What are the Risks of ACL Surgery?

ACL reconstruction is safe and effective, for patients of all ages, and most complications are rare. However, like any operation there are some risks involved with ACL surgery.  Below is a summary of these complications, but you should discuss these further with your surgeon.

Risks of ACL Surgery Educational Video

Skin Infection

Occurs in less than one percent of patients and is usually mild. You may require some tablet antibiotics but there would be no long-term consequences.

Deep Infection within the Knee Joint

Occurs very rarely; approximately 1 in a thousand patients. If this occurred you would require another key-hole operation to wash the infection out, and antibiotics for a number of weeks.

Numbness of Skin

It is not uncommon for patients to have a ‘numb patch’ of skin on the outside of their leg. This is due to very small nerves being cut when the skin incision is made on your leg. This will cause no functional problems, but it may feel unusual. It may improve significantly over a 6-month period. Taking 500mg of vitamin C twice a day for 3 months will assist this recovery (250mg twice a day for children under 16 years of age).In some patients this numbness may be permanent.


It may take 2-6 weeks for you to get your knee fully straight. Ideally, you would achieve this by 2 weeks, but in some patients this takes longer. Pain, swelling and scar tissue formation within the knee can all limit this.

If your knee remained stiff for 3 months or longer then you may require another key-hole operation to remove scar tissue from within your knee joint, to improve your range of motion. Rarely, a patient may never regain their full knee straightening.

Blood Clot/DVT

The risk of a blood clot, or DVT, is low after an ACL reconstruction. Most patients will not require any blood thinning medication.

ACL Re-Rupture

There is a risk that you could re-rupture your reconstructed ACL. The risk of re-rupture depends upon your age, gender, type of sport you wish to return to, and also how much time and effort you put into rehabilitation. You are more likely to rupture the ACL in your other, non-injured, knee than you are your reconstructed knee. Well performed surgery and quality rehabilitation are the two most important factors in preventing ACL re-rupture. If you did re-rupture your reconstructed knee, then it can be reconstructed again. The recovery is the same as the original procedure.


Swelling can persist within your knee for several months. It takes 12 months for the graft to fully heal inside your knee, and as long as on-going healing is occurring there can be associated swelling. Your knee is also recovering from the bone and cartilage bruising that occurred during the initial injury. As you return to training and sports your knee may also swell as it adjusts to increasing loads.

Pain and Arthritis

There is a longer-term risk of pain and arthritis within your knee, largely due to the bone and cartilage bruising that occurred at the time of injury. A severe meniscus or articular cartilage injury will also increase your lifetime risk of arthritis.

Dr Matthew Hutchinson – ACL Surgeon Adelaide

Dr Matthew Hutchinson is an Australian and internationally trained orthopaedic surgeon who treats both Adults and Growing Athletes with hip, knee and ankle conditions.

Dr Hutchinson is a consultant orthopaedic surgeon to a number of professional sporting teams within the AFL, AFLW, SANFL, NBL and Super Netball League. He provides the same very high standard of care to ‘weekend warriors’ and emerging junior athletes as he does to those currently competing at the highest level.