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ACL reconstruction – four questions answered

Rugby is a common cause of an ACL tearFour commonly-asked questions about ACL reconstruction:

  • How is an ACL reconstruction performed?
  • Is ACL surgery major surgery?
  • How long does an ACL reconstruction take?
  • Is ACL surgery painful?..

  1. How is an ACL reconstruction performed?

People who have an ACL tear and need to have ACL surgery (ACL reconstruction) often don’t fully understand what is involved in the procedure. Some people do not want to know all the details but it is important to have a basic understanding of what is being done.

The ACL or anterior cruciate ligament is one of four major stabilising ligaments in the knee. It is commonly injured after sporting activities. These includes rugby, soccer, netball and basketball but it may also be injured in a non-sports related injury. The ACL has poor healing potential. A tear usually results in instability. Surgery is usually recommended for young people and active individuals. For more information on whether or not you need to have an ACL reconstruction, please see this article: Do I need to have ACL surgery?

The actual technique used to perform the ACL surgery varies widely. The materials used to fix the new tendon (graft) in position in the knee also varies according to surgeon preference. Despite these factors no specific technique has been shown to be significantly superior to another. The results and outcomes of the various techniques are good, providing that basic (but important) surgical principles are adhered to.

Before surgery

An ACL tear is a common knee injuryI perform ACL surgery in the safe and controlled environment of an operating theatre. You are normally admitted to hospital on the day of surgery. It is possible to do an ACL reconstruction as a day-case procedure, but most patients stay overnight. This is for monitoring and pain control purposes.

When you are admitted to the hospital you will need to be starved. This means that you should have had nothing to eat or drink in the six hours before the surgery. It is okay to have small sips of clear fluid such as water or black tea and coffee for up to 2 hours before the surgery. If you are on any chronic medication you may take these as normal on the morning of surgery.

The exception is if you are a diabetic. You must not take any diabetic medication on the day of surgery. If you have diabetes your glucose is checked on admission to the ward. You may receive insulin to control your blood sugar levels. You should also not be any blood thinning agents. The stopping of these medications will have been discussed with you prior to the surgery.

Once admitted to the ward you will be prepared for the operating theatre. The orthotist will visit you and measure you for the appropriate size leg brace. You will also be measured for TED (thrombo-embolic deterrent) stockings. These are used to lower your risk of getting a blood clot (DVT). These are compressive, above-knee stockings that are applied to your legs at the end of the procedure. You will go to the operating theatre with the brace and stockings with you.

In the operating theatre

When it is time for your surgery a porter will fetch you and transfer you to the operating theatre. You will be lying flat on your back in a comfortable position on the operating table. A tourniquet will be applied to your thigh. This will be inflated during the procedure (and once you are asleep) to prevent bleeding and allow for good vision.

The anaesthetic

My preference for an ACL reconstruction is to perform the procedure under a general anaesthetic. With a general anaesthetic you are placed into a deep sleep and your breathing is controlled by the anaesthetist. In addition to the general anaesthetic, a local anaesthetic nerve block is often given. This is usually given after you are sleeping already so you will feel and remember nothing.

It is possible to do ACL surgery under a spinal anaesthetic. One disadvantage of doing it this way is that you may mobilise slower afterwards. You may also have increased risk of developing a blood clot.

The incisions

The incisions depend largely on what type of graft is being used to create your new ACL. The commonest graft is your own hamstring tendons. These are removed from your thigh through a small incision in the upper part of your shinbone (tibia). The incision usually measures 2 to 3 cm in length. If you have a patellar tendon or a quadriceps tendon graft then you will have a slightly longer incision. This will be on the front of your knee just below or just above the kneecap.

There will be three or four other incisions which are made for the arthroscopy. These are very small “stab” incisions, measuring about half a centimetre in size.

The graft

ACL reconstruction may be needed after a sports injuryThe three commonly-used grafts used to reconstruct the ACL are your own hamstring tendons, your patellar tendon or your quadriceps tendon. My preference is to use the hamstring tendons (further reading: ACL graft options in ACL reconstruction – which one?). These long cord-like tendons are located in the back of your thigh. They assist with bending of the hip and of the knee. One or both of the hamstring tendons on the inner aspect of the knee are removed (semitendinosis and gracilis). These tendons are combined and folded over to form a sturdy graft of suitable diameter and strength. The use of these tendons does not normally result in any significant functional impairment after the operation. There is some evidence to show that these tendons may re-grow to some extent.

An arthroscopy of the knee is performed. The knee is filled with fluid to expand the joint. A special high-definition camera is then inserted into the knee to make a thorough inspection. Any other injuries such as meniscal tears can be diagnosed and repaired at the time of the ACL surgery.

