Anterior Cruciate Ligament (ACL) Reconstruction

Learn everything about your treatment

  • Overview

    What is Anterior Cruciate Ligament (ACL) Reconstruction?

    The knee is made of three bones: the femur, the tibia, and the patella. Layers of firm connective tissue called cartilage cover the bones where they meet to help them glide over one another and allow for smooth movement. The bones of the knee are held in place by bands of dense, fibrous connective tissue bands called ligaments. The strongest of these is the cruciate ligament inside the knee. This ligament has two branches: the anterior (ACL) closer to the front of the knee, and the posterior (PCL) directly behind the ACL. The cruciate ligament is also known as the cruciform ligament (from the Latin for ‘cross’) because the ligaments cross in different directions to form an ‘x’ shape.

    The cruciate ligament gives the knee both stability and flexibility. It controls the back and forth motion of the lower half of the leg, limits excessive movement that might allow the knee to bend slightly backwards (hyperextend), as well as control the degree to which the lower leg can twist inwards (invert).

    The ACL is the most likely ligament in the knee to be damaged. Tears to it are one of the most common knee injuries and are usually caused by overstretching. This type of injury commonly happens during sports, when stopping suddenly, or during impact.

    ACL tears are commonly caused by:

    • Poor landing after jumping (especially if the leg is straightened)
    • Stopping suddenly
    • Changing direction suddenly
    • A blow to the knee (often from the front)

    The tear may be partial or total and is often accompanied by a ‘popping’ sensation when the injury occurs.

    What Can an Anterior Cruciate Ligament (ACL) Reconstruction Achieve?

    Not everyone with an ACL tear will need reconstruction surgery. Deciding if surgery would be of benefit must be based on several factors. These include age, activity level, and the degree of damage to the ACL.

    As well as improving existing symptoms, ACL reconstruction may help the surrounding structures of the knee remain healthy. Reconstructing the ACL can prevent further stress, uneven weight distribution, and wear and tear on the knee.

  • Candidates

    Who is an Ideal Candidate for ACL Reconstruction?

    Younger and generally healthy patients with no significant medical conditions make the best candidates for ACL reconstruction.

    Patients with arthritis in their knee or a history of difficult-to-manage diabetes may not be suitable for this procedure. Candidates should be as fit and healthy as possible before the procedure to reduce recovery times and improve outcomes.

    Physiotherapy before the procedure may also be necessary to reduce swelling in the affected knee and strengthen the muscles around the ACL.

    Smokers will be advised to stop at least 2 weeks before surgery and continue to refrain during recovery as smoking has been shown to be associated with worse surgery outcomes.

    You may be recommended for an ACL reconstruction if:

    • The condition of your knee is affecting your quality of life
    • You have strong muscles in your legs (or are able to build strength before surgery)
    • You are a very active person or activity is important to you
    • You have a physical or active occupation and immobility would affect your income
    • Your knee feels very unstable
    • Your knee is at risk of further damage without a reconstruction
    • You are in pain
    • Your knee is constantly giving way
    • You are able to adhere to a strict physiotherapy regimen

    Other important considerations:

    • The swelling in your knee must have settled before surgery
    • If your knee has a full range of movement before surgery you will likely have a better postoperative outcome

    Who Is Not Suitable for ACL Reconstruction?

    Not every patient with a torn ACL requires ACL reconstruction. If you are not experiencing significant difficulties or your quality of life is not impacted too greatly, then surgery may not be your best option.

    In general you may not be recommended an ACL reconstruction if:

    • Your knee generally feels stable
    • You do not have an active lifestyle
    • You are older and less active
    • You are unable to adhere to a physiotherapy programme
    • Your knee is not causing you pain

    Not having ACL reconstruction surgery may mean the knee continues to feel unstable, limit mobility, and allow for uneven weight distribution and wear in the knee. This can increase the risk of further damage to the knee including: a tear to the meniscus, articular cartilage destruction, and damage to the other ligaments.

