A New Method in Knee Arthrosis: Customized Knee Prosthesis

//A New Method in Knee Arthrosis: Customized Knee Prosthesis


The wear in the knee cartilage, “osteoarthritis” in medical terms, and “arthrosis” as it is more commonly known, is a serious problem that limits the daily activities of many people and results in pain. In most cases it cannot be linked to a specific cause, and the wear develops by itself. It often begins during the middle ages, and with advancing age it causes further deformation in the knee joint. Less commonly, the condition may arise at an earlier age due to an underlying disease (for example rheumatoid arthritis, previous fracture in the knee).

Initial measures to manage osteoarthritis include weight loss to decrease the loads impacted on the knee, painkillers, exercises that strengthen the muscles, physical therapy, drug injections into the knee, bone operations to correct the disrupted weight bearing axis of knee, and cleaning of the joint space by closed operations. When the cartilage wear further progresses, these methods often become ineffective, and the method that can be applied next is a knee prosthesis.

A knee prosthesis may be partial (half) or total. If only a part of the knee cartilage is destroyed and other parts and the ligamentous structures in the knee are intact, a partial prosthesis can be applied successfully. This enables surgery through a smaller cut, as well as painless and rapid movement of the patient that allows ambulation with weight bearing.

When cartilage injury is widespread throughout the knee, a complete (total) knee prosthesis is necessary. In this operation, the cartilage surfaces are cut and removed in a geometric shape, the normal axis of the knee is established, and then the surfaces are covered with appropriate metals, with a plastic piece in between the two metals. Thereby a knee joint that is painless, having a correct axis, and comfortable to walk on, is established. The results of total knee replacement today are very good.

A customized knee prosthesis is a new method that relies on using MR scans taken before the operation, and using them on a computer software to make a plan in both partial and complete knee prostheses. A three dimensional animation of knee-arthrosis-1the patient’s knee is constructed from the MRI images, the disrupted load axis is determined, geometric cuts are calculated millimetrically, the prosthesis sized most appropriately to the patient is determined, and the condition after insertion is checked on the computer by the surgeon who will perform the operation. Once the surgeon approves the final condition, all measurements are sent to the center of the prosthesis company abroad, and two plastic guiding pieces are manufactured specific only to that patient, then they are sterilized and delivered. These two plastic pieces are parts that are produced by using the patient’s knee as a template, so that the cuts will be performed millimetrically and will be applied in a manner that will not allow angular errors. The surgeon uses these plastic parts as a guide during surgery, makes the cuts in the knee according to the dimension of the prosthesis that is most appropriate for the patient as determined before the operation, and finally inserts the prosthesis. The advantages of the method are;

  • The three dimensional structure of the knee is known beforehand, so that all planning is made before the operation and encountering surprises before the operation is prevented.
  • The most appropriate sized prosthesis is inserted with the most appropriate angle and measurement values, and with no error.
  • Shortening of the operative time.
  • Opening of the bone canal, which is performed in the standart approach, is not made in this procedure, therefore risks of clot formation and pulmonary embolus are decreased.
  • The number of the instruments that will be used during the operation is significantly reduced, therefore the infection risk is decreased.The disadvantage of the method is, once a decision for the operation is made there is a need to wait for 3 weeks for taking the MRI and manufacturing the guide pieces customized for the patient.What needs to be known about this method;This is not production of a patient customized prosthesis. The most appropriate prosthesis is determined beforehand, and some measurements that should normally be made during the operation and some of which are only estimates, are made on the computer so that two plastic pieces specific for the patient are produced. These pieces are used as guides by the surgeon during the operation.This operation is not an operation under computer guidance. A computer helps to make a detailed plan before the operation, and guide pieces are produced according to the program.This operation is not robotic surgery. The planning before the operation is made on the computer by the surgeon, and the operation is carried out using classical methods, without support from the computer or the robot.
2017-04-14T19:05:37+00:00 News|