Local anesthetics block pain in a small area of the body. In orthopaedic surgery, they may be used as anesthesia during a procedure or as part of a pain management program after surgery.
For pain management, local anesthetics can be administered multiple ways. If using a pump, this will be administered through the insertion of a catheter near the surgical site. If injected, also called periarticular injection, these are administered in the surgical incision. Either form of administration can involve multiple anesthetics.
These anesthetics can also be injected into the back using an epidural catheter. They work by blocking the pain signals that travel along the nerves to your brain.
Local anesthetics do not have the side effects of drowsiness, constipation, or breathing problems that you get with opioids. In orthopedic surgery, the most commonly used local anesthetics include lidocaine, bupivacaine, liposomal bupivacaine, ropivacaine, ketorolac and epinephrine.
Using local anesthetics carries the risk of a possible allergic reaction and may cause nerve damage, muscle spasms, and convulsions. For the most part, side effects can be avoided when you share your complete medical history with your doctor.
Regional anesthetics offer the advantage of providing anesthesia of a large body area during surgery and pain relief for several hours afterward.
Medication is injected around the nerves in the part of your body having surgery and block feeling and movement in the lower part of your body (spinal, epidural), the arm (intra-scalene, supraclavicular, axillary) leg or legs (femoral, sciatic) or even as locally as a finger or toe. The reader may be more familiar with dental blocks used by dentists before performing dental treatments.
Often, you can remain conscious during the procedure and require only light sedation. For major surgeries, sedation will ensure you are relatively unconscious throughout while still able to protect the airway by swallowing or coughing. Other times, regional blocks may be used to supplement general anesthesia. Either way, you will have little or no pain when you wake up.
Spinal and epidural anesthesia are neuraxial blocks. They block feeling and movement below the level at which they are given, typically the lower portion of the spine. They can numb the area from the lower abdomen and pelvis down to the toes.
A spinal is given as a single injection of a local anesthetic or morphine directly into the caudal area. Since it is only a single injection its effect will last for the duration of the procedure and up to 24 hours afterward.
Epidural anesthesia is given in the space around the spinal canal. The canal itself is protected by a lining membrane called the dura. The medication will pass through the dura and reach the spinal nerves. A small tube or catheter may be placed in the space around the dura and left in place for the duration of the surgery or even in special circumstances up to one or two days after surgery. Medication may be given at intervals through the catheter.
Epidural anesthesia often has less effect on the motor nerves than spinal and will allow for some function and mobility even when then catheter is in place.
In addition to orthopaedic procedures, epidural anesthesia is often given to women during childbirth specifically because of its short duration.
The most common side effects of giving opioids via the spine are nausea and severe itching. The most serious side effect is respiratory depression, which means that your breathing slows down and becomes shallow because the numb area goes up to and including the bottom few ribs which includes the diaphragm and can therefore inhibit the breathing. Although this rarely happens, your surgical team will closely monitor you for several hours in order to prevent or address all side effects.