  • Procedure

    ACL Reconstruction Technique

    ACL reconstruction is largely performed as an elective procedure. This means you decide when you want to have the surgery performed. Your surgeon will likely make sure there is a good amount of time between the initial injury and the surgery. This allows the swelling in the knee to subside. You may need to wear a brace on your knee and use a walking aid during this time. You may also be prescribed physiotherapy to make sure the muscles in your leg are as strong as possible before surgery. This helps greatly with the recovery process.

    As suturing together a torn ACL is generally ineffective, the most successful method involves replacing the damaged ligament entirely with new tissue. This can be done in a number of ways.

    The tissue needed to replace the ACL can come either from your own body or that of a donor. A donor is someone who has chosen to give all or part of their body to help others after they have died. The tissue (also called graft) that comes from your body is called an autograft, whereas a graft from a donor is called an allograft. Another option may be to use a synthetic graft.

    Autografts are most commonly taken from the:

    • Patellar tendon located on the front of the knee
    • Hamstring tendon on the inner side of the back of the knee
    • Quadricep tendon above the knee

    The most common donor site during an allograft is the patellar tendon or the Achilles tendon above the heel. The choice of the type of graft used depends heavily on the individual circumstances of the patient. However, in general, autografts tend to be more suitable for very active people because allografts may provide a slightly weaker final tendon. Synthetic grafts are also sometimes used, though they are usually better suited to revision surgery or extensive knee-tendon reconstruction.

    An ACL reconstruction may be performed under a general anaesthetic (when you are given medication to help you sleep). A spinal anaesthetic called an epidural with sedation is also commonly used. For this, numbing medication is injected into the spine to block any feeling in the lower half of the body, then another sedative is given to help relax the patient during surgery. Sometimes, if requested, the patient can watch the surgery take place via a television screen.

    There are two techniques: arthroscopic, and open.

    During an arthroscopic procedure, fine tools and a camera are inserted through small (1cm) incisions around the knee.

    Open knee surgery requires an incision down the entire front of the knee.

    Below is a short overview of what happens after anaesthesia is administered:

    1. Your knee is cleaned and prepared
    2. Incisions are made
    3. Your knee and surrounding structures are examined
    4. The damaged ACL is removed
    5. The graft is either harvested or prepared
    6. Holes are drilled into the tibia and fibula
    7. The graft is passed through holes and secured into place
    8. Range of movement of the knee is checked
    9. The wound is closed and dressed

    A more detailed description of the procedure is explained in the Procedure section.

    How is Anterior Cruciate Ligament (ACL) Reconstruction Performed?

    The surgery time depends on the type of injury and the techniques being used during the reconstruction. However, ACL reconstruction generally takes between 1 and 2.5 hours.


    On the day of surgery, you will meet with the surgeon performing the procedure. They discuss the details of the operation with you one more time then ask you to sign a consent form. This is a legal document showing you understand the risks associated with surgery and are still happy to go ahead and that you give the surgeon permission to operate on you.


    The anaesthetist will then prepare the anaesthetic to prepare you for surgery. If general anaesthetic is used, they will administer drugs to you that put you in a deep sleep. If an epidural or spinal block is used, they will inject an anaesthetic into your spine so you don’t feel anything in the lower half of your body. They will also give you an additional sedative drug alongside the spinal block to help you feel relaxed during the operation.


    If your own tissue is being used to make your new ACL, your surgeon will make a larger cut on the front of your knee through which the autograft will be removed

    The type of incisions (cuts) your surgeon will make on your knee will depend on the type of technique they use.

    For arthroscopic surgery, a few small incisions will be made on the knee. These incisions allow a small camera and other small instruments to be inserted into the knee. These instruments and camera the instruments needed.

    For open surgery, the knee will be cut from the patella to the tibia. If your own tissue will be used as a graft, the incision may need to be larger.

    No matter the technique, once the incisions are made, the surgeon will start by having a thorough look inside the knee to ensure there are no other damaged areas. If found, these may need to be repaired at the same time. After this, the damaged ACL is removed. The graft is then harvested. The technique will vary depending on the location it is harvested from.

    When the graft is ready, the surgeon will drill holes into the tibia and fibula where the ACL originally sat. The graft is then passed through these holes and secured in place either with special ‘headless’ screws or staples. These will stay in your knee permanently.

