Purpose: Total knee arthroplasty (TKA) is associated with moderate to severe postoperative pain. This study evaluates the technique of local infiltration analgesia (LIA), by comparing it to saline injections in addition to a standardized multimodal regimen including an adductor canal block.
Methods: Between September 2015 and March 2016, forty patients aged 18 years and older, ASA I-III, undergoing primary unilateral cemented TKA under spinal anesthesia were randomized to receive either LIA (LIA group) or normal saline (sham LIA group). Morphine consumption during the first 24 postoperative hours, time to first IV morphine dose request, pain intensity at rest and passive knee flexion, complication rates, patient satisfaction and duration of hospitalization were documented (Clinicaltrials.gov, identifier: NCT03206554).
Results: Compared with the sham LIA group, the LIA group showed statistically significant lower morphine consumption at all times (6, 12, 18, 24 h-P value: 0.035, 0.008, 0.015 and 0.003, respectively). Time to first IV morphine dose request did not differ significantly between groups (P = 0.902). The intergroup difference in NRS pain scores was statistically significant, with the LIA group showing lower resting and dynamic pain scores in all instances and additionally higher patient satisfaction. The groups did not differ in terms of complication rates and duration of hospitalization.
Conclusions: Performing LIA in addition to a standardized multimodal analgesia regimen results in superior pain control, demonstrated as reduced opioid needs and lower resting and dynamic pain intensity scores on the first postoperative day after TKA. Further studies are needed to establish an LIA protocol that could maximize postoperative pain control.
Keywords: Analgesia; Knee replacement arthroplasty; Local infiltration analgesia; Regional anesthesia.