1 Introduction

The legalization and increasing social acceptance of cannabis have led to a significant rise in its use among patients undergoing elective surgical procedures, including total joint arthroplasty (TJA). Estimates suggest that up to one-third of orthopaedic patients report cannabis use, often for chronic pain relief or recreation.^1–5 Despite this growing prevalence, the impact of cannabis use, both tetrahydrocannabinol (THC) and cannabidiol (CBD), on surgical outcomes remains controversial in orthopaedics.^6–15

Cannabis use may alter surgical outcomes due to its effects on pain perception, immune modulation, and coagulation. Several studies have suggested an association between cannabis use and increased complications, including thromboembolic events, infections, and implant-related failures.^16–18 Other studies report no significant differences in perioperative outcomes when comparing cannabis users to matched non-users.^6,15,19,20 Notably, multiple meta-analyses have reported an increased risk of revision and deep vein thrombosis (DVT) following TKA in cannabis users, whereas findings for THA outcomes have been more variable.^12,16

Prior literature on opioid consumption in this population is similarly inconsistent. While some studies suggest cannabis use may reduce opioid needs postoperatively, others have shown increased opioid consumption and pain scores in cannabis users.^{1,4,6,7,10,11,13,14,16,18–25}

Outcomes specific to THA and TKA have not been independently stratified in most large studies, limiting clinical applicability. Given the limitations and heterogeneity of outcomes reported in the literature, our study sought to evaluate short- and mid-term postoperative outcomes in cannabis users undergoing TJA, using a large, nationally representative database.

2 Methods

This retrospective cohort study used the TriNetX Research Network, a national database containing de-identified patient-level data from 106 healthcare organizations worldwide. Due to the absence of individually identifiable data, this study was exempt from Institutional Review Board approval. Patients who underwent primary THA or TKA between February 24, 2003, and February 24, 2023 were identified using standardized procedural codes (Supplemental 1). Patients were divided into two cohorts: those with a documented diagnosis of cannabis use disorder (CUD) within 1 year before surgery and those without any history of CUD. CUD is defined by the same behavioral and clinical criteria used to characterize addiction to other substances, including impaired control, tolerance, withdrawal, and continued use despite adverse consequences.

Propensity score matching was performed to reduce the impact of confounding variables and ensure balanced comparisons between cohorts. Patients were matched in a 1:1 ratio using greedy nearest-neighbor matching with a caliper of 0.1 pooled standard deviations, and propensity scores were estimated using logistic regression. In this method, each cannabis user was matched to a non-user with the closest propensity score within the specified caliper, without reconsidering previous matches. Cannabis users were matched to non-users based on demographics and clinical variables, including age, sex, diabetes, hypertension, chronic kidney disease (CKD), opioid related disorders, tobacco use, anxiety, and mood disorders (Tables 1 and 2). This yielded 1504 matched THA pairs (mean age 54.6 ± 12.2 years, 60.3 % men) and 1354 matched TKA pairs (mean age 58.7 ± 10.1 years, 55.2 % men). Outcome measures included 90-day emergency department (ED) visits, hospitalizations, sepsis, myocardial infarction (MI), pulmonary embolism (PE), DVT, surgical site infection (SSI), stroke, pneumonia, urinary tract infection (UTI), wound disruption, transfusion, anemia, acute kidney injury (AKI) and post-operative opioid use; and 2-year orthopaedic complications including prosthetic joint infection (PJI), periprosthetic fracture, aseptic loosening, dislocation, and revision. Statistical analysis was performed using the TriNetX platform, which utilizes Java, R, and Python for statistical computing. Bivariate comparisons were made using z-test for discrete or categorical variables and Student's t-test for continuous variables. Risk ratios (RR) were also calculated to compare the likelihood of postoperative outcomes between cohorts.

3 Results

Following propensity-score matching, cannabis use was associated with a statistically significant increase in 90-day ED visits in both TKA (13.1 % vs 9.9 %, p = 0.008, RR = 1.33, NNH ≈ 31) and THA (16.1 % vs 12.6 %, p = 0.006, RR = 1.28, NNH ≈ 29) cohorts. Similarly, postoperative opioid use was more frequent among cannabis users undergoing TKA (92.8 % vs 88.6 %, p < 0.001, RR = 1.05, NNH ≈ 24) and THA (91.8 % vs 86.4 %, p < 0.001, RR = 1.06 NNH ≈ 19) (Table 3). No significant differences were observed in 90-day hospitalizations, sepsis, MI, PE, DVT, SSI, stroke, pneumonia, UTI, transfusions, anemia, or AKI across either cohort. Notably, wound disruption was more common in cannabis users following THA (2.1 % vs 1.0 %, p = 0.017, RR = 2.07, NNH ≈ 91), while no significant difference was seen in TKA (2.4 % vs 2.2 %, p = 0.797, RR = 1.07).