    Closing of incisions

    Before finishing the procedure your surgeon will make sure the graft is strong enough to hold your knee together and that it can securely achieve a full range of movement. The wound will then be sutured (stitched) closed and dressed with a sterile bandage.

    Return to the ward

    After the procedure, you will be taken to a recovery ward or your room while you recover from anaesthesia and slowly wake up. Although the procedure can be performed as a day case, it is common to stay one night in hospital after ACL reconstruction surgery.

  • Your consultation

    Your consultation

    What Should I Expect from My ACL Reconstruction Consultation?

    Before having an ACL reconstruction you will meet with your surgeon for a consultation. During this, your surgeon will perform a physical exam and ask you questions about your medical history and what medications you take. To get the best idea about what type of treatment is best for you, your surgeon will ask you questions about your activity levels and occupation as well as the ways your injury is affecting your day to day life. Your surgeon may also request you have other tests done including x-ray scans or blood tests before proceeding with surgery.

    During this consultation, your surgeon will explain the procedure to you in more detail and give you an opportunity to ask any questions you may have. You will discuss the type of anaesthetic most appropriate for you, discuss the options for the ACL graft, and what you can expect after surgery regarding recovery and physiotherapy. You may also be measured for a leg brace for you to use after the operation.

    What Questions Should You Ask During Your ACL Reconstruction Consultation?

    It can be difficult to remember everything you want to ask during your consultation, so you may want to take notes and bring them to the appointment. If you are at a loss for things to ask, try thinking about the things you do in your everyday life and ask how surgery could affect them.

    To follow are some suggested questions:

    • How long will I need to be in hospital for?
    • How long will my new ACL last?
    • When can I go back to work?
    • When can I return to sports?
    • What will the scars look like and where will they be on my body?
    • Are there any considerations for recovery and child or pet care?
    • When can I bath and shower normally again?

  • Risks and Complications

    What are the Main Risks and Complications of ACL Reconstruction?

    Like any surgery, ACL reconstruction is associated with potential risks and complications.

    The following includes some general surgical risks, we well as some more specific to ACL reconstruction.

    Specific Risks

    Drill Hole Placement

    Your surgeon will drill holes called sockets or tunnels through your bones to secure the ACL graft. If these holes are misaligned, the graft may press into the bones of the knee as it bends or straightens. This can cause restricted movement and may mean you will not be able to straighten your knee. This can sometimes be resolved by physiotherapy but it is more likely to require revision surgery. This may involve shaving part of the obstructing bone or drilling new tunnels to move the graft into a better position.

    Graft Failure or Re-Rupture

    Autografts are very strong and may well be even stronger than the original ACL. Failure of the graft is usually due to the positioning, tension, or fixture point of the graft.

    If the graft does fail, this will likely result in a loss of stability in the knee. This may require revision surgery. Revision surgery may be more difficult and has a lower long-term success rate than the original ACL reconstruction.

    Ongoing or Worsening Knee Issues

    After the surgery, you may continue to experience symptoms or they may change or worsen. You may have more stiffness, swelling or weakness or you may find that your knee is not able to move in the way it did before your injury.

    Some techniques are associated with a higher risk of pain after the procedure. For example, grafts taken from the patella tendon have a higher risk of pain after surgery compared to other donor graft locations. Although a low risk, this technique may also contribute to patella fractures or patella tendon tears. Some symptoms may continue long-term, but they may be improved with intensive physiotherapy.

    General Surgical Risks


    You will likely experience some bruising after surgery. This is to be expected and can vary from person to person. For some, bruising spreads farther than the immediate knee area towards the ankle and sometimes the foot. It is more likely to extend down the inside of your leg and may include the back of the knee, particularly if the graft is taken from the hamstring.

    Bruising will likely heal and disappear over time.


    All operations are associated with a risk of infection, however, there are strict surgical methods that reduce this risk. Sterile tools and instruments, rigorous cleaning, and even special air conditioning to keep the air clean in the operating room all aim to keep the risk of infection as low as possible.

    There is a higher risk of infection with open ACL reconstruction versus arthroscopic, however, even this risk is relatively low. One of the more common types of infection associated with this procedure is septic arthritis. During septic arthritis bacteria infects a joint which causes inflammation. Symptoms include knee pain, fever, and stiffness in the knee. If this complication develops, antibiotics and urgent medical attention are necessary.

