david.stock@thecountyclinic.co.uk | T: 01604 795412 | F: 01604 795413

Anterior Cruciate Ligament (ACL) Reconstruction

What is the Anterior Cruciate ligament (ACL)?

The anterior cruciate ligament (ACL) is a 3-4cm long band of fibrous tissue in the centre of the knee that connects the femur (thigh bone) to the tibia (shin bone). It is essential in controlling the rotation forces developed during cutting (rapid changes in direction) and pivoting activities.


What are the causes of ACL ruptures?

It is estimated that 70 percent of ACL injuries occur through non-contact mechanisms while 30 percent result from direct contact with another player or object.

The mechanism of injury is often associated with deceleration coupled with cutting, pivoting or sidestepping manoeuvres, awkward landings or “out of control” play. Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes in certain sport. The common sports in which ruptures occur are football, netball and skiing.

What are the symptoms of an ACL rupture?

You may hear or feel a “crack or pop” at the time of injury. Immediately after the injury, patients usually experience pain and swelling and the knee feels unstable and may give way. They are usually not able to continue playing.

Within a few hours after a new ACL injury, the knee usually swells and there is loss of movement and pain.

It may be difficult to walk for several days, however, after seven to ten days the swelling settles and walking is possible with the joint gradually returning to full movement.

By four weeks following injury the knee becomes almost normal. Patients who return to sport following injury usually notice weakness or instability and experience giving way. Each time the knee gives way the knee may become painful and swollen again.

What happens to the knee after an ACL rupture?

Approximately 50 percent of ACL injuries occur in combination with damage to the meniscus (biological shock absorbers), articular cartilage (surface lining of the bone), or other ligaments.

Additionally, patients may have bruising of the bone beneath the cartilage surface (bone bruising). This may be seen on a magnetic resonance imaging (MRI) scan and may indicate injury to the overlying articular cartilage.

What happens to the knee without surgery varies from patient to patient. It depends on the patient’s activity level, degree of injury and instability symptoms.

After a complete ACL tear, some patients are able to participate in cutting or pivoting-type sports, while others have instability during even normal activities, such as walking.

With ongoing instability, up to 90% of patients will have meniscal damage 10 years after the initial injury, and 70% will have damage to their articular cartilage, the cause of arthritis.

How is an ACL rupture diagnosed?

ACL ruptures are commonly missed by examining doctors.

A classical history can be obtained in approximately 90% of cases (twisting , heard/felt pop, couldn’t play on, knee swelled up shortly afterwards and the knee feels unstable). If this is the story given, an ACL rupture should be suspected until proved otherwise.

There are three tests used when examining the knee to look for a ruptured ACL:

  • Lachman
  • Anterior draw
  • Pivot shift test

All of these look for increased forward movement of the tibia (shin bone ) compared to the femur (thigh bone .

A ruptured ACL cannot be seen on an xray. It is usual to have an magnetic resonance imaging (MRI) scan as this will show not only the ACL rupture but also damage to the other structures in the knee as well.


Why does it fail to heal?

The ACL passes through the middle of the knee joint and is surrounded by joint fluid. Tissues in the body heal by forming scar tissue which requires the formation of a blood clot. Due to its unique location the ends of the broken ACL are rarely in contact and a clot does not form allowing it to heal.

An ACL reconstruction is sometimes referred to, incorrectly, as an ACL repair. A torn anterior cruciate ligament cannot be “repaired”, and must instead be reconstructed using tissue taken from somewhere else.

Why do we reconstruct ACLs?

The goal of treatment of an injured knee is to return the patient to their desired level of activity and prevent further long term injury to the joint.

Each patient’s requirements are different. Treatment may be without surgery (conservative treatment) or with surgery (surgical treatment).

Those patients who have a ruptured ACL and are content with activities that require little in the way of side stepping/ pivoting (running in straight lines, cycling & swimming) may only require conservative treatment to achieve stability.

Those patients who wish to pursue competitive sports or sports that involve cutting movements (football, rugby, netball), or experience giving way during daily living, will probably require surgical treatment in the hope of giving them a stable knee.

How is the initial injury treated?

Click here to watch a video outlining the procedure

It is likely you will go to a hospital casualty department when you first injure your knee. The management of any soft tissue injury is essentially the same.


