Total knee arthroplasty(TKA) is a major surgery and the postoperative pain can be severe. Inadequate pain relief may lead to delayed mobilisation, greater risk of developing deep vein thrombosis, coronary ischemia, poor wound healing, longer hospital stay and decreased patient satisfaction. Severe postoperative pain also increase the risk of developing long term persisting pain. Conventional pain managements with intermittent parenteral opioids and non-steroid anti-inflammatory drugs have been proved to be less effective and are often lead to unwanted side effect. Currently, there is a trend to use multimodal pain management to minimize narcotic consumption and to avoid narcotic-related side effects. The use of transdermal opioid patch has not been well established. The purpose of this study was to investigate the analgesic effects of various transdermal non-opioid patches in patients after elective total knee arthroplasty in a prospective, randomised control trial.

After receiving Institutional Review Board approval, 89 patients(89 knees) received primary unilateral total knee arthroplasty were included in this study. All patients were randomly allocated into three groups. The 3 groups were demographically similar for sex, age, and body mass index. They received patches with 5% lidocaine, flurbiprofen and only vehicle patches without any medication. The patches were placed on the tourniquet area postoperatively, then on patient-directed area of discomfort every 6–8 hours. Each patient received the same standard postoperative analgesics including single intra-articular injection, NSAID, acetaminophen, and rescue opioids as needed. All patients were interviews everyday and the primary outcome was the visual analog scale. Besides, consumption of rescue opioids, progress of active movement, and inpatient stay were also recorded. Our hypotheses were transdermal non-opioid patches would provide effective pain relief and reduce the consumption of opioids as well as their side effects.

There were 30, 29, and 30 patients in group I, II and III. The mean ischemic time(tourniquet time) was 56.0, 61.4, 55.5 minutes, respectively. The narcotics consumptions were 11.77, 20.12, and 15.57 mg, respectively. The day achieved active flexion to 90 degrees were 1.83, 1.97, and 2.03 days, respectively. The inpatient stay was 6.47 days for group I patients, 6.81 days for group II patients, and 6.77 days for group III patients. The mean episodes of breakthrough pain(VAS>4) were 3, 3, and 3.7 times, respectively. There was no related adverse effects occurred with the use of non-opioid trasndermal patches.

Compared to placebo group, favourable results were noted in non-opioid transdermal patches, including opioid consumption, active knee flexion, inpatient stay and episodes of breakthrough pain in spite of insignificant statistical difference. High satisfaction without any complication were noted. Besides, non-opioid transdermal patches are also cost effective. There were only a few literature discussing about non-opioid patches in patients with total knee arthroplasty. The results showed indifferent pain improvement and no significant additional pain relief. Our results were compatible with current related studies, which showed no significant improvement. This is the first study to compare the analgesic efficacy of different non-opioid tansdermal patches in a prospective randomised trial.