Knee replacement: Can the robot save you?

If you opted to read this article you likely have a painful knee, perhaps due to arthritis. You may have had limited success with cortisone or hyaluronic acid injections or perhaps platelet rich plasma. You tried glucosamine for a few months. It may have helped a bit. Being active is a great way to fight father time and control stress, but will your knee let you continue with the same activities you have enjoyed for years? Whether it is skiing or just walking without pain, you are seeking a solution.

Once you have exhausted non-operative measures you may be thinking about surgery. The least invasive of the procedures is arthroscopic surgery. The surgeon introduces a camera about the size of a pen into your knee. The surgeon can look into the knee to remove torn or loose tissue. As an arthritic treatment, the success is limited.

Osteotomies are procedures where the bone is cut and realigned in order to unload the arthritic portion of the knee. This procedure is technically challenging for the surgeon, but can yield very good results. Recovery can be several months.

Total knee arthroplasty TKA (replacement) is the most invasive knee surgery but yields predictably good results. Individuals with arthritis in more than one of the three compartments of the knee benefit from this procedure. Surgery is about an hour. Hospital stay could be 1-2 days and patients can be doing very well by 4-6 weeks.

Robotic Assisted Partial Knee Replacement

Partial knee replacement, also known as unicompartmental knee arthroplasty (UKA) is indicated for individuals with arthritis localized to one of the three compartments of the knee, typically the medial or inside of the knee. UKA has presented surgeons with technical challenges that may have been solved with recent advances in computer and robotic-assisted surgery.

The advantages over total knee replacement are that with UKA you are only resurfacing the arthritic portion of the knee while leaving the remaining articular surface and ligaments intact. TKA requires removal of all articular surfaces and at least partial ligament sacrificing. Recovery is faster than with TKA and patients are left with a more natural feeling knee.

Traditional knee replacement utilizes cutting blocks that are placed on the knee and the surgeon has to determine a "best fit" based on feel. Adding the robot to the procedure gives the surgeon data to determine the proper fit and balance of the knee. With the recent advent of robotic assistance, surgeons can have more predictable outcomes for this once technically demanding procedure. The alignment and movement of the knee can be restored to their pre-arthritic state. As with total knee replacement, the implants do not last forever and may need to be replaced in the future.

When using the robotic system, the knee anatomy is loaded into a computer either by using a preoperative CT scan or with intraoperative knee mapping technology. With mapping, the surgeon traces over the bones with a metal probe and an image is generated on the computer screen. This allows the surgeon to properly size the knee and determine where the bone cuts need to be made.

Next, the knee is put through range of motion and prepositioned markers on the leg allow us to determine the proper knee alignment. The computer then creates a virtual cutting template. With the surgeon holding a high speed burr in hand, the computer directs the surgeon on where to cut based on a color coded image on the computer screen. The computer can shut off the cutting instrument if outside of the template.

Once the implants are in place, the surgeon can recheck the knee's alignment with the assistance of the computer. The knee anatomy should be restored to its pre-arthritic state. The procedure can be done as an outpatient and recovery is faster than for a total knee replacement. It is a more natural feeling knee and should lead to a higher level of function than for a total knee. With more precise alignment, it is believed that the implants will last longer; however long term data is not yet available.

Robotic-assisted knee resurfacing offers a viable alternative to total knee arthroplasty and conventional partial knee replacement.

Elliott Leitman, M.D. is an orthopaedic surgeon at First State Orthopaedics in Newark, DE, and serves as Team Physician for the Delaware 87ers and Lincoln University.

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