Patient Information Leaflet : Knee Arthroscopy
Below you will find answers to the following typical questions
What Is It?
Arthroscopy literally means looking inside a joint. Modern day techniques allow us to do this by means of an arthroscope (small telescope) which we insert into the knee joint through a 1 cm incision, hence the term “Keyhole Surgery”. A second small incision (cut into the skin) allows the passage of instruments into the knee joint to deal with any abnormalities seen
Why do we do it?
Arthroscopy of the knee is useful for three main reasons:
1. It allows us to diagnose conditions (confirm the cause of knee symptoms and problems) and plan further treatments
2. To allow treatment of those problems, i.e. undertake surgery to remove damaged tissue from inside the knee
3. A third and very useful reason for undertaking arthroscopy is that before any incision is made I will undertake an “examination under anaesthetic” of the knee joint comparing it with the other knee. This gives valuable information with regard to any joint laxity or ligament damage which may or may not need surgery. Should any ligament disruption be seen by me at the time of arthroscopy, ligament reconstruction surgery will not be undertaken unless I have thoroughly discussed this prior to the arthroscopy operation.
Some common procedures undertaken through the arthroscope are:
Removal of cartilage (meniscal) tears
Meniscal tears, i.e. splits in the gristle or cartilage on each side of the knee used to absorb impact, are a very common problem. Any tears of the menisci can lead to loose flaps which can get caught between the bone surfaces causing symptoms of sudden and sharp pain; locking, so that you cannot bend or straighten your knee properly; and instability, i.e. the knee gives way from under you. Often these symptoms are associated with marked swelling of the knee (effusion). It is a relatively simple and successful treatment to remove the torn portion arthroscopically.
Biopsy
Often carried out for recurrent knee pain and swelling when there is no obvious cause such as a fall or injury. This can be caused by inflammation of the joint lining (synovitis). This inflammation can be caused by many factors such as inflammatory joint disease (rheumatoid disease or gout) or reactive inflammation (reactive synovitis) often seen following a recent cold or flu. Occasionally there are abnormalities of the joint due to abnormal growth which can be benign (non-life threatening) or even malignant (life threatening cancers) and in order to diagnose these conditions biopsies can be taken from the affected areas to be looked at under the microscope.
Osteo arthritis
This is a form of wear and
tear of the joint which is caused by advancing age. This is the commonest form
of arthritis and is due to a gradual deterioration of the joint lining where the
bearing surface breaks up and becomes uneven, and no longer allows smooth joint
movement without pain and graunching.
Other
signs of this wear and tear osteo arthritis are gradual stiffening of the knee
joint, moderate swelling of the joint and changes seen on xrays, particularly
weight bearing xrays. Xray changes include narrowing of the joint space and
altered bone around the joint such as new bone (osteophytes) or weakened bone
(cysts). Arthroscopy
can often help in first of all gauging the extent of any joint surface damage in
order to plan further treatment and secondly to “tidy up” the knee joint by
washing out debris which has built up over the years and smoothing off some of
the worst affected areas.
What Are The Risks?
Overall arthroscopy of the knee is a very safe operation. However, all operations are associated with risks which are variable in frequency depending on the type of operation undertaken. Some of the more common and more significant risks are discussed below.
Infection
Any operation which involves making incisions can lead to post operative infection. This is usually an infection of the superficial tissues only (skin and underlying layers) and is treated with antibiotics. Occasionally the infection can go deep into the knee joint itself (deep infection rather than superficial infection) and this can be very serious, indeed life threatening. Such a complication if it occurs requires re-admission to hospital and often re-operation to wash out any infection from the knee joint and prolonged periods of antibiotics, often initially intravenously. For arthroscopy this is said to occur in around 1 in 1000 cases.
Deep venous thrombosis (DVT)
Venous thrombosis involves blood clots forming usually in the deep veins of the legs. This is usually due to reduced blood flow as part of the operation and the period of reduced movement of the affected leg, both before and after the operation. The thrombosis can occur in either leg, but usually in the operated leg. Blood clots often occur following even minor operations such as arthroscopy of the knee, but are often small enough to be unnoticed. However, occasionally the blood clot blocks large enough veins to cause symptoms of pain and swelling of the calf and foot and requires treatment with blood thinning agents (either Heparin or Warfarin) once the diagnosis has been confirmed by further investigation such as ultrasound scanning of the veins or injection of dye (venogram). Significant venous thrombosis (sufficient to cause a patient to go to his doctor or back to his specialist) occurs in around 1 in 200 cases of knee arthroscopies. However, following treatment the outlook generally is excellent with full restoration of blood flow and normal function within three-six months of treatment.
Pulmonary embolus
An embolus is a blood clot which has broken off from a DVT and travelled in the veins back to the heart and either causes blockage in the heart chambers or goes through the heart and blocks part of the blood supply to the lung fields. The latter is called a pulmonary emboli and if the blood clot is large enough it can cut off sufficient blood flow to the lungs to cause collapse and even death. Thankfully this is very rare, around 1 in 10,000. Around 1 in 1000 patients who undergo arthroscopy develop pulmonary emboli sufficient to cause chest pain and shortness of breath for a short period after their operation and again this leads to re-admission to hospital for further investigation and treatment. With adequate treatment (blood thinning agents) most patients make a full and complete recovery from pulmonary emboli within three-six months.
Death
Arthroscopy is carried out under a general anaesthetic in the vast majority of cases. Occasionally regional such as a spinal anaesthetic or even local anaesthetic can be employed but this is unusual. Use of anaesthetics (regional or general) carry risks of drug interactions or failure of anaesthetic machines and general anaesthetic procedures have a risk of major complication such as brain damage or death in around 1 in 1,000,000 cases. Modern equipment and anaesthetic techniques make these risks as low as is possible to achieve.