Preoperative dexamethasone for pain relief after total knee arthroplasty：A randomised controlled trial
BACKGROUND: Corticosteroids can reduce pain but the optimal dose and safety profiles are still uncertain.
OBJECTIVE: This study aimed to evaluate two different doses of dexamethasone for pain management and their side effects after total knee arthroplasty.
DESIGN: A prospective randomised, controlled trial.
SETTING: A tertiary teaching hospital in Hong Kong.
PATIENTS: One hundred and forty-six patients were randomly allocated to one of three study groups.
INTERVENTIONS: Before operation, patients in group D8,D16 and P received dexamethasone 8 mg, dexamethasone 16 mg and placebo (0.9% saline), respectively.
MAIN OUTCOME MEASURES: The primary outcome was postoperative pain score. Secondary outcomes were opioid consumption, physical parameters of the knees and side effects of dexamethasone.
RESULTS: Compared with placebo, group D16 patients had significantly less pain during maximal active flexion on post-operative day 3[-1.3(95%CI，2.2~0.31)，P=0.005].There was also a significant dose-dependent trend between pain scores and dexamethasone dose (P=0.002). Compared with placebo, patients in group D16 consumed significantly less opioid [-6.4 mg (95% CI, -11.6 to -1.2), P=0.025] and had stronger quadriceps power on the first three postoperative days (all P<0.05). They also had significantly longer walking distance on postoperative day 1 [7.8 m ([95% CI, 0.85 to 14.7),P=0.023] with less assistance during walking on the first two postoperative days (all P<0.029) and significantly better quality-of-recovery scores on postoperative day 1 (P=0.018). There were significant dose-dependent trends between all the above parameters and dexamethasone dose (all P<0.05). No significant differences were found in the incidence of chronic pain or knee function 3, 6 and 12 months postoperatively.
CONCLUSION: Dexamethasone 16 mg given before total knee arthroplasty led to a reduction in postoperative pain, less opioid consumption, stronger quadriceps muscle power, better mobilisation and better overall quality-of-recovery after operation. No long-term improvement in reduction in pain and function of the knee was found.