Anterior Cruciate Ligament (ACL) Anatomy
The anterior cruciate ligament is a thick rope like structure made from collagen that joins the femur to the tibia.
Its main function is to provide rotational stability to a the knee joint. The anterior cruciate ligament is one of the major stabilising ligaments in the knee. It acts as a strong brace.
Causes of ACL Injuries
ACL injuries are one of the most common ligament injuries in the body. Once the anterior cruciate ligament is torn it has a poor ability to heal and typically will not heal if untreated.
The ACL can tear with different types of injury such as:
- Twisting and rotational injuries, such as occurs with a sudden change in direction or speed
- Contact injuries in collision sports or road accidents
- Hyperextension injuries
- Hyperflexion injuries
Symptoms of an ACL Injury
Patients report the following associated symptoms of anterior cruciate ligament injuries:
- An audible 'pop' sound from the knee
- A sensation of something tearing inside the knee.
- A feeling as if the knee has momentarily 'come out of its joint'.
These symptoms are usually followed by:
- Swelling of the knee
- Difficulty walking and
Instability of the knee is particularly noticeable:
- on uneven ground or
- During sport when a patient attempts a sidestepping or twisting manoeuvre.
Types of ACL Injury
- Most ACL injuries are complete tears.
- Partial ACL tears are very rare.
- When partial tears occur, they usually progress to complete tears over time
ACL Injury Diagnosis
ACL tears are diagnosed by the following:
- History of injury
- Nature of knee pain and other symptoms
- Physical examination
- Imaging tests
In your assessment I will:
- Take a medical history
- Perform a physical examination
- Assess the joint's range of motion
- Organise appropriate imaging tests
- X-rays may be required to look for evidence of fractures or pre-existing osteoarthritis in older athletes
- MRI scans will show the ACL tear as well as any meniscal or cartilage damage
Untreated Anterior Cruciate Ligament Injuries
When this ligament tears, unfortunately it doesn't heal and often leads to instability of the knee.
If untreated, additional ligament problems are more likely to develop for both active adults and children. A significant number of patients with an untreated (unreconstructed) ACL tear have recurrent:
- Knee instability
- Buckling of the knee
- Giving-way of the knee
These recurrences must be avoided as these episodes cause further problems like cartilage and meniscus tears and premature wear and tear resulting in arthritis of the knee.
Giving Up Sport Option
Patients with ACL tears who do not wish to have an ACL reconstruction are strongly advised to give up all sport that requires turning, twisting and side-stepping. Some of these patients will continue to experience episodes of instability of the knee with ordinary activities of daily living (ADL's).
Physiotherapy is advisable.
Active Patients Option
Most athletes with a torn ACL will opt for surgical ACL reconstruction to stabilize the knee so as to allow normal unrestricted activities.
ACL Reconstruction Surgery
The procedure for anterior cruciate ligament reconstruction replaces a patient's torn anterior cruciate ligament (ACL) tendon with a new tendon or tendons to restore knee stability.
The surgery involves:
- Removal of the spare hamstring tendons (semitendinosis and gracilis), taking care to protect and preserve the attached muscles
- Drilling a hole into the tibia (shin bone)
- Drilling a second hole the femur (thigh bone)
- Anchoring the tendon graft in the tunnels created within the bones
- Securing the replacement ACL tendon with screws or cross pins
Benefits of the Arthroscopic Method
I use a minimally invasive arthroscopic approach to ACL reconstruction.
By performing ACL reconstruction surgery using the advanced arthroscopic approach and a tiny camera (arthroscope), patients benefit by:
- Smaller incisions with little scarring
- Less pain and lower complication rates
- Quicker postoperative recovery, and
- Easier progression toward regaining full knee movement
Using this method also enables me to examine the cartilage and menisci within your knee and where necessary repair them at the same procedure
Anterior Cruciate Ligament (ACL) Tendon Choice
There are three common graft types used for anterior cruciate ligament (ACL) reconstruction:
- Hamstring tendons
- Patellar tendon
- Allograft from the bone and tissue bank
ACL Reconstruction Using Hamstring Tendons
The damaged anterior cruciate ligament is replaced using hamstring tendons from the inner side of your thigh.
ACL Reconstruction Using the Patellar Tendon
The damaged anterior cruciate ligament is replaced using a graft from the patellar tendon,taken from the front of your knee.
ACL Reconstruction Using Allograft
The damaged anterior cruciate ligament is replaced using a donor allograft from the bone and tissue bank.
Preparation for Surgery
Once it has been decided that surgery is required, preparation is necessary to achieve the best results and a quick problem free recovery.
Preparing mentally and physically for surgery is an important step toward a successful result.
