Reduction of Opioid Quantities at Discharge After TKA Did Not Increase the Risk of Manipulation Under Anesthesia: An Institutional Experience

In response to the opioid epidemic, our arthroplasty service sequentially reduced the opioid quantities prescribed at primary total knee arthroplasty (TKA) discharge. However, its effect on postdischarge pain control and rehabilitation is unknown. We assessed if this decrease was associated with an increase in the risk of manipulation under anesthesia (MUA).

We retrospectively reviewed 8799 patients undergoing primary TKA from 2016 to 2019 at a single institution. There were two institution-wide reductions in the amount of opioids prescribed at discharge; therefore, we divided patients into 3 periods (P1, P2, and P3). The mean discharge morphine milligram equivalents (MMEs) went from 900 MMEs to ~525 MMEs to ~320 MMEs in P1, P2, and P3, respectively. We analyzed MUA rates and if lower discharge MMEs was a risk factor for MUA in a multivariate model. We also compared refill patterns (rates, number, refill MMEs, and total MMEs) between MUA and non-MUA patients.

The rate of MUA did not increase with reduced discharged opioids (5.5% in P1, 5.8% in P2, and 4.6% in P3, P = .74). In a multivariate analysis, discharge MMEs of <450 was not a significant risk factor for MUA. However, a diagnosis of chronic pain (OR = 1.86, P < .001) and an elevated body mass index (OR = 1.02 per unit increase, P < .001) were significant risk factors. We did not find significant differences in any opioid prescription refill patterns in MUA and non-MUA patients.

Serial reductions in discharge MMEs after primary TKA did not significantly affect the rate of MUA, a surrogate marker for pain control and the rehabilitative process.