The study had a favorable long-term outcome regarding incidence of radiographic knee OA, knee function and symptoms, and need for ACL reconstruction. Although risk factors for posttraumatic OA are multifactorial, the primary risk factor that stood out in this study was if a meniscectomy had been performed. Early activity modification and neuromuscular knee rehabilitation might also have been related to the low prevalence of radiographic knee OA. In patients with ACL injury willing to moderate activity level to avoid reinjury, initial treatment without ACL reconstruction should be considered.

Early activity modification and neuromuscular rehabilitation resulted in a good knee function and an acceptable activity level in the majority of the nonreconstructed patients. The decline in activity level of patients engaged in contact sports at the time of injury affected their subjective quality of life more than patients involved in noncontact sports.

We found a relatively low prevalence of mild PF OA after ACL injury treated non-operatively, and it had limited impact on knee symptoms and patient-relevant knee function. At follow-up PF OA was associated with higher activity level, meniscal injury, extension and flexion deficit, and ACL reconstruction.

The point estimates suggests about 25-50% lower risk of consultation for knee OA after meniscus repair as compared to APM. However, the consultation rate for knee OA after repair was still at least two times higher as compared to the general population.