Medical Tourniquets

It may come as a surprise to many that medical tourniquets are commonly used during orthopedic surgery on the lower extremities – ranging from just above the knee down to the toes.

Total knee replacement is one of these surgical areas where tourniquet use is both common, and seen by many surgeons as essential. However, their use in knee replacement is certainly not universal, as many surgeons make strong arguments against their use and find success operating without them.  

As you would suppose in today’s world of Google, social media, and online health advice, opinions about tourniquet use in knee replacement are abundant and often contradictory. As a patient seeking treatment, this can serve as another topic to complicate your surgical decision-making, choice of surgeon, and elevate anxiety as you decide about your total knee replacement. It’s important to ask questions directly to your doctor to help you make decisions about your care.

You may be asking… why would we need a tourniquet in the first place? 

When your surgeon makes an incision on your leg, bleeding is common. This bleeding is usually very controllable and shouldn’t be a problem to your health or survival.

However, bleeding during knee replacement surgery can cause your surgeon several problems. First, bleeding can obscure or limit what your surgeon can see in your knee while he or she operates. The tissues in your knee have different colors and textures that we rely on as landmarks and guides for the operation. When covered in blood, they can be hard to distinguish and define making the operation both slower and more difficult. By using a tourniquet, your surgeon can go through the operation and not be encumbered or limited by this problem.  

The second issue bleeding can cause is in the way we permanently attach the knee replacement implants to your bone. Often times, this is done with bone cement. Bone cement starts off quite soft.  This early stage of cement is what we call the “sticky phase” because the cement in this phase is actually very sticky. We apply it to the metal implants in this early stage and it sticks to the metal. 

Several minutes later, the cement enters its next phase called the “doughy” phase. This is the phase when it’s applied to your bone. The part of your bone that we cement the implant onto looks a lot like sea coral – it has lots of little open spaces in it. The cement in this doughy phase pushes into these spaces like meandering fingers. 

When the cement enters its last phase of hardening, the cement that is sticking to the implant has now intruded into all these spaces in the bone. It then hardens like granite, locking everything together.

The issue is that these spaces in the bone aren’t empty. They’re full of blood and fat. For the cement to get in there, the blood and fat needs to be gone. We clean the bone with some special washing tools.  However, if the leg is getting blood from the body (no tourniquet is on) the space will just fill back up with blood, potentially compromising the cement’s ability to bond the implant to your bone. This is a key reason so many surgeons use a tourniquet when doing your surgery.

There are ways around each of these issues. They present their own challenge, but the technique is simply referred to as a tourniquet-less total knee. Bleeding can be controlled with careful surgical technique and the blood can be quickly washed out before the cement goes in. 

Many surgeons I know handle tourniquet issues by inflating the tourniquet just before cementing in the knee implants, thus using it for only 10 minutes during the case. A final way to avoid this issue is to use what are called cementless implants – implants that are compressed to the bone, with metal surfaces that bone can grow in to, rather than cement to hold them in place.  

So, why would a surgeon choose to either use or not use a tourniquet? 

The advantages of tourniquet use I described above are widely accepted. However, some surgeons worry about several things with tourniquet use. First is the risk that tourniquets can cause post-operative pain. Another is that the tourniquet can cause injury to a patient. There are important nerves and vascular structures in the area under the tourniquet that could be subject to injury from this pressure – particularly the femoral nerve, artery, and vein.

Yet another concern is the worry that leaving the leg without blood supply during the operation could predispose it to infection. Your body fights off infection with its own white blood cells and the antibiotics we give you before surgery. As these are delivered by your blood, it seems a common sense conclusion that this interruption of blood supply could be a problem.

Passionate arguments are made and defended among surgeons and patients alike along these lines. It can leave one to conclude that tourniquet use should be avoided.

Tourniquets can certainly cause both pain and injury, but this depends on several variables. When I trained in knee replacement 20 years ago, most of us used very high, or tight, tourniquet levels. Few were concerned with just how much we were squeezing the leg. Now, it’s universally recognized that high pressures are not advisable, so the pressures we use today are much lower than they used to be. Use of lower pressures has made the issue of pain or injury drastically reduced. 

The other factor to consider is the length of time the tourniquet is tightened around your leg. In a first-time knee replacement surgery, tourniquet times under one hour are achievable. This time of tourniquet use is a very important variable. 

You may have an idea as to what the internet, your friends, or social media say about tourniquet use.  The most important thing is, what does the science say… meaning, what has our research shown us.

Like many areas of debate in knee replacement, there are available studies showing that tourniquets are very safe to use and others saying the surgery would be better done without them.

So, where does that leave you now? 

Maybe confused because now you know the different opinions on the topic. Maybe wondering now about what criteria to use to choose your surgeon. This scientific inconsistency about this topic is not unusual in our world. In the end, it comes down to what works best in your surgeon’s hands. If they use a tourniquet, ask if they use low pressures during surgery. If they don’t use one, ask how they handle the different variables that could arise during surgery. Ask what the risks are and what complications he or she has encountered or learned about with the use of tourniquets, and without.