There are several methods used to control pain in the first 24-hours after an anterior cruciate ligament (ACL) repair. Narcotics can be delivered by mouth (oral), by injection into the muscle (intramuscular), by injection into the joint (intraarticular), or directly into the blood stream (intravenously).
A nerve block to the femoral nerve in the leg blocks any pain signals from reaching the brain. The success of the nerve block depends on the placement and dose of the drug. The drug is delivered to the nerve through a needle placed just under the outer lining of the nerve called the nerve sheath.
The surgeon uses a neurostimulator to find the exact location of the nerve. The patient is lightly sedated but awake enough to answer questions. Once the nerve is blocked, the surgeon pinches the skin and muscle to see if it is numb.
Nerve block failure can occur if the drug dose isn't enough or if the catheter delivering the drug has been displaced or moved by accident. Sometimes the patient just has what's called breakthrough pain.
With breakthrough pain the patient can receive additional pain medication. This could be via any of the three delivery methods mentioned.