[The time-related risk for knee osteoarthritis after ACL injury. Results from a systematic review].

The aim of this review was to evaluate the time-related risk for knee osteoarthritis in patients after ACL injury.The primary search was carried out in different medical databases with the deadline 12.01.2014. The search strategy for the evaluation was [ACL] AND [osteoarthritis] including "all fields". All 1656 title/abstracts were reviewed by two independent researchers who selected 140 papers for full text review. Finally, a total of 21 relevant publications were identified for inclusion in this current paper.The incidence of knee osteoarthritis rises significantly over time. Two years after injury it was 6.9%, after 5 years 32.2%, after 7 years 36.3%, and after 10 years 79.6%. At the same time, the crude relative risk of OA rises as the time interval since injury increases. The relative risk of OA has already doubled by 2 years after ACL injury). By 7 years it has increased fivefold and compared with OA status at the time of injury it is still increasing significantly after 10 years.The ACL injury is a significant risk factor for the development of early-onset secondary knee osteoarthritis. Within 5 years of the injury the knee shows clear signs of osteoarthritis on MRI. However, these lesions are often not associated with any clinical signs. Knee osteoarthritis as a severe disease starts 8 years or later after the injury, when it requires treatment.