What are the risks of tourniquet use in knee arthroscopy?

Knee arthroscopy is a minimally invasive surgical technique used to access and operate on the knee joint. It is commonly used to perform knee replacements.

However, there are different ways of performing a knee replacement arthroscopically, such as whether or not to use a tourniquet during the procedure to control the flow of blood into the leg being operated upon.

Who needs knee arthroscopy?

Knee arthroscopy is performed for people with problematic knees that cause symptoms such as pain, giving way, swelling, and locking. These knee problems may or may not have been caused by an obvious injury, and some result from simple wear-and-tear. Typically, these symptoms have failed to respond to non-surgical treatments such as anti-inflammatory medication, rest, and physiotherapy.

Pre-operative X-rays and MRI scans will have helped with the diagnosis and excluded conditions that will not respond to arthroscopy (such as severe osteoarthritis). MRI scans and X-rays may also detect bone abnormalities which would be missed at arthroscopy and should always be performed before arthroscopy. However, an MRI scan may miss subtle abnormalities such as joint surface damage, abnormalities in the lining of the joint and detection of loose cartilaginous bodies. Therefore, the two scan types are complementary.

What is knee arthroscopy?

Arthroscopy or 'keyhole surgery' is an operation to inspect the interior of the knee joint using a small fibre optic lens (telescope) with a camera. Typically, two incisions of 4mm in length are required. This is usually performed under general anaesthetic, but can be performed under a spinal anaesthetic (numbing the body from the waist down).

The knee is distended with a salty solution to enhance the view and to wash out any debris and blood. Excellent views all around the knee can be obtained, and still photographs and videos are taken to demonstrate the problem to the patient afterwards.

Many treatments can be carried out arthroscopically, such as:

• Trimming or the repair of torn menisci
• Removal of loose bodies (pieces of bone or cartilage)
• Trimming of loose flaps of the joint surfaces, which is often done with the microfracture technique (tapping a sharp pin into any exposed bone to stimulate repair)
• Repair of damaged ligaments (anterior cruciate)

Less common procedures include removing the diseased lining of the knee in inflammatory arthritis and elevating fractures of the joint surface.

The surgical instruments are inserted through another small incision and comprise simple hand-operated punches and scissors, power shavers, radiofrequency probes and various sophisticated external jigs to enable accurate placement of repaired ligaments.

Why use a tourniquet?

It has always been taught that a bloodless view is essential for knee arthroscopy. The standard practice is to reduce the amount of blood in the leg by elevation, or rolling a tight inflated rubber tube over the leg or occasionally by using a spiral rubber bandage.

A padded pneumatic (inflatable) tourniquet is applied to the thigh and then inflated to above the blood pressure (approximately 300 mmHg) to prevent blood flow into the leg for the duration of the operation.

What are the risks of using a tourniquet?

Common risks:

Tourniquets are very painful. The anaesthetist has to combat this by giving extra anaesthetic agents and painkillers during the operation. These drugs result in a slightly delayed recovery from the anaesthetic. Side effects such as nausea, vomiting, and drowsiness are also not unusual.

Immediately after the release of the tourniquet, transient increased blood flow to the limb (reactive hyperaemia) occurs, often causing bleeding into the joint (haemarthrosis), resulting in pain and swelling. Post-operative tourniquet pain is due to the lack of blood supply to the leg muscles which can persist for several days, needing strong painkillers.

Animal experiments have demonstrated loss of muscle mass and reduced contractile function after tourniquet use of two hours. This is particularly noticeable in slow twitch muscle fibres. Reduced quadriceps function (as measured by surface electromyography) has also been reported in humans for 6-12 months after tourniquet surgery in total knee replacements. This was not seen in a control group who did not have a tourniquet. This may be particularly relevant for the athlete wishing to return to full function as quickly as possible.

Rare risks:

In long procedures, the tourniquet needs to be released after about two hours or less to avoid increased pressure building up in the muscle compartments, which reduces the blood supply (acute compartment syndrome). This complication requires emergency surgery with large relieving skin incisions and a subsequent third operation to close the wounds after about a week. In rare cases, skin grafting is also required. If the condition is not recognised and treated immediately, permanent damage may occur to nerves blood vessels and muscle, causing painful deformity with loss of feeling and power in the foot and ankle. In exceptional cases, amputation may result.

If antiseptic skin preparations soak into the padding under the tourniquet, painful blistering can occur with mild resultant scarring. Poorly applied tourniquets with inadequate padding or extreme pressure in the tourniquet can cause nerve damage which may cause pain, numbness and muscle paralysis (foot drop). This occurs in 1 in 3700 patients. This rare complication causes permanent damage and is seen in 0.032% of patients.

There is a risk of blood clot in the deep veins of the leg (DVT) after knee arthroscopy. The overall incidence is approximately 1.6 % (according to one recent study of pooled results). Some individuals have a much higher risk than others. There is no published evidence of increased DVT risk in knee arthroscopy due to tourniquet use. However, tourniquet use in knee replacement has been reported by some authors to cause a higher incidence of distal DVT (blood clot in the deep veins of the calf). DVT can cause persistent pain and swelling in the leg. It can also detach and travel to the lungs (pulmonary embolus), causing chest pain, shortness of breath, and occasionally death. It therefore seems sensible to avoid a tourniquet which might add to the risk.

Very rarely, the squeezing of the blood out of the leg and the application of the tourniquet can send an undiagnosed blood clot (DVT) to the lungs (pulmonary embolus), causing death at the time of surgery. This is of particular concern in patients who have been immobile due to injury, illness, or obesity.

How do you reduce bleeding without a tourniquet and what are the benefits?

My practice is to inject the two incisions and the interior of the knee joint with local anaesthetic and adrenaline solution once the patient is anaesthetised, approximately five minutes before starting surgery. This numbs the knee joint and minimises bleeding. It is possible to carry out arthroscopy using this technique alone providing the patient is relaxed and cooperative. Blood loss is negligible and the view is as good as that with a tourniquet. Using this method, anaesthetists often remark that they have given very little anaesthetic agent and opioid painkillers and the patient has a very light anaesthetic.

As a consequence, patients wake up very quickly and return home quickly, often just a few hours later. Most do not require crutches, and most patients seem to experience minimal post-operative pain and swelling with this technique. If a patient has experienced arthroscopic surgery with a tourniquet previously, they always report a very positive experience without. Physiotherapists also notice a more rapid recovery without tourniquet use and rarely need to provide much outpatient treatment.

What are the disadvantages of not using a tourniquet?

• For the patient: There are no disadvantages, only benefits, such as a lighter anaesthetic, less pain and swelling, a faster recovery and of course reduced risk of serious complications.
• For the surgeon: Very occasional, minor bleeding which always responds to simple washing out of the knee once or twice.

If you are considering knee surgery, make an appointment with an expert to discuss your options.