Increased hazard ratio of a second ACL injury after return to sport for each positive hypermobility test on the Beighton Score: a registry study.

Background Generalized joint hypermobility increases the risk of second anterior cruciate ligament (ACL) injury. The clinical diagnosis of GJH relies on a binary threshold of positive joint hypermobility tests, based on age and patient sex, which may overlook the degree of hypermobility. Purpose To analyze the association between the number of positive joint hypermobility tests on the Beighton Score and the hazard ratio (HR) of second anterior cruciate ligament (ACL) injury in patients who return to sport (RTS) after primary ACL reconstruction, which included secondary, stratified analyses of graft rupture and contralateral ACL injury. Design: Registry study. Methods Data was extracted in January 2026 from an ACL-rehabilitation-specific registry, YYY. Included patients were 15–50 years who underwent primary ACL reconstruction with hamstring tendon or bone-patellar tendon-bone autograft, had a documented Beighton Score, participated in knee-strenuous sports before injury, had RTS, reported second ACL injury or had ≥ 1 year follow-up without second ACL injury after RTS. Multivariable Cox proportional hazard regression was used to estimate the HR of second ACL injury (measured from RTS) based on the Beighton Score, adjusted for age, return to pre-injury physical activity level or higher, graft choice, knee hyperextension (≥ 10° knee extension), and patient sex. Results The analysis included 935 patients (mean age 23.7 ± 7.8 years, 51.4% female), with median Beighton Score of 2 (interquartile range: 4). The median follow-up time was 54.4 months. Second ACL injury was reported in 122 (13.0%) patients. The adjusted HR of second ACL injury after RTS was 1.10 times greater for each positive joint hypermobility test on the Beighton Score (95% CI: 1.003–1.22, p = 0.044). Conclusion The HR of second ACL injury after RTS in patients who had undergone primary ACL reconstruction increased by 10% for each positive joint hypermobility test on the Beighton Score.