Anterior Cruciate Ligament Tear (ACL).

What is ACL?

The ACL is one of the major ligaments in the knee that connects the thigh bone (femur) to the shin bone (tibia). It is main of the four ligaments stabilising knee joint.

When in sports, in motorbike accident, two wheeler accident or in domestic twisting injury occurs in the knees – this is the ligament that is commonly torn.Although the ACL is referred to as one ligament, it consists of two functional bundles. These two bundles are named for the place where they attach on the leg bone (tibia). There is an anteromedial (AM) bundle, which inserts more towards the front andtowards the inside of the leg bone (tibia). The posterolateral (PL) bundle inserts most towards the back and towards the outside of the tibia.

What is the function of ACL?

The ACL is an important ligament located inside the knee joint, which acts as the primary stabilizer preventing forward displacement of the leg upon the thigh bone.The ACL provides stability to the knee, while also allowing for normal knee movement. The AM bundle is tight when the knee is bent and provides stability in the forward direction. The PL bundle is loose when the knee is bent, and allows for rotation of the knee. When the knee is straight the two bundles are parallel to each other, but when the knee is bent the two bundles cross each other. Although the two bundles have slightly different functions, the bundles do not work independently, but rather they work together to keep the knee stable while still allowing you to jump, run and play sports.

How do I get my ACL torn?

ACL tears are very common with highest occurrence is in individuals between 15 to 25 years of age who participate in pivoting and cutting sports. However, ACL tears can occur at all ages and in all sporting activities after either contact or non-contact injuries.

Usually an ACL tear occurs during sporting activities, two wheeler vehicular accident or may be in domestic accidents. They can be torn in a sudden pivoting or cutting motion, or planting of the foot while the rest of the body turns.

What symptoms could I have when my ACL is torn?

Patients frequently report “hearing a pop” at the time of injury and often have large swelling and pain soon after, in the injured knee.Sometimes in day to day activities patient with torn ACL experience frequent “giving Way” (Subluxate) leading to periodic increase in the pain in the injured knee.They feel less confident on their injured knee in brisk walking, walking on uneven surface, walking on wet or slippery surfaces.

They are uncomfortable in Jumping down from the small height like few steps and not willing to run/jog even for small distances.Negotiating staircase down is often difficult for them. Some of them feel unexplained pain of exertion.

If they have been having meniscus tear with the ACL tear they can experience episodes of “locking of knee” (not able to move knee joint) lasting from few minutes to few hours to few days. In short patients of ACL are otherwise able to lead near normal life with significant restrictions.

How is an ACL tear diagnosed?

This is done through a thorough history of your injury as well as through a variety of physical exams which include anterior drawer test, Lachman’s test, pivot shift test each of these tests aids in determining the functional status of the ACL.The physical examination in clinic is used to make the provisional diagnosis.

MRI scans are used to image the ACL, confirm the diagnosis and evaluate for other possible injuries, like meniscus tears.

I also take x-rays of the knee. You cannot see the ACL on x-ray, but I do this to make sure there is no problem with the bones, such as a fracture.

When my ACL is torn, does it heal naturally?

No, it does not heal. This ligament mostly being made of fibres like elastic tissue, both ends of the torn ligament move away from each other gradually and eventually there will be empty space between two torn ends which cannot bridge naturally leaving it unhealed.

When my ACL is torn, is it compulsory to undergo surgery?

There are some middle to old aged patients who are able to function without an intact ACL. These patients modify their lifestyle by eliminating aggressive normal activities that require pivoting and cutting. However, sometimes during everyday activities the ACL-deficient knee can buckle or “give way” (Subluxate) resulting in painful episodes with swelling. In short one has to restrict the life significantly so as to not provoke the episode of the giving way.

Importantly, there is a risk of damage to the menisci (the cartilage shock absorbers) and articular cartilage (the slippery gliding surface on the ends of the bones) with each subluxation event. This damage can lead to degenerative arthritis and subsequent meniscus tears. These tear of meniscus and damage to articular cartilage is largely irrecoverable even when patient opt for surgery at the later date. Because of these concerns a majority of active and young patients elect to undergo ACL surgery when the ligament tears.

After ACL tear- what is the proper time to get surgery done?

