Sex-Specific Outcomes After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

Background: Despite the significant difference between men and women in incidence of anterior cruciate ligament (ACL) injuries, there is a paucity of consistent information on the influence of patient sex on outcomes after ACL reconstruction. A previous meta-analysis has demonstrated that female patients have worse outcomes with regard to laxity, revision rate, Lysholm score, and Tegner activity score and are less likely to return to sports (RTS). Purpose: To conduct a systematic review and meta-analysis to evaluate and compare sex-specific outcomes after ACL reconstruction. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review was performed using PubMed, PubMed Central, Embase, OVID, and Cochrane databases per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The following search terms were used: “anterior cruciate ligament reconstruction” OR “ACL reconstruction” OR “anterior cruciate ligament” OR “ACL” AND “gender” OR “sex” OR “male” OR “female” AND “outcome” AND “2015-Present” to gather all relevant articles between 2015 and 2020. A risk-of-bias assessment and quality assessment was conducted on included studies. Results: Of 9594 studies initially identified, 20 studies with 35,935 male and 21,455 female patients were included for analysis. The 7 studies reporting International Knee Documentation Committee (IKDC) scores showed that male patients had statistically significantly higher postoperative scores (mean difference, 3.02 95% CI, 1.19-4.84; P< .01; I 2 = 66%), and 7 studies that reported the rate of ACL revision showed there was no significant difference between male and female patients (odds ratio, 0.85 95% CI, 0.45-1.60; P = .61; I 2 = 94%). The 7 studies that reported rates of rerupture showed that males were significantly more likely than females to have a graft rerupture (odds ratio, 1.35 95% CI, 1.22-1.50; P < .01; I 2 = 0%). Male patients reported a higher RTS rate than did their female counterparts (59.82% compared with 42.89%); however, no formal statistical analysis could be done because of the variability in reporting techniques. Conclusion: Male and female patients with ACL injuries demonstrated similar outcomes regarding their rates of revision; however, male patients were found to have statistically significantly higher postoperative IKDC scores but at the same time higher rerupture rates. Our findings suggest that sex-based differences in outcomes after ACL reconstruction vary based on which metric is used. These results must be considered when counseling patients with ACL injuries.