KNEE KEYHOLE SURGERY
WHAT IS ARTHROSCOPY?
Key-hole surgery (called arthroscopy) of the knee is used to assess problems inside the joint and treat this where possible. Arthroscopy requires two or three small (5mm) incisions in the knee joint to allow insertion of the instruments. Occasionally the incision is larger than this to allow removal of a large loose fragment from the knee. This procedure involves the insertion of small instruments connected to a camera and video equipment through a fibre optic cable.
A number of knee conditions can be treated with this procedure from simple cartilage tears and removal of loose bodies to smoothing of damaged joint surfaces for example. Photographs of inside the knee are taken during the surgery to demonstrate to the patient what was found.
Typically hospital admission occurs on the day of surgery, providing a patient has previously been medically assessed as fit for surgery. Arthroscopic knee procedures are usually under a general anaesthetic and performed as a day case, that is without overnight stay.
Above: Pictures of the knee joint taken during the surgery, with an example of a tear of the meniscus.
DETAIL OF THE PROCEDURE FOR ATHROSCOPIC KNEE SURGERY
Once in the operating theatre, the patient's skin is prepared with antiseptic solution in order to remove bacteria from the skin before placing sterile drapes are around the leg. Using a scalpel, the surgeon makes two small incisions (approximately 5mm) one on either side of the knee cap tendon (patella tendon) to allow the introduction of the key hole camera (arthroscope) and hook probe instrument. The surgeon then makes a thorough assessment of the joint, before deciding on the appropriate operation such as removal of a damaged meniscus, or a smoothing of the cartilage (called debridement) for example. The hook probe is removed and further instruments are introduced to perform the procedure. A commonly used instrument is a power shaver with diameters as small as 3.5mm, which allows removal of tissue and suction at the same time.
The length of time for arthroscopic knee surgery depends on the procedure being performed, although is typically between 15 - 30 minutes. Following the surgery, a long lasting pain relieving solution (local anaesthetic) is injected into the joint allowing early mobility after the operation with minimal pain at discharge. The small incisions are dressed before a bandage is wrapped around the knee to stay in place for 48 hours. It is normally possible for patients to able to bend their knee and lift it while straight within minutes of the operation. Full weight bearing is usually permitted (depending on the procedure performed) and crutches are provided to aid walking for a few days. Discomfort can gradually return over the next 12 hours as the action of the pain relieving medication finishes although it is unusual for this to be sufficient to prevent mobility. Where arthritis has been diagnosed, the duration of discomfort can last several weeks. During the recovery period it is common for the knee to be slightly swollen. Physiotherapy exercises are encouraged for a period of at least 4 weeks, following a return to sports can commence. It can take three months following a procedure before the knee feels settled.
Preoperative Management
The patient should avoid driving and undertake only essential walking for the first two to three days. Simple pain medication is prescribed for a few days as the knee may ache after the surgery, cold packs may also be used as required. Physiotherapy is then required to help strengthen muscles around the knee and this will be arranged prior to discharge from hospital.
Dressings
The soft padded dressing around the knee can normally be removed after 48 hours. Typically there are no stitches to be removed, with only a light dressing applied to cover the wounds to help keep them clean. The wounds should be kept dry until healed, typically around a week following surgery. Once the wounds have dried, showering or bathing can commence.
Rehabilitation
For the first few days, simple rehabilitation exercises including straight leg raising, knee and ankle movements and tensioning of the quadriceps [thigh] muscles should be undertaken as recommended by the Surgeon or Physiotherapist.
Return to Activity
Generally, a return to activities takes between two and six weeks following arthroscopic knee surgery. Recovery, however, depends on the extent of damage found within the knee, the treatment performed, the type of activities to which the patient wishes to return and the general fitness of the patient.
Approximate recovery times following simple arthroscopic surgery are:- • Driving 2-4 days • Sedentary (office type) work 2-5 days • Physical work 1-3 weeks • Light training 3 weeks • Return to full impact activities 4-6 weeks
Wounds
The small wounds can remain tender and thickened for a few weeks following arthroscopic knee surgery. Occasionally, a lump remains under one or other of the wounds for several weeks which will gradually resolve.
Ongoing problems
Simple pain medication is prescribed for a few days as the knee will ache after the surgery. Physiotherapy is then required to help strengthen muscles around the knee and this will be arranged prior to discharge. Patients are reviewed in the clinic after approximately 6 weeks to check on progress. Most patients can return to work in about 7 days if the job involves mainly sitting. If a job is more manual or demanding sometimes a delay of between 2 and 3 weeks is advised. Participation in most sports including swimming should be possible after 3 weeks. However it is important to understand that full recovery can take many months.
Continued symptoms following arthroscopic knee surgery are usually the result of an ongoing problem within the knee for which the surgery was recommended and not as a result of the procedure itself.
Results
In the short term there is no doubt that arthroscopy requires a short hospital stay (it is usually a daycase operation) and has minimal perioperative complications. It allows the surgeon to be more conservative than when using open techniques, which may mean that further procedures are required for symptoms in the future. For example, after arthroscopic meniscectomy up to 15% of patients may requires further meniscal resection at a later date. Arthroscopy performed for osteoarthritis of the knee is unpredictable. The aim is to clear out any debris and smooth off irregular surfaces.
Risks
Despite receiving high quality care, complications can occur, although a benefit of keyhole surgery is that major complications are rare. In broad terms complications can occur either during or after surgery. We will describe these complications related to orthopaedic surgery, rather than surgery in general, or anaesthesia. These include infection, deep vein thrombosis (blood clots), excessive swelling or bleeding and damage to small blood vessels or nerves around the knee. It is possible that in some patients the pre-operative symptoms do not significantly improve after arthroscopy.
During surgery complications include:
Major damage to the nerves & blood vessels that supply the lower leg and foot are rare. Damage to the nerves in the skin that supply feeling to the area over the kneecap are quite common, although these are of no functional significance. It is also quite common, however, for patients to bleed following surgery from small skin blood vessels beneath the surgical incisions. Fracture, Tendon and Ligament damage are very uncommon.
After surgery, complications are fortunately rare. These include:
Haemarthrosis (1%). This is a term that describes bleeding into a joint. As the surgical incisions are so small there is nowhere for the blood to escape and consequently it can build up within the knee and may require surgical drainage. It can be quite painful and may result in stiffening of the knee joint in the long term.
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Infection (0.2%)
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DVT 1%, PE <1%
Finally, though they have not been described here, the general complications of all surgery apply and should not be forgotten. Cardiovascular problems, urological problems, gastrointestinal troubles, and others, can occur. Do not forget that surgery is never as simple as it seems!