Mechanical vs Kinematic TKA Alignment. Which Wins?

What is the difference between different total knee arthroplasty (TKA) alignment approaches, and which is more likely to delivery better clinical outcomes? A team from the Hospital for Special Surgery (HSS) collected and analyzed data from 100 consecutive TKA patients.

Each individual had received a TKA using a mechanical alignment technique and was then 1:1 matched to 100 patients who’d received their TKA using a kinematic alignment technique (same implant and robotic technology).

The study, “Head-to-Head Comparison of Kinematic Alignment Versus Mechanical Alignment for Total Knee Arthroplasty,” was published in the January 26, 2022 edition of The Journal of Arthroplasty.

“Knee alignment is the hottest topic in knee replacement surgery in 2022,” said co-author Jonathan Vigdorchik, M.D., an adult reconstruction and joint replacement surgeon at HSS in New York. “Historically, surgeons have always targeted mechanical alignment, because in the 1990s when they tried anatomic techniques, they did not have instruments or implants to make those techniques successful. However, now in 2022, we have technologies available to better achieve targets in knee replacement and with those technologies, we can make minor adjustments that will make large impacts in outcomes.”

Knee Injury and Osteoarthritis Outcome Score Joint Replacement was significantly better in the kinematic alignment group at 6 weeks, 1 year, and 2 years. The Forgotten Joint Score at 1 and 2 years after surgery was significantly higher in the kinematic alignment group.

The researchers determined that whereas the mean Visual Analog Scale scores were higher in the mechanical alignment group during the first 6 weeks, the two groups were statistically similar at 1 year.

As for the 6-week Veterans RAND 12 Item Health Survey mental and physical components, the groups were statistically similar; patients did not differ in 6-week or 1-year knee range of motion scores.

Dr. Vigdorchik explained the results to OTW saying: “Kinematic alignment techniques, with small adjustments from historical mechanical alignment techniques, have been proven to increase patient satisfaction while showing excellent survivorship. As techniques and technologies develop, surgeons will start to employ kinematic alignment techniques to improve patient outcomes. We can now begin to think of a knee replacement as a true resurfacing procedure, anatomically in a patient-specific fashion, and hopefully improve outcomes for our patients.”