At 2-year follow-up, no significant differences were observed in rates of periprosthetic fracture (2.0 % vs 1.3 %, p = 0.154, RR = 1.50), PJI (4.4 % vs 4.6 %, p = 0.724, RR = 0.94), prosthetic dislocation (3.4 % vs 2.6 %, p = 0.162, RR = 1.34), or revision (6.2 % vs 7.1 %, p = 0.340, RR = 0.88). However, CUD patients undergoing THA demonstrated a significantly higher rate of aseptic mechanical loosening than non-users (1.9 % vs 0.9 %, p = 0.030, RR = 2.00, NNH ≈ 100) (Table 4). In the TKA cohort, no statistically significant differences were found across all evaluated outcomes, including periprosthetic fracture (0.8 % vs 0.9 %, p = 0.834, RR = 0.92), PJI (4.9 % vs 3.8 %, p = 0.160), RR = 1.29, dislocation (0.7 % vs 0.9 %, p = 0.669, RR = 0.83), aseptic loosening (1.0 % vs 0.7 %, p = 0.530, RR = 1.30), and revision (5.3 % vs 5.2 %, p = 0.932, RR = 1.01).

4 Discussion

Our findings demonstrate that preoperative cannabis use is associated with increased 90-day ED visits and postoperative opioid use in both THA and TKA cohorts. Additionally, wound disruption was more common among cannabis users undergoing THA. At the 2-year follow-up, THA patients with cannabis use had a significantly higher incidence of aseptic loosening compared to non-users, while no significant differences were observed in other implant-related complications or among TKA recipients. These results suggest that cannabis use may negatively impact postoperative recovery, pain management, and long-term implant integrity, particularly in total hip arthroplasty.

Several prior database studies have explored the relationship between cannabis use and arthroplasty outcomes, offering important context for our findings. Law et al. used Medicare claims data to report increased early revision rates among cannabis users undergoing TKA, though their analysis focused primarily on short-term outcomes within 90 days.²⁶ Similarly, Vakharia et al. evaluated perioperative complications in patients with cannabis use disorder undergoing THA and observed higher rates of medical complications and implant-related failures, but their cohort did not examine opioid use or ED visits.²⁷ Our study builds on these efforts by incorporating both TKA and THA cohorts, applying propensity score matching, and extending follow-up to include two-year implant-related complications. This allowed us to identify differences in opioid consumption, healthcare utilization, and aseptic loosening, particularly following THA, which may reflect underlying differences in patient behavior, implant biomechanics, or recovery trajectories.

Other large-scale investigations have reported more neutral associations between cannabis use and surgical outcomes. Rahmon et al. found that patients with cannabis use disorder undergoing TJA had shorter hospital stays and increased rates of home discharge, without significant differences in complication rates.²¹ Kirchner et al. similarly observed no increase in perioperative complications in THA patients who self-reported cannabis use, and Denduluri et al. found no association between preoperative cannabis use and adverse short-term outcomes in a Veterans Affairs population.^3,15 While our findings differ in certain respects, such variation may reflect differences in study design, outcome definitions, exposure classification, or follow-up intervals. By evaluating both short-term utilization and long-term implant survivorship within a single framework, our analysis contributes to the growing body of evidence and underscores the need for continued research to clarify cannabis's role in the perioperative setting.

This study has several limitations inherent to its retrospective design and reliance on administrative data. Cannabis use was identified using diagnostic codes for cannabis-related disorders, which may underrepresent the true prevalence of use and fail to capture important details such as dose, frequency, route of administration (e.g., inhaled vs. ingested), or cannabinoid composition (THC vs. CBD). Consequently, the observed associations may not generalize to all cannabis users, particularly those with intermittent or non-disordered use. Additionally, while propensity score matching was employed to minimize confounding, unmeasured variables, such as socioeconomic status, perioperative pain regimens, or adherence to follow-up, may have impacted the results. Our outcomes were also limited to those captured within the TriNetX network, and we could not assess functional outcomes, patient-reported satisfaction, or radiographic data. Lastly, causal inference is limited, and further prospective, dose-dependent investigations are warranted to clarify the impact of cannabis use on perioperative care and long-term implant survivorship in total joint arthroplasty.

5 Conclusion

Preoperative cannabis use was associated with increased ED visits and opioid use following TJA. THA patients were particularly susceptible to the effects of cannabis with increased risks of wound complications and aseptic loosening. No significant differences were found in implant-related complications following TKA. These findings support the need for heightened perioperative vigilance and patient counseling regarding cannabis use in arthroplasty patients. Future prospective comparative studies will be required to understand the impact of recreational use versus diagnosed cannabis use disorder, dose-dependent relationships, and the impact of various routes of consumption to devise peri-op management strategies to prevent poor total joint arthroplasty outcomes.

Author contribution

Z.F. - conceptualization, design, analysis, interpretation, manuscript writing; S.L. - analysis, interpretation, manuscript writing; A.C. - design, analysis, interpretation, manuscript writing; J.T. - analysis, interpretation, manuscript writing; J.U. - analysis, interpretation, manuscript writing; Z.E.A - design, analysis, interpretation, manuscript writing, final approval.

Ethics statement

Human Ethics and Consent to Participate declarations are not applicable to our study.

Ethics statement

Guadian/Patient Consent to Participate declarations are not applicable to our study.

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. The authors have no relevant financial or non-financial interests to disclose.