Anesthesia for Hip & Knee Surgery

At some point before your joint replacement surgery, your doctor will raise the issue of anesthesia. Many people will jokingly say, “Just put me out, Doc, and wake me when it’s over.” But the selection of anesthesia is a major decision that could have a significant impact on your recovery. It deserves careful consideration and discussion with your surgeon and your anesthesiologist.

Several factors must be considered when selecting an anesthesia, including:

  • Your past experiences and preferences-Have you ever had anesthesia before? What kind? Did you have a reaction to the anesthesia? What happened? How do other members of your family react to anesthesia?
  • Your current health and physical condition-Do you smoke? Are you overweight? Do you drink or use “recreational” drugs? Are you being treated for any condition other than your joint replacement?
  • Your reactions to medications-Do you have any allergies? Have you ever experienced bad side effects from a drug? Which drug? What kind of side effects? What medications, nutritional supplements, vitamins or herbal remedies are you currently taking?
  • The risks involved-Risks vary, depending on your health and selection of anesthesia, but may include breathing difficulties, blood loss, and allergic reactions. Your surgeon and anesthesiologist will discuss specific risks with you.
  • The skill and preferences of your surgical team

There are three broad categories of anesthesia-general, regional, and local. You are probably familiar with local anesthesia, the kind your dentist uses when repairing your teeth. Local anesthesia numbs only the specific area being treated. Most joint replacement surgeries use either general or regional anesthesia.


General anesthesia

General anesthesia affects your entire body. It acts on the brain and nervous system, leaving you in a deep sleep. Usually, it is given by injection or inhalation. When general anesthesia is used, the anesthesiologist will also place a breathing tube down your throat and administer oxygen to assist your breathing. General anesthesia is commonly used if you are having an extensive surgical procedure that takes a long time. There are several types of general anesthetics; your anesthesiologist will discuss specific selections with you.

As with any anesthesia, there are risks, which may be increased if you already have heart disease or a chronic lung condition. General anesthesia slows both your heartbeat and breathing rates, so your heart, blood pressure, breathing and temperature are constantly monitored during the surgery. It also causes your blood vessels to open wider (dilate), which can result in a heavier loss of blood during the surgery. You may want to consider donating blood in advance of your surgery. The tube inserted down your throat may give you a sore throat and hoarse voice for a few days. Headache, nausea and drowsiness are also common.

Regional anesthesia

Regional anesthesia focuses on numbing a specific area of the body, without affecting your brain or breathing. Because you remain conscious, you will be given sedatives to relax you and put you in a light sleep. The two types of regional anesthesia used most frequently in joint replacement surgery are spinal blocks and epidural blocks. For surgery below the hip, a combination block that targets the lumbar plexus and the sciatic nerve can numb only one leg.

In a spinal block, the anesthesia is injected into the fluid surrounding the spinal cord in the lower part of your back. This produces a rapid numbing effect that can last for hours, depending on the drug used. An epidural block uses a small tube (catheter) inserted in your lower back to deliver large quantities of local anesthetics over a longer time period. The epidural block and the spinal block are administered in very similar in location. However, the epidural catheter is placed slightly closer to the skin and further from the spinal cord than the spinal block injection. There are several advantages to using a regional anesthesia during hip or knee replacement surgery. Studies have shown that there is less blood loss during the surgery, and fewer complications from blood clotting afterwards. Side effects from regional anesthesia include headaches, trouble urinating, and allergic reactions, which could be quite serious.


Pain relief after surgery

The goals of postoperative pain management are to enable you to do the required physical therapy and to minimize pain and stress. If a general or spinal anesthesia was used during your surgery, postoperative pain relief may be delivered intravenously. You will be able to control the flow of medication, within preset limits, as you feel the need for additional relief. This process is often referred to as patient-controlled anesthesia, or PCA.

If an epidural block was used during your surgery, the epidural catheter can be left in place and anesthesia continued afterwards to help control pain. You will also have control over the amount of pain medication you receive, within preset limits. You will be closely monitored to ensure that no complications such as excessive sedation or compartment syndrome, an excessive build-up of pressure within the muscles, develop. Your doctor may also prescribe other pain relievers, such as aspirin or ibuprofen, to help control pain after surgery. However, if you are also taking drugs to help prevent blood clots, your use of these pain relievers or any other medications that could further thin the blood will need to be monitored closely.

The proper use of pain relievers before, during, and after your surgery is an extremely important aspect of your treatment, can encourage healing, and can make your joint replacement a more satisfying experience. Take time to discuss the options with your doctor and to ask questions about things you don’t understand.