Anterior Cruciate ligament

The anterior cruciate ligament (ACL) is a band of dense connective tissue which courses from the femur to the tibia. There are two components of the ACL, the anteromedial bundle (AMB) and the posterolateral bundle (PLB).

Anterior cruciate ligament is one of the main stabiliser of the knee and in association with other ligaments and meniscus it provides stability to the knee.

Function of ACL

ACL Provide stability to the knee in anteroposterior planeThe main function ACL is to prevent the anterior movement of tibia over femur. This function prevents anterior tibial subluxation over femur and provide stability in anteroposterior plane.

ACL also Provide rotational stability to the knee- ACL Prevents internal rotation of the tibia in relation to femur and hence it provides rotational stability to the knee too

The ACL has mechanoreceptors that detect changes in direction of movement, position of the knee joint, and changes in acceleration, speed, and tension.[4] hence it provides proprioceptive function to the knee too.

A key factor in instability after ACL injuries is having altered neuromuscular function secondary to diminished somatosensory information.[4] For athletes who participate in sports involving cutting, jumping, and rapid deceleration, the knee must be stable in terminal extension, which is the screwhome mechanism.

How does ACL Injury Occur

Anterior cruciate ligament (ACL) injuries are caused when the knee is straightened beyond its normal limits (hyperextended), twisted, or bent side to side.

Typical situations that can lead to ACL injuries include:

Changing direction quickly or cutting around an obstacle or another player with one foot solidly planted on the ground. (This can happen in sports that put high demand on the ACL, such as basketball, football, soccer, skiing, and gymnastics.)

Landing after a jump with a sudden slowing down, especially if the leg is straight or slightly bent (such as in basketball).

Falling off a ladder, stepping off a curb, jumping from a moderate or extreme height, stepping into a hole, or missing a step when walking down a staircase. Injuries like these tend to be caused by stopping suddenly, with the leg straight or slightly bent.

What are the symptoms of ACL Injury
Symptoms of a severe and Sudden (Acute) Anterior Cruciate Ligament (ACL) injury include:

Feeling or hearing a "pop" in the knee at the time of injury

Sudden instability in the knee. (The knee feels wobbly, buckles, or gives out.) This may happen after a jump or change in direction or after a direct blow to the side of the knee.

Pain on the outside and back of the knee

Knee swelling within the first few hours of the injury. This may be a sign of bleeding inside the joint. Swelling that occurs suddenly is usually a sign of a serious knee injury

Limited knee movement because of swelling and/or pain.

After an acute injury, you will almost always have to stop the activity you are doing, but you may be able to walk.

Chronic ACL Deficiency

The main symptom of chronic (long-lasting and recurrent) ACL deficiency is an unstable knee joint. The knee buckles or gives out, sometimes with pain and swelling. This happens more often over time. But not everyone with an ACL injury develops a chronic ACL deficiency.

How do we diagnose ACL Injury

ACL Injury is Diagnosed by your sports injury specialist in a step wise manner as follows

A detailed history is taken asking about the pattern of fall, severity of fall, did the knee swell immediately after injury, did one hear a pop sound during the fall, did the knee twist and relocate back, did one have a feel of subluxation in the knee post injury too.

Then clinical examination is done on the injured knee to check for the swelling, tender areas of the knee, Movement and check for the Stability of the knee by doing test like drawer test, Lachman test, Pivot shift, dial test etc in all planes.

Correlating the History with the examination the doctor can come to a conclusion whether the injury would have led to any significant damage to structures of the knee or not.

Then the doctor advises for an X-Ray to look for any bony injury and an MRI to look for Injury of the ligament, Meniscus, tendons, cartilage etc and then a confirmed diagnosis is made and treatment is planned accordingly

Treatment of ACL Tear

When a patient is 1st diagnosed with an ACL tear and Dr Advices that surgery is the only option that can cure the ACL so what is the first question that comes to the brain.

Is ACL SURGERY really required what are the other options apart from SURGERY If I curtail my activities can I avoid surgery

Treatment of ACL tear depends upon the grade of ACL tear. It is either grade 1,2,3 or high grade and low grade

For grade 1 injuries surgery is usually never required. Treatment goes as rest for 3-4 weeks followed by extensive rehab and one can expect recovery in 2-3 months time.

For grade 2 and 3 injuries Arthroscopic ACL reconstruction is usually required

What other option do you have apart from surgery

1. Grade 2 injury patients can heal with medication, rest and rehab. The results of all these treatment modalities may succeed may not succeed in healing your ACL.

So if problem persist even after 2-3 month of treatment surgery will be the only next option to get back to sports.

2. For people who can modify their activities like stopping sports, fitness regime and lead a sedentary life. - Surgery is required for sedentary life style people also because knee subluxates in minor activities also and it leads to injury of other structures too like meniscus, cartilage, other ligament injury etc and it also leads to early degenerative changes in the knee. So surgery is required even for sedentary people who can curtail their activities.

