Through the keyhole…what happens in a knee arthroscopy?

An arthroscopy, sometimes called keyhole surgery is a common form of knee surgery. This blog will look at reasons why you might be recommended to have this surgery and what you should expect. Recent clinical evidence which has changed some of the indications for a knee arthroscopy will also be discussed.


What is a knee arthroscopy?
A knee arthroscopy is a type of surgery using a tiny camera to look inside the knee. Very small incisions are made, usually just below your knee cap on either side, where the joint is easily accessed. As the wounds are so small, you will usually only need a few stitches and the infection risk is much smaller than in open surgery. Salt water is pumped into the joint to inflate it and a camera is inserted though one of the incisions. It is attached to a monitor so the surgeon can see clearly what is going on inside your knee and repair or remove the problem using special instruments. Pictures are usually taken and you will be able to see them yourself after the procedure.
The procedure is often done under general anaesthetic but it could also be done under local anaesthetic or with a femoral nerve block. The type of anaesthesia offered may depend on your surgeon, the indications for the arthroscopy and your own age and medical background.
Why might I need a knee arthroscopy?
Most of the time an arthroscopy is carried out after a problems has been identified from your examination and history and confirmed on an MRI scan. Research has indicated that it is more cost efficient to confirm a diagnosis by MRI first rather than use the arthroscopy as a diagnostic investigation. The most common indications for a knee arthroscopy are:
• A torn meniscus. The menisci are two wedge shaped pieces of fibrocartilage which cushion the space between the bones in the knee joint. They are usually injured in a twisting injury to the joint, for example when playing football.
The menisci are known to have a poor blood supply and so tears do not usually heal. A tear to the meniscus can cause an uneven joint surface and result in locking of the knee in certain positions or giving way of the joint. Tears can be tidied up, resected, removed or repaired through arthroscopy.
However the history and age of the patient are particularly important. Degenerative tears of the meniscus are very common in older patients as the cartilage become dehydrated and overused with time. In these cases arthroscopy is not always advisable as there is evidence that it can accelerate the progression of osteoarthritis in the knee joint.
• A torn or damaged Anterior Cruciate Ligament (ACL) or Posterior Cruciate Ligament (PCL). These ligaments do not repair themselves if they are fully torn. However they can be replaced through an arthroscopic operation, often using a part of either the hamstring or patella tendon.

Surgery is indicated in an athletic person who wishes to return to sport in some capacity as the absence of ligament support could accelerate degeneration of the knee joint. Less active older patients should be encouraged to look at more conservative rehabilitation to compensate for the laxity at the knee joint avoiding an operation.
Other indications include:
• Swollen (inflamed) or damaged lining of the joint. This lining is called the synovium. Sometimes a procedure called a synovectomy may be mentioned, where part or all of an inflamed synovial membrane is removed
• Problems with the knee cap (patella)-either a painful condition known as chondromalacia patella or a knee cap which is considered to be out of optimum alignment (a procedure known as a lateral release may be used).
• The removal of loose bodies -Small pieces of broken cartilage in the knee joint. These may relate to a previous meniscus tear and are often associated with arthritis.
• Repair of a defect in the articular cartilage
• Some fractures of the bones of the knee –some tibial plateau fractures (fractures to the weightbearing surface of the tibia) can be repaired arthrocopically.
How long should the operation take?
This will depend on exactly what the operation involves. As you can see above there may be different procedures taking place during a knee arthroscopy so the procedure length can vary. The usual time would be between 30-60 minutes but your surgeon should be able to give you a more accurate guideline before the procedure.
What happens afterwards?
The vast majority of knee arthroscopies are performed in day surgery and you will leave the hospital shortly after the operation. If you have been given a general anaesthetic you will be given specific advice associated with this, in particular you should have a responsible adult take you home and stay with you for the first 24 hours after the operation to ensure no adverse affects from the anaesthetic.
You will usually have swabs or butterfly type plasters over the wounds themselves and a large bandage covering this to protect the area. You should elevate the knee and apply ice packs to help minimise the swelling post operation, taking care to keep the dressings dry. Swelling post operatively can delay recovery as it is associated with muscle inhibition.
A physiotherapist will often visit you briefly before you leave hospital to check you can walk and advise you on exercises to help your recovery from the operation. Most commonly you will be asked to bend and straighten the knee as much as you can comfortably to prevent stiffness and perform contractions of the thigh muscles (your quadriceps) to prevent muscle inhibition after the operation.
Many people walk without any aid after the surgery. However if you are struggling with pain or swelling then you may be offered 1 or 2 crutches to help you walk more comfortably for the first few days. In rare cases, often where bone drilling or an extensive meniscus repair takes place during the operation you may be advised to limit weight bearing on the leg or to wear a brace which restricts some of your movement to protect the healing area. It is important to note that this is only in very specific cases and your surgeon will advise you if this applies to you. The vast majority of patients should weight bear and move as much as comfortable after the surgery as this helps to maintain normal muscle activity at the knee joint.
Your wounds will heal within a few days. If dissolvable stitches were used they will be removed after 1 or 2 weeks. Often this takes place at the follow up appointment where you will be advised of the findings and details of the operation itself and your expected recovery time. This can vary depending on the detail of the operation. For example a simple resection of the meniscus may feel better within a few days once the soreness from the operation has eased. If there was underlying arthritis it may take longer to recover. If there has been any bone drilling during the operation you may expect that area to feel uncomfortable for several weeks or months depending on the extent of the drilling. If you have a had a specific ligament repair –the ACL for example, you will be given a specific protocol for your recovery as this must take place over 4-6 month in order to respect the healing of the graft.
At your follow up appointment, physiotherapy treatment will be recommended if you have ongoing problems such as; continued swelling and pain, restricted range of movement of the knee joint, notable muscle wasting or difficulty walking.
Physiotherapy following a basic knee arthroscopy
If you have continued pain and swelling, your physiotherapist may use a cryocuff (pressure cuff filled with ice cold water). Massage and gentle manual therapy at the joint will help you to regain your range of movement. Supervised exercise, sometimes using a muscle stimulator such as a COMPEX device, can be very helpful if you are struggling with muscle inhibition. Pilates exercises such as footwork on the reformer is often a good way to increase quadriceps activation without overloading the knee joint. Improving your muscle activation will help to improve your walking and stair climbing ability.
As you progress your physiotherapist will include weight bearing exercises for your balance and proprioception. These are particularly important as the internal surface of the joint is changed by the surgery and there is thought to be a higher risk of developing degenerative changes at an earlier age.

Finally -Important points to note
• You will recover more quickly from the surgery if you have good muscle activation at the knee beforehand. For this reason more and more surgeons are recommending a course of physiotherapy before considering the operation, even if a meniscus tear has been identified on an MRI scan.
• A knee arthroscopy to simply perform a ‘lavage’ (washout) and debridement of an arthritic knee is no longer a treatment of choice. In fact an arthroscopy is not recommended if you have signs of joint narrowing (stage 3 osteoarthritis) even if you have an additional meniscus tear.
• As this is a change in practice which has occurred fairly recently you may want to discuss the indications for your arthroscopy with your surgeon in order to ensure that the benefit outweighs both immediate and future risks.

By Nikki Richards MPHTY(Sports)BSc(Hons)Physio

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