The anterior cruciate ligament is one of the major stabilizing ligaments in the knee. It is a strong rope- like structure located in the center of the knee running from the femur to the tibia.
When this ligament tears, unfortunately, it doesn't heal and often leads to the feeling of instability in the knee.
ACL reconstruction is a commonly performed surgical procedure and with recent advances in arthroscopic surgery, can now be performed with minimal incisions and low complication rates.
The ACL is the major stabilizing ligament in the knee. It prevents the tibia (shin bone) moving abnormally on the femur (thigh bone). When this abnormal movement occurs, it is referred to as instability and the patient is aware of this abnormal movement.
Often, other structures such as the meniscus, the articular cartilage (lining the joint), or other ligaments can also be damaged at the same time as a cruciate injury, and these may need to be addressed at the time of surgery.
- Most injuries are sports-related involving a twisting or sudden deceleration injury to the knee.
- It can occur with a sudden change of direction or a direct blow, e.g., a tackle, landing awkwardly.
- Often there is a popping sound when the ligament ruptures.
- Swelling usually occurs within hours.
- There is often the feeling of the knee popping out of joint.
- It is rare to be able to continue playing sport with the initial injury.
Once the initial injury settles down, the main symptom is instability or giving way of the knee. This usually occurs with running activities, but can occur with simple walking or other activities of daily living.
The diagnosis can often be made on the history alone.
Examination reveals instability of the knee, if adequately relaxed or not too painful.
An MRI (Magnetic Resonance Imaging) can be helpful to confirm the diagnosis and to look for damage to other structures within the knee.
At times, the final diagnosis can only be made under an anesthetic or with an arthroscopy.
What are the treatment options?
Initial Non-surgical Treatment
- Physical Therapy to regain motion and strengthen the muscles
Long term Treatment
Not everyone needs surgery for an ACL tear. Some people can compensate for the injured ligament with strengthening exercises or a brace. Avoiding pivoting activities is also an option. If recurrent episodes of instability occur, further damage to important structures, such as menisci and cartilage, within the knee may result, which can lead to early arthritis.
- Young patients wishing to maintain an active lifestyle
- Sports involving twisting activities, e.g., soccer, basketball, volleyball, football
- People with dangerous occupations, e.g., policemen, firemen, roofers, scaffolders
- Giving way with activities of daily living
Surgical techniques have improved significantly over the last decade, complications are reduced and recovery much quicker than in the past.
The surgery is performed arthroscopically. The ruptured ligament is removed and then tunnels (holes) in the bone are drilled to accept the new graft. This graft which replaces your old ACL is taken either from the patella tendon, hamstring tendon, or cadaver (allograft). There are advantages & disadvantages of each, with the final decision based on the surgeon's recommendation and patient’s preference.
The graft is prepared to take the form of a new tendon and passed through the drill holes in the bone.
The new tendon is then fixed into the bone with various devices to hold it in place while the ligament heals into the bone (usually 6 months).
The rest of the knee can be clearly visualized at the same time and any other damage is dealt with, e.g., meniscal tears.
The wounds are then closed, and a dressing is applied.
Physiotherapy is an integral part of the treatment and is recommended to start as early as possible. Pre-operative 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.
The remaining rehabilitation will be 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 come into play such as confidence, fitness, and adequate training.
Professional atheletes often return at 6 months but recreational athletes may take 10 -12 months depending on motivation and 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 meniscus, articular cartilage or other ligaments.
The following is a more detailed rehabilitation protocol useful for patients and physiotherapists. It is a guide only and must be adjusted on an individual basis taking into account pain, other pathology, work and other social factors.
Stage 1-Acute (0 - 2 Weeks)
- Wound healing
- Reduce swelling
- Regain full extension
- Full weight bearing
- Wean off crutches
- Promote muscle control
- Pain and swelling reduction with ice, intermittent pressure pump, soft tissue massage and exercise
- Patella mobilization
- Active range of motion knee exercises, calf and hamstring stretching, contraction (non- weight bearing progressing to standing), muscle control and full weight bearing. Aim for full extension by 2 weeks. Full flexion will take longer and generally will come with gradual stretching. Care needs to be taken with hamstring co-contraction as this may result in hamstring strains if too vigorous. Light hamstring loading continues into the next stage with progression of general rehabilitation.
- Gait retraining encouraging extension at heel strike
Stage 2- Quadriceps Control (2-6 Weeks)
- Full active range of motion
- Normal gait with reasonable weight tolerance
- Minimal pain and effusion
- Develop muscular control for controlled pain-free single leg lunge
- Avoid hamstring strain
- Develop early proprioceptive awareness
- Use active, passive and hands-on techniques to promote full range of motion.
- Progress to closed chain exercises (quarter squats and single leg lunge) as pain allows. The emphasis is on pain-free loading, VMO and gluteal activation
- Introduce gym based exercise equipment including leg press and stationary cycle.
- Water based exercises can begin once the wound has healed, including treading water, gentle swimming avoiding breaststroke.
