Risks & Complications
ACL and meniscal surgery are very common and effective surgeries. With ACL surgery, in more than 80% of cases, the procedure fully restores the functioning of the knee. Similarly, 90% of Meniscal surgery patients make a full recovery with no long-term consequences.
However, as with all surgeries, there is a degree of risk involved and will depend on a number of factors including your age, lifestyle, exercise and injury history. Your surgeon can talk to you in more detail about these risks, and whether your specific circumstances make any of them more likely.
a. Anterior Knee Pain
The most common complication of ACL surgery is pain around the kneecap. Just under 20% of patients are affected, but it’s more often found in patients who have had a patellar tendon graft, where the bone is removed from the kneecap as part of the procedure.
These patients can also have additional complications including patellar fracture and patellar tendon tear, although these are very uncommon.
Typical anterior knee pain is thought to be a result of altered mechanics of the joint and can often be overcome with physical therapy.
If you are an athlete and experience anterior knee pain post-surgery, it’s doubly important that you follow your post-operative rehab plan fully in order to ensure that your knee mechanics improve and your pain subsides.
b. Infection After Surgery
The risk of infection is low (less than 1%) but can be serious when it occurs. When the infection is inside the knee joint, there is concern about the ACL graft becoming infected. Your body cannot effectively fight infection on the graft, which sometimes needs to be removed to cure the infection.
To minimise any risk of infection, it's essential that you follow your surgeon's specific instructions both before and after surgery. Many surgeons recommend cleaning the knee with antibacterial soap prior to surgery. You must also make sure to follow any specific bandage instructions after surgery.
If you do have signs of infection (mainly around 7-10 days), including fever, chills, increasing knee swelling or pain, let your surgeon know as soon as possible.
c. Blood clots
The risk of a blood clot forming post-surgery and causing problems is very low - fewer than 1 in 1,000 patients are affected. However, if your surgical team considers that you may be at greater than normal risk, you may be given anti-clotting medication.
d. Bleeding inside the knee joint
Known as septic arthritis, this can cause pain and swelling.
e. Accidental damage to the nerves of the interior of the knee joint
This can lead to loss of sensation or numbness (either temporary or permanent)
f. Stiffness (Arthrofibrosis)
Stiffness after surgery is common. In order to minimise any stiffness, it’s important to get the knee moving quickly after surgery.
Whilst most patients with post-operative stiffness respond well to physical rehabilitation, one exception is when a cyclops lesion develops post-surgery. This occurs when a ball of scar tissue forms in the front of the knee, preventing it from straightening fully. In this instance, a secondary and smaller surgery may be required to clean out the scar tissue.
g. Knee weakness and instability
Although ACL reconstructions and Meniscal Repairs are common and widely practised procedures with high success rates, a small number of patients experience long-term weakness and or instability after surgery. In some cases, further surgery may be required.
h. Surgery is unsuccessful
In a small number of cases, surgery is not successful, either because the repair does not heal properly, or the patient does not follow the recommended recovery procedures. In which case, it may be necessary to repeat the surgery.
ACL grafts are very strong and repeat rupture of the ACL graft post-surgery is uncommon, but not unknown. If there is a re-rupture of the graft, your surgeon will first assess whether the issue is with the grafted tissue or the surgery itself.
If your graft used autograft tissue (your own tissue, from the patellar tendon or hamstring tendon) it will be stronger than your own ACL. Failure of these grafts is most likely to be an issue resulting from the surgery itself.
If Allograft tissue (donor tissue) was used, any failure is more likely to be due to the tissue itself as it is not as strong as your own tissue, and re-rupture rates are known to be higher with this type of graft.
That is why people with highly active lifestyles, including competitive athletes, often opt to have their own tissue used for surgery, even though rehab can be more difficult as a result
If you believe you have any of the complications detailed above when you are home, contact your doctor.
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