In general, there are fewcriteria that must be met before the ACL can be surgically reconstructed:

  • Swelling in the knee must go down to near-normal levels
  • Range-of-motion (bending and straightening) of the injured knee must be nearly 50% of the uninjured knee.
  • Good Quadriceps muscle strength must be present. This means that while lying flat on your back you should be able to raise your leg off the ground while holding it is straight. I call this a “straight leg raise”.

Usually it takes a few weeks after injury before ACL reconstruction can be performed.

The mode of injury like domestic accident or vehicular accident. The velocity of the injury low, moderate or high velocity also play big role in the decision.

The presence of any associated injuries to the knee joint involving cartilage, Contusion of the marrow, meniscus, or other ligaments may change the time-frame for surgery.

It is very tailor made decision, considering various diverse factors mentioned above, arrive at by your surgeon in your best interest, regarding the time of the surgery.

What is done during surgery?

The Purpose of anatomic ACL reconstruction is to regain stability and return to pre-injury activity level& maintain long term knee health.

The surgical procedure itself takes between 40 and 90 minutes. To reconstruct the ACL, you are given regional/ general anaesthesia and arthroscopy is performed. This means I look inside the joint with a small camera using small punctures and very small delicate instrumentation.

  • lateral portal which is puncture towards the outside of the knee is used to insert the arthroscope in the joint.
  • medial portal which ispuncture towards the inside of the knee is used to insert highly specialised small instruments in the joint for the procedure.
  • One inch long incision over the tibia is used to mostly harvest the graft andcreate the tibial tunnel through which graft is introduced to the joint and attach the new ACL to the tibia.


A new ACL is created using “a graft”, which is tissue as mentioned earlier from your own body. The sizes of these grafts are based on your own body size body type and ACL size.

To attach the ACL graft to the bone with very precise and special instruments tunnels are drilled in the bone according to the size and length of the graft and then ACL graft is placed into the tunnels and fixed to the femur and tibia bones with a combination ofspecial buttons, screws and sometimes with staples depending upon the need condition of the bone and graft.


Where do the grafts for ACL reconstruction come from?

  • The graft tissue comes from your own body (autograft)
  • Autograft options include different tendons from different muscles: Hamstrings Tendons, Quadriceps Tendon, and Patellar Tendon (BTB), peroneus longus tendon, hamstring tendon from opposite knee.
  • Advantages to autograft include no risk of disease transmission and potentially quicker healing of the new ACL.   
  • Allograft (Tissues harvested from Dead people) options also include a variety of different tendons from different muscles: Hamstrings Tendons, Tibialis Anterior Tendon, Posterior Tibialis Tendon, Patellar Tendon, Quadriceps Tendon, Achilles Tendon, and the Tensor Fascia Lata. But it is not available in India. It also has inherent risk of disease transmission like hepatitis and HIV. It takes prolonged healing time of ACL.

How long do I need to stay in hospital after arthroscopic surgery?

Arthroscopic ACL reconstruction surgery is usually performed as a “day case,” meaning that you can
go home the same day as the operation. Some people may need to stay in hospital for a couple of days to
recover from the operation, but your surgeon will advise you on this.

How does the newly reconstructed ACL heal after my surgery?

Typically the graft heals to the bone through bleeding created by drilling the tunnels.The type of fixation material also helps newly reconstructed ACL to heal in the tunnels. It will get its normal synovial covering in 3 months, then the blood supply from it will help in further naturalisation process.

What is the recovery time after ACL surgery?

  • Within a day or two patient is able to walk with walker or crutches with as much weight as tolerated and also the surgeon decides the amount of weight given depending upon other lesions/pathology/simultaneous surgery.
  • After 10 days stitches are removed if skin stitches are taken and knee bending is started.
  • Long AK-BK Knee brace is worn full day till 1 month and night time for 3 months.
  • After 15 to 20 days depending upon the strength of thigh muscles patient can walk without support and go outside to do table work/office work.
  • After 1 month patient can walk without brace and start stair climbing up and down.
  • Patient can drive 4 wheeler after 6 weeks but should avoid 2 wheeler for atleast 4 months to avoid twisting force on the operated knee during which time ACL is still under healing phase and not so strong.
  • After 3-4 moths one can start walking normally, jogging on flat surface straight and almost have full knee bending.
  • After 6 months sports specific training is started and one can do crossed leg sitting as well as squatting.
  • After 9 months return to sports is allowed with proper proprioceptive and agility training.