ACL is the abbreviation for the Anterior Cruciate Ligament. This is one of the major stabilising ligaments within the knee. It connects the femur (thigh bone) to the tibia (leg bone) and prevents abnormal movement (instability) occurring between the two. More specifically it provides rotatory stability to the knee to allow movements such as pivoting or sudden change in direction to occur without the knee giving way.
The most common mechanism of injury is from a non-contact injury that typically occurs whilst attempting a pivoting or cutting (change of direction) manoeuvre during sport [Figure 1]. The injury can also occur from contact activity (e.g. being tackled from the side) when your knee buckles inwards whilst the leg is held in a fixed position. Not uncommonly, a "cracking or popping" sensation is felt at the time of the injury. The injury is associated with a lot of swelling within the knee that typically occurs at the time of, or soon after the injury. The leg is often painful to walk on for several days.
Figure 1. Picture of torn ACL
An ACL rupture may be associated with an injury to other stabilising ligaments within the knee. Rupture of your ACL is commonly associated with tears that involve the shock absorbing cartilages (menisci) of the knee. Depending on the location and size of these tears, they may be surgically repaired or trimmed at the time of your surgery. Bruising (oedema) of the bones also occurs at the time of injury because your femur and tibia are driven into each other by the violent forces that cause the ligament to rupture. No specific treatment is required for this “bone bruising”.
The first line of treatment following injury to the ACL should be those of the RICE principle (Rest, Ice, Compression, and Elevation). Early review by a physiotherapist is important to reduce swelling, improving movement and minimise wasting of muscles around the knee joint. Crutches are generally recommended to avoid excessive weight on the injured limb primarily during the early stages until you can walk without pain.
The treatment of ACL tears will vary across individuals based on their expectations, lifestyle, sporting aims etc. The major aim is to return the patient to their desired level of activity, both in regards to sport as well as other activities such as your occupation, whilst minimising the risk of injury to other structures within the knee.
Patients with an ACL tear who do not wish to return to pivoting sports can often be managed with this approach. Running in a straight line, swimming, bike riding and golf are activities that are suitable. Physiotherapy is critical in the recovery phase to restore movement and strength to the lower limb. The latter phase of your rehabilitation should focus on proprioceptive re-training. These are exercises that improve the protective reflexes around the joint to minimise further instability episodes and reduce the risk of further joint injury.
Most patients who want to return to pivoting sports will require a reconstruction to prevent their knee buckling during these activities. Other indications for surgery include young patients with high activity levels and people who work in an environment where knee stability is critical for safety and function. If your knee is giving way regularly and this is interfering with your quality of life, you may want to consider an operation. This instability may occur during sport or during activities of daily living.
An ACL reconstruction is not an urgent or emergency operation. The best outcomes from reconstructive surgery have been shown to occur in people whose knees have had some time to stabilise and recover. In the majority of cases, we prefer to rehabilitate your knee prior to undergoing surgery. Long term studies suggest that there is a lower risk of injury to the meniscus if surgery is performed within the first 6 months, when compared to those who do not have surgery. For elite athletes, surgery will usually be performed after a shorter period of rehabilitation. Occasionally, ACL reconstruction surgery is required sooner such as when other ligaments on the outer side of the knee (posterolateral corner) are torn or when a displaced tear of the meniscus is causing the knee to lock.
Physiotherapy prior to surgery is important to reduce the swelling, regain movement and limit the loss of strength in the muscles around your knee. It also teaches you the exercises needed for rehabilitation after the surgery.
The ACL is reconstructed using a graft to replace the torn ligament. The idea is for the graft to biologically incorporate within the knee and restore stability to the injured limb. At SKS, we recommend use of the hamstring (HS) tendons for the majority of patients [Figure 2]. The hamstrings lie at the back of the thigh and connect to the inner side of the tibia below the knee. One or two tendons are removed to form a graft of adequate thickness. The HS ACL Reconstruction has the advantages of a faster post-operative recovery, better cosmesis and less post-operative pain with kneeling and squatting activities. SKS use special techniques (quadruple semitendinosus, 6-strand and 8-strand grafts) to optimise the diameter of the new ACL to maximise its strength.
Figure 2. Side view of knee, showing attachment of hamstring tendons to medial (inner) tibia bone. The 25cm length gracilis and semitendinosus tendon are removed through a 3cm incision over the pes anserinus, using a special device called a tendon stripper.
Other graft options exist including patellar tendon bone grafts (PTB) [Figure 3], the quadriceps tendon (from the front of the thigh to the kneecap) and cadaveric grafts (allografts). We do not advocate the use of any synthetic grafts (eg LARS) because of concerns of greater risk of long term damage to the knee joint surfaces. There are pros and cons to all graft choices and a discussion with the operating surgeon will determine what is best for you.
Figure 3. Patellar Tendon Bone Graft. The middle one-third of patellar tendon is removed with 25mm bone attachments on either end.
Prior to undergoing surgery you will have further imaging of your knee to assess for associated injuries. The best test for this is an MRI scan [Figure 4] which allows accurate assessment of damage to all the soft tissues around the knee such as other ligaments, cartilage and menisci. This will aid with the planning of your surgery and also allow us to provide you with more accurate information with regards to your likely rehabilitation program. Do not shave or wax the leg prior to surgery, and cease smoking and any blood thinning medications.
