Print this topic

HealthInfo Waitaha Canterbury

Surgery for an ACL injury

Pokanga mō te nape rīpeka o mua

If you've completed a rehabilitation programme with a physiotherapist but your knee is still unstable, it's likely you'll need surgery.

An orthopaedic surgeon will assess your knee and tell you if they recommend surgery. As well as having an unstable knee, other reasons you could need surgery include:

Before surgery

It's best not to have surgery immediately after an ACL injury. The results are better after your knee has had time to settle down and you've strengthened your leg with a rehabilitation programme.


Surgery to reconstruct your ACL can be done in a few ways. This page from the NHS website in the UK explains the types of surgery.

After surgery

After surgery, you'll need to follow the surgeon's instructions carefully until you see your physiotherapist one or two weeks later. Your physiotherapist will then give you another exercise programme to get your knee working properly again and strengthen your leg.

It will take at least six months and maybe as long as a year to fully rehabilitate your knee so it's essential that you follow your physiotherapist's instructions and do all the exercises. If anything is stopping you from doing the exercises, talk to your physiotherapist about it.

After surgery and completing an exercise programme:

Young athletes are more likely to return to sport after surgery.

People often worry about developing arthritis after an ACL injury. As long as you did not hurt anything else other than your ACL, the risk of arthritis is low. But your risk increases if you also damaged other parts of your knee, if you have not been able to get normal movement back after rehabilitation or surgery or if you're overweight.

Even after surgery and the later exercise programme, 12% of people injure their knee again. So, it's important to follow a programme to avoid that.

Written by a Christchurch physiotherapist. Adapted by HealthInfo clinical advisers. Last reviewed July 2022.


Page reference: 219209

Review key: HIHIL-240273