A knee arthroscopy is a key hole operation using 2 or more small incisions (each about 1cm) from which a camera and instruments can be used to look and perform procedures inside the knee. It is most commonly used to treat symptomatic tears to the menisci (shock absorbency discs, commonly known as cartilages).
The menisci are a commonly injured structure within the knee and injuries can occur in any age group. In younger patients the meniscus is tough and rubbery, but can be torn in fairly vigorous twisting injuries (traumatic tear), usually related to sporting injuries. The meniscus grows weaker and less elastic with age, and can be torn with fairly minor injuries in the older population, even sometimes a simple squat (degenerative tear). Other uses of arthroscopy in the knee are for removing loose bodies (small fragments floating around in the knee), dealing with localised joint surface damage and rarely for diagnostic purposes. Majority of the time arthroscopy is used in patients with mechanical symptoms, e.g. locking or jamming of the knee.
Signs and Symptoms
The most common problem caused by a torn meniscus is pain. The pain may be felt along the line of the joint where the meniscus lies or it can be vaguer and felt all over the knee. It is often made worse with twisting, squatting or impact activities where the meniscus can be pinched. With rest, the symptoms may settle. The joint may often swell and get inflamed. If the torn part of meniscus is large, the knee may lock or jam (get stuck in certain positions of moving the knee). This is caused by a large fragment getting caught in the hinge mechanism of the knee and acting like a wedge preventing the knee from fully straightening. If the problem is due to a loose body, again locking or jamming of the knee can occur and if there is damage to the joint surface, localised pain may be a significant symptom.
Initial treatment for a torn meniscus is directed towards reducing the pain and swelling in the knee. This can be achieved by resting the knee, using icepacks and taking anti-inflammatory medications. You may be referred and asked to see a physiotherapist to reduce the pain and swelling and improve the range of movement. If the knee is locked and cannot be straightened out, surgery may be recommended as soon as reasonably possible to remove the torn portion that is caught in the knee joint. Once a meniscus is torn, it will most likely not heal on its own as the blood supply to most of the meniscus is poor. Despite this, symptoms in a large number of patients with degenerative tears will settle with appropriate conservative treatment (anti-inflammatory medication and rest). The symptoms may recur intermittently but if they do, it can be managed relatively easily as retaining the degenerate meniscus may be better for the knee in the long term (slows the rate of arthritic changes). If the symptoms continue or progressively get worse, surgery will be required to either remove the torn portion of the meniscus or to repair the tear. When dealing with a loose body which is causing on-going problems, surgery is recommended to remove the troublesome fragment and to have a look and deal with any relevant causative factors at the same time. If arthroscopy is recommended and performed for on-going localised pain due to damage to the joint surface, then a micro fracture procedure may be performed (drilling of the exposed bony surface to promote growth of a protective fibrous layer) to control symptoms.
Small incisions are made in the knee to allow the insertion of a small TV camera into the joint. Through another small incision, special instruments are used to remove the torn portion of meniscus while the arthroscope is used to see what is happening. When operating for mensical tears, in some cases the meniscus tear can be repaired. If this is the case, sutures are then placed into the torn meniscus until the tear is repaired. Repair of the meniscus is not possible in all cases and young people with relatively recent meniscal tears are the most likely candidates for repair. Degenerative type tears in older people are not usually repairable. At the time of surgery, other beneficial procedures to your joint surface may be required (e.g. micro fracture) and if this is the case, they will be carried out and explained in detail to you. Routine antibiotics will not be required prior to surgery. The operation will normally take about 30-40 minutes. Once the operation has been completed, the incisions are closed with steri-strips (no sutures are used) and dressings applied. You will have a crepe bandage over your knee.
What is involved for you as the patient?
Healthy patients are admitted to the day surgery unit or a ward on the morning of their surgery. You should inform your surgeon and anaesthetist of any medical conditions or previous medical treatment as this may affect your operation. It is extremely important that there are no cuts, scratches, pimples or ulcers on your lower limb as this greatly increases the risk of infection. Your surgery will be postponed until the skin lesions have healed. You should not shave or wax your legs for one week prior to surgery.
After the operation you will be required to stay in hospital for a few hours till you are over the effects of the anaesthetic, have had something to eat and drink and have been up and about with the physiotherapist. Overnight stay may occasionally be required due to the effects of the anaesthetic or an inability to manage with crutches. The crepe bandage comes off 24-48 hours after the operation and the inner dressings peel off at about 10 days after the operation. The dressings and wounds need to be kept dry till they are fully healed.
A physiotherapist will see you after the surgery to mobilise you and show you how to use your crutches. They will give you a programme of exercises to perform when you return home. Sedentary and office workers may return to work approximately 2-3 days following surgery. Most patients should be walking normally 7 days following surgery although there is considerable patient to patient variation.
Should the left knee be involved then driving an automatic car is possible as soon as pain allows. Should the right knee be involved driving is permitted when you are able to walk without crutches. You must not drive a motor vehicle whilst taking severe pain killing medications.
Return to vigorous activities will be determined by the extent of the damage to your meniscus and the amount of meniscus that required removal. If minimal damage was present then you may return to vigorous activities after 6 weeks. If significant damage was present then you may be advised to avoid impact loading activities in order to prevent the onset of early arthritis developing within the joint. If you had any other associated procedures during your surgery, then you will be told about this after your operation and your post-operative rehabilitation and physiotherapy plan will be altered accordingly. Follow-up will be organised about 6 -8 weeks after the surgery.
Complications Related to Surgery
As with all operations if at any stage anything seems amiss it is better to call up for advice rather than wait and worry. If you experience severe pain and swelling in the first few days following surgery, contact your GP for advice. A fever, or redness or swelling around the knee, an unexplained increase in pain should all be brought to the attention of your doctor.
Deep vein thrombosis and pulmonary embolus: Although this complication is rare following arthroscopic surgery, a combination of knee injury, prolonged transport and immobilisation of the limb, smoking and the oral contraceptive pill or hormonal replacement therapy all multiply to increase the risk. Any past history of thrombosis should be brought to the attention of the surgeon prior to your operation. The oral contraceptive pill, hormonal replacement therapy and smoking should cease one week prior to surgery to minimise the risks.
Excessive bleeding resulting in a haematoma is known to occur with patients taking non-steroidal anti-inflammatory drugs. They should be stopped at least one week prior to surgery.
Surgery is carried out under strict germ free conditions in an operating theatre. There is a less than 1 in 200 chance of developing an infection within the joint. This may require treatment with antibiotics or may require hospitalisation and arthroscopic washout of the joint. Subsequent to such procedures prolonged periods of antibiotics are required and the post-operative recovery may be delayed.
Pain and Swelling:
In rare cases your knee may become more painful and swollen after the operation. This usually settles with rest, ice, and anti-inflammatory medications.
Port Site Tenderness:
Commonly the small scars at the front of the knee where the camera and instruments are inserted are irritable and slightly swollen. This often makes kneeling uncomfortable. This normally settles after a few months.
Depending on the findings at the time of the surgery you may have on-going pain if for example; there is extensive damage to the joint surface that cannot be addressed at that time. You may require a further arthroscopy or other operative intervention at a future date if you have on-going symptoms.
Numbness Around the Port Sites:
A small proportion of patients experience some numbness around the portal sites as some superficial nerves get damaged. This improves with time but may never get back to normal in a very small percentage of cases. It will not affect your knee function in any way.
Abnormal Wound Healing:
Sometimes the scar can become thickened when it heals.Complications related to a General anaesthetic: These are very rare following knee arthroscopy surgery. The anaesthetist will discuss this with you prior to the operation.