  • Protection – Avoid further injury to the knee by trying to play on. Avoid walking on it if it is painful, you may be given a pair of crutches and shown how to use them.
  • Rest – for 48 hours this helps prevent further injury and helps the knee recover from the injury.
  • Ice – cooling the knee helps reduce swelling and helps with pain control. I encourage the use of a cryocuff. Most people use frozen bags of peas. Wrap these in a damp towel and use for no more than 10 minutes being careful not to burn your skin. This can be repeated every few hours.
  • Compression – a double tubigrip (elasticated stocking) should be used during the day and taken off at night. When possible take the tubigrip off and use the cryocuff.
  • Elevation – when possible rest with your foot up, supported, higher than your hip.

Take regular pain killers and anti-inflammatories (if allowed).

What happens in conservative treatment?

Physiotherapy (physio) is aimed at reducing swelling, restoring the range of motion of the joint and restoring full muscle power. Proprioceptive training is used to develop the necessary protective neuromuscular reflexes that are required to protect the joint for normal daily activities.

What happens in surgical treatment?

The goal of an ACL reconstruction is to prevent instability by restoring the function of the torn ligament, allowing the patient to return to their normal activities. It is also hoped that the stability protects the knee from further damage.

A patient with a torn ACL whose knee is unstable risks developing further knee damage and should therefore consider ACL reconstruction.

It is common to see ACL injuries combined with damage to the menisci (50%), articular cartilage (30%), collateral ligaments (30%), joint capsule, or a combination of the above. As many as 50% of meniscus tears may be repairable and may heal better if the repair is done in combination with the ACL reconstruction.

Before choosing surgery, you should understand the time and effort rehabilitation (recovery) will take. You will need to adhere to a rehabilitation program for at least 6 months before you can return to full activity. The success of the surgery depends on this.

Prehabilitation. Before surgery your knee must have a nearly normal comfortable range of movement. For the weeks leading up to the surgery you will start your physiotherapy.

You will be admitted on the day of surgery. It is usual not to have anything to eat or drink 6 hours before the operation.

Reconstruction involves placing a graft inside the knee to replace the damaged ACL. The graft can be either natural (from your own body – autograft, or from a donor – allograft) or synthetic. It is more common to use autograft. A number of different autografts are used including part of the patella tendon and the hamstring tendons.

I normally use hamstring autografts. Two of the three hamstring tendons are harvested and folded in half to make a cable of four strands.

It is usual to have a general anaesthetic. The leg is painted in a dark brown antiseptic solution to reduce the risk of infection. It is best to wear old , dark coloured underwear as this stains clothes.

A tourniquet (a form of tight bandage) is placed around your thigh and inflated when you are asleep to reduce bleeding and improve visualization. If the procedure takes a long time it can cause discomfort in the thigh muscles and some numbness in the leg for a few days after the operation.

After the graft has been prepared the procedure is undertaken arthroscopically. This involves inserting an arthroscope (a small tube roughly the size of a pencil) which contains special optical fibres and lenses. The arthroscope is connected to a video camera and the interior of the joint is seen on a television monitor.

Two to three small incisions are made at the front of the knee. The arthroscope is passed through one and instruments needed to undertake the surgery are passed into the knee through the other.

Fluid is passed into the knee to inflate it, allowing better visualization. A small puncture wound is usually made on the side of the knee to allow this fluid to flow through the joint. At the end of the operation, the fluid is drained from the knee.


Tunnels are drilled through the shin and thigh bone.


The graft is attached to a device that looks like a toggle on a coat (ENDOBUTTON). Using this, the graft is pulled through the knee into the tunnels. The toggle is flipped so it sits against the bone securing the graft in thigh bone.


The graft is then fixed in the shin bone using a screw.

Pictures are taken during the procedure from the video monitor so that afterward you can see what was found and what was done. Most reconstructions take between 60- 90 minutes.

Local anaesthetic is injected into the knee to minimise discomfort after surgery. A relatively tight bandage is then applied.

Stitches or clips are used to close the wounds and then covered with dressings.

As you begin to wake up from the surgery you will then be transferred to a bed in the theatre and taken to the recovery room. Once the recovery nurse is satisfied you are sufficiently awake you will be taken back to the ward.

Either in recovery or on the ward the bandages are reduced and a cryocuff applied. This helps reduce swelling and pain.

What are the side effects and complications?

Anterior cruciate ligament reconstruction is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and complications.


These are the unwanted but mostly temporary effects you may get after having the procedure.

You should expect some pain, stiffness, swelling and bruising around the knee. This is likely to last for some weeks and will gradually improve as the knee heals and as you get back to your normal day-to-day activities.

There will be several scars around the knee.

Your hamstring muscles will recover quickly and the tendons regrow. However, the scar tissue that forms may tear. This is felt as a pop or tear behind the knee on the inner side. This will usually set your rehabilitation back a few days only. Scar tissue may tear more than once but does not usually occur after 6-8 weeks post operative.


