ANATOMY and FUNCTION
The anterior cruciate ligament (ACL) is one of a pair of stabilising ligaments, (the other being the PCL or posterior cruciate ligament) located in the centre of the knee. It is a strong rope-like structure connecting the femur to the tibia through the intercondylar notch. It provides 85% of the restraining force preventing the femur from sliding backwards and rotating abnormally on the tibia. It is required for normal function of the knee.
One of the main functions of the ACL is to provide stability during rotational movements such as turning, twisting, and sidestepping.
ACL tears and ruptures are one of the most common knee injuries. They usually do not heal satisfactorily and so the knee remains unstable and likely to give way. ACL tears are often associated with damage to other structures in the knee such as tears of the medial or lateral meniscus, medial ligament tears, articular cartilage damage, bone bruising and occasionally bone fractures.
Reconstruction of the ACL is important to provide stability and help reduce the possibility of further injury or damage to the knee.
HISTORY OF INJURY
There is usually a significant injury involving a twisting movement of the knee such as when changing directions whilst running. The ACL can tear after landing from a jump, stopping rapidly, or with direct contact such as a tackle during contact sport. This injury is particularly common in sports such as football, soccer, basketball and netball, but can also occur in many other activities. Skiing is a sport that is associated with a high rate of injuries to the ACL.
When the ACL ruptures the patient often hears a loud pop and feels something giving way in the knee. The injury is usually very painful for 15 minutes or so. Most people cannot continue with their activity and the knee generally swells up within hours.
Initial management of an ACL injury requires rest and elevation, ice and a compressive bandage on the knee. Crutches and analgesics may be required. Physiotherapy can be helpful to reduce swelling and regain motion.
Careful clinical examination is required and an X ray is done to exclude possible fracture. An MRI may also be done to confirm the diagnosis and exclude damage to other structures in the knee.
Most patients who tear their ACL will elect to have it surgically reconstructed.
Anterior cruciate ligament reconstruction (ACL reconstruction) is a tissue graft replacement of the ACL to restore its function and enable patients to return to full activities including sport with a stable knee. A stable knee is less likely to suffer further damage than a cruciate deficient unstable knee, especially if a return to sport is anticipated.
Other patients choose to modify their activities and give up sport to avoid episodes of instability. If you do not elect to have surgery I strongly advise that you give up sports that involve pivoting side stepping or rotation, as repeated episodes of instability are very likely to cause irreparable damage to the knee. Damage to the articular cartilage following repeated episodes of giving way of the knee can lead to osteoarthritis.
In general the younger and more active you are then the stronger the recommendation for reconstruction. I recommend surgery if you wish to get back to sports that involve twisting or pivoting and also in patients with physically demanding occupations such as policemen, firemen, builders, scaffolders and roof tilers. This is a safety issue to prevent instability in dangerous situations.
There is no urgency in performing this operation and in fact I sometimes recommend that some patients allow a short time for the knee to settle down and regain near full range of motion prior to surgery. Patients are advised however to avoid sport and rotational activities while the knee is unstable.
ACL reconstruction involves replacing the torn cruciate ligament with either the hamstring tendons or patellar tendon from the same leg.
My definite preference is to use hamstring tendons to reconstruct the ACL. I have personally done more than 5000 ACL reconstructions using hamstring grafts. I believe that the hamstring technique offers the following advantages –
- Stronger graft
- Fewer complications and side effects
- Faster recovery and easier rehabilitation
- Less post-operative pain
- Less muscle wasting after surgery
- Less anterior knee pain
- Easier to kneel comfortably after surgery
- Minimal scarring.
Preparing for your surgery:
It is useful to do some quadriceps exercises (up to the point of mild discomfort) prior to your operation. These exercises are designed to maintain muscle strength to the quadriceps group, which is on the front of your thigh. It is very important to also continue these exercises post-operatively.
Anticoagulant medication such as Plavix, Cartia and aspirin, should also be ceased 7 days prior to surgery. Some other anticoagulants such as Warfarin should be ceased with advice from your treating physician. All vitamins and supplements e.g. fish oil, should be ceased 10 days prior to surgery. All other regular prescribed medication should be continued.
ACL reconstruction surgery is performed under general anaesthetic. You will be able to discuss this with your anaesthetist on the day of your surgery.
Your knee and leg should be free of any skin infection or irritation. Please contact me or my nurse if you have any cuts or sores on your knee or anywhere else on your body. Use an antibacterial wash on your knee and leg daily for a week prior to surgery if possible. (e.g. Phisohex)
You will be admitted to hospital on the day of your operation.
The hospital will call you in the afternoon prior to your procedure with your fasting details and admission time.
The anaesthetist will see you before your operation to discuss your anaesthetic. He will also give you some advice regarding post operative medication and pain management.
