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Since 1968 when the first total knee replacement was performed in the US total joint arthroplasty has been proven to be one of the most cost effective procedures performed. One of the reasons is that during the procedure, the cause of the pain and disability that the patient is experiencing is eliminated and replaced with prosthetic metal and plastic. As long as the implants are placed correctly and they have average wear, the patient can resume normal day to day activities for many years (after appropriate rehab). One relatively new advancement in total knee arthroplasty is the use of custom made implants and instruments. Just like a fingerprint, every patient’s knee anatomy is different. The importance of a custom made implant that matches the patients specific anatomy is obvious.

The majority of implants on the market today are provided “off the shelf” (OTS).  This means that the surgeon uses cutting instruments to form the bone to fit the available sizes that are in the room.  With a custom implant the surgeon uses instruments that are 3D printed based on that patient’s CT scan. The implants are manufactured based on the same CT scan and shipped to the hospital before the surgery.  This insures a precise fit to the patient’s unique anatomy.  A few of the advantages of this technique are that it minimizes the risk of implant failure or complications and reduces  pain and discomfort post-surgery.  Through an improved range of motion, the patient can perform daily activities more easily, which will also help with physical therapy.  If the implants match the patient’s original anatomy, they might last longer and have a lower risk of revision surgeries.  All of these advantages lead to improved outcomes and quality of life, which in-turn leads to a higher likelihood of returning to previous activities and hobbies.

The process of making sure a custom total knee implant is right for you starts with a consultation with an orthopedic surgeon.  An important concept the surgeon will want to cover is the fact that the success of the procedure primarily rests on the patient’s willingness and motivation to complete their rehab.  Once the patient understands that this is actually more important than the implant, they can proceed to the next step.  The surgeon will order some initial images (x-rays) to confirm the patient is a candidate.  This is to rule out any abnormalities that would be outside the parameters of the CAD design.  After that, a CT scan is obtained and sent out to get a 3D model and personalized surgical plan.  The surgeon will want to show the patient the plan so that there are no questions before the implant is made.  If all still looks good, the custom implants and instruments are manufactured, sterilized and sent to the hospital. Surgery is then scheduled and rehab is put on the calendar too.  Is this the future of orthopedics? of medicine in general?  It would be nice to think ahead and see every patient getting a personalized implant, put there by a competent surgeon using custom, personalized, 3D printed  instruments.  There are a couple of big obstacles that we have not covered yet.  For one of them there is no easy answer, and they both will be covered in the next section.

To recap, there are several agreed upon advantages to having a custom-made total knee replacement.  The procedure is effective.  The implant fits the patient’s unique anatomy.  This reduces the risk of implant failure or complications.  We talked about how this can reduce pain and discomfort post surgery.  After the surgery, having a custom implant can lead to an improved range of motion over the OTS implants.  This can lead to more easily performed daily activities and more effective physical therapy and rehabilitation.  The custom implants are designed to last longer and therefore have a lower risk of revision surgeries.  Finally, these implants have lead to improved patient satisfaction scores.  A happy patient is more likely to complete their rehab and have an improved quality of life which leads to a higher likelihood of returning to previous activities.   Having said all of this, we can’t overstate the importance of consulting with a qualified orthopedic surgeon before you embark on this journey.  As we asked earlier, is this the future of surgery?  Some people think so.  After a review of the literature, we might be lead to think that too.  There are many reasons to consider this technology, but what about the issue of cost?  Personalized medicine is a hot topic right now and personalized, custom-made orthopedic implants fit into that category nicely.  The other obstacle is logistics.  These implants are manufactured and sent to the hospital just a few days before the surgery.  The advantage of this “just in time” delivery method is the lack of storage needed to keep them.  The down side? …If unplanned circumstances occur (weather, courier mishaps, etc.) it can cause a last minute delay in the surgery.  But can we make it work so that all stakeholders will embrace it?  Medicine seems to move forward slowly at times.  Maybe this is one of those times where the technology has to wait for the rest of the community to catch up and figures out how to do this.