The anterior cruciate ligament or ‘ACL’ is a ligament inside the knee joint that provides stability to the knee by stopping the forward translation of the tibia (shin bone) relative to the femur (thigh bone).
The most common method of injuring the ACL is a bending and twisting movement of the knee with the foot planted on the ground. This movements can occur when changing direction sharply in a sprint or due to an awkward landing from a jump. The ACL can also be injured by a direct blow to the knee resulting in an inward rotation movement Injuries to the ACL can be categorised from Grade 1 (small strain with less than 50% of the ligament torn), grade 2 (more than 50% of the ligament torn with the remaining tissue intact) to grade 3 (full rupture).
When the ACL is completely torn there is often an audible ‘popping’ noise and feeling of something within the knee joint moving out of and then back into place. Pain is usually experienced for the first few minutes after the injury and often subsides quickly. The injured knee may feel unstable when walking and running or perform a twisting motion. Significant swelling normally occurs within the first couple of hours and lasts for up to 10 days. It is common to experience muscle tightness and weakness around the knee immediately after your injury.
ACL tears are initially assessed using physical tests where a physiotherapist or doctor assesses the integrity of the ligament. They consider how much movement the knee joint has relative to the other side. This test should be done at the time of injury as swelling can make the test hard to complete. An MRI may be needed to assess the degree of the ligament tear and to check if the meniscus or medial collateral ligament (MCL) is also injured.
It is important to book an appointment with your physiotherapist for assessment, they will lodge your ACC claim and refer you to a specialist if necessary. They can provide and fit you with a knee brace to aid stability, provide crutches and show you how to best manage the swelling and pain.
Grade 1 ACL tears are managed conservatively with physiotherapy, there is no need for surgical intervention. Your knee may have some pain and swelling. On testing of the ligament there is no laxity. Physiotherapy is initially focused on reducing pain and swelling, restoring range of motion and a normal walking pattern in the first 0-2 weeks. From week 3 onwards, your physio will focus on restoring strength, balance and proprioception (the brains ability to sense where your knee is in space) using progessive exercise program. Your physiotherapist will use the limb symmetry index to benchmark your progress. You should aim for a minimum of 90% symmetry with the uninjured side on strength testing. For individuals who require a high level of function such as those who play ball sports, runners or dancers, return to sport testing will need to be completed to ensure that you have the ability to return safely without concern of re-injury.
An estimated time frame is 8 weeks for a full return to sport.
Grade 2 ACL tears are managed conservatively with physiotherapy, there is no need for surgical intervention. They are slower to heal than grade 1 tears so rehabilitation will take longer. There may be pain and moderate swelling and some laxity on testing. Physiotherapy will initially focus on reducing pain and swelling, restoring range of motion and a normal walking pattern in the first 0 – 2 weeks. From week 3 onwards, your physio will focus on restoring strength, balance and proprioception (the brains ability to sense where your knee is in space) using progessive exercise program. Your physiotherapist will use the limb symmetry index to benchmark your progress. You should aim for a minimum of 90% symmetry with the uninjured side on strength testing. For individuals who require a high level of function such as those who play ball sports, runners or dancers, return to sport testing will need to be completed to ensure that you have the ability to return safely without concern of re-injury.
An estimated time frame for rehabilitation is 12-26 weeks for a full return to sport.
Grade 3 ACL tears may be managed conservatively with physiotherapy or surgically. You will need to make a shared decision between you and your orthopaedic specialist based on your goals and time frames. Physiotherapy is an important part of the rehabilitation for both options. Initially your physio will focus on restoring range of motion, managing pain and swelling and restoring normal gait. This is progressed into a structured exercise program focusing on strength, balance and function. As with Grade1 and 2 injuries, you should aim for a minimum of 90% on the limb symmetry index when comparing testing between the injured and non-injured sides. Return to sport testing is an essential part of completing rehabilitation in a grade 3 tear as it indicates a reduced risk of future injury.
An estimated time frame for rehabilitation is 12 months from the date of injury with conservative management or from the date of surgery.
Rehabilitation plans differ depending if you choose to go down the surgical or non-surgical route, but the below rehabilitation phases are to give you a guide on what you can expect during your rehabilitation. Which ever pathway you choose you can expect your rehabilitation to be 12 months.
The beginning phase is focused on managing the swelling and bring down your pain. Rest, ice, compression, and elevation are all good ways to help bring the swelling in your knee. Once your pain and swelling has reduced you will be focused on restoring knee extension (straightening your knee), the focus on being able to bend your knee will vary depending on if you have had surgery.
Squatting, single leg balance, walking and cycling are all common exercises in the early phases of an ACL rehabilitation. At this stage your swelling in your knee should have subsided and you should feel like you are back to walking normally again.
The majority of ACL rehabilitation will consist of a gym component. This is because your knees have to absorb a lot of force, so they need to have the sufficient strength to cope. Using weights in the gym allows you to utilise the overload principal to stimulate extra strength around your knee. Using the limb symmetry index is a great to benchmark how strong your knee needs to be. Ensuring your knee strength is within 10% of the other side is a great way to know how much more you need to keeping pushing yourself.
Hopping, jumping and running are all important movements to get back to doing the things you love. These are known as plyometric movements. Ensuring you have the sufficient strength, balance and co-ordination to stop yourself on landing is one of the biggest factors that increases your risk of re-injury. See our sports injury rehab page for some of the common return to sport testing we like to use at Link Health and Fitness.
We have experienced senior clinicians with one of the best equipped facilities on Auckland’s North Shore. Our patients have access to a full gym and Pilates studio to allow us to develop an exercise program specific to your needs. Independent gym exercise is an important part of most ACL rehabilitation. At Link Health and Fitness a physiotherapist is always available during staffed hours to offer you additional support.