    In the unlikely event you develop an infection after surgery, you may show the following symptoms:

    • Feeling feverish with a temperature above 38° C
    • Increasing redness or swelling around the wound site in the first 2 days after surgery
    • Yellow, thick, or foul-smelling fluid coming from your incisions
    • Pain that is not relieved by your normal painkillers

    If you believe you have an infection, seek urgent medical advice and contact your surgeon. An infection will require you to take antibiotics. In some cases, you may require further surgery to clean the infected area.

    Blood Clots

    Blood clots are a potential risk of any surgery and are slightly more common with orthopaedic procedures because of the limited mobility during recovery. Blood clots can develop in the legs after long periods of inactivity. These clots can move to the lungs, which can be both dangerous and difficult to treat. Your surgeon will give you advice and treatment to prevent blood clots after the operation, including how to keep mobile and (if appropriate) the importance of wearing compression socks and special injections to thin the blood.

    Other complications, such as postoperative nausea and vomiting, or a negative reaction to the drugs or anaesthetic are rare but can occur. Your anaesthetist will monitor you closely during the procedure to help reduce your risk of developing these complications.

  • Preparing for Your Treatment

    How Can I Prepare for my ACL Reconstruction?

    Before surgery, it is ideal that the knee is not swollen and has a full range of motion. The muscles in the affected leg will need to be as strong as possible before surgery to ensure the best recovery process. A course of physiotherapy lasting several weeks may be recommended to help you manage this.

    It is important to avoid taking ibuprofen or any medicines in the Nsaid category for at least 1 to 2 weeks before the operation as these medications increase the risk of excessive bleeding after surgery. These drugs may need to be avoided for a period of time after surgery as well.

    Listen to and follow the exact recommendations and directions given to you by your surgeon regarding medications and food or drink before and after surgery.

    You must stop smoking at least 2 weeks before and after surgery because smoking increases the likelihood of complications and slows healing. You should also try to be in the best health possible before surgery to make recovery as easy as possible.

  • Aftercare

    What can I expect after an ACL Reconstruction?

    Please also see ‘is there anything I need to do in the first 24 hours?’

    Mobility Aids

    You will not be able to bear any weight on your knee for 2 to 3 weeks after surgery. This may extend to a total of 4 to 8 weeks if other procedures were done in addition to the ACL reconstruction. You will be given crutches or another mobility aid to use in this time. Your surgeon will give you individual guidance regarding how long you will need to use a mobility aid during recovery.

    Knee Brace

    You may be required to wear a brace on your knee as you recover. This helps ensure your knee only moves in certain directions in set amounts. Your surgeon or physiotherapist will fit this brace for you. It is very important you do not alter the fit yourself. You will be given guidance on the day-to-day activities you can and cannot perform. For example, going up or down stairs, what position to ideally sleep in, and how to wash while wearing the brace.


    You will be given a physiotherapy programme that is individual to you. These appointments will take place over 2 to 6 months depending on your overall fitness and recovery progress. The programme will be extremely important to your recovery and the long-term efficiency of your knee and new ACL.

    Typically programmes start 1 to 2 weeks after surgery although you will likely be given gentle exercises to do at home immediately following your procedure.

    The content or the course will vary depending on your needs however all programmes will focus on:

    • Building strength in your leg muscles
    • Getting as good a range of movement as possible as quickly as possible
    • Keeping you active

    Wound Care, Ice Packs, and Wound Dressings

    The wound from the incision on the knee will be closed with stitches or staples. If staples or non-absorbable stitches have been used, you will need to return to the hospital in 7 to 14 days to have them removed. After this, a type of medical tape called wound closure strips may be placed on the incision.

    You will have a dressing and a bandage covering the wound on your knee. It is important that you keep these clean and do not get them wet or remove the dressings yourself.

    You may be advised to apply ice packs or special ice dressings to your knee after surgery to help reduce swelling. Take care not to get ice on your bare skin.