Your rehabilitation after the operation is an important factor in the success of your surgery. Please ensure that physiotherapy is organised prior to your surgery so you can get to know the therapist who you will be working with and that you will have an understanding of the exercises required following surgery. Please ensure your physiotherapist has a copy of the SKS ACL Accelerated Rehabilitation Protocol. This can be downloaded at www.sydneyknee.com.au, or faxed to your physio from our office.
Figure 4. MRI scan showing tear of ACL
You will be admitted to hospital on the day of your surgery. Your anaesthetist will discuss with you the type of anaesthetic you will have and your options for post-operative pain relief. Most patients have a general anaesthetic. Antibiotics are delivered via a drip to decrease the risk of developing an infection. After your anaesthetic has been administered, a tight band (tourniquet) will be applied to your upper thigh and everything except your knee will be covered by sterile drapes.
One or two of your hamstring tendons (gracilis and semitendinosis) will be removed from the back of your thigh through an incision on the front of your knee. This is done with a special instrument called a tendon stripper. In some cases (eg. a revision operation), the knee cap ligament (the middle third of the patellar ligament) or the hamstring tendons from your opposite leg may need to be used.
With the aid of a specialised telescope (arthroscope), the inside of your knee is inspected for any associated damage. If any is found (eg. a meniscal tear), it will be addressed at the time of surgery. A tunnel will be drilled through the tibia and femur at the anatomic positions of the ACL. The tendons will be passed through these tunnels and anchored in place with specialised implants (screws and buttons) to provide fixation to your new ligament. [Figure 5]
Figure 5. ACL reconstruction using HS tendons and button fixation (Arthrex)
Your knee will be injected with local anaesthetic to help reduce post-operative pain. All your wounds will be closed using a combination of normal and dissolving sutures. Your leg will then be wrapped in a well-padded dressing prior to leaving the operating theatre. A brace is not usually required after your surgery.
You will wake up in the recovery ward where you will be closely monitored until you are ready to return to your ward. Here you will continue to be observed until you are fully awake. An x-ray of your knee will be taken the day of your surgery. During your stay, you will be seen by a physiotherapist who will provide you with exercises for your knee and assist you in walking. You will be able take all your weight through the operated leg after the operation. Once you are mobilising safely and your pain is controlled by oral pain medication, you will be able to go home. The majority of patients can be discharged home on the same day as their surgery.
During the first week at home, your knee will be swollen and feel stiff. It is normal to require regular pain medication during this period. It is of utmost importance that you perform your rehabilitation exercises regularly whilst at home so that you get the greatest possible benefit from your surgery. These exercises are given to you on an instruction sheet prior to your hospital discharge. Prior to discharge from hospital, a post-operative visit to your surgeon will be organised approximately 10-14 days following your surgery.
Physiotherapy (rehabilitation) is critical to the success of the surgery. If you cannot strictly follow the necessary precautions and rehabilitation, then it is best off not having surgery as complications such as graft loosing, graft rupture, stiffness and chronic pain can result.
It is important to start physiotherapy within 2-4 days of your surgery. You will require physiotherapy twice a week for approximately 6 weeks then reducing the amount of visits after this. Rehabilitation after an ACL reconstruction takes approximately 6-12 months. During this period you will take part in a structured rehabilitation program with your physiotherapist, and gradually return to your normal activities. This process is designed to safely improve the strength, motion and balance (proprioception) in your knee whilst the ACL graft heals. [See ACL Rehabilitation Protocol]
As a general rule, you are walking with crutches for approximately one week, commence stationary bike exercise by 2 weeks, jogging in straight line by 3 months and commence sports specific agility drills (PEP program) and non-contact training by 6 months. Return to sports is any where between 9-12 months and is determined by many factors including the speed of recovery, associated injuries to the joint and the age of the patient. Patients 18 years or younger are often held off sport for 12 months as studies now show that this age group has a much higher chance of injuring the graft again. You will have follow-up visits with your surgeon at 2 and 8 weeks, then six and twelve months after your surgery.
When can I return to my normal sporting activities?
Most people return to sport somewhere between 9 to 12 months. This will depend on the appropriate completion of the rehabilitation program, as well as the PEP program.
When can I return to work?
If you work in an office setting, you may be able to return to work within 7-10 day. However, if your occupation requires a lot of walking or heavy manual labour, your return to work may be more prolonged, and may require a period of time on restricted duties.
When do I commence physiotherapy?
Physiotherapy usually starts 2-3 days after surgery. You will also see a physiotherapist in hospital who will teach you how to walk with crutches and demonstrate some exercises to do when you go home.
When can I drive again after surgery?
As a general rule, you cannot drive until you are off crutches and are not taking pain-killers that can cause drowsiness such as endone.
Will I have pain after the operation?
Most people will have mild to moderate pain in and around the knee for 2 weeks after surgery. This is generally well controlled with regular oral medication, ice and rest.
What complications can occur from surgery?
It is important to realise that complications can occur and are usually unpredictable. All due care is taken before, during and after the operation to try to ensure that complications do not occur. Sometimes complications may occur despite ever effort being made to avoid them. Should a complication occur, you will be informed and advised on the most appropriate treatment required to optimise the outcome of the initial surgery. If you have any questions or concerns during your recovery, it is important to contact your surgeon at SKS on (02) 8307 0333, or ring the hospital where the surgery occurred out of hours and they can be notified.
The most common complications following ACL Reconstruction surgery are:
If you have any concerns or questions about this operation, please contact your surgeon at Sydney Knee Specialists on (02) 8307 0333.
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