When people hear the term ‘knee reconstruction’ in the news, it most commonly refers to repair or augmentation of a torn anterior cruciate ligament (ACL). The ACL is a ligament that sits in the middle of the knee joint with its partner, the posterior cruciate ligament (PCL). They are named based on where they attach to the top of the shin bone – the ACL at the front, and the PCL at the back. The term ‘cruciate’ stems from the fact that they cross over each other in the joint. These ligaments function to stop the forward and backward movement of the tibia (shin) on the femur (thigh). The ACL also has a particular role in controlling rotation movements of the knee, and it is loss of this function that is the most debilitating when the ligament tears. You require the ACL for pivoting activities, such as an sport that requires side-stepping or rapid changes of direction. Failure of the ligament, apart from the pain and discomfort of the initial episode, can lead to recurrent episodes of instability and pain. Longer term, a ruptured ACL and the damage done to the knee joint surfaces at the time of injury, leads to an increased risk of degenerative arthritis later in life.
How do I know if I have ruptured my ACL?
The classic story for a ruptured ACL is painful collapse of the knee when you tried to rotate on a bent knee – usually a side-step, or trying to pivot whilst moving quickly. It is often described as an audible pop, with rapid development of knee swelling. The knee is painful to move, but you can usually still put weight through the leg. These symptoms will slowly improve over a period of 6 weeks, with the normal outcome being a return to painless full knee range of motion and no instability with straight line activity. The problems occur with attempts to pivot at the knee, where the knee will sublux and collapse, either with or without pain. Other injuries can also be sustained at the time of initial injury, with a meniscal tear a common occurrence when the ACL ruptures.
If you are experiencing any or all of these symptoms, contact your local doctor and seek review with an orthopaedic surgeon.
Will it get better on its own or do I need to get it fixed?
Yes and no. What happens to the ligament after it ruptures varies from person to person. In some, the ligament heals and function restored, though this is quite uncommon. In others, the torn ligament can stick itself to the PCL, and you will have some function but not full. This may allow you to perform activities without any problems, or may cause milder symptoms. In many, the ligaments do not heal and are slowly removed by the body or scar to surrounding tissue, and with knee rotation you will experience collapse. What really matters is whether or not the symptoms are stopping you from doing that in life you need or want to do. If you are able to perform your daily and occupational duties without any problems, and do not wish to return to pivoting sports, you do not need your ACL reconstructed. If you do experience instability and it is impacting your quality of life, you can have it reconstructed.
Wouldn’t it be easier to simply stitch the torn ends back together?
This certainly is the case for most tendons and ligaments that rupture, however, experience has shown us that the likelihood of a successful repair healing with full functionality is very low. Partly this is due to the local environment – the ACL sits bathed in joint fluid in the middle of your knee, and this impairs direct healing. Much like re-tying 2 pieces of rope together, the integrity of the repair site is often not as strong as the original intact ligament. More reliable outcomes are obtained when a new ligament is placed to augment the torn ligament. This involves removing only as much of the torn ligaments as is necessary to perform the procedure, and inserting either a new organic ligament (such as harversting your hamstring or patella tendons), or inserting a synthetic ligament.
If I have the ligament reconstructed, will it rupture again?
This is always a possibility, with many factors that can contribute. Perhaps the biggest is the fact that if you tore the natural ligament once, and you return to the same activity, you could end up in the same situation again. In this instance, regardless of how well the reconstruction went, the ‘new’ ligament could likewise fail. A common problem is that the full rehabilitation process is not completed before returning to high level activity, and an understrength reconstruction fails. It is vitally important that you diligently follow all your rehabilitation instructions. Though top level athletes can return to sport 6 months after an ACL reconstruction, the average punter will take 1-2 years to be back at peak fitness, and so a realistic expectation needs to be set early.
Will my knee function normally after the reconstruction?
If the ligament repair achieves desired fixation and is rehabilitated to appropriate strength before attempting high impact activities, yes. The aim of the procedure is to preserve full knee ROM and restore stability. Despite a perfectly executed procedure with no complications, the repair is never as good or as completely stable as the un-injured knee. However, for all intents and purposes, it will function as required. There are many reasons that the procedure can fail, and Dr Host will discuss these with you in detail prior to embarking on any surgery.
Will having the reconstruction stop me from getting knee arthritis in later life?
It was originally thought that this would be the case, and it does make sense that restoring stability to the knee should prevent further episodes of instability that could damage the cartilage further. Recent literature has suggested that in long term followup this is not the case. It is believed that the main determinant of developing post-traumatic arthritis is the damage done to the joint cartilage at the initial injury. If the smooth cartilage surface is in any way disrupted, with time it will only wear more. How quickly it develops is dependent on activity level, weight, genetic factors, and occupation. A successful ACL reconstruction will restore stability of the knee and allow you to return to pivoting activities, but will not alter your chance of developing arthritis.
How can the diagnosis be confirmed?
An MRI scan is the definitive test used to confirm a rupture of the ACL, however a thorough history and examination will usually reveal the problem. If you are concerned you may have ruptured your ACL, contact your local doctor and seek orthopaedic surgical review.
What do I need to do before surgery?
Surgery cannot be performed safely until you have recovered full, painless knee range of motion. This will usually take 6 weeks. Dr Host recommends seeking physiotherapy review early to design and implement a rehabilitation program. Once you have recovered full motion, gradually work on strenghtening the surrounding muscles and try to return to your usual activities. If you cannot due to recurrent instability, you may require surgery. If you can resume your usual activities with minimal impairment, there is no need to rush down the path of surgery – give it more time and see how you go.
How long am I in hospital for with a knee reconstruction?
Knee reconstructions are performed as day surgery, though a single night stay in hospital is also not unreasonable – it will be tailored to the individual and the support structure you have at home.
When will I be able to walk after the surgery?
You will be able to walk immediately after the surgery. No braces or splints are required – knee range of motion is encouraged early. You will undoubtedly require crutches initially, but these can be dispensed of once you are comfortable mobilising. The rehabilitation is a graduated progression from walking and gentle range of motion, to strengthening and running, with pivoting activities last of all. This whole process will take 6-12 months, with ongoing improvement over 1-3 years.
What should I do after my surgery?
You will be seen in hospital by physiotherapists who will commence your rehabilitation program, and further inpatient or outpatient reviews will be arranged.
This surgery is performed using arthroscopy and open surgery, so pain and swelling are expected, but should not be severe. Dr Host and his team will endeavour to have you on an analgesic regime that keeps you comfortable, and you are encouraged to frequently ice the affected knee in order to keep swelling down. Dressings can be debulked 48 hours after surgery, and if the waterproof dressings remain intact, you can get the area wet. Leave all dressings intact until your 2 week review.
What should I look out for following surgery?
If you experience an increase in pain or swelling, and if the knee becomes red and hot to touch, you should seek urgent review with Dr Host or your local GP. You may be developing an infection, and the earlier treatment is started, the better your result.
If you develop any lower leg/calf swelling or pain, or any shortness of breath, chest pain or rapid breathing and pulse, seek urgent review at your closest hospital.
What rehabilitation must I do after the procedure?
A detailed plan will be provided to you by your physiotherapist, and will be reinforced following surgery prior to discharge home, and at subsequent outpatient reviews.
When can I drive after my procedure?
You are not allowed to drive for at least 2 weeks after the surgery, regardless of the limb involved. Following this, it depends on your function. If you are safely able to control the vehicle, you are able to drive. If your ROM and mobility are slower to recover, delay driving longer. You do not want to cause harm to yourself or others that could have been avoided – a sensible approach is best.