- A treatment plan will be created specifically tailored for you
- I will need a complete list of your medications so that I can advise which ones should be stopped prior to surgery
- The admitting hospital will advise you of the fasting time and your arrival time on the day before surgery
- Do not eat or drink anything, including water, for 6 hours before surgery
- Stop taking aspirin, warfarin, anti-inflammatory medications or drugs that increase the risk of bleeding one week before surgery
- Stop or cut down smoking to reduce your surgery risks and improve your recovery
Risks of Knee Surgery
ACL reconstruction is a safe and effective procedure. Complications are very uncommon. However, as with any operation, ACL surgery has potential risks and complications. Surgical complications may include:
- Stiffness of the knee
- Re-rupture of the graft.
- Blood clots
- Damage to local tissue
- Other rare complications
Please feel free to discuss any concerns you may have with me or my staff before any procedure.
If you are having Day Surgery, remember the following:
- Arrange for someone to take you home, as driving is not recommended for at least 24 hours
- Do not drink or eat anything in the car on the trip home as the combination of anaesthesia, food, and car motion can cause nausea or vomiting.
- Wait until you are hungry before trying to eat.
- Begin with light meals and avoid greasy food for the first 24 hours
After Your Operation:
After your operation you will have a drip in your arm for pain medication and antibiotics.
Most patients will leave hospital later in the same day. Some patients will choose an overnight stay. We are very flexible about length of stay following ACL surgery.
The initial replaced ACL's fixation strength will be sufficient to allow early movement and exercise. Splints and braces are not usually necessary.
Crutches are required for 4-5 days following the reconstruction. Once you are off crutches and waling well, you may begin driving.
Return to Work
You may return to light work duties after 1 week. You will not be fit to perform work duties that involve:
- Prolonged standing,
- Heavy lifting,
- Bending or
- Excessive stair climbing
for a minimum of 4 – 6 weeks.
Postoperative Recovery Plan
The physiotherapist will prepare an exercise program. Much of the exercise program can be done at home or at a gym, under your physiotherapist's guidance.
Panadeine Forte tablets are usually all that is required for pain management for the first 5-7 days. Thereafter, regular over the counter Panadol and Nurofen should be enough to control the pain (especially at night).
You may remove the bandages from around the knee on the day following surgery. Leave the waterproof dressing that are adherent to the skin intact. You may shower with them on but don't have a long bath or go swimming until we have changed the dressing at the first post-operative appointment.
The Accelerated Rehab Program at a Glance:
- Ice your knee as directed by your physiotherapist
- Full extension (make sure your knee comes out straight)
- Full weight-bearing, wean off crutches
- Quads and hamstrings co-contractions
- Straight leg raises
- Ankle range of motion (ROM) exercises
The first postoperative appointment is usually made 5-7 days following surgery. The dressing will be changed at this visit.
Week 2 – 6:
- Full weight-bearing – no limp – gait training
- Ice before and after exercise to reduce swelling
- Isometric quad exercise
- Isokinetic closed chain exercises.
- Step work, leg press, squats
- Active knee flexion and extension
- Stationary bike
- Swimming – no restriction except avoid breast stroke
- 21 days commence proprioception retraining
Weeks 6 – 12:
The ends of the new graft will heal into the newly created bony tunnels over 6-12 weeks.
An early return to exercise and sport is possible once the wounds have healed and the swelling in the knee has settled. The graft is strong enough to allow unlimited movement of the knee and immediate full weight bearing
- Progressive training
- Step work, leg press, squats
- Sport specific drills
After Week 12
Following this period the graft will gradually increase in strength as new structural fibres are laid down. The results of ACL Reconstruction surgery are good in most cases.
Recovery from knee surgery can be a slow process
- By 6 months the knee is usually strong enough to resume all sports although it is important to achieve 'match fitness' before returning to the field or ski slopes
- There is no restriction to range of motion
- No bracing required
The Full Accelerated ACL 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
1-Focal hamstring loading begins and is progressed steadily throughout the next stages of rehabilitation
a) Active prone knee flexion which can be quickly progressed to include a light weight and gradually increasing weights
b) 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
c) 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
2-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
3-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
4-Running may begin towards the latter part of this stage. Prior to running certain criteria must be met
a) No anterior knee pain
b) A pain free lunge and hop that is comparable to the other side
c) 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.
5-Increased proprioceptive manoeuvres with standing leg balance and progressive hopping based activity
6-Expand calf routine to include eccentric loading
STAGE 4 SPORT SPECIFIC TRAINING (3-6 MONTHS)
1-improve leg strength
2-develop running endurance speed, change of direction
4-prepare for return to sport and recreational lifestyle
1-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
2-Advanced proprioception to include controlled hopping and turning and balance correction
3-Monitor potential problems associated with increasing loads
4-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
1-Full training for 1 month prior to active return to competitive sport
2-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
3-To improve running endurance leading up to a normal training session
4-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
At least 90% quadriceps strength
Thigh and calf circumference within 2cm of the uninjured side
Ability to complete 2 consecutive training sessions
Out of Town Patients
For out of town patients an appointment with a local doctor or physiotherapist 7 – 10 days post surgery for a wound check and the removal of sutures.
An appointment with Professor Waller should be made at around 6 weeks post surgery.