Patient Population:

Mean reported ages at the time of initial intervention for injury ranged from approx. 20 years to 33.6. At the time of follow-up, reported mean ages ranged from 31 to 53 years of age. Sex was not reported for participants in all studies; however, based on the numbers reported in Appendix 2, it appears as though, overall, the majority of participants were male (72%). Pre-injury activity levels were reported using Tegner scores in 11 studies ranging from 5.7 – 9. Follow-up scores reported in 15 studies ranged from 3.7-6.4.

Intervention:

Surgical procedures reported as treatments for ACL injury included: primary repair with or without “augmentations, bone-patellar tendon-bone grafts, looped semitendinosus tendon grafts or fascia lata allografts”.

Comparison:

Prevalence of osteoarthritis (assessed radiologically) in the tibiofemoral joint 10+ years following ACL injury.  Presence of knee OA was determined based on cut-off values of 3 different radiologic classification systems (Kellgren and Lawrence Grade 2, International Knee Documentation Committee grade C, Ahlback Grade 1). Study also abstracted reported risk factors associated with OA more than 10 years post injury.

Outcome:

1. Prevalence: The highest rated (prospective) studies reported prevalence of knee OA in individuals with isolated ACL injury of 0-13% and 21-48% in individuals with combined injuries.  There were no significant differences in prevalence rates in individuals who were treated surgically vs. conservatively at the time of injury; however, the highest rated, prospective study reported no OA (at 15 year follow-up) in individuals whose ACL injury had been treated conservatively.

2. Risk factors: 3 studies attempted to demonstrate an association between various potential risk factors and the development of knee OA through statistical regression methods.  Risk factors identified included ACL surgery, age, BMI, <90% on single-legged hop test compared with the uninjured side 1-year post surgery, loss of extension and knee laxity (p.1437).  Additional risk factors identified via between-group comparisons included: meniscectomy, age >25 years at surgery, obesity, >6 months between injury and surgery, high level of sports activity, OA in the contralateral knee, chondral lesions, knee joint laxity.   Most frequently reported risk factors: meniscal injury & meniscectomy.