Do Medical and Recreational Marijuana State Laws Impact Trends in Postoperative Opioid Prescriptions Among Patients Who Have Undergone TJA?
Authors: Grant Andrew , Niu Ruijia , Michalowski Anna , Abdeen Ayesha , Smith Eric L. 
Published: February 2025

Background
Total joint arthroplasty (TJA) is a painful procedure frequently managed with opioid medication, which puts patients at risk for chronic opioid use. Marijuana is a pain modifier and may be an effector of opioid-use reduction. Recently, many states have legalized the use of medical and recreational marijuana, and these legalization events have correlated with reductions in opioid prescriptions. This trend has not yet been demonstrated in the context of orthopaedic surgery, and there is limited evidence overall investigating the effect of marijuana on perioperative opioid use in TJA.

Question/purposes
(1) Is legalization of medical marijuana associated with changes in perioperative opioid use in patients who have undergone TJA? (2) Is legalization of recreational marijuana associated with changes in perioperative opioid use in patients who have undergone TJA? (3) Are these changes observed in any specific subpopulations of patients who have undergone TJA?

Methods
The MarketScan Commercial and Medicare Supplemental Claims and Encounters Database was queried to assess the relative effect of marijuana legalization on perioperative opioid use in THA and TKA between May 1, 2017, and September 30, 2021, which was around and after the time that the opioid crisis was declared a public health emergency. We identified 129,132 inpatient TJA procedures (THA = 49,718, TKA = 79,414). The perioperative period was defined as 30 days before surgery and 90 days after surgery. We used the recreational and medical marijuana legalization effective dates in all 50 states and Washington, DC to conduct a difference-in-difference analysis to compare trends of outpatient opioid prescriptions among patients who underwent TJA in states with legalizations of medical or recreational marijuana with those among patients who underwent TJA in states without a change in marijuana legalization status.

Results
We observed no impact of medical marijuana legalization on morphine milligram equivalent (MME)/day (difference-in-difference change 4.38 [95% confidence interval (CI) -4.49 to 13.22]). However, recreational marijuana legalization implementation was associated with an increase in MME/day (difference-in-difference change 8.83 [95% CI 0.22 to 17.43]). When we looked at specific patient groups, the implementations of medical and recreational marijuana laws were both associated with increases in perioperative opioid prescriptions in women, while recreational marijuana legalization was associated with increased opioid use in patients undergoing TKA and patients without prior use of opioids.

Conclusion
We did not identify differences with respect to medical marijuana legalization implementation. However, we found that recreational marijuana legalization was associated with an increase in perioperative MME/day for TJA. This is important because surgeons in states with the implementation of recreational marijuana law should be aware of the potential for increased marijuana availability for their patients and how this may impact their postoperative course, particularly with respect to pain and opioid utilization.

Level of Evidence
Level III, therapeutic study.