Understanding arthritis
Cartilage is the cushion, which covers the knee joint surfaces like the rubber on your car tyre. Movement in the absence of cartilage leads to a grinding of bone on bone and production of debris, which causes swelling, pain and destruction. This is what happens in knee arthritis.
“This grinding process in the knee joint continues in spite of medications, which only reduce swelling and pain but do not restore the lost cartilage.” This process can be slowed down by weight reduction, activity modification, muscle strengthening exercises with judicious use of anti-inflammatory medication. The time to consider surgical intervention comes when the patient is functionally incapacitated or in danger due to severe bone destruction.
About Conventional Total Knee Replacement
Total knee replacement surgery is one of the most cost effective ways of treating severe knee arthritis. This surgery simply involves removing the damaged bone surfaces and replacing them with metal and plastic.
Total knee replacement is a good established operation for end stage knee arthritis.
Knee Replacement surgery has advanced significantly with the use of high bending implants, gender specific implants (special implants for women) and computer assisted surgery, but, the operation continues to be done through a midline muscle and tendon cutting approach as shown in the diagram below on the right. The red line depicts the conventional approach to expose the knee joint.
Less attention has been given to preserving soft tissues during this operation. The bone work is done satisfactorily but the soft tissue damage that occurs during the operation is often not given due importance. The conventional technique damages the quadriceps muscle and other normal tissues. It causes more bleeding and post operative pain. The damage to the muscle is slow to recover and in a lot of cases the muscle may never come back to full potential. This leads to slower rehab in spite of very intensive physiotherapy. Knee bending is slower and often incomplete.
We have to appreciate the fact that the purpose of knee replacement is to replace the damaged articular surface. This has to be done with minimum damage to other normal tissues for best results. TISSUE PRESERVING TOTAL KNEE REPLACEMENT (TPTKR) is a step in this direction.
Tissue Preserving Total Knee Replacement (TPTKR)
TPTKR is an attempt to make a good surgery better. It goes beyond the general scope of conventional knee replacement surgery. The quadriceps muscle is one of the most important muscles around the knee. One cannot stand without a functioning and strong quadriceps. The stronger this muscle the better is the functioning and survival of the knee replacement. A successful knee replacement cannot be done in patients who have a very weak quadriceps muscle. This muscle is weaker in old patients and also affected by the arthritis. It therefore does not make good sense to damage this quadriceps muscle any more than it already is. This is even more important in older patients whose tissue reserve is already low. About 60-70% of patients who present with severe end stage arthritis for total knee replacement surgery are older than 60 years. These patients have a lower functional reserve than younger patients, their muscles are weaker and they often have other co-morbid conditions. TPTKR addresses this by causing less soft tissue damage.
Tissue preserving total knee replacement surgery is appreciating the fact that the purpose of the operation is to purely replace the unhealthy surfaces with new materials, and at the same time correcting deformity and achieving stability. The technique allows you to achieve this objective with minimum collateral damage. This method combines three important steps
a) Muscle preserving exposure
b) Computer navigation techniques
c) Appropriate implant choice
Let us understand each step:
a) THE MUSCLE SPARING EXPOSURE
The muscle sparing technique does not cut the QUADRICEPS muscle and damage it. It allows entry into the joint along the side of the muscle by simply flipping it to the side and not cutting through it. It gives satisfactory exposure with standard instruments. It is minimally invasive in the true sense and allows easy access even in obese patients. The joint exposure is ample and allows satisfactory bone preparation and cuts with implantation for a durable result. Specialised dissection and joint positioning pushes it beyond the standard subvastus exposure.
THE QUADRICEPS MUSCLE AND TENDON
b) Navigation technology increases the accuracy of bone cuts and alignment. There is less need for ligament releases and minimal bone resection is carried out. The exposure of the joint is ample enough to insert the computer arrays in the bone through the incision itself without further damage
c) Great importance is given to the use of established implants most appropriate for the patient’s condition and anatomy. For example, in case of female patients we can combine the muscle sparing technique with gender specific knee replacement design which is less metal in the knee for the same size and less constraining on the tissues.
This method achieves the following –
• Good surgical exposure
• Less soft tissue damage
• No blood transfusion
• Less bone damage
• Good surgical implantation
Advantages of tissue preserving surgery
• Less post surgery pain
• Less bleeding (we rarely transfuse blood including patients who undergo both knee replacements in one sitting)
• Faster return of knee function – muscle strength and control comes back more quickly – allows faster rehabilitation. Patients can walk on day of surgery in most cases
• Shorter hospital stay
• Less soft tissue damage and a better result
• Early return of knee motion
• Recovery time is less than one third of that with conventional technique.
In the tissue preserving technique the skin incision size depends on the size of the patient. Incision size has little bearing on the postoperative result. A good knee replacement happens when we remember that not only do we have to execute the bone work properly but at the same time preserve the tissues that are going to stabilize and move these bones.

















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