,It has been customary for decades to use a pneumatic tourniquet during total knee replacement surgery. Inflation of the tourniquet initiated the very first total knee replacement I saw as a medical student, every total knee replacement I did during training, and nearly every total knee I performed while in practice.
The perceived benefit of tourniquet use was reduced blood loss and better visualization of the tissues during surgery.
Total blood loss is defined as any blood loss during surgery, PLUS any postoperative blood loss into dressings or drains, or into the joint or leg. This can be quantified by comparing pre-operative hematocrit (blood count) with the lowest post-operative hematocrit.
A recent paper suggests that total blood loss paradoxically INCREASES if a tourniquet is used during surgery. A variety of additional recent papers suggest the same thing. How can this be?
Reactive Hyperemia (a period of increased blood flow after tourniquet release)
While a tourniquet is inflated, arterial inflow to the limb is stopped. This is nice for the surgeon during the operation as visualization is easier, and no time needs to be spent controlling bleeding. Many surgeons release the tourniquet at the conclusion of the operation, but prior to closing the incision. This allows any bleeding to be controlled. This was what I always did, because I wanted to be sure all active bleeding was stopped prior to wound closure. I hoped to minimize any post-operative bleeding as well as total tourniquet time. Some surgeons do not choose to do this but maintain the tourniquet until a compressive dressing has been applied.
The problem is that after the period of ischemia (no blood flow), the tissues demand more blood supply, and the blood flow to the limb increases for a period of time after surgery. This is known as reactive hyperemia. As a result, sometimes after surgery, blood will collect in the knee, accumulate in the dressing, and/or be removed in a drain. This can be uncomfortable for patients and it increases total blood loss.
There are other downsides of tourniquet use. Intravenous antibiotics are given just prior to initiation of surgery to help reduce the chance of infection. While this medication is infused prior to tourniquet inflation, once the tourniquet is inflated, blood is no longer circulating and thus, antibiotic medication is not circulating either. Ischemic tissues will become cold making cellular activity and enzymes less effective. Ischemia is stressful to the tissues. This increases inflammation. The tourniquet applies significant pressure to the soft tissues. This can contribute to pain and bruising of the thigh postoperatively. Because the tourniquet stops blood flow, it also increases the chance of blood clot formation.
I encountered occasional cases where the tourniquet didn't work well. This can happen if a patient has high blood pressure, their arteries are calcified, or if their thigh is large. In these cases the tourniquet restricts venous outflow but allows arterial inflow since arterial pressure is higher. We refer to this as a "venous tourniquet." When this happened I would drop the tourniquet and carry on as usual. The operation went fine. A bit more time was needed to stop bleeding during surgery, but the results were no different than when using a tourniquet.
Based on this, the theoretical negative tourniquet effects, and the recent papers suggesting tourniquet paradoxically increases total blood loss, I decided to stop inflating the tourniquet for total knee replacements.
I spend a few more minutes controlling bleeding during the surgical approach. Once this initial bleeding is controlled, there is minimal ongoing blood loss for the remainder of the case. This is analogous to total hip replacement where tourniquet use is impossible due to the location of surgery.
Visualization is excellent. The bone ends are irrigated using pulsatile lavage, and dried as usual prior to implanting the knee replacement components. By this stage of the operation, the knee looks basically the same as it does when using a tourniquet. Prior to closure, all bleeding has stopped. No drain is necessary. Tranexamic acid is a medication that helps reduce blood loss, and we use this in most patients.
I have been very pleased with the results since I have discontinued routine use of the tourniquet for total knee replacement surgery. I found patients are more comfortable and there is noticeably less swelling and bruising. Knee range of motion has been returning quicker.
We are continually working on process improvement to allow patients to return to their normal life as rapidly as possible. This begins with preoperative education, continues with a multimodality pain management plan, a 3-dimensionally planned, robotically assisted joint replacement operation, and early mobilization. My experience is that discontinuing use of the pneumatic tourniquet is yet another step to help patients recover quicker.
Nearly every patient will experience some degree of permanent numbness on the lateral (outside) side of the knee after knee replacement surgery. This is anticipated. It is so common, most surgeons do not discuss this with their patients prior to surgery. It is not a complication, but a necessary side-effect of achieving a safe exposure to perform knee replacement surgery.
What is going on?
There are cutaneous (skin) nerves that cross the front of the knee from the inside (medial) to the outside (lateral). A knee replacement incision is made longitudinally over the front (anterior) of the knee. These small nerves must be cut to allow deeper exposure. Other than a numb patch on the outside of the knee, there is generally no other negative effect.
Once rehabilitated, patients rarely even mention this finding. Most are just thrilled their arthritic pain is gone and they are back to their desired activities again.
Orthopedic Surgeon focused on the entire patient, not just a single joint.