Registries and multi-centre prospective cohort studies are contributing more and more to our knowledge regarding anterior cruciate ligament reconstruction (ACLR). An important question is the applicability of data from one cohort to patients in other locations. Previous work has demonstrated many similarities but also significant differences in patients and operative techniques between two large cohorts of primary ACLRs: the US-based Multicenter Orthopaedic Outcomes Network (MOON) cohort and the Norwegian Knee Ligament Registry (NKLR).