Material and Method: A prospective randomized controlled trial of knee osteoarthritis patients age more than 55 years undergoing total knee arthroplasty at Maharat Nakhon Ratchasima hospital from January 2011 through June 2012 was performed. A group receiving intra-operative periarticular injections was compared to a control group receiving no injections. Half of a group of forty-two patients, 2 males and 40 females, average age 67.9 years (range 57-84 years), were randomly assigned to receive the periarticular injection (the injection group), the others to the control group. Pain was measured by two methods: visual analog score at 6, 12, 24 and 48 hours post-operation and by patient controlled analgesia (PCA) measuring the daily amount of intravenous morphine used. The amount of blood loss post operation (in the redivac drain), degree of knee flexion, time to onset of assisted ambulation, length of hospital stay and any complications were also analyzed.

Results: The mean VAS at 6 and 12 hours post operation of the injection group were 2.67 and 2.48, whereas the values for the control group were 6.10 and 4.95, respectively (p<0.05). Mean quantities of morphine used by PCA by the injection group during the first day was 9.43 mg, significantly lower than the 18.81 mg used by the control group. Average blood loss of the injection group at 263.8 ml was also significantly below the 362.1 ml of the control group (p<0.05). The degree of knee flexion, time to onset of assist ambulation, length of hospital stay and complications, however, were not significantly different between the groups.

Conclusion: Multimodal drugs, periarticular injections consisting of diclofenac, adrenaline, Marcaine plus a patient controled anesthetic machine (PCA) with morphine can significantly reduce post-operative pain and blood loss in total knee arthroplasty without significant adverse effects.

Keywords: Periarticular injection, Multimodal drugs, Diclofenac, Total knee arthroplasty, Blood loss