What is an anterior cruciate ligament (ACL) reconstruction?
The anterior cruciate ligament (ACL) is an important major stabilising ligament within the knee. ACL sprains or tears are one of the most common knee injuries seen, particularly in those sports that involve twisting movements of the knee (such as football and netball). Unfortunately, ACL tears do not heal, often leading instead to instability of the knee. An ACL reconstruction is a surgical procedure to stabilise the knee by replacing (reconstructing) the torn ACL with another ligament graft. The graft is taken from tissues around the knee, such as the hamstring tendons or patella (knee cap) tendon. An artificial tendon graft may also be used. ACL reconstructions are usually performed arthroscopically (i.e., keyhole surgery).
Torn ACL remnant
ACL reconstructed with hamstring graft
Post ACL reconstruction with endo-button and RCI screw fixation
Post ACL reconstruction with endo-button and RCI screw fixation
What are the symptoms of ACL injury?
When you injure your ACL, you may hear a “popping” noise or a “snapping” sensation. You may also feel your knee giving way. This is followed by sudden pain and swelling. It may be difficult to walk for several days. The acute symptoms of pain and swelling eventually resolve spontaneously. However, the sensation of the knee ‘giving way’ or instability often persists when attempting to return to sporting activities.
Other symptoms include loss of full range of motion, inability to fully straighten the knee, pain with walking and tenderness along the joint line. These symptoms may also suggest concomitant injuries to the meniscus or articular cartilage.
How do you diagnose ACL injury?
A well-trained doctor or other paramedical professional will suspect an ACL injury based on your symptoms and a thorough examination of your knee. The diagnosis can often be made on the history and examination alone.
X-rays are often normal or may show an associated fracture (broken bone) known as a “segond lesion” indicative of an ACL injury.
MRI may be required if the diagnosis is unclear or if other soft tissue injuries are suspected, such as concomitant ligament injuries, meniscus or articular cartilage injuries.
What are the causes of ACL injury?
The ACL can be injured in several ways:
- Changing direction rapidly
- Stopping suddenly
- Slowing down while running
- Landing from a jump incorrectly
- Direct contact or collision, such as a football tackle
Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes in certain sports. It has been proposed that this is due to differences in physical conditioning, muscular strength and neuromuscular control. Other suggested causes include differences in pelvis and lower extremity (leg) alignment, increased looseness in ligaments, and the effects of oestrogen on ligament properties.
What is the treatment for ACL injuries?
A torn ACL will not heal without surgery. However, not everyone requires surgery, and treatment is tailored to the patient’s individual needs. The less active patient may be able to return to a quieter lifestyle without surgery. Surgery is recommended for ongoing episodes of instability as the instability can cause further damage to important structures in the knee, which may result in early arthritis. Patients wishing to return to sports involving cutting or pivoting movements (e.g., soccer, football, netball, etc.) or with physical jobs involving cutting or pivoting movements (e.g., policeman, fireman, builders, etc.) will require surgery to restore function and stability.
Non-surgical treatment involves physical therapy and rehabilitation to strengthen the quadriceps and hamstrings muscles, to stabilise the knee and maintain range of movement. Bracing may be required to protect your knee from instability.
Most ACL tears cannot be sutured (stitched) back together. Surgical treatment to repair the torn ACL involves reconstructing the ACL with a tissue graft. The graft is taken from tissues around the knee, such as the hamstring tendons or patella (knee cap) tendon or from an artificial tendon graft. The choice of graft is determined by the individual patient’s requirements. ACL reconstructions are usually performed arthroscopically (keyhole surgery) as it is less invasive, requiring only an overnight stay with less pain and quicker recovery.
Rehabilitation and recovery after ACL reconstruction
Participating and completing a tailored exercise program before (i.e. pre-habilitation) and after surgery (i.e. rehabilitation) with a trained physiotherapist will achieve the best result for you post-surgery. Physiotherapy is an integral part of the treatment and is recommended to start as early as possible. Preoperative physiotherapy is helpful to better prepare the knee for surgery. The early aim is to regain range of motion, reduce swelling and achieve full weight-bearing.
Rehabilitation is supervised by a physiotherapist and will involve activities such as exercise bike riding, swimming, proprioceptive exercises and muscle strengthening. Cycling can begin at 2 months, jogging can generally begin at around 3 months. The graft is strong enough to allow sport at around 6 months; however, other factors do come into play, such as confidence, fitness and adequate training. Professional athletes often return at 6 months, but recreational athletes may take 10-12 months, depending on motivation levels and the time put into rehabilitation.
The rehabilitation and overall success of the procedure can be affected by associated injuries to the knee such as damage to the meniscus, articular cartilage or other ligaments.
When can I walk after an ACL reconstruction?
Full weight-bearing and walking is allowed immediately and encouraged after an ACL reconstruction. Initially, this will be aided by crutches and a knee splint, but once you regain strength and mobility, crutches can be discarded. The knee splint can be removed to perform your postoperative rehabilitation exercises and regain range of movement.
When can I drive after an ACL reconstruction?
