Cannabis Use Disorder Associated With Increased Risk of Postoperative Complications After Hip or Knee Arthroplasties: A Meta-analysis of Observational Studies.

INTRODUCTION With the legalization of marijuana in the United States, the number of patients with cannabis use disorder (CUD) in the joint arthroplasty population has increased markedly. The primary purpose of this meta-analysis was to determine whether there were differences in clinical and economic outcomes after total joint arthroplasty (TJA) between patients with and without perioperative CUD. METHODS We searched PubMed, Embase, Scopus, and Web of Science databases up to July 2018 to identify all eligible studies investigating the association of CUD with postoperative outcomes in patients undergoing TJA. Postoperative outcomes assessed consisted of complications, readmission, length of stay (LOS), implant revision, and cost of care. For dichotomous outcomes, pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using a random effects model. RESULTS We identified 10 retrospective cohort studies with a total of 17,981,628 study participants. Patients with CUD had significantly higher odds of medical complications (OR 1.33 [95% CI 1.07 to 1.66], P = 0.01) and implant-related complications (OR 1.75 [95% CI: 1.64 to 1.88], P < 0.00001) than noncannabis users. Specifically, CUD was associated with significantly increased odds of cardiac complications (OR 1.95 [95% CI 1.50 to 2.54], P < 0.00001), cerebrovascular accidents (OR 2.06 [95% CI 1.66 to 2.57], P < 0.00001), postoperative infections (OR 1.68 [95% CI 1.34 to 2.10], P < 0.00001), periprosthetic fracture (OR 1.42 [95% CI 1.19 to 1.70], P < 0.0001), mechanical loosening (OR 1.54 [95% CI 1.42 to 1.66], P < 0.00001), and dislocation/instability (OR 1.88 [95% CI 1.32 to 2.68], P = 0.0005). Longer LOS and higher cost of care were also found in patients with CUD. CONCLUSION This study strengthens the body of evidence that patients with CUD face higher risk of postoperative complications and greater financial burden after knee and hip arthroplasties. Physicians should inform patients about adverse outcomes and undertake appropriate risk adjustments before elective orthopaedic surgery. LEVEL OF EVIDENCE Level III.