This summary is to improve knowledge and understanding of the rehabilitation involved after anterior cruciate ligament reconstruction. It includes basic anatomy and information about the operation itself.

Background Anatomy

The knee is a complicated joint between the femur (thighbone) and the tibia (shinbone). The anterior cruciate ligament (ACL) runs from the back of the femur to the front of the tibia. It is one of the main restraining ligaments in the knee and acts to prevent excessive forward movement of the tibia. Its main function is to give the knee stability during rotational movements like twisting, turning and sidestepping.

The ACL is most likely to be injured in a non-contact twisting movement. A tearing or popping sensation is frequently reported at the time of injury and immediate swelling is common due to bleeding from the ruptured ligament. Injuries to the joint surfaces (articular cartilage) or menisci (footballer’s cartilage) can also occur at the same time.

The ACL also provides important information about balance to the joint and surrounding muscles. When it has been torn, it is unable to heal and the balance information it carries is also lost. Sometimes, these balance mechanisms can be improved with specific exercises and stop the knee giving way. However, when the exercises are not enough, then reconstruction of the ACL may become necessary. It must be said that reconstructed ligaments can never totally replace the function of the original ligament.

The Operation

The surgery is designed to allow individuals to return to their normal function and sporting activities. It should stabilise the knee and stop the knee buckling or giving way. However, the results can be unpredictable.

Published reports indicate 85 – 90% of people consider their knee to be functioning normally or near normal after surgery.

The reconstructed ligament is not the same as the original but appears to give satisfactory results. Wear and tear arthritis is associated with ligament injuries and is not necessarily prevented by ligament reconstruction surgery.

The Procedure

The operation to reconstruct the ligament involves replacing it with a graft taken from tissues around the knee. The two commonly used are the middle third of the patella tendon or the hamstring tendons.

Hamstring Graft Patella Tendon Graft Both are equally strong and give similar long-term results, but the patella tendon graft is the more traditional. The incision for this procedure is down the front of the knee and around 10cms in length.

Hamstring grafts tend to be used for those who have to kneel in their job or sport, or have existing pain at the front of their knee. The incision is on the front and inside of the knee and is around 5cm in length.

Ultimately, the decision on graft selection is made by you, the patient, based upon advice from Mr Aslam.

The surgery itself is done under general anaesthesia and takes around 1-2 hours. If any other structure has been damaged, for example, a meniscal cartilage, then it is usually dealt with at the same time. This, however, may only be apparent at the time of surgery.

If the knee is very inflamed, during examination, in theatre, the ligament reconstruction may need to be delayed to avoid excessive knee stiffness afterwards. This would mean a second surgery would be required when the knee was less inflamed.

Tunnels are made in the tibia and femur and the graft is passed into the knee. It is held in place with either screws or buttons. These materials do not usually need to be removed unless they are causing problems. This could be done at a minimum of 12 months after surgery.


Complications do occur. Some are minor, but others may require further surgery. It is important you understand this before undertaking surgery. Examples include:

Anaesthetic risks – will be discussed with you by your Anaesthetist
Failure to provide sufficient stability to be able to return to full sporting activities 5%
Deep vein thrombosis – ‘clot in the calf’ 3%
Pulmonary Embolism – ‘clot in the lung’ 0.5%
Graft failure 2-5%
Superficial wound infection 1%
Infection in joint (septic arthritis) 0.1%
Reflex Sympathetic Dystrophy (RSD). (An abnormal pain reaction to any surgery, which may need prolonged physiotherapy or pain clinic)1%
Arthrofibrosis (knee joint stiffness)1%
Further surgery to cartilage 2-5%
Removal of metalwork 3%
Increasing movement at the knee joint, normalising walking patterns, reducing pain and swelling and starting balance exercises.

The graft needs time to heal and the exercises are designed to strengthen the leg muscles without placing unnecessary stresses on the healing graft. Exercises are generally performed with the foot in contact with the floor or weights machine. As knee control improves, the exercises are progressed.

