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 ligaments in the knee. It prevents the tibia (Shin bone) from 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, articular cartilage (lining the joint) or other ligaments, can be damaged at the same time as a cruciate injury and these may need to be addressed at the time of surgery.
Once the initial injury settles down, the main symptom is instability or giving away of the knee. This usually occurs with running activities, but can occur on simple walking or other activities of daily living. Episodes of instability can cause further damage to important structures within the knee that may result in early arthritis.
The diagnoses 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 if there is doubt as well as to look for damage of other structures within the knee.
At times, the final diagnoses can only be made under anesthetic or with arthroscopy.
Not everyone needs surgery. Some people can compensate for the injured ligament with strengthening exercises or a brace.
It is strongly advised to give up sports involving twisting activities, if you have an ACL injury.
Surgical techniques have improved significantly over the last decade, complications are reduced and recovery is 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 hamstring tendon or the patella tendon. There are advantages and disadvantages of each, with the final decision based on your surgeon’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, often with a drain and a dressing applied.
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.
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 fitness and training.
Professional sportsmen 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.
Acute (0 – 2 Weeks)
Stage 2- Quadriceps Control (2-6 Weeks)
Stage 3- Hamstring/Quadriceps Strengthening (6-12 Weeks)
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.
Prior to running, certain criteria must be met:
Stage Four-Sport Specific (3-6 Months)
Stage Five-Return to Sport (6 Months Plus)
A safe return to sporting activities
Complications are not common but can occur. Prior to making the decision of having 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, which can lead to ongoing health concerns, prolonged hospitalization.
The following are 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 and bruising
This is due to bleeding in the soft tissues and will settle with time.
It 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 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
There 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 to 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. There can be pain or swelling in these areas, which usually resolve 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 an experienced surgeon who performs a lot of these procedures, 95% of people have a successful result. It is generally recommended in patients wishing to return to an active lifestyle; especially those wishing to play sports involving running and twisting.
The above information hopefully has educated you on the choices available to you, the procedure and the risks involved. If you have any further questions you should consult with your surgeon.