This is a review article in which the authors comb the medical literature to try and identify clearly the long term outcomes of injury to the anterior cruciate ligament (ACL) and menisci, and especially the development of osteoarthritis (OA).
They look initially at the incidence of ACL injury, noting that it is particularly high in young people playing sports that involve pivoting, with young women being 3-5 times more at risk than young men playing similar sports sports. Half of all patients with ACL tears are likely to have an associated meniscus tear at the time of injury, and over time patients with ACL damage are likely to sustain further damage to the meniscus.
The authors point out that there are wide variations in the reported incidence and outcomes of such injury, but this is because there is wide variability in the diagnostic criteria for assessing the injury and for assessing OA. But on average if one looks at MRI studies of patients from 10-64 years of old with knee injuries, 5% show some damage to the ACL. From other studies they determine that more than 15% have damage to the menisci. If one accepts the reports from multiple studies that 10-20 years after such injuries 50% of such patients will have developed OA, with pain, diminished function and reduced quality of life, one gets an idea of the magnitude of this problem.
Furthermore, they do not find in the literature convincing evidence that ACL reconstruction reduces the incidence of eventual OA. They are not sure whether this is because the studies are of insufficient quality, or that the current state of the art in surgical reconstruction leaves much to be desired or maybe even that the initial injury, when bone can be bruised and joint cartilage damaged, sets off an irreversible cascade of events that ends up with OA. Because of these findings, they place emphasis on prevention of ACL injuries and also on prevention of re-injury of the ACL impaired knee, because the literature shows that subsequent new tears of the meniscus increase the risk of OA.