Factors Contributing to Achilles Tendon Re-rupture: A Systematic Review.

Acute Achilles tendon rupture (ATR) is common among active adults, yet factors associated with re-rupture remain inconsistently reported. Because available studies differ substantially in design, follow-up duration, and outcome definitions, this systematic review evaluates which treatment strategies and patient-related factors are associated with Achilles tendon re-rupture without overstating precision. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, we systematically searched PubMed, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and the Cochrane Library (2004-October 23, 2024) for studies reporting re-rupture after acute ATR. Eligible studies included adults with clinically and/or imaging-confirmed ATR and evaluated associations between baseline characteristics, treatment approaches, or rehabilitation strategies and subsequent re-rupture. Owing to substantial heterogeneity, data were synthesized narratively, and crude numerical ranges were reported descriptively. Study quality was assessed with the National Institutes of Health (NIH) Quality Assessment Tools. Eleven studies (44,557 patients) met the inclusion criteria. Reported re-rupture rates varied widely across treatment strategies, reflecting heterogeneous follow-up periods, definitions of re-rupture, and surgical techniques. Higher recurrence rates reported with specific techniques, such as the Tenolig percutaneous system, were derived from small, non-randomized studies and should be interpreted cautiously. More broadly, available evidence within the included studies did not consistently identify a superior standard repair method. Early weight-bearing (EWB) and functional rehabilitation, when examined, did not demonstrate a clear association with higher re-rupture frequency, though protocols varied substantially. Baseline factors such as male sex and pre-existing tendinopathy were observed more frequently among patients who sustained re-rupture, but findings were inconsistent across studies. Re-rupture after ATR appears to occur within a multifactorial context involving patient- and treatment-related characteristics, but current evidence does not clearly favor one contemporary repair strategy over another. Early functional rehabilitation was commonly implemented without higher observed re-rupture frequencies within structured protocols. Future studies should use consistent definitions, standardized rehabilitation pathways, and more uniform outcome reporting to improve comparability.