What is ACL reconstruction?
ACL reconstruction is surgical treatment of an anterior cruciate ligament (ACL) tear. The is one of the four main ligaments of the knee. The ACL runs diagonally through the middle of the kneejoint and prevents the tibia (shin bone) from sliding out in front of the femur (thighbone). This provides rotational stability to the knee.
Although the ligaments of knee are strong, they are frequently injured. During the injury, the ligament is stretched (or sprained) and tears occur in the fibres. Sprains are graded on severity:
- A grade 1 sprain is when the ligament is mildly damaged — it has been slightly stretched, but is still able to help keep the knee joint stable
- A grade 2 sprain is when the ligament is stretched to the point where it becomes loose — this is often referred to as a partial tear of the ligament
- A grade 3 sprain occurs when there is a complete tear of the ligament — the ligament has been split into two pieces, and the knee joint is unstable
Unfortunately, when the ACL is fully torn there is usually very little healing potential, which can lead to long-term instability.
How does ACL reconstruction work?
The aim of ACL reconstructive surgery is to give back stability to the knee. Unfortunately, a torn ACL does not heal by itself and in most ACL tears cannot be stitched back together. Therefore, the ligament must be reconstructed.This involves a tissue graft that a new ligament can grow on. Grafts are usually ‘harvested’ from other tendons in your body such as your patella tendon, hamstring tendon, Achilles tendon or quadriceps tendon. When your own tissue is used, the graft is called an autograft. Alternatively, a graft may come from a deceased donor, in which case it’s called an allograft.
ACL reconstruction can be performedas a day procedure, meaning you can go home on the same day as the surgery. It is done under general or spinal anaesthesia (epidural). ACL reconstruction is commonly performed arthroscopically, but open surgery may be needed. If your own tissue is being used as the graft, there will be an incision over the graft harvest site.
During arthroscopic ACL reconstruction, your surgeon makes an incision into your knee joint and inserts the tiny camera of the arthroscope. Images are transmitted onto a large screen so your surgeon can clearly see the inside of your joint. One or two other incisions are made to allow a tiny surgical drill into the joint. This is used to make small tunnels in the bottom of the thighbone and the top of the shin bone. The graft is pulled through the tunnels and anchored to the bone with screws or staples.
Once the ligament reconstruction is complete, your surgeon may repair other parts of the knee or just close the incisions with stitches or tape. A wound dressing will be placed and your knee will be bandaged.
What to expect after ACL reconstruction
It’s common to have some swelling of your knee, shin and ankle. Try and keep your leg elevated as much as possible to reduce swelling. Pain should be minimal (due to local anaesthesia), but you be given pain medication as needed.
Before you go home, your therapist will teach you how to walk safely on crutches and some simple exercises. These exercises are the start of your post-op rehabilitation program.
About 10–14 days after surgery, the dressing and stitches are removed. At this stage you’ll be able to shower and you may be able to return to office-style work.
Physiotherapy is an import part of the treatment for an ACL injury. Not only is it beneficial after surgery, it is also very important to restore strength and motion to the knee before surgery (sometimes called pre-habilitation).
Your rehabilitation program will be supervised by your physiotherapist and will involve exercises to prevent stiffness and improve strength and flexibility. The exercises will change as you heal. Most people can start low-impact activities such as swimming and cycling around 4 weeks after surgery. High-impact activities are usually possible by 6 months.
Full recovery takes between 6 and 12 months.