Anaesthesia for Joint Replacement Surgery

The most common Joint Replacement Surgery is for the Hip or Knee, however other joints may be replaced on occasions.

Patients requiring this type of surgery tend to be in the older age group and it is not uncommon that these patients are on treatment for other medical conditions. A pre-anaesthetic consultation and general medical workup is commonly provided to have the patient in the optimum condition for this major type of surgery. This surgery is commonly the end stage management for arthritis of the joint involved and medication for pain in these joints has often been taken for some time previously.

Advice will generally be given to the medications taken in the one to two weeks prior to the surgery and it may be necessary to stop or modify some medications as they may have adverse effects after the surgery. Drugs such as aspirin or some pain medications may 'thin' the blood and cause undue bleeding post-operatively. Other blood thinning drugs such as warfarin or heparin need to be carefully managed in the leadup to surgery. If not managed satisfactorily surgery may need to be canceled and rebooked. Some medications may be taken up to the morning of the surgery.

The pre-operative consultation by your anaesthetist should clarify your particular medication and when you may take it. This gives your Anaesthetist the opportunity to assess you and your particular needs and requirements during surgery and also gives you the opportunity to discuss any concerns you may have. There are risk factors for all anaesthetics performed and your anaesthetist should provide you with information relating to your surgery.

You will be required to fast prior to your surgery but if medications are required you may take these with a small sip of water.

The surgical procedure may take from one and a half to three hours or longer especially if the joint has previously been replaced.

The type of Anaesthesia performed will depend on general health, current medication regime and the decisions for pain relief after the operation.

General anaesthetic, Regional anaesthetic (spinal or epidural) or a combination of the two may be employed for your operation. You and your anaesthetist will decide which is best for you.

To begin with a needle will be placed in a hand or arm and an intravenous drip will be commenced.

The Epidural or Spinal technique requires a needle to be inserted in the lower back between the vertebrae. The Anaesthetist will usually perform this with you awake, have you either lying on the side or sitting and leaning forward, and will scrub up and undertake precautions to prevent infection. A small amount of local anaesthetic is first injected into the area before the Spinal or Epidural needle is inserted. Once the local is in the procedure is not painful.

If the Epidural or Spinal Anaesthetic technique is employed alone, sufficient Local Anaesthetic is injected to provide pain free surgery.

Usually if an Epidural is performed a small catheter is inserted into the space and can be used for some days after the surgery to provide pain relief.

A general anaesthetic may be used in addition to a regional (spinal or epidural) technique. In this case you will be totally asleep. However, because of the pain relieving effects of the regional anaesthetic, you are able to have a 'lighter' anaesthetic for your operation and improved pain relief in the initial post-op period. Ina general anaesthetic a breathing tube is inserted once you are asleep. This occasionally causes mild sore throat.

All patients will be monitored continuously during the surgery for the level of oxygen in the blood, blood pressure, heart rate and heart monitoring (ECG) and if general anaesthesia is used your breathing will also be continuously monitored. Precautions to prevent blood clots forming will be applied during and after surgery.

Blood Transfusion may be required during or after the surgery. Your surgeon will have given information. In many cases you will have donated your own blood in the weeks prior to the surgery. If required your own blood will be given to you first and only if really necessary will other blood bank blood be given.

Post-operative pain relief is an essential part of the procedure. Several techniques can be used to provide pain relief after join replacement. Your anaesthetist will advise which is best for your surgery. If an epidural technique is used, the catheter that has been left in place can be used to continue giving pain relieving medication. In the case of a spinal anesthetic, along acting pain relieving medication can be added to the mixture. Another form of pain relief can be given by way of the Intravenous Drip either continuously or intermittently using a Patient Controlled Analgesia (PCA) technique where you push a button when you feel pain coming on. The apparatus is adjusted so that no matter how many times you push the button it will only supply a pre-designated amount of the drug in a set period of time. It is important that only you push the button and that you keep the pain relief going when you feel the pain coming on.

Another technique which may be used for pain relief after the Knee Surgery is a Femoral Nerve Block. A needle is inserted into the groin and an injection of local anaesthetic give. The object of this is to increase the effect of pain relief after the operation, making you more comfortable.

Other medications employed are antibiotics as infection is to be meticulously avoided and anti blood clotting medication to prevent Deep Venous Thrombosis (DVT) and Pulmonary Embolus (Lung Clots).

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