Local infiltration analgesia (LIA) provides effective analgesia early after total knee arthroplasty but has limited efficacy after total hip arthroplasty, according to results of a systematic review.
“LIA should preferably be used in combination with evidence-based multimodal systemic analgesia,” Dr. Lasse O. Andersen from Bispebjerg Hospital in Copenhagen, Denmark told Reuters Health by email. “For hip arthroplasty, systemic analgesia will be adequate (this is well-documented) with no additional analgesic effect of LIA, but for total knee arthroplasty the analgesic effect of LIA is overall well-documented, even in combination with multimodal systemic analgesia.”
Previous studies have been limited by the lack of comparable systemic analgesia between groups that receive LIA and those that don’t, the researchers note. There have also been wide variations in the combinations of LIA techniques and drugs.
Dr. Andersen and Dr. Henrik Kehlet from Copenhagen University critically evaluated the analgesic efficacy of intraoperative LIA in total hip arthroplasty (THA) and total knee arthroplasty (TKA) in a systematic search and review of 27 randomized trials in the first 72 hours after surgery.
The studies included 888 TKA patients and 756 THA patients. Only two of the THA trials were considered to have a low risk of bias; the remaining eight had incomplete blinding or differences in systemic analgesia in the control and intervention groups. Among the 17 TKA trials, only two were considered to have a low risk of bias. The others suffered from the same problems as the THA trials with a high risk of bias.
Seven trials of LIA versus saline or no injection in THA patients showed no significant difference in pain scores when combined with a multimodal systemic analgesic regimen, according to the June 17 British Journal of Anaesthesia report.
In contrast, seven similar trials in TKA patients showed reduced pain scores and reduced opioid consumption in the first 32 hours after surgery in patients who received LIA.
Trials comparing LIA with peripheral nerve block (PNB) were confounded by the use of different techniques of PNB and different systemic analgesias between treatment groups.
The researchers said that the high risk of bias in trials comparing LIA with epidural analgesia, systemic analgesia, and intrathecal morphine limited the ability to reach definitive conclusions about efficacy.
Similarly, data on hospital length of stay were variable and appeared not to be related to the choice of analgesic technique in the trials that reported it.
“It would be helpful if clinical researchers provided similar analgesics to both/all study groups – the literature is confounded by administration of various analgesics (NSAID/steroids/opioids, etc.) with the local anesthetic/LIA solution and no control for this was provided in the control group in most studies,” Dr. Andersen said. “That makes it hard to decide whether intraoperative infiltration of local anesthetic in high volumes provides better analgesia than the treatment given to the control group.”
“In studies on postoperative pain, there is a need to minimize the confounding factors, because the level of postoperative pain is very different between individuals, so caution on confounding factors should be taken when designing future studies,” Dr. Andersen said.
“Finally,” Dr. Andersen said, “when assessing the effect of LIA on length of stay (LOS), future studies are required to analyze ‘why is the patient in hospital today,’ since our review clearly shows insufficient presentation of data and we summarize that LIA may not influence LOS, which depends on so many other factors than pain.”