Complications are problems that may occur during or after the operation. Most people aren’t affected. These can be divided into those related to any operation and those related to the ACL operation itself.

Possible complications of any operation:

  • Reaction to anaesthetic.
  • Blood clots.

These can form in the legs and travel to the lungs (pulmonary embolus I in 2000) which can be fatal. If they stay in the legs (deep vein thrombosis 5 in 1000) you will need to be treated with blood thinners for about 3-6months.

Possible complications of ACL surgery

  • Infection of the wound or joint (5 in a 1000) – Antibiotics are given during surgery to help prevent this. The operation is carried out in a special operating theatre. Joint infections are rare following an ACL reconstruction, but if this happens you may need arthroscopic wash-out of the knee joint and a long course of antibiotics.
  • Nerve and blood vessel damage – This could result in altered sensation or loss of feeling in the skin over the knee. There is always a patch of numbness on the outer part of the upper leg next to the incision, which is permanent. Rare risks (1 in 10,000) from injury to the popliteal artery and weakness or paralysis of the leg or foot.
  • Instability – Recurrent instability due to rupture or stretching of the reconstructed ligament (reported to be between 3 and 34 in 100). Graft failure due to poorly understood biologic reasons occurs in approximately 1 in 100 of grafts and a further 1 in 100 of grafts rupture during the rehabilitation programme. After 2 years if you return to normal activities the risk of further ACL injury returns to near normal The risk of rupturing the reconstruction is similar to that of rupturing the ACL in the other knee
  • Stiffness – Knee stiffness or loss of motion has been reported at between 5 and 25 in 100. This is treated with physiotherapy.
  • Extensor mechanism failure – Rupture of the patellar tendon or patella fracture may occur due to weakening at the site of graft harvest if the patella tendon is used as a graft.
  • Growth plate injury – In young children or adolescents with ACL tears, ACL reconstruction creates a possible risk of injury to the growing areas of the knee. The technique to reconstruct the ACL is altered slightly or the operation may be delayed.
  • Patella (kneecap) pain – Postoperative anterior knee pain is especially common after patellar tendon autograft ACL reconstruction. The incidence of pain behind the kneecap varies between 4 and 56 in100. The incidence of pain on kneeling may be as high as 42 in 100.

What is recovery like after ACL reconstruction?

Patients are usually ready to go home the next day on crutches.

You should keep the incisions clean, dry and covered. They will be covered with tegaderm dressings. The aim of the dressing is to keep the edges of the cuts together, just like any normal cut. Tegaderm dressings allow showering, but not bathing. You should try and maintain the dressings for 10 days. If the dressing is peeling and you are not keen to take it off, then it may be best to reinforce it with a further dressing on top, and try to keep it as dry as possible.

I occasionally ask the patient to wear a brace after the operation.

Most patients should be walking normally 14 days following surgery although there is considerable patient to patient variation.

If the left knee is operated on then driving an automatic car is possible as soon as pain allows. You must not drive a motor vehicle whilst taking strong pain killing medications.

If the right knee is operated on driving is permitted when you are able to do an emergency stop quickly and safely.

Please check with your insurance company that you are covered before starting to drive again.

During your follow-up visit, I will inspect the knee and the incisions. Any stitches will be removed. The surgery undertaken will be explained and your rehabilitation program discussed.

The knee will tend to swell for the first 6 weeks. It is important reduce the swelling as much as possible, less swelling , less pain and a quicker recovery.


  • Rest – for 48 hours after the operation only undertaking activities that are necessary.
  • Ice – cooling the knee helps reduce swelling and helps with pain control. I encourage the use of a cryocuff which can be used continuously throughout the day, taking it off at night. If you are using ice instead of a cryocuff, always cover the ice with either a towel or pillowcase. You can “ice” for 10 minutes at a time during the day approximately every 1-2 hours. This helps to reduce pain and inflammation.
  • Compression – after 48 hours when you begin to get up and around, a double tubigrip (elasticated stocking) should be used during the day and taken off at night. Whenever possible take the tubigrip off and use the cryocuff.
  • Elevation – when possible after the initial 48 hours rest with your foot up, supported, higher than your hip.

Even if you are not in pain, it is best to take anti-inflammatories (such as ibuprofen if allowed) and pain killers (such as paracetamol) for the first 5 days. Some patients find anti-inflammatories make them nauseous and give them a “stomach upset”. Always read the patient information that comes with your medicine and if you have any questions, ask your pharmacist for advice.

