Increased postoperative dexamethasone and gabapentin reduces opioid consumption after total knee arthroplasty.

PURPOSE

Dexamethasone and gabapentin are used in multimodal pain management protocols to reduce postoperative pain after total knee arthroplasty. For both analgesic adjuvants, the optimal dose regimen to reduce opioid usage is still unclear.

METHODS

The opioid consumption of patients undergoing primary TKA before and after a change of the analgesic adjuvant medication in our protocol (old protocol: 4 mg of dexamethasone daily for 2 days, 600 mg gabapentin daily for 1 week; new protocol: 10 mg dexamethasone daily for 2 days, 300 mg gabapentin every 8 h for 1 week) were retrospectively compared. All surgeries were performed under spinal anesthesia. Peri- and postoperative pain medication remained unchanged.

RESULTS

A total of 186 patients who received TKA between 11/29/2016 and 06/09/2017 were screened. Six patients who received general anesthesia, 4 patients who underwent simultaneous bilateral TKA, and 16 patients with ongoing opioid consumption at the time of surgery were excluded, leaving 80 patients in each group. Opioid consumption within 24 h [morphine equivalents in mg: mean 50.5, standard deviation (SD) 30.0 (old) vs. 39.8, SD 24.2 (new); P = 0.0470], cumulative consumption over 48 h (97.3, SD 64.4 vs. 70.4, SD 51.2; P = 0.0040) and cumulative consumption over 72 h (108.1, SD 79.5 vs. 82.5, SD 72.6; P = 0.0080), were all significantly lower in the new protocol.

CONCLUSION

Increased postoperative administration of dexamethasone and gabapentin after TKA is associated with lower opioid consumption. Within the first 48 h, up to about 25% of opioids can be spared, comparing high-dose to low-dose protocols.

LEVEL OF EVIDENCE

Therapeutic Level III.