The surgery is performed arthroscopically (keyhole). The inside of the knee is thoroughly visualised and any other problems such as meniscal tears are dealt with as part of the procedure. Your ACL reconstruction involves taking the hamstring tendons through a small incision just below the knee and fashioning them into a four stranded graft which is used to reconstruct the anterior cruciate ligament. Tunnels are then drilled in the tibia and femur (the two bones making up the knee joint) and the graft is passed through the joint. The graft is then fixed at each end to stabilise it and allow it to heal to the bone. My fixation technique is to use the Arthrex Tightrope Endobutton construct in the femur and a bio-absorbable screw to anchor the graft in the tibia. This screw is made from tricalcium phosphate and is very strong. It dissolves and is reabsorbed long after the graft has healed in the bony tunnel. These implants do not need to be removed and will not set off security alarms at airports.
At the end of the procedure I inject the knee with long acting local anaesthetic to help keep pain to a minimum.
Wounds are covered with small waterproof dressings and the leg bandaged with a compression bandage.
You will be taken to the recovery ward where you are monitored prior to being returned to the day surgery ward.
I will visit you in the ward before discharge. I will discuss the operative findings with you. You will be shown some exercises to do at home and advised by the physiotherapist on the use of crutches.
Day surgery staff will allow you to leave the hospital when you are comfortable and mobile.
You should be accompanied home by a relative or friend. You may not drive yourself for at least 24 hours.
Early recovery after surgery
Recovery from this operation involves reducing the swelling, strengthening the muscles and reducing pain.
Please read and follow the Post-Operative instructions.
- Please note that it is normal for the knee to be sore and swollen following ACL reconstruction. Activity should be increased gradually. Avoid prolonged walking or standing for the first few days. You should avoid squatting or kneeling or attempting to bend your knee beyond 90 degrees if the knee is painful or swollen. It is safe to walk but do not spend too much time on your feet. Use the crutches until you are comfortable without them. The graft in the knee is very stable so full weight bearing through the leg is permitted and encouraged. You can walk around but rest as much as possible for the first week and elevate your leg when sitting. Most patients require crutches for the first few days after surgery.
- You may remove the bandage at home on the day following surgery.
- Leave the waterproof dressings which are under the bandage intact until your post-operative review. These dressings allow for showering. Do not soak in a bath or swim. If the dressings become wet or lift off, remove and replace dressings only if you have spoken to me or my nurse. It is normal for some blood to collect under these dressings. This is safe. There may also be some bruising around the knee.
- To reduce pain and swelling use Ibuprofen (Nurofen) taken regularly. Take Panadol or Panadeine Forte for pain as prescribed. Excessive activity or standing for long periods can increase the swelling and pain in the knee. Try and rest as much as possible in the first few days.
- Keep the leg elevated as much as possible after the operation. Apply an ice pack to the knee for 20 minutes at a time to reduce swelling and pain. When applying ice packs, ensure that you place a wet cloth between your skin and the ice pack to prevent an ice burn.
- Strengthening your quadriceps is important in restoring function to the knee. Do the straight leg raising exercises as shown on the post operative exercise sheet. Do 10 straight leg raises every hour whilst awake. It is safe to bend the knee up to the point of mild discomfort. Avoid deep squats.
- I will see you in my office in the week following your surgery. We will discuss your physiotherapy and arrange certificates for time away from work. Report to me any unusual or worrying symptoms, e.g. excessive swelling, calf pain, redness or persistent elevated temperature.
- Time off work depends on your work requirements and is very variable .Office workers usually require 1-2 weeks off work and manual labourers 6-8 weeks.
Physiotherapy is an integral part of treatment following ACL reconstruction and I recommend you start as early as possible after your post operative visit.
Preoperative physiotherapy is sometimes helpful to better prepare the knee for surgery. The early aim is to regain range of motion, reduce swelling and achieve full weight bearing.
Your ACL rehabilitation will be supervised by a physiotherapist as per my Accelerated ACL Rehabilitation Program and will involve activities such as exercise bike riding, swimming, proprioceptive exercises and muscle strengthening. Cycling can begin at 1 month, 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 sport specific training.
Professional sportsmen often return at 6 months but recreational athletes may take longer, 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 menisci, articular cartilage or other ligaments.
THE ACCELERATED ANTERIOR CRUCIATE LIGAMENT REHABILITATION PROGRAM for my patients is printed in full at the end of this document.
Risks and complications
Complications following ACL reconstruction are unusual, but surgical and medical complications can occur and may prolong or limit your recovery. The decision to proceed with surgery is made because the advantages outweigh the disadvantages.
Complications can include
- Allergic reactions to medications.
- Haemarthrosis or bleeding into the joint. Treated with rest, elevation of the leg and ice and occasionally sterile aspiration.
- Excessive swelling and bruising of the leg, due to bleeding in the joint and surrounding tissues. It can cause short term pain and make it difficult to bend the knee. Treatment includes ice, elevation, anti-inflammatory medication and physiotherapy with a compression pump.
- Infection superficial or deep requiring antibiotics. Infection is rare.
- Blood Clots (DVT). Uncommon due to early mobilisation.
- Damage to nerves or blood vessels. Wound or scar irritation. Some sensitivity or small areas of numbness may occur at the wound sites. This usually decreases over time and will not affect the function of your knee.