What is done in preparation for an ACL reconstruction?

It is important that you understand what is involved in an ACL reconstruction and that you are both physically and mentally prepared.

I will explain the operation to you during our consultation. On the morning of the operation we will complete a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.

ACL reconstruction has some potential complications. It is important that you understand what is involved in the surgery. Rehabilitation is long and intensive. If it is not undertaken the results of the surgery may be compromised.

Patients who are on anticoagulants (blood thinners) will probably need to stop these before the operation. Please inform me of any medication you take when we first meet and bring them with you when you come to hospital. Patients should cease smoking and taking the oral contraceptive pill 6 weeks prior to surgery as this increases the risk of thrombo-embolism (life threatening blood clots).

The anaesthetist will review you before the operation.

Any signs of ongoing infection in the body (including colds) usually postpones arthroscopy. You should not shave or wax your legs for one week prior to surgery.


Physiotherapy is a crucial part of successful ACL surgery, with exercises beginning immediately after the surgery. Much of the success of ACL reconstructive surgery depends on the patient’s dedication to rigorous physical therapy. Rehabilitation should be supervised by an experienced physiotherapist. Not everyone will progress at the same rate, the timings below are only guidelines.

The graft is weakest between 4-8 weeks and it is better to go too slowly during this time and protect the graft

Phase 1: 1 to 4 weeks

Key objective markers:

  • Eliminate swelling.
  • Regain full extension (straightening).
  • Achieve 100 deg flexion (bend).
  • Begin gentle hamstring and quadriceps strengthening.
  • Re-educate walking.


  • ICE/ compression 10 minutes 4-5 times a day. Use compression bandage, wrapped from mid shin to mid thigh. Crushed ice/ ice pack/Aircast. Elevate leg above hip. Support knee. “pump” quads.
  • Mobilise scar tissue with E45 cream.
  • Mobilise knee cap gently.
  • In sitting, static knee flexions using good leg to provide resistance in varying degrees of knee flexion. 10 sec holds 20 times at 3 to 4 different angles to 100 degrees. At least 4 times a day. Do not push into sharp pain.
  • In sitting, towel under knee push knee down by tensing quads. Hold 30 seconds and repeat often (at least 6 times a day).
  • In sitting, gently stretch knee into extension using hand. Hold each stretch 30 secs, 3 times, at least 4 times a day. Do not push into sharp pain.
  • In lying gently stretch hamstrings 3 x 30 sec, 4 times each day.
  • Begin light cycling- max 10 minutes very low load and speed.
  • 3 x 5 gym ball squats, taking maximum of 30-40% weight through right side.
  • Pool walking – when wound healing allows. 10 minutes easy
  • Practice balancing when standing near supportive surface!!

Phase 2: 4 to 8 weeks post op

Key objective markers:

  • Eliminate swelling.
  • Maintain full extension.
  • Maintain 130deg flexion.
  • Continue hamstring and quadriceps strengthening.
  • Re-educate walking.
  • Begin balancing.


  • ICE/ compression 10 minutes 4-5 times a day. Use compression bandage, wrapped from mid shin to mid thigh. Crushed ice/ ice pack/Aircast. Elevate leg above hip. Support knee. “pump” quads.
  • Mobilise scar tissue with E45 cream.
  • Mobilise knee cap gently.
  • In sitting, static knee flexions using good leg to provide resistance in varying degrees of knee flexion. 10 sec holds 20 times at 3 to 4 different angles to 130 degrees. At least 4 times a day. Do not push into sharp pain.
  • In sitting, gently stretch knee into extension using hand. Hold each stretch 30 secs, 3 times, at least 4 times a day. Do not push into sharp pain.
  • In lying stretch hamstrings 3 x 30 each day, 4 times a day.
  • Begin cycling 20 to 30 minutes a day – still static bike.
  • Practice balancing as often as possible (in slight knee flexion).
  • Wall squats progressing into normal squats 3×10, 3 x day.
  • Lunges (maintain knee control as discussed) 3×10, 3 x day.
  • Lateral lunges 3×10, 3 x day.
  • Step ups, progressing into step downs as able 3×10, 3 x day.
  • Hamstring curls using swiss ball 3×10, 3 x day.
  • “Good mornings” in standing using 2kg weight 3×10 (weight on right leg, knee slightly bent, lean forwards at hip), 3 x day.

Phase 3: 8-12 weeks post op

Key objective markers:

  • Monitor swelling.
  • Maintain range of movement.
  • Hamstring and quadriceps strengthening.
  • Progressive balance work.
  • CV fitness.


