Primary versus rerupture of the anterior cruciate ligament: rupture site patterns and graft elongation—a systematic review and meta-analysis

Background: While the rupture pattern of the native anterior cruciate ligament (ACL) has been well characterized-most frequently occurring in the proximal third of the ligament-there is limited consensus on whether reconstructed ACLs fail in a similar fashion. The purpose of this meta-analysis is to compare rupture localization patterns between first ruptures and reruptures. Materials and methods: MEDLINE (PubMed), Embase, and the Cochrane Library databases were searched to identify studies analyzing rupture locations after both first rupture and rerupture. The main extracted outcome was the anatomical site of ACL rupture, categorized as proximal, mid-substance, distal, or elongation. A random-effects meta-analysis was performed to calculate pooled proportions and odds ratios (ORs), with between-study heterogeneity assessed using the I2 statistic. Results: The pooled meta-analysis revealed no significant differences (p > 0.05) in the distribution of proximal, mid-substance, or distal rupture locations between the first rupture and rerupture groups. However, graft elongation was significantly more frequent in reruptures (p < 0.05). Using first rupture as the reference, the odds of elongation were 1.63-fold higher in the rerupture group (OR 1.63, 95% CI 1.46-1.83; p < 0.001). Conclusions: This meta-analysis found no statistically significant differences in rupture-site localization between first ruptures and reruptures, indicating that reconstructed ACLs tend to fail in anatomical patterns resembling those of the native ligament. However, the markedly higher incidence of graft elongation observed in the rerupture cohort suggests a distinct mode of failure. These findings highlight graft elongation as a specific mechanism that may be influenced by surgical or biological factors, warranting further investigation. Level of evidence: Systematic review and meta-analysis of Level 4 studies. Study registration: PROSPERO Registry CRD420251073835.