ACL Reconstruction Surgery

Written By: Chloe Wilson, BSc(Hons) Physiotherapy
Reviewed by: KPE Medical Review Board

ACL reconstruction surgery involves replacing a torn anterior cruciate ligament with graft tissue from around the knee.

If other structures in the knee have also been damaged at the time of the ACL injury, such as the meniscus, they are also repaired at the same time. 

In many cases, surgery can be avoided after ACL injuries by working on an intensive rehabilitation programme.  However, if there is persistent pain and instability, or for high-level athletes, ACL surgery is advised.  

The ACL is the key stabilising ligament of the knee and is most commonly damaged when the knee is excessively twisted or pushed too far backwards.

When this is the case, ACL reconstruction surgery is recommended to prevent new and ongoing problems. 

The main criteria for ACL reconstruction surgery are:

• Complete rupture of the ligament (3rd degree tear) and/or
• Knee repeatedly unstable – giving way
• Person wants to return to pivoting sport
• Person able to comply with post-operative rehab programme
• Associated meniscus damage
• Non-surgical treatment (rehab programme) has failed

Another popular choice with ACL reconstruction surgery is a patella tendon graft. The patella tendon is found just below the kneecap. The middle third section of the healthy patellar tendon is removed from the front of the knee, along with small sections of patella and shin bone which are still attached to the tendon at either end.

The pieces of bone are then grafted onto the knee where the ACL was previously attached.

Advantages: Easier to fix into place because of the bone blocks at either end
Disadvantages: Removal of part of the patellar tendon can lead to inflammation and resultant patellar tendonitis and anterior knee pain. Cannot be done if your tendon is too narrow or short

ACL reconstruction surgery is usually carried out arthroscopically (keyhole surgery) under general anaesthetic and takes approximately 1-2 hours.

• 3 very small incisions (cuts) are made around the front of the knee.
  
  
• A flexible camera with a light (an arthroscope) is placed through one hole which sends images through the fibre optic cables to a TV monitor in the operating room.  
  
  
• The knee is examined to confirm the diagnosis of a ligament tear and to look for any cartilage damage. 
  
  
• Saline fluid is pumped into the joint to wash out any blood and debris and to expand the knee so the surgeon has a better view of the joint.
  
  
• Medical instruments are inserted into the knee which have the necessary tools attached to them to carry out the operation. 
  
  
• Tunnels are drilled into the thigh and shin bones (femur and tibia) ready for the new graft.
  
  
• A separate incision (about 2-3 inches) is made to obtain the new ACL graft (known as harvesting) from either the patellar or hamstring tendons. 
  
  
• The graft is prepared to the right length and width as described above.
  

• Once the torn ACL and any debris has been removed, the graft is then fed through the tunnels and the top is attached to the femur, usually by a screw (metal, plastic or calcium based product that turns into bone).
  
  
• Tension is then placed on the graft to ensure it is the right length and it is fixed to the tibia. In time, new bone will form at the attachment sites, making it even more solid.
  
  
• Any damage to the meniscus will then be repaired or tidied up and the wounds will be closed with stitches. A sterile dressing will be applied that is worn for the first few days while the wound starts to heal.

Following ACL reconstruction surgery, you will be taken to recovery for 2-3 hours.  People are often able to go home later that day, but sometimes you have to stay on hospital for a day or two.  The surgeon may want you to wear a knee brace for the first few weeks to protect the knee.

After surgery, there is a long rehabilitation programme to regain full strength and stability, usually 4-6 months.  Most people do get back to playing full contact sport after 6-12 months of rehabilitation, but not everyone returns to their pre-injury level.

You can find out more about the process, including a recovery timeline guide with information on how long it takes to get back to certain activities in the ACL recovery section.