Many factors influence the success of surgery and it is hoped that this information will help towards optimising results.

ACL Rehabilitation Pre-operatively

Rehabilitation begins before surgery to ensure you and your knee are ready for an operation. It is important to have full range of movement and good quadriceps and hamstring strength. Usually, you will have attended an ACL Deficient Class but continue to have problems with instability. You will have been examined by Mr Aslam and had an opportunity to ask questions. You will attend a pre-operative assessment to determine fitness for anaesthesia including a general health check and blood tests. You will complete questionnaires and documentation so that outcomes can be monitored.

The Day of the Operation

You will be seen by the Anaesthetist to ensure you are still fit for anaesthesia.

Post-operative pain management will be discussed.

On return to the ward, you will have the following: Dressings – wool and crepe bandage on the knee and a splint to keep the knee straight. Drips and drains – there will be small tubes in your knee and into the back of your hand. You might also have a tube into your bladder (catheter).

Cryo-cuff – an iced water compression cuff on the knee to help reduce pain and swelling.

Analgesia – this may be oral medication or patient controlled analgesia (PCA), which looks similar to a drip. You can, within limits, give yourself painkillers.

Exercises – to commence as soon as you are able to aid circulation and help reduce blood clot formation. These include vigorous movement of toes and ankles, quadriceps and hamstring tightening and gentle knee bends.



Dressings removed and clean ones applied. Drain removed.
PCA removed, usually in the morning.
Alternative painkillers to be prescribed.
Cryo-cuff use continued.
Continue with exercises and increase knee bending with the aid of a sliding board. Add straight leg raise and knee straightening (heel on towel).
Mobilise with crutches and take as much weight through the operated leg as is tolerated unless instructed otherwise.
Avoid active exercise with the leg off the floor from 30° knee bend to fully straight for the first 6 weeks.
Can be discharged from hospital if progressing well, managing exercises and safe on stairs.
You will go home in a knee splint if unable to straight leg raise.
You should attend for outpatient physiotherapy 5-7 days after discharge and be able to flex the knee 60-90°at this first appointment.


The wound is to be kept dry until healed and the dressing can be changed if soiled. A District Nurse may be organised by the Ward if needed.
Regular ice application.
Physiotherapy appointment arranged.
Return to work
Sedentary jobs
Manual jobs
Return to driving at 6 weeks for manual geared cars and automatic cars if it is the right leg that has been operated on. If it is the left leg that has been operated on, you may drive an automatic car once the wounds are healed at 2 weeks.
Expect bruising in thigh and lower leg.
Remember you scar is highly susceptible to the sun and use of a high factor sun block is advised.


Knee fully straight and able to straight leg raise (if unable to SLR, wear knee splint). Aim for 90° of flexion (knee bend).
Independent on crutches and safe on the stairs.
Discomfort controlled with medication.

Out-Patient Exercise Programme

After attending individual physiotherapy sessions, you may be transferred to an ACL class in the gym. This is usually somewhere between 2-6 weeks post-operatively depending on your progress. The classes will be hard work. To enable you to monitor your progress, you should keep a record of repetitions and weights and always aim to beat your previous scores (unless advised otherwise).

The classes are based on a timed circuit and exercises are progressed, as they become easier to perform. Most of the exercises can be modified so they can be performed at home. You will attend the gym once a week, but it is important you continue with daily rehabilitation exercises. It can be useful to put ice on your knee for 10-15 minutes at the end of exercise sessions.

The above is based on having had a routine ACL reconstruction. Modification of these guidelines may be necessary if your surgery is more complex and this will be done via your Physiotherapist under the instruction of Mr Aslam.

Exercises are to be performed daily. They are split into different stages depending on the time from your operation. All exercises should be pain free when performed. If you have any problems with them please consult the Physiotherapist who is looking after you.