Introduction

Recent legalization of medical and recreational cannabis use in the United States and Canada has lead to rapidly increasing cannabis use. Cannabis use rates are approaching those of tobacco in North America, and use has surpassed that of tobacco in certain age groups. However, there is little data that examines the relationship between cannabis use and outcomes, complications, and total cost following knee arthroscopy. Additionally, while opioid use and abuse has become an epidemic, there is little data on how concurrent cannabis use influences opioid consumption following knee arthroscopy. We hypothesized that there would be no difference between cannabis users and nonusers on knee arthroscopy complications, cost, or opioid use.

Methods

Data was collected from a large commercial insurance database (PearlDiver, USA) between the years 2010-2019. Patients who underwent knee arthroscopy with reported cannabis use were identified using Common Procedural Terminology (CPT) codes and the appropriate International Classification of Diseases (ICD) codes. This group was then matched by age, procedure, gender, Charleston Comorbidity Index (CCI), Elixhauser Comorbidity Index (ECI), obesity, tobacco use, diabetes to a group of similar patients without self-reported cannabis use. Opioid use over the episode of care, evaluated by morphine milligram equivalents (MME), and 30-day cost were compared between groups using unequal variance t-test. Complication rates between groups were examined using odd’s ratio (OR).

Results

A total of 8190 patients (56% male and 44% female) were included in the cannabis use and no cannabis use groups, respectively. Patients with reported cannabis use received significantly fewer postoperative opioids on average (1710 +/- 3292 MME) than those without cannabis use (2253 +/- 5010 MME) (p< 0.0001). At 30 days after knee arthroscopy, cannabis users had significantly fewer deep vein thrombosis (DVT) (OR 0.636 [95%CI 0.492-0.823]; p<0.001) and pulmonary emboli (PE) (OR 0.362 [95%CI 0.217-0.605]; p<0.001), which was significant at 90 days postoperatively for both DVT (OR 0.715 [95%CI 0.577-0.888]; p=0.002) and PE
(OR 0.414 [95%CI 0.271-0.636]; p<0.001). The 10 day mortality rate was significantly higher in cannabis users (OR 3.207 [95%CI 1.156-6.528]; p=0.001). Patients who use cannabis have a slightly, but statistically significantly higher 30-day cost after knee arthroscopy ($1637 +/- $2177) than those without reported use ($1517 +/- $1805) (p < 0.0001).

Conclusion

Following knee arthroscopy, patients with cannabis use receive fewer prescription opioid medications. Cannabis use is associated with lower 90-day risk for DVT and PE, but also increased risk of 10-day mortality. Patients with cannabis use have a small, but higher cost for the knee arthroscopy episode of care.