Not every person that tears their ACL requires surgery. The main reason to perform a reconstruction is in an active person who wants to return to “at-risk” activities. These include all codes football, netball, basketball, snow skiing. All these activities please a large load through the ACL. Other reasons to reconstruct the knee are recurrent giving way and the presence of associated injuries such as meniscus tears and the involvement of other ligaments. Occasionally someone will require a stable knee because of their occupational demands.
In older and particularly less active people, it is entirely reasonable to rehabilitate from an ACL tear. Rehabilitation involves regaining movement and a strengthening program.
One of the concerns in not having surgery is that often when a person returns to their sport, the knee may give way again. It has been my observation that often this second injury is more major and can lead to a significant meniscal damage resulting in the knee “locking”. The incidence of this occurring is not well documented in the orthopaedic literature but is not uncommon. The loss of a meniscus in an ACL-deficient knee can predispose to osteoarthritis in the future.
Therefore if you have ruptured your ACL, you need to know the pros and cons of your treatment options. If you are younger and more active, an ACL reconstruction may give you the best chance of a stable knee. If associated structures are injured, surgery may also be the best way forward. Common associated injuries are meniscus tears or damage to the medial ligament.