You should not drive for 48 hours after an anaesthetic. After 48 hours, your ability to drive will depend on the side you had your operation, left or right, and the type of vehicle you drive, manual or automatic. If you had a left knee procedure and drive an automatic, you can drive whenever you feel comfortable. Otherwise, it is recommended that you do not drive for 6 weeks.
When can I return to work after an ACL reconstruction?
Your return to work will vary depending on the procedure performed and the type of work you are engaged in. Most people can return to office work within 2-3 weeks. Labour intensive work however, may require you to take 4-6 weeks before returning to full duties.
When can I play after an ACL reconstruction?
A structured rehabilitation program is implemented after an ACL reconstruction. The first 6 weeks consist of “closed-chain” exercises. This is followed by “open-chain” exercises for the next 6 weeks (including cycling and swimming). From 3 months on, jogging can recommence and a graduated sports-specific rehabilitation program is structured. The aim is to return to non-contact sports in 6 months and contact sports in 9-12 months.
How long will I take to heal after an ACL reconstruction?
The wounds take 7-10 days to heal. Most patients improve dramatically in the first 6 weeks. Occasionally, there are periods where the knee may become sore and then settle again. This is part of the normal healing process. It takes 6-9 months for your knee to fully recover from an ACL reconstruction. Continued improvements may be gained up to 1 year post-surgery.
How much pain will I experience after an ACL reconstruction?
Most patients are pleasantly surprised at how little pain they have after surgery. This is because a local anaesthetic is injected around the wound during the procedure and it is performed arthroscopically (i.e. keyhole surgery), which is less invasive. You will be provided with adequate analgesics to take at home.
What are the risks of having an ACL reconstruction?
Complications are not common, but can occur. Prior to making any decision to have surgery, it is important that you understand the potential risks so that you can make an informed decision regarding the advantages and disadvantages of surgery. The following list is by no means exhaustive, so it is important to discuss your concerns with your your surgeon.
Specific risks of ACL reconstruction:
- Joint stiffness: Unless the ACL reconstruction is treated for a concomitant ligament injury or meniscal injury, it is usually not performed right away. This delay allows the inflammation and swelling to settle and allows the knee to regain full range of movement. Performing an ACL reconstruction too early increases the risk of arthrofibrosis or scarring in the joint and may result in stiffness.
- Nerve or vessel damage: There are small nerves under the skin that cannot be avoided; cutting them may lead to areas of numbness in the front of the knee. This area of numbness normally reduces in size with time and does not cause any functional problems with the knee. Very rarely, there can be damage to important nerves or vessels in the leg.
- Graft failure: The reconstructed graft is not indestructible, and like the native ACL, it can also rupture. The rate is approximately 5%. If the graft ruptures, it can be revised if required by using other grafts.
- Graft donor site issues: There may be bruising, pain and swelling from where the graft (hamstrings or patella tendon) was taken. This will resolve with time.
- Reflex sympathetic dystrophy: This is an extremely rare condition that is not entirely understood, but can cause unexplained and excessive pain, and stiffness after surgery (or even after trivial injury).
Other general surgical risks include risk of infection, bleeding and clots in the leg (DVT) or lung postoperatively.
Apart from surgical risks, medical (including allergies) and anaesthetic complications can occur, and these can affect your general well-being and health.
- Knee Arthroscopy
- ACL Reconstruction
- Total Knee Replacement
- Arthroscopic Meniscal Repair
- MPFL Reconstruction
- Cartilage Repair and Transplantation
- High Tibial Osteotomy
- Revision Knee Replacement
- Patient Matched Knee Rreplacement
- Unicompartmental (Partial) Knee Replacement
- Computer Assisted Total Knee Replacement
- ACL Injury: Should it be fixed?
- Activities After a Knee Replacement
- Additional Resources on the Knee
- Adolescent Anterior Knee Pain
- Arthritis of the Knee
- Care of the Aging Knee: Baby Boomers May Need Lifestyle Changes
- Cemented and Cementless Knee Replacement
- Deep Vein Thrombosis
- Frequently Asked Questions about Osteoarthritis of the Knee
- Goosefoot (Pes Anserine) Bursitis of the Knee
- Knee Arthroscopy
- Knee Arthroscopy Exercise Guide
- Knee Implants
- Knee Replacement Exercise Guide
- Kneecap (Prepatellar) Bursitis
- Meniscal Tear
- Meniscal Transplants
- Minimally Invasive Total Knee Replacement
- Nonsurgical Treatment Options for Osteoarthritis of the Knee
- Orthopaedists Research Female Knee Problems
- Osgood-Schlatter Disease (Knee Pain)
- Osteonecrosis of the Knee
- Posterior Cruciate Ligament (PCL) Tear
- Rotating Platform/Mobile-bearing Knees
- Runner’s Knee (Patellofemoral Pain)
- Surgical Treatment of Osteoarthritis of the Knee
- The Knee
- Total Knee Replacement
- Unstable Kneecap
- Viscosupplementation Treatment for Arthritis