For the ACL reconstruction a tunnel is created in the thigh bone (femur). Another tunnel is created in the shinbone (tibia). These are carefully positioned to ensure optimal functioning of the new ACL graft.

The new ACL graft is then inserted into the knee joint and threaded through the tunnels in the femur and tibia. It is secured usually by a small metal button on the outside of the femur. In the tibia it is secured using either an absorbable interference screw or a metal button. Sometimes a secondary is fixation point used on the tibia as a backup. Another screw or staple is usually used for this. The knee is tested for full range of movement and stability and the fluid is drained from the joint.

Wound closure

Incisions are closed with dissolving stitches and waterproof dressings are applied. I use a TED compression stocking and apply a wool and crepe bandage to the knee after the operation is completed. When you wake up you will also have a brace on your leg.

After the surgery

You will spend a short period of time in the recovery room after having woken up from the general anaesthetic. After that you will then be transferred to the ward. As soon as you are comfortable and have had something to eat and drink and are not feeling nauseous you will be seen by the physiotherapist. They will begin assisting you with basic mobilisation. This includes getting out of bed, using crutches and going to the bathroom.

You will be discharged home the following day. You will be asked to return to the rooms for a follow-up appointment approximately 10 days after the operation. At this stage the dressings will be removed and the wound will be inspected.

  1. Is ACL surgery major surgery?

Hockey injuries are a common cause of ACL tearsA common question I get asked is whether or not an ACL reconstruction is major surgery. I usually described as a “big operation” but not “major surgery”. These are purely subjective terms, however. It is certainly not a five or 10 minute procedure like a ganglion removal or a carpal tunnel release. Is also not as big an operation as a total knee replacement. The blood loss is minimal, and because it is done arthroscopically it is “minimally invasive”.

An ACL reconstruction is a highly technical procedure. It is usually only performed by an orthopaedic surgeon who has the necessary training and experience to perform it correctly. Not all orthopaedic surgeons will therefore do this procedure.

  1. How long does an ACL reconstruction take?

I was once told by one of my mentors that a good ACL reconstruction should never take the surgeon less than one hour to do. If one considers all the steps that are performed in the procedure it is easy to understand why. Nowadays the surgical technique is quite streamlined. It has been made easier to some extent by the newer fixation devices and graft preparation techniques. If there are no other structures in the knee which have to be repaired then it is possible to perform an ACL reconstruction safely in under an hour. Sometimes it can be done in 45 minutes or less. If there are other procedures which need to be performed (e.g. meniscal repair, extra-articular tenodesis) then it may take closer to 2 hours.

I always emphasise to my patients that it takes as long as it takes to do it right. My aim is always to work efficiently, effectively and expertly and, of course, safely. I do not to try and do the procedure as fast as possible. One must also bear in mind that it takes time to administer and wake up from the anaesthetic. There is also extra time involved in preparation before the actual surgery begins It is important to tell your loved ones that you may be in the operating theatre for two or three hours and this is completely normal.

  1. Is ACL surgery painful?

The ACL reconstruction itself is done under a general or spinal anaesthetic and therefore no pain is felt during the procedure. If you have a general anaesthetic then you will obviously be asleep. Even if you have a spinal anaesthetic, sedation is usually administered as well to help you sleep during the procedure. You will therefore not be aware of anything that is going on during the operation.

I use local anaesthetic to numb all the areas of skin where incisions are made. At the end of the procedure I also use local anaesthetic to inject around the capsule of the knee joint. This helps with post-operative pain relief. If a local nerve block is used then this will also assist in controlling the pain after the procedure.

In my experience patients usually wake up and feel quite comfortable initially. When the local anaesthetic wears off they makes begin to experience some discomfort. Fortunately we can control this using a variety of pain medications. These may be given in your drip while in hospital, and orally in tablet form when you go home.

There are obviously limitations as to the amount of strong medication that can be taken to control pain. Most people still experience some discomfort after the operation. The good news is that this is never unbearable and is only rarely severe enough to disturb one’s sleep.

In summary…

ACL surgery (ACL reconstruction) is a common procedure which should only be performed by orthopaedic surgeons with suitable training and experience in the correct technique. I hope I have answered some of the more commonly-asked questions about the procedure in this article.

Yours in good health,

Dr Warren Matthee

MB BCh (Wits), MRCS (England), MMed (Ortho Surg), FC Orth (SA)

Orthopaedic Surgeon

(011) 304 6784

About the author…

I am an orthopaedic surgeon with a special interest in sports injuries and minimally invasive (arthroscopic) surgery of the knee and shoulder. I treat patients at Waterfall Hospital in Waterfall/Midrand and Morningside Mediclinic in Sandton. Besides these, I also treat patients from other areas as well, including Rosebank, Sunninghill and Fourways.

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    Good rehab is essential after an ACL reconstruction