- Muscle weakness following your injury and surgery. This should improve over time with physiotherapy and exercise.
- Stiffness, which may result from scar tissue formation but is uncommon. Treatment includes physiotherapy and occasionally arthroscopy to remove scar tissue.
- Graft rupture or stretching: This can occur with future injuries after returning to sport. Graft rupture is approximately 5% which is about the same risk as rupturing the ACL in the other leg. If the graft ruptures it can be revised using hamstring tendons from the other leg or with a donor allograft from the bone and tissue bank. In some cases the graft can stretch over time. This is more likely to occur in patients with ligamentous laxity.
- Problems relating to the fixation devices. Occasionally in some patients the bioabsorbable screw does not fully dissolve and causes irritation. Remnants of the screw can be easily removed with surgery through the same incision.
- Donor site problems are uncommon with hamstring tendon grafts. Some pain and swelling in the region of the hamstrings at the back of the knee is usually temporary. About 1 in 8 patients will experience a minor hamstring tear during their rehabilitation, usually around 3-6 weeks post-op. It causes some pain in the back of the thigh and interrupts the rehab program for a week or two but rarely affects the long term function of the knee. Rarely, patients may suffer further hamstring tears/sprains that can affect function. Permanent hamstring weakness is unusual following ACL reconstruction but can occur.
- Reflex sympathetic dystrophy which is a rare condition, the mechanism of which is not fully understood. It involves an overactivity of the nerves in the leg causing unexplained pain.
- Compartment syndrome. An extremely rare condition which is due to excessive swelling in the knee cutting off the circulation to the muscles. Treatment for this condition requires a fasciotomy operation to relieve this pressure. This is something described in the literature but I have not seen it in over 5000 cases.
- Ongoing Pain. This can be unpredictable but is more common in knees with damage to other structures such as the articular cartilage.
- Persistent limp following ACL reconstruction is unusual and usually means that the knee has not regained full movement.
- Unsightly scarring is unusual but possible, especially in dark skinned patients.
You should note that other, rare complications may occur that may not be listed above. You may also speak to your anaesthetist about anaesthetic complications. Please feel free to discuss any queries with me or my nurse.
ACL reconstruction performed arthroscopically by an experienced knee surgeon is a very safe and effective procedure. Most patients achieve excellent stability and return to the sport of their choice after completing the rehabilitation program. Please feel free to ask questions at any stage. You can be assured my best attention at all times.
Please note that my surgical practice is a subspecialty practice. I operate within my defined area of interest and expertise. I believe that this results in better outcomes for patients and a very low complication rate. Patients are only offered the option of surgery after non operative forms of treatment have been considered. Surgery is offered when I consider the potential advantage of this form of treatment outweighs the possible complications and side effects. Surgery is only offered when I feel that this form of treatment is likely to lead to a better outcome for the patient than non-operative forms of management. In the case of elective surgery, the patient is encouraged to consider the non-operative options of treatment and take time to make an informed choice about the preferred course of management. You are free to discuss this with me or your referring medical practitioner. If elective surgery is proposed, please feel free to take as much time as you need to come to an informed decision. If you are not completely comfortable with the decision to proceed with surgery, you are free to take up further discussion with me or seek an independent second opinion. This can be arranged through your referring medical practitioner.
THE ACCELERATED ANTERIOR CRUCIATE LIGAMENT REHABILITATION PROGRAM
The following is a more detailed rehabilitation protocol useful for patients and physiotherapists, courtesy of Alan Davies, Diane Long and Mark Kenna at the Eastern Suburbs Sports Medicine Centre, Bondi Junction.
STAGE 1: ACUTE (0 – 2 WEEKS)
- Allow wound healing
- Reduce swelling
- Regain full extension
- Achieve full weight bearing
- Wean off crutches
- Promote muscle control
- Pain and swelling reduction with ice, intermittent pressure pump, soft tissue massage and exercise
- Patella mobilisation
- Active range of motion knee exercises, calf and hamstring stretching, quadriceps and hamstring co-contraction, 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. Resisted hamstring loading should be avoided for approximately 6 weeks.
- Gait retraining encouraging extension at heel strike. Full weight bearing as soon as possible is desirable.
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 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), and exercises using a kick board.
- Begin proprioceptive exercises including single standing leg balance on the ground and mini-trampoline. This can progress by introducing body movement whilst standing on one leg
- Bilateral and single calf raises and stretching
- 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
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 allows. It is important to monitor any effusions following exercise and if it is increasing then the 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
Prior to 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 authorised 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 activities. Circumference measures of thigh and calf to within 1 cm of other side.
At this stage you will be supplied with the PEP Safe Return to Sport Program. This program is designed to assist you to return to sport safely with a reduced risk of re-injury.
Before returning to sport you should have achieved the following;
- Full range of motion
- No effusion
- No pain
- At least 90% quadriceps strength
- Thigh and calf circumference within 2cm of the uninjured side
- Good proprioception
- Ability to complete 2 consecutive training sessions