So to conclude - For grade 1 injury surgery is usually not required. For grade 2 injury one can try with conservative treatment and if problem resolves then extensive rehab can get you back to sports in 2-3 month. If problem persist then Surgery For grade 3 injury Arthroscopic ACL reconstruction surgery is the best option and the only option.

How we do ACL Surgery

Acl surgery is an Arthroscopic surgery (Key Hole Surgery) done with very minimal cut in the knee. The graft used is the hamstring tendons which are Semi-tendinosus and Gracilis and these are prepared into new ACL and fixed in the femur and tibia inside the knee.

We use two most favoured techniques of ACL fixation

1. All- inside ACL with internal brace - In this technique ACL graft is fixed on femur and tibia with tight rope fixation and fibre tape is used for additional protection of the graft.

2. ACL reconstruction using endobutton/ Tight rope on femur and biocomposite (absorbable) screws on tibia.

Why Two procedure Till very recent times the gold standard has been endobutton and biocomposite screw and even today no study proves the merit of one over the other in long term (>6month) All-Inside ACL with fibre tape protection has just one advantage that the recovery time is a little quick, a difference of 1 month. But this comes at an expense of almost 50-60k which is a big amount for some of the sportsmen who are still growing. And some of the recent advances in absorbable screws like the Regenzorb variant leaving no tunnel at all and holes in the screw allowing bone marrow to heal the graft with the bone comes with excellent results So if cost is a constraint we recommend that one can easily go for the endobutton and regenzorb screws which can be done within 1Lakh with imported implants.

The results of All-Inside ACL with fibre tape are equally good and we offer this to patients with no cost constraint at all and who has time limitation of getting back to sports.

So you can decide easily as to which surgery fits you best in terms of time to return to sports and cost involved.


The answer now is Yes

ACL reconstruction has been the gold standard for high grade ACL injury but studies prove that ACL reconstruction does not prevent osteoarthritis and therefore there has been a renewed interest in primary repair of ACL.

The independent suture tape reinforcement (ISTR) technique for ACL repair consists of an ultra-high-strength 2-mm-wide tape that bridges the ligament and is fixed on the femur with a button and a knotless bone anchor on the tibia. A looped wire holds the distal ACL stump to its femoral attachment. This technique reinforces the ligament as a secondary stabilizer, encouraging natural healing of the ligament by protecting it during the healing phase and supporting early mobilization.

1. ACL injury at proximal attachment of femur

2. Which is not retracted

3. Of good quality

4. Of less than 3 month duration

Can be considered for ACL Repair.


Compared with other ACL repair techniques, one of the key features of the ISTR technique is the secondary stabilizer. The ISTR reinforces the ACL and acts as a safety belt, encouraging natural healing of the ligament by protecting it during the healing phase and supporting early mobilization.3 The ISTR technique is less invasive than ACL reconstruction; the 3.5-mm bone tunnels are about half the size of the reconstruction bone tunnels. In the case of a rerupture, a standard ACL reconstruction can still be performed as no bridges are burned. The native ACL is spared, providing proprioceptive properties, which could contribute to a shorter rehabilitation period. Furthermore, there is no hamstring or patella tendon harvesting comorbidity as no graft is needed

Complications of ACL surgery

Whenever a person is advised surgery the most common negative thought that comes to ones mind is

1. Can things go wrong

2. And if yes to what extent

Just like any other surgery the the risk of complications like Infection, stiffness, pain, weakness all can happen with ACL surgery too Now ACL surgery is usually done in a continuous flow of normal saline inside the joint and hence the risk of infection is very very low and is very safe with respect to infection.

The risk increases significantly by using additional implants inside the joint and other supporting implants.

Stiffness of the knee post ACL has been documented mostly in patients undergoing immediate surgery. So getting the surgery done after 1-2 weeks is best to avert this complications.

Other causes of stiffness can again be low grade infection into the joint, inflammation and synovitis which can be due to mal-positioned ACL in either tibial or femoral attachment. So just the right and perfect technique can solve this issue.

Pain is a part of any surgery so it is very common to experience pain initially specifically during rehab and it gradually vanishes and normal day today activity resumes in just 1-2 weeks time.

Weakness of the muscles above and below the knee is another issue with acl injury. It happens right after ACL injury and one can easily identify this by simply comparing the thigh girth of both the knees. The whole Physio protocol revolves around strengthening these muscles and improving the mobility of the knee.

So in simple words just stretching and strengthening of the muscles above and below the knees can give wondrous results.

So to conclude ACL surgery is one of the safest surgery in terms of complications and the chances of things going wrong is extremely low and there is a remedy for everything.