    Showering and Bathing

    You may be advised to use a special plastic cover on your leg when you shower to prevent the wounds from getting wet. You will likely be advised not to wash your wounds until they are healed. After this point, gentle soap and clean water are generally all that is needed to tend to the area. Carefully pat wounds dry with a clean towel after bathing.


    You will likely experience some pain in your knee and leg after your ACL reconstruction. This is to be expected after surgery and you will be given advice on how to manage this discomfort. You may be given medication at the hospital to take home with you or be advised on the best type of non-prescription pain-reliever to use.

    How will I feel after surgery?

    One of the main benefits of having an ACL reconstruction is having a stronger, more stable knee that no longer gives way. Once recovered, this may provide relief from knee discomfort and pain for some patients and allow them to return to pre-injury activities.

    While it is normal to experience pain after surgery, this will ease in time. You will be given advice on what pain-relieving medication to take. You may be advised to avoid ibuprofen and similar drugs in the weeks before and after surgery as they can increase the risk of bleeding.

    Is there anything I need to do in the first 24 hours after surgery?

    Before you go home you will be shown how to use your crutches or other mobility aid. If you need a brace, it will also be fitted and explained before you are discharged from hospital.

    Expect to receive advice on showering, dressing, driving and other day-to-day activities. You will be given compression stockings and be shown how to do special exercises to prevent blood clots. You may also be shown how to give yourself injections to self-administer blood-thinners to further reduce your likelihood of developing a blood clot.

    Some people go home the same day as their surgery, others may need to stay in hospital for a night following an ACL reconstruction surgery. No matter what, you will need someone to stay with you for the first 24 hours after surgery to make sure you are safe as the effects of anaesthetic fully wear off.

    After this point, some people find it helpful to have a friend or family member stay with them or be on call to help when needed. Your surgeon will discuss what is most suitable for you during your consultation.

    Elevating and icing the knee is important in the first stages of recovery as they help reduce or avoid swelling. You will be given advice on how to do this safely and how many times a day. Often this will involve propping your foot under pillows in front of you while reclined or lying down.

    How much time do I need to take off work?

    Your return to work will be dependent on your occupation. For a job that is more sedentary like sitting at a desk, you may be able to return to work after 2 to 3 weeks. For a job that involves manual or physical labour, or a long journey to work, you may need to be off work for up to 3 months.

    When can I return to exercise and sport?

    The length of time it takes to return to sports or physical activity varies from person to person. Typically 6 months is expected for general sports and exercise, however, this may take 8 to 12 months for professional athletes or very high-impact activities or sports.

    What other points should I consider?

    You will be advised not to drive for a period of time after your operation. Driving without permission from your surgeon will likely invalidate your insurance. Often, patients are advised to avoid driving for at least 3 to 4 weeks after surgery. Safely driving depends on when you are able to comfortably put weight on your foot.

  • FAQs

    How long will I be in the hospital following ACL reconstruction surgery?

    Some people are able to go home the same day, others may need to stay in hospital for at least a night.

    When can I go back to work after ACL reconstruction surgery?

    You may need to take between 2 weeks and 3 months off work depending on your profession.

    When can I return to sports following ACL reconstruction surgery?

    This varies on your abilities before the injury and the type of surgery you had, however typically it will take at least 6 months to return to sports.

    What will the scars from ACL reconstruction surgery look like?

    That will depend on the type of surgery and where the graft was taken from. For an open technique, the scar will run down the front of the knee and tibia, for an arthroscopic procedure, there will be multiple small incisions (about 1 cm) around the knee. There will be an additional scar if the graft was removed from somewhere on the leg other than the knee. Your surgeon will give you advice on how to minimise scarring.

    Are there any considerations for ACL reconstruction surgery regarding child or pet care?

    As you will be unable to bear weight on your knee and will be using a mobility aid, like crutches, and potentially wearing a brace, taking care of pets and especially small children will be challenging as you recover. You will also not be able to drive for a portion of your recovery. Arranging for friends or family to help you care for your dependents will be necessary.

    When can I bathe and shower normally following ACL reconstruction surgery?

    You will be advised to wear a protective cuffed plastic cover on your leg to help you shower until the wounds are fully healed. It may not be possible to use the bath until your wounds are fully healed unless you are able to keep your leg out of the water and at a safe and appropriate angle.