Andrew S. Murtha, MD addresses the controversy surrounding kinematic vs mechanical alignment in total knee arthroplasty.
Since the introduction of kinematically aligned knee arthroplasty in the mid-2000s, there has been controversy surrounding kinematic (KA) vs mechanical alignment (MA) in total knee arthroplasty (TKA). Kinematic alignment in total knee arthroplasty (TKA) attempts to restore natural limb alignment, maintaining the natural kinematic axis and ligament balance of the patient's knee. In contrast, the classic method of mechanical alignment aims to create a neutral hip-knee-ankle (HKA) axis. Advocates for KA say the technique intended to mimic a patient’s natural knee alignment will result in a more natural feeling and functioning knee. SmartTRAK had the opportunity to interview Andrew S. Murtha, MD regarding the growing interest in KA, what is driving this interest and what the future holds for KA vs MA with feedback from Benjamin Stronach, MD, associate professor at the University of Arkansas for Medical Sciences. Dr. Murtha is a board-certified orthopedic surgeon who is currently an adult reconstruction fellow at Houston Methodist Hospital. He is also a member of the American Association of Hip and Knee Surgeons’ (AAHKS) committee on Patient and Public Relations.
SmartTRAK: What has been your experience with kinematic alignment in total knee arthroplasty?
Andrews S. Murtha, MD: Kinematic alignment is a technical strategy in total knee arthroplasty that aims to individualize implant position by replacing only the cartilage and bone lost during the arthritis process. In its truest form, it does not place restrictions on the alignment of the components. I do not use an unrestricted kinematic alignment strategy in my practice, but the concept has expanded parameters for what is considered acceptable implant position.
In your estimation, based on your experience, what percentage of surgeons currently use KA vs mechanical alignment?
AM: In my experience, the majority of orthopedic surgeons use an adjusted mechanical alignment strategy. However, there does seem to be greater acceptance for slightly modifying the bone cuts to accommodate the patient’s native anatomy, thus reducing the need for large soft tissue releases to balance the knee. I would estimate that the percentage of surgeons using a truly unrestricted, caliper-based, resurfacing-type kinematic alignment strategy is relatively low.
What trends are you seeing in clinical practice – is KA increasing, decreasing or staying the same? What do you think is driving or limiting adoption?
AM: In general, interest in the kinematic alignment strategy has grown over the past 15 years. This interest seems to be driven by