Ryan Koonce, MD

CUSTOM KNEE TECHOLOGIES

June 14, 2023

A common question patients ask is “Do you use custom knee implants?”  Technology is an important part of the advancement of outcomes in knee replacement.  This technology is welcomed and adopted by surgeons when it proven via studies to do one or more of the following:  decrease complications, increase patient satisfaction, enhance short or long-term success rates, aid in recovery, or decrease the overall cost of the procedure. 

Since we are all unique in our anatomy and genetic makeup, it seems logical that having options that customize a procedure to the individual patient might lead to a better outcome.  While I believe this is the direction we are heading in the future, the studies to date have not shown a significant advantage of having customized options.  Currently, there are two customized knee technologies on the market:

Patient-Specific Instrumentation (PSI):  When the tibia and femur are cut and prepared to accept metal components, we use special jigs to make the correct angle and depth of cut.  PSI utilizes a CT scan or MRI to make a 3-D model of the knee joint and customized jigs are manufactured to make those same cuts.  This makes sense and sounds intriguing.  Unfortunately, the studies have not shown an advantage of this technology to produce superior outcomes consistently over a well-trained surgeon, so I don’t recommend the cost and hassle of the extra imaging studies.  In fact, the American Academy of Orthopedic Surgeons recommends against this technology in their OrthoGuidelines published in 2022 on this subject.  Their statement, after a committee review of the available research, is:  The practitioner should not use patient-specific technology (e.g., guides, cutting blocks) because there is no significant difference in patient outcomes, function, or pain as compared to conventional total knee arthroplasty (TKA). Additionally, it does not reduce operating time, blood loss, length of stay, and/or complications.

From:  https://www.orthoguidelines.org/topic?id=1041&tab=all_guidelines

Custom Knee Implants:  At least one company is successfully marketing knee implants that are manufactured for a specific patient based on a preoperative CT scan.  The idea is attractive to patients because they get a truly custom knee.  Studies have not shown that these custom implants are better, and in my opinion, these are more of a marketing tool than a helpful technology.   The reality is that good knee replacement systems have off-the-shelf size options to reliably fit just about any knee. I choose from thousands of size combinations when I do a knee replacement.  There are also scenarios where the custom knee might appear to fit before surgery based on bone images, but a size change is needed in the operating room due to soft tissue tension, which is a critical part of the surgery.  In this scenario, the custom knee implants end up being discarded.  I don’t like the idea of being confined to a single size for this reason, and most of the surgeons I know do not use custom knee implants.