Background Total knee arthroplasty (TKA) is a common surgical procedure in patients with end-stage osteoarthritis to reduce pain and improve locomotor function. However, TKA may result in severe postoperative pain, usually requiring hospitalization from 5 to 10 days to provide effective analgesia (1). Local infiltration analgesia (LIA) is a simple technique for the treatment of postoperative pain after TKA. However, the specific efficacy of LIA has been confounded by frequent limitations in study design (2).

Objectives To investigate the efficacy of LIA in patients with TKA.

Methods The study was designed as a randomized double blind placebo control trial. A total of 63 patients with primary total knee arthroplasty were randomized either to receive a periarticular local infiltration analgesia or to receive placebo injection (63 patients: 57 knee in LIA group, 44 knee in placebo group). Pain intensity, active range of motion, knee function score [Hospital for Special Surgery (HSS) score] and length of hospital stay (LOS) were evaluated. Functional activities were evaluated using the Iowa Level of Assistance Scale, and walking speed was evaluated using the Iowa Ambulation Velocity Scale. The dates of ability to perform straight leg raise actively and to reach 70° of knee flexion were recorded. Patients and investigator were blinded the groups.

Results There were no significant differences between the groups for demographic characteristic. Lower pain scores were recorded on postoperative day 1 and postoperative day 2 after the operation in Group LIA (p<.0001 and p=0.022, respectively). Higher range of motion of knee flexion and extension postoperative day 1 and postoperative day 2 in Group LIA (Flexion:p=0.004 and p=0.020, respectively; extension: p=0.028 and p=0.022 respectively). There were also a significant differences in terms of the date of 70° knee flexion reach (p=0.034) and ability to perform straight leg raise actively in favour of Group LIA (p=0.034). There was no significant difference between the groups in the HSS score, Iowa Level of Assistance Scale, Iowa Ambulation Velocity Scale and LOS.

Conclusions Andersen and Kehlet reported that LIA significantly reduced pain intensity, specifically during standing and walking up to 48 h after operation. Our results suggest that LIA significantly reduced pain intensity in early postoperative day. This results are corroborate with Andersen and Kehlet's study (2). We also have found a better recovery of knee flexion immediately after operation. Possible mechanisms of better recovery of knee flexion could be lower pain scores. Patients with lower pain scores can also perform earlier straight leg raise. However, LIA technique did not provide additional impact on LOS because LOS depends on many other factors. In conclusion, LIA significantly reduced pain intensity, improve recovery of active range of motion but did not provide additional impact on LOS compared with placebo injection in patients with TKA.

1. Kerr, DR, & Kohan, L. (2008). Local infiltration analgesia: a technique for the control of acute postoperative pain following knee and hip surgery: a case study of 325 patients. Acta Orthopaedica, 79(2), 174–183.

2. Andersen, LØ, & Kehlet, H. (2014). Analgesic efficacy of local infiltration analgesia in hip and knee arthroplasty: a systematic review. British journal of anaesthesia, aeu155.

Disclosure of Interest None declared