The term knee reconstruction is commonly used
to refer to reconstruction of the anterior cruciate ligament (ACL). This ligament is in the middle of the knee and controls the movement of the two main bones of the knee, the tibia and femur (Fig.1). It is particularly important for twisting and turning movements that occur in football, netball, basketball and snow skiing.

ACL diagram

Rupture (tearing) of the ACL can therefore lead to instability. This is felt as giving way with certain activities, usually those that involve a sudden change in direction. When giving way occurs, there is a risk of damage to the cartilages (menisci) and this in turn puts the knee at risk of developing premature osteoarthritis. Although it is an aim of reconstructive surgery, it is unclear whether anterior cruciate ligament reconstruction actually reduces the risk of developing osteoarthritis.

The main reason for reconstructing the ACL is to stop or to prevent instability. In many situations this instability can be predicted soon after the injury occurs and a decision made to operate without waiting for the instability to develop. However, in other cases it may be less clear and people may choose to rehabilitate their knee and try to return to their normal activities without surgery. Whether they can get back to their normal activities without surgery depends on many factors – how much healing of the torn ACL takes place, other injuries to the knee, the intrinsic stability of the knee, rehabilitation, and the individual’s ability to modify their activities.

It is important to remember that ACL reconstruction is almost always an elective procedure. From a medical point of view, there is no rush to make a decision, provided the knee is not giving way.
If ACL reconstruction is to be performed, it is essential to prepare the knee for surgery. The key is to get back full extension (straightening) of the knee. Although it may feel that there is something in the front of the knee that is blocking full extension, this is rarely the case, particularly after the initial injury. A key component is to reduce swelling by regular icing and wearing a compression bandage or sleeve. Having the heel supported on a rolled towel and using the quadriceps muscle at the front of the thigh to lock the knee out straight is the key exercise (Fig.2). Flexion (bending) is also important and riding an exercise bike will help this, together with strengthening the quadriceps muscle.


These notes have been prepared by orthopaedic surgeons at OrthoSport Victoria. They are general overviews and information aimed for use by their specific patients and reflects their views, opinions and recommendations. This does not constitute medical advice. The contents are provided for information and education purposes only and not for the purpose of rendering medical advice. Please seek the advice of your specific surgeon or other health care provider with any questions regarding medical conditions and treatment.