By Richard P. Driessnack, MD
Custom total knee replacement is a relatively new technology that I adopted in 2015. Why this new concept? It has been known that while total knee replacement has been a very successful procedure for millions of patients with disabling knee arthritis, there remain some who, despite having a technically well-done surgery, continue to have symptoms of pain after their surgery. The reasons for this outcome are not totally clear. Some studies have shown that as many as 15 to 25 percent of patients can fall into this category.
Theories of why this group of patients has problems vary, but one theory was that the mechanical fit of the implant was not a good match for the individual knee. This led to the development of a custom knee by Conformis, a company based in Boston, MA. The concept is that by matching the size and shape of the implant exactly to the size and shape of the individual patient’s knee bones, the comfort would be improved and the mechanical performance of the knee optimized. This is how it works: A CT scan is done from the hip to the ankle, and a detailed 3D model of the knee is built on the computer. Engineers then design the femoral and tibial implants to give the best fit and shape.
This design is then sent to the manufacturing plant, where the individual implant is built. Along with the implant, custom cutting blocks are printed for each patient’s surgery on a 3D printer, allowing the surgeon to use these blocks in performing the operation without using drill holes in the bones, and achieving minimal bone resection and maximum bone conservation. Thus, each patient receives the best-fitting implant in their knee, and, theoretically, the best fit will lead to lower dissatisfaction ratings. This has, in fact, been found to be the case in larger studies with the custom knee.
Along with the custom knee implants, it is critical to remember that each patient’s knee is also different in terms of looseness, tightness, alignment, muscle balance, and strength. All principles of knee replacement still need to be followed by the surgeon performing the operation, and, in particular, the ligaments need to be balanced as much as possible. This is the job of the surgeon. I have found that one of the great benefits of the custom ConforMIS knee is that the rotational alignment of the femoral and tibial components seem to be perfect more often than the off-the-shelf implants, and this should also lead to better clinical results.
I have performed about 250 ConforMIS knee replacements since 2015. I have been very satisfied with the results. My patients have had less time in the hospital, faster recoveries, and very satisfying clinical results. If you are interested in discussing whether this knee might work for you, please call my office for an appointment.
For more information, contact OSF Orthopedics at 309-676-5546 or on the web at www.PeoriaJointReplacement.com. They have two locations: OSF Orthopedics — Downtown Peoria, 303 North William Kumpf Boulevard, Peoria; and OSF Orthopedics — North Peoria, 7800 N. Sommer St., Peoria.