Cannabis Use Among Lower-Extremity Arthroplasty Patients Does Not Lead to Worse Postoperative Outcomes

Smoking and general categorizations of substance use are linked with increased postoperative complications following total knee arthroplasty (TKA) and total hip arthroplasty (THA). There is a lack of similar evidence on how cannabis use may affect outcomes after arthroplasty. The present study aims to compare postoperative outcomes in cannabis users versus non-cannabis users who underwent THA/TKA. We hypothesize that cannabis users will have no difference in primarily the complication rate, revision rate, and secondarily post-operative Patient-Reported Outcomes Information System (PROMIS) scores, hospital stay, or pain compared to matched controls.

Billing codes were used to generate lists of hip/knee arthroplasty patients from 2013 to 2019 at our institution. In the case group, cannabis use was confirmed via chart review. Cannabis-using patients were matched appropriately with non-users by (1) the same arthroplasty procedure; (2) BMI ± 3.5; (3) age ± 3 years; (4) sex. Data on postoperative outcomes were collected from charts and compared between groups using either a Chi-square test for qualitative variables or a paired t-test for quantitative variables.

A total of 24 patients with an average age of 57.1 and a BMI of 30.6 were confirmed to have isolated cannabis use. They were matched to 24 patients with an average age of 57.6 and a BMI of 31.4. There were no significant differences in the complication rate (4.2% vs 4.2%, p=1.00), the revision rate (0% vs 4.2%, p=0.31), days of hospital stay (2.7 vs 3.3, p=0.22), or postoperative pain (4.7 vs 4.9, p=0.86). Similarly, there were no significant differences in all PROMIS score measures.

Current research shows that cannabis use may lead to increased revision arthroplasty and decreased mortality, with mixed findings regarding post-surgical complications. The present study suggests that cannabis-using patients have no difference in postoperative complication rate, revision rate, PROMIS scores, hospital stay, or pain compared to matched controls.