Preoperative Cannabis Use Associated with an Increased Rate of Revision Surgery Following Spinal Fusion: Systematic Review and Meta-Analysis

Introduction: The use of cannabis as a method of chronic pain relief has skyrocketed since its legalization in states across the US. Clinicians currently have a limited scope regarding the effectiveness of marijuana on surgical procedures. This study aims to determine the effect of preoperative cannabis use on the rate of surgical revision following spinal fusion.

Methods: A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. PubMed, Embase, and Scopus were searched, identifying studies assessing spinal fusion with reported preoperative cannabis use. Outcomes of interest included reoperation due to pseudoarthrosis with a follow-up time of at least six months. Subgroups of cervical fusions alone and lumbar fusions alone were also analyzed. Certainty in evidence and bias were assessed using the GRADE criteria and ROBINS-I tool. Prospero #CRD42023463548.

Results: Four studies met inclusion criteria with a total of 788 patients (188 cannabis user group, 600 non-user group). The rate of pseudoarthrosis revisions among cannabis users was higher than in non-users for all spinal fusions (RR: 3.58, CI: 1.67 to 7.66, p = 0.001). For cervical fusions alone, there remained a higher rate of pseudoarthrosis revisions for cannabis users compared to non-users (RR: 4.47, CI: 1.93 to 10.36, p = 0.0005). For lumbar fusions alone, there was no difference in the rates of pseudoarthrosis revisions between cannabis users and non-users (RR: 1.21, CI: 0.28 to 7.73, p = 0.79).

Conclusion : Cannabis use was shown to be associated with a higher rate of pseudoarthrosis revisions in spinal fusions on meta-analysis. On subgroup stratification by spine region, cannabis use remained associated with pseudoarthrosis revisions on cervical fusions alone but not lumbar fusions alone. Further research with larger, randomized studies is required to fully elucidate the relationship between cannabis use and fusion, both in general and by spinal region.