  • ICE/ compression as required.
  • Mobilise scar tissue with E45 cream.
  • In lying stretch hamstrings 3 x 30 seconds each day, 4 times a day.
  • Increase difficulty of cycling- hills/ resistance as able.
  • Squats: 5 sets 10-12 reps (add weight if available), 2 times a day.
  • Lunges: 5 sets 10-12 reps, 2 times a day.
  • Step ups 100 reps, 2 times a day.
  • Hamstring curls using swiss ball 5×10, 2 times a day.

Balance drills:

  • Single leg with knee slightly bent +/- throw and catch ball.
  • Single leg with knee slightly +/- turning head side to side.
  • When able to do comfortably:
  • Clock face drills (touching hand down at each “hour” point).
  • Forwards/ backwards hopping, 3 x 8 – 14 as control allows.
  • Rotation control: balance on leg, knee slightly bent, rotate body out but keep knee in line with middle of foot.

Phase 4: 12 weeks+

Key objective markers:

  • Hamstring and quadriceps strengthening.
  • Progressive balance work.
  • CV fitness.
  • Functional performance testing.


  • 3 sessions per week as able.
  • 8-12 repetitions 3 sets with limited rest (45 seconds).



  • Single leg with knee slightly bent +/- throw and catch ball.
  • Single leg with knee slightly +/- turning head side to side.
  • When able to do comfortably:
  • Clock face drills (touching hand down at each “hour” point).
  • Rotational Control.
  • Balance on leg, knee slightly bent, rotate body out but keep knee in line with middle of foot.


  • Leg Press (double leg, progressing to single leg as able).
  • Squats.
  • Lunges.
  • Step ups.
  • Lateral lunges.
  • Knee extensions.
  • Hamstring curls.

Outlook (Prognosis)

It can take between 6 and 12 months for you to recover your knee function after an ACL reconstruction. However, this depends on the individual and other damage to the knee.


“I recently had an ACL reconstruction due to a sporting injury. Mr. Stock and his team were very professional throughout and the level of attention I received was second to none. During my experience every stage was thoroughly explained and I was made to feel that nothing was too much trouble. I wouldn’t hesitate to recommend him”


“Two years ago I had a nasty skiing accident in France where I damaged both knees. Upon my return to the UK Mr. Stock organised an MRI and diagnosed that I had ruptured both ACL’s. I commenced physio but unfortunately both knees remained unstable so Mr. Stock agreed to do bilateral reconstructive knee surgery.

Obviously, this meant I was totally immobile for a while and had 3 months off work while I attended physiotherapy and rebuilt up the muscle in my legs. I have never looked back.

I’m fitter now than I have ever been. I can do anything I used to do and my knees are strong and pain free. I enjoy long walks, cycling, yoga, swimming, tennis and I am back to running 3 times a week. I plan to go skiing again with the family this year. I can’t wait.

I would like to thank Mr. Stock for his skill and patience. I’m not sure he was terribly keen on operating on both knees at one time as it’s very rarely carried out. But as a busy Mother of 4 I really did not have the time for 2 recuperations, I wanted it done in one go! It was very hard at the time but I am thrilled with the results. Thank you”


“I want to take this opportunity to say a big thank you to David Stock for his skill, not only as a surgeon, but also for his advice and friendship over the last two years.

I was unfortunate to suffer with ACL damage to my left knee whilst representing England at under 18 schoolboys football, which required surgery and resulted in my not playing again at any level for about 10 months.

It was through my own doctor, Dr. Simon Lowe, who pointed me in David’s direction in the first place, to which I am grateful. After a successful operation and a tailored physio programme under the skilled supervision of Philip Duffell (recommended by David), I was back playing competitive football for my university team and Forest Green Rovers.

David always feared that due to the relative weakness inherent in my knees, there would be every chance that a similar injury could happen to my right knee. Despite religiously following the rehabilitation routine and getting myself to reach peak physical fitness and strength, the worse possible scenario occurred repeating an identical injury to my right knee whilst playing for the university, which required similar surgery and rehabilitation.

To say I was gutted doesn’t even come close to describing how I felt, especially missing out on the rest of the England schoolboy season the year before and playing for the university where I had gained a full scholarship on the back of my football achievements. I am now coming to the end of the rehab programme, again under the watchful eyes of both David and Philip. Both of these guys have been magnificent and have shared my motivation and determination to get myself back on the road to recovery, both physically and mentally.

It’s through working with these special people over the last two years that I still have the dream of playing football to the highest level possible, but along the way they have also given me invaluable guidance and advice that has helped shape my thinking and approach for the future. Thank you”