Total Knee Replacement is a highly successful surgery. Patients disabled with knee pain who can barely walk on their deformed legs underwent a dramatic transformation after the surgery. They experience complete relief from pain and complete correction of the deformity. After surgery, they don’t need painkillers. They can walk normally without a stick or walker and at a normal pace.
However, the surgery is a major procedure involving cutting of muscle and bone. This leads to a slow and painful recovery. Post surgery pain after knee replacement can be unbearable and remains as a major deterrent to someone who wants to undergo the operation. Traditional methods of pain control include intravenous or intramuscular analgesic injections and epidural pumps. Intravenous medicines have safety issues and are not effective. Epidural pumps involve placing an epidural catheter (a very thin tube) in the epidural space near the spinal cord. Through this tube, medicine is administered which numbs the spinal nerves and relieves pain.
A well functioning epidural pump is very effective but has certain problems. Firstly, placing an epidural catheter is a blind procedure and many times the catheter is not in an ideal position. As a result, it fails to reduce pain. Secondly, epidural pumps may cause a drop in blood pressure in some patients which requires constant monitoring. Lastly, epidural medicines may cause temporary sensory loss and motor weakness in the legs which makes walking after surgery difficult.
In recent years, technological advancements in the science of anaesthesia and pain management have made painless knee replacement possible. Patients are standing and walking by evening on the day of surgery! Nerve blocks are a known technique of analgesia (pain relief). Two technologies have become available to the anaesthetist in the operation theatre which has revolutionised the efficacy of nerve blocks.
First is a nerve locator
As its name suggests it helps in precisely locating a peripheral nerve which then can be blocked by administrating medicine.
Second is portable ultrasound
Combining these technologies increases the accuracy of locating a nerve to 95%. This allows the anaesthetist to confidently block peripheral nerves (nerves outside the spinal cord) with predictable success. In the case of knee replacement, a femoral block and an adductor canal block is used to numb the pain. These blocks are effective and safe. There is no drop in blood pressure and no motor weakness. As a result, we have successfully eliminated the need for epidural pumps.
Another advance that we routinely use is called LIA – Local Infiltration Analgesia. This involves injecting a combination of medicines in the local tissues around the knee joint at the end of the surgery. With modern drugs and optimal doses, this technique alone numbs the knee for 12 to 24 hours. Again the technique is safe and effective. it does not require monitoring of blood pressure and does not cause any weakness.
The last addition is that of pain patches. Newer opioid analgesics (artificial morphine substitutes) are available as pain patches. A single patch can work for a week. The action is not only long lasting but fast as the medicine is directly absorbed in the blood from the skin (bypassing the stomach).
Not only is total knee replacement a highly successful surgery, it is now a comfortable and pleasant experience as well. Today’s analgesia is safe and effective. All patients are able to walk on the day after surgery and many manage to walk on the same day. Nerve blocks, LIA and Pain Patches are so effective that they have made painless knee replacement a reality today.