How did I pop my ACL?
First and foremost, let start with how you got this injury, understanding the mechanics of this injury is important for you to get to the root cause of it.
The ACL is one of the 4 main ligaments that provide stability of the knee joint by controlling and preventing rotation of the knee. Like any ligament, it will tear when there is excessive force applied to the knee (especially twisting force).
Injury to the ACL is usually caused by trauma-sometimes we also term this contact injury (e.g. impact force to the side of the knee during a game) or due to poor control of the knee during single leg tasks-conversely we call them non-contact injury (e.g. a sudden change in direction or pivoting against a locked knee). There is a big difference between the two: Contact injury and non-contact. Contact is largely due to luck, you are at the wrong place, wrong time and at the receiving end of an impact. The poor knee simply could not take the impact of the force and the ACL rupture.
A non-contact injury usually means that the knee is harboring an aberrant movement error all this while. Most commonly, your knee may be already doing a small twisting motion whenever your knee bends or squat. In other words, your knee movement is basically like an accident waiting to happen. This faulty movement must be corrected as part of your physiotherapy, otherwise the root cause is not solved.
Pop! And now what?

The pain is usually excruciating, and the patient often reports a “popping” sound, swelling and giving way of the knee after the injury. An ACL injury is usually diagnosed via specific clinical tests and through an MRI scan.
Treatment goals are to return the patient to his/ her pre-injury levels of function. Surgery may be required to repair and reconstruct the torn ligament. It may take one up to about 9-12 months to return to sports after an ACL injury, depending if the individual has chosen conservative management of his/her ACL tear or opted for surgery.
Do I need surgery?
The biggest decision after knowing about your injury is: Surgery or conservative approach?
You may want to consider the following:
- Your levels of activity before injury (Is your sport competitive, for leisure?)
- Your expectation after the injury has healed (Do you intent to go back to the same level of competitiveness?)
- Most importantly whether you are willing to undergo substantial amounts of rehabilitation post-surgery. (The whole rehabilitation is long, very long. You need time, physical and mental strength to complete the whole physiotherapy treatment for optimal results)
A standardized activity level assessment of patients before and after surgery helps patients and surgeons decide if surgery is necessary. This guide developed by the International Knee Documentation Committee (a collaboration of American and European orthopedic surgeons) is as follow:
- Level 1: jumping, pivoting and hard cutting
- Level 2: heavy manual work or side-to side sports
- Level 3: light manual work and non-cutting sports like running/ cycling
- Level 4: sedentary lifestyle without sports
The non-surgical approach is usually considered for patients with level 3 or 4 lifestyles.
Conservative Approach? What can physiotherapy do for non-operated ACL tears?

Conservative, non-surgical treatment methods like physiotherapy would be helpful for clients who are less active and do not frequently participate in physical activities that require running, jumping and or pivoting. Physiotherapy can help to restore range of motion and strength to match that of the un-injured leg. Give yourself up to 3 months to feel normal and functional again.
The initial management of an ACL tear includes Rest, Ice, Compression and Elevation (R.I.C.E), along with the use of a knee brace to limit unnecessary movements of the knee for the first 2-4 weeks. This allows for recovery of the knee from the initial pain and inflammation.
Physiotherapy will commence after, with the aim to restore the range of motion and the strength of the injured knee. A functional sports brace may also be suggested to provide extra support and stability of the knee for more vigorous activities (e.g. trekking/ hiking) even after recovery.
However, physiotherapy and the use of bracing do not restore the stability of the knee to 100%. You will still be at a higher risk of having your knee joint give way, especially if you do not continue with your strengthening exercises to maintain the stability of your affected knee. In such cases, surgery might be recommended as the next option.
Physiotherapy for operated ACL tears (Pre and Post Surgery!)
Surgery is usually suggested for clients who want to return to level 1 and 2 of activities (see the list above). Athletes will also likely require surgery to repair their torn ACL if they want to return to their level of competition.
If surgery is planned for, pre-operative physiotherapy will be done to help with strengthening the muscles that support and surround the knee. Knee physiotherapy will focus on regaining the range of motion of the affected knee through manual therapy techniques like joint mobilizations. This helps to reduce the chance of excessive scar formation around and within the knee that can limit the movement of the knee post surgery.
Strengthening of the quadriceps, hamstrings, gluts and core muscles pre-surgery are also essential for good post-operative outcomes. Pain and swelling management, along with the appropriate use of walking aids like crutches will also be taught for the management of the knee.

(Important! If you are reading this and waiting for your surgery, and still sitting on your bum. ASK your surgeon to send you for pre surgery physiotherapy! We have had many patients who benefited greatly from pre-surgery physiotherapy.)
If you have had surgery, physiotherapy treatment is also essential almost immediately post operation. Similarly, the initial focus would be for the client to regain his/her range of motion of the knee joint and the surrounding muscles. The newly reconstructed ligament needs time to heal (up to about 12 weeks) and you need to ensure that you do not tear or overstretch the graft.
The aim would be for you to achieve full knee extension and to be able to bend till 90 deg. By 6 to 8 weeks post surgery, the knee should be able to achieve full range of motion unless indicated by the surgeon to avoid certain ranges.
This would be followed up by a strength and conditioning program to increase the strength of the surrounding knee muscles, as well as to gradually increase the amount of stress the ligament can take.
Home or gym-based exercises would be suggested accordingly based on the patient’s needs and requirements. The aim would be to restore the strength and function of the knee to what it was before the injury within 4-6 months post surgery.
The last phase of rehabilitation is focused on the functional return to sports for the client, which includes agility, change of direction training as well as explosive power/ strength training. This is to ensure that you would be able to return to your pre-injury level of sporting function, as well as to protect and minimize unnecessary stress and strain on your knee during high level sporting activities.
Lastly, there is a mini “return to sports” test that you have to pass to return to your sports. Passing this physical test will give you a good indication if the strength and function of your knees are symmetrical and definitely the confidence to return to your sports.