What is the ACL?

There are four ligaments in your knee: the medial collateral (MCL), lateral collateral (LCL), anterior cruciate (ACL), and the posterior cruciate (PCL). The ACL is located in the middle of the knee. It stops the tibia (shin bone) from sliding out in front of the femur (thighbone).

Anterior Cruciate Ligament (ACL) injury is a common occurrence among active teens, young adults, and sportspersons. ACL is a 36 – 40 mm long band of fibrous tissue that connects the femur (thigh bone) to the tibia (shin bone). Its primary function is to control stability when the legs perform a twisting action, such as pivoting, landing from a jump, side stepping, and so on. People sometimes sidestep or attempt a pivot, which may lead to their whole body rotating around the knee, triggering a force that snaps the ligament.

ACL rupture is characterized by patients as a popping or cracking sound, followed by severe pain and swelling. In short, an ACL injury may include:

  • An audible pop at the time of injury
  • Instability of the knee
  • Pain followed by inability to continue activity
  • Development of a large hemarthrosis

There are levels of severity of an ACL Tear, from a slight tear in the ligament to a complete rupture. A complete rupture of the ACL will result in significant pain and very little function of the knee joint. Surgery is potentially the only way of treating a complete rupture.

The levels of tear are as follows:

Grade 1 tear: a small number of fibres are torn resulting in some pain but the joint will function relatively normally.

Grade 2 tear: a large number of fibres are torn and the knee joint will lose a lot of functionality.

Grade 3 tear: the ACL ligament is completely torn and the knee becomes unstable. There will be very little if no function of the knee. Surgery is most likely required.


Most ACL injuries can be diagnosed by the patient’s description of how they got injured. For instance, if a patient says that they sustained the injury after falling to the ground and twisting their knees, which was accompanied by a popping sound and then followed by swelling and severe pain, it is a clear indication for an ACL injury. If however, the doctor suspects an ACL injury, they may perform one or more physical examinations to assess the stability of the patient’s knee and the nature of injury. Commonly leveraged tests include:

Anterior Drawer Test

The patient is asked to lie on the back with the face up. The injured knee is kept at 90 degree flexion position. The examiner tries to displace the tibia from the femur. An ACL tear is suggested if there is more than 6mm of tibial displacement.

Pivot Shift Test

This test is used to determine how the injured knee will function in the future. The examiner holds the ankle with one hand and the area around the knee by the other and maintains 20 degrees of internal tibial rotation. The examiner then holds the leg sideways and applies a valgus force to the knee while it is slowly flexed. As the knee is flexed in the range of 30 to 40 degrees, if the tibia’s position on the femur reduces – ACL injury is considered positive.

Lachman Test

Here is the patient is asked to lie supine and keep the knee in 30 degree flexion position. The examiner tries to pull the tibia forward to assess the amount of anterior displacement of the tibia in comparison to the femur. The examiner also assesses the endpoint quality – firm, marginal or soft. ACL injury is confirmed if there is asymmetry in side-to-side laxity or a soft endpoint. In addition to these tests, a Magnetic Resonance Imaging (MRI) is also performed to check for bone bruising that occurs in most ACL injuries. Although an MRI helps physicians to confirm ACL, it shouldn’t be used as a substitute for physical tests.


For minor grade 1 or grade 2 tears the treatment is often a combination of rest and Physiotherapy. In order to fully rest and support the knee joint, a knee brace would be very useful. The body cannot heal correctly if there is continuing damage to the ligament, so appropriate rest involves keeping any twisting or hyperextension to an absolute minimum. There may only be a little pain but if the problem is not treated in the immediate aftermath of the event, then the recovery time will increase and it could become a chronic condition which will increase the chances of future tears and may require surgery. Not all patients dealing with an ACL injury need to undergo surgery. Those who have an inactive lifestyle or those who perform light manual work may be advised a number of non-invasive remedies, including orthopedic pain relief products. In certain cases, however, the doctor may recommend a surgical treatment to fully restore the movement of the knee and eliminate the pain, for good. Let’s take a closer look at both the options.



During the first 72 hours, the patients are usually recommended, “RICE” short for “Rest, Ice, Compression, and Elevation”, and might be asked to continue with it throughout the recovery period. Regular icing and wearing a compression bandage or a knee brace on a day-to-day basis helps prevent further damage to the ligament and supports healing.


Based on the severity and type of injury, the doctor may prescribe physiotherapy to reduce swelling and/or restore the motion of the injured knee. The therapy includes pain-free stretching and strengthening exercises focused on thigh muscles (quadriceps), bum (gluteus), and hamstrings, to improve knee support.



Under this treatment, a tissue or bone from the body of the patient is used to reconstruct the ACL. Although there are various types of donor tissues used in autografts, the one that is commonly used is an accessory hamstring. Sometimes, a part of the patellar tendon is also used.


Under this treatment, a tissue or bone from a donor’s body is used to reconstruct the ACL. To be more precise, the anterior tibialis tendon or patellar tendon is generally used for reconstruction. As the tissue used here is from a second person, there is a risk of the reconstructed ACL being rejected by the patient’s body.

Bridge-enhanced Repair

Under this treatment, the surgeons use stitches and a sponge that hold the blood of the patient. They serve as a bridging scaffold to stimulate healing in the ACL. This process is considered better than the other as the patients can keep their ACL for future use.

Note: Before advising a surgical treatment, orthopedic surgeons consider a number of factors, including but not limited to:

  • Pre-injury activity level of the patient
  • Patient’s wish to return to high-demand sports such as soccer and basketball
  • Abnormal laxity
  • Associated injuries
  • Patient’s post-treatment expectations

Last Few Words

ACL injury, for years, meant the end of the line for sportspersons and a permanent agony even for those with a regular lifestyle. Thanks to medical and technological advancements, now it is possible for injured individuals to completely recover from a ligament injury and resume their routine lives, albeit with certain precautions. In all cases, an extended delay in seeking expert consultation can worsen the issue, which may cause a permanent damage to the knee. Although there is no dearth of orthopedic products suppliers, it is advisable to consult an orthopedic surgeon, rather than using any orthopedic products without a prescription.