Objectives We aimed to determine the lifetime genetic risk for anterior cruciate ligament (ACL) rupture.
Methods We used a twin study approach, linking the Swedish Twin Register with national healthcare data to form a 30 year, population wide, longitudinal twin cohort. We studied ACL rupture in this cohort of 88 414 identical and fraternal twin pairs, aged ≥17 years, to determine the familial risk and heritability of ACL rupture.
Results The incidence rate of ACL rupture was 70 (95% CI 66 to 74) per 100 000 person years. The familial risk, which is the excess risk ratio (RR) of the second twin having ACL rupture given that the first twin has had such a rupture, was higher in identical twin pairs (RR=8.6, 95% CI 6.2 to 11.0) than in fraternal twin pairs (RR=1.9, 95% CI 0.9 to 3.0). The overall heritability of ACL rupture was high, 69% (95% CI 47 to 91), increasing from 60% at age 17 years to 80% at age 60 years. Women and men had similar familial risk and heritability of ACL rupture.
Conclusion The genetic contribution to ACL rupture of ~69% is high and suggests strong familial clustering. If clinicians recognise the high genetic risk of such injury, they may be better able to counsel athletes whose near relatives have had ACL rupture.
- contact sports
- injury prevention
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Contributors KM had access to all of the data in the study and takes full responsibility for the integrity of the data and the accuracy of the data analysis. KM performed statistical analyses and drafted the manuscript. AT, VH, RF and ME contributed with acquisition of the data, conceptual design, analyses and interpretation of the results. All authors contributed in drafting the article or critically revising it for important intellectual content. All authors gave final approval for the version to be submitted.
Funding The study was funded by the Swedish Research Council (E0234801), the Greta and Johan Kock Foundation, the Swedish Rheumatism Association, the Österlund Foundation, Governmental Funding of Clinical Research within the National Health Service (ALF) and the Faculty of Medicine, Lund University, Sweden.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the ethical review board at Lund University, Sweden.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available. The data are deidentified participant data not available for public use.
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