- Begin proprioceptive exercises including single standing leg balance on the ground and mini tramp. This can progress by introducing body movement whilst standing on one leg
- Bilateral and single calf raises and stretching
- If hamstring graft, avoid isolated loading of the hamstrings due to ease of tear. Hamstrings will be progressively loaded through closed chain and gym based activity
Stage 3- Hamstring/Quadriceps Strengthening (6-12 Weeks)
- Begin specific hamstring loading
- Increase total leg strength
- Promote good quadriceps control in lunge and hopping activity in preparation for running
- Focal hamstring loading begins and is progressed steadily throughout the next stages of rehabilitation
- Active prone knee flexion which can be quickly progressed to include a light weight and gradually increasing weights
- Bilateral bridging off a chair. This can be progressed by moving onto a single leg bridge and then single leg bridge with weight held across the abdomen
- Single straight leg dead lift initially active with increasing difficulty by adding dumbbells
If hamstring graft, with respect to hamstring loading, they should never be pushed into pain and should be carefully progressed. Any subtle strain or tightness following exercises should be managed with a reduction in hamstring based exercises
- Gym based activity including leg presses, light squats and stationary bike which can be progressively increased in intensity as pain and control allow. It is important to monitor any effusions following exercise and if it is increasing then exercise should be toned down
- Once single leg lunge control is comparable to the other side, hopping can be introduced. Hops can be made more difficult by including variations such as forward/back, side to side off a step and in a quadrant
- Running may begin towards the latter part of this stage
Prior to running, certain criteria must be met:
- No anterior knee pain
- A pain free lunge and hop that is comparable to the other side
- The knee must have no effusion
- Before jogging start having brisk walks, ideally on a treadmill to monitor landing
- Action and any effusion- this should be done for several weeks before jogging properly
- Increased proprioceptive manoeuvres with standing leg balance and progressive hopping based activity
- Expand calf routine to include eccentric loading
Stage 4-Sport Specific (3-6 Months)
- Improve leg strength
- Develop running endurance speed, change of direction
- Advanced proprioception
- Prepare for return to sport and recreational lifestyle
- Controlled sport specific activities should be included in the progression of running and gym loads. Increasing effusion post running that isn't easily managed with ice should result in a reduction in running loads
- Advanced proprioception to include controlled hopping and turning and balance correction
- Monitor potential problems associated with increasing loads
- No open chain resisted leg extension exercises unless authorized by your surgeon
Stage 5-Return to Sport (6 Months Plus)
A safe return to sporting activities
- Full training for 1 month prior to active return to competitive sport
- Preparation for body contact sports. Begin with low intensity one on one contests and progress by increasing intensity and complexity in preparation for drills that one might be expected to do at training
- To improve running endurance leading up to a normal training session
- Full range, no effusion, good quadriceps control for lunge, hopping and hop and turn type activity. Circumference measures of thigh and calf to within 1 cm of the other side
Complications are not common but can occur. Prior to making the decision to have this operation, it is important you understand these so you can make an informed decision on the advantages and disadvantages of surgery.
These can be medical (Anesthetic) complications and surgical complications.
Medical (Anesthetic) complications
Medical complications include those of the anesthetic and your general well-being. Almost any medical condition can occur so this list is not complete. Complications include:
Allergic reactions to medications
Blood loss requiring transfusion with its low risk of disease transmission, heart attacks, strokes, kidney failure, pneumonia, bladder infections. Complications from nerve blocks such as infection or nerve damage. Serious medical problems can lead to ongoing health concerns, prolonged hospitalization.
The following is a list of surgical complications. These are all rare but can occur. Most are treatable and do not lead to long term problems.
Approximately 1 in 200. Treatment involves either oral or antibiotics through the drip, or rarely, further surgery to wash the infection out.
Deep vein thrombosis
These are clots in the veins of the leg. If they occur, you may need blood thinning medication in the form of injections or tablets. Very rarely they can travel to the lung (Pulmonary Embolus) which can cause breathing difficulties or even death.
Excessive swelling & bruising
This is due to bleeding in the soft tissues and will settle with time.
Can result from scar tissue within the joint, and is minimized by advances in surgical technique and rapid rehabilitation. Full range of movements cannot always be guaranteed.
The graft can fail the same as a normal cruciate ligament does. Failure rate is approximately 5%. If the graft stretches or ruptures, it can still be revised if required, by using tendons from the other leg.
Damage to nerves or vessels
These are small nerves under the skin which cannot be avoided and cutting them leads to areas of numbness in the leg. This normally reduces in size over time and does not cause any functional problems with the knee. Very rarely, there can be damage to more important nerves or vessels causing weakness in the leg.
All grafts need to be fixed to the bone using various devices (hardware) such as screws or staples. These can cause irritation of the wound and may require removal once the graft has grown into the bone.
Donor site problems
Donor site means where the graft is taken from. In general, either the hamstrings or patella tendon are used. These can cause pain or swelling in these areas which usually resolves over time.
Can occur especially if there is damage to other structures inside the knee.
Reflex Sympathetic Dystrophy
An extremely rare condition that is not entirely understood, which can cause unexplained and excessive pain.
Anterior Cruciate Ligament reconstruction is a common and very successful procedure. In the hands of experienced surgeons, who perform a lot of these procedures, 95% of people have a successful result. It is generally recommended in the patient wishing to return to an active lifestyle, especially those wishing to play sports involving running and twisting.