvement of long-term pain relief for patients with chronic post-surgical pain after total hip replacement, according to research presented at the World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (WCO).
The same effect is not observed for total knee replacement.
Rachael Gooberman-Hill, PhD, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom, presented results from 2 double-blind, single-centre trials here on March 27. “About 1 in 10 patients who has total hip replacement, and 1 in 5 patients who has total knee replacement, has long-term pain afterwards,” stated Dr. Gooberman-Hill.
Severe acute post-operative pain is a predictive risk factor for chronic post-surgical pain, and local anaesthetic infiltration has been shown to reduce acute post-operative pain. Dr. Gooberman-Hill and colleagues decided to determine whether local anaesthetic infiltration reduces pain at 12 months after primary total hip replacement and after total knee replacement.
In the first study, researchers randomised 322 patients waiting for primary total hip-replacement surgery 1:1 to standard care without or with local anaesthetic infiltration. The second study similarly randomised 316 patients recruited from pre-operative clinics who were waiting for total knee replacement.
Standard care involved spinal anaesthetic and sedation or general anaesthetic for total hip replacement, and femoral-nerve block and sedation or general anaesthetic for total knee replacement. The intervention group in each study received standard care plus local anaesthetic infiltration, as 60 mL bupivacaine 0.25% with adrenaline (epinephrine) 1:200,000 intraoperatively.
The primary outcome was Western Ontario McMaster (WOMAC) pain score at 12 months following the primary operation.
For the total hip replacement study, there was a significant between-group difference in favour of the intervention for the mean WOMAC pain score at 12 months (4.47; P = .015). Patients with local anaesthetic infiltration were more likely to experience none, mild, or moderate pain instead of severe or extreme pain at 12 months, compared with standard care alone (odds ratio, 10.19; P = .004). The range of secondary outcomes included acute post-operative pain severity, analgesia, joint function and pain, neuropathic pain, and adverse events. For total hip replacement, the only beneficial indication was for neuropathic pain 12 months post-operatively, which was significantly less severe in the intervention group compared with standard care alone (relative risk, 0.17; P = .021).
“In the knee replacement [study], we found no strong evidence of an effect of the intervention on the primary outcome, or on any secondary outcomes,” Dr. Gooberman-Hill noted. The between-group difference did not reach significance in favour of the intervention for the mean WOMAC pain score at 12 months (difference in means 3.83; P = .107).
“We would suggest that there is a use for local anaesthetic infiltration at the time of hip-replacement surgery,” she concluded.
Funding for this analysis was provided by the National Institute for Health Research (NIHR), Twickenham, England, under its Programme Grants for Applied Research programme.