Treatment
Total Knee Replacement
A total knee replacement, also known as a total knee arthroplasty, is a surgical procedure that involves opening of the knee joint through a front-facing incision. During the surgery, the damaged joint surfaces are carefully removed, and metal and plastic components are used to resurface the joint. These components are usually securely cemented into position, addressing issues with all three bones of the knee: the femur, tibia, and patella. Advanced techniques, such as custom instruments, augmented reality, computer navigation, and robotics may be employed during the procedure. Patients are allowed to walk right after surgery, and it is performed as an outpatient procedure, which eliminates the need for a hospital stay.
Kinematic Alignment Knee Replacement
No two knees are exactly alike. Each person has a unique bone shape, joint line, and natural alignment. Kinematic alignment is a personalized approach to total knee replacement that uses these individual features to help determine how the knee implants should be positioned.
Traditional knee replacement commonly uses mechanical alignment, which places the implants according to standardized alignment targets. Kinematic alignment takes a different approach. The goal is to restore the position and angle of the knee joint as closely as possible to its natural alignment before arthritis changed the joint. By positioning the implants to match each patient’s individual anatomy, the surgeon can create a knee replacement that is balanced around the patient rather than placing every knee into the same alignment.
Dr. Mercuri has particular expertise in subvastus kinematic alignment and uses advanced technologies to help measure and reproduce each patient’s individual anatomy during surgery. Research has shown that kinematically aligned knee replacements can provide excellent function, pain relief, and patient satisfaction while maintaining durable implant survival over time. Some studies have also found improvements in early function and other patient-reported outcomes compared with traditional mechanical alignment.
For appropriate patients, kinematic alignment is one part of a personalized approach to knee replacement. The goal is not simply to make an X-ray look straight, but to place the implants in a position that respects the natural anatomy and function of each patient’s knee.
Medacta GMK SpheriKA: A Knee Designed for Kinematic Alignment
What is a total knee replacement implant?
Total knee replacement surgery replaces the bone and cartilage damaged by arthritis with metal and plastic implants. The surfaces of the thigh and shin bones are replaced with high-resistance metal components, called the femoral component and tibial baseplate. Between them, a plastic insert takes over the job of the cartilage, letting the thigh and shin bones glide smoothly on each other. All materials used in a total knee replacement are highly biocompatible.
Why total knee replacement?
With almost 50 years of history, total knee replacement surgery is a very common and safe procedure for the treatment of severe arthritis. Approximately 1,000,000 knee replacements are performed annually worldwide.
The main benefits of a successful total knee replacement are:
- Reduction of knee pain. Pain may be rapidly and dramatically reduced, or potentially eliminated.
- Recovery of mobility. You may dramatically improve the mobility of your knee.
- Improvement in quality of life. Your everyday activities may no longer be limited by pain and reduced mobility.
GMK SpheriKA: built for the way your knee naturally moves
A normal knee is a complex structure. When it bends, the outer (lateral) side rolls back, while the inner (medial) side stays stable. The GMK SpheriKA implant is the newest generation of Medacta’s medially stabilized knee, and the first implant designed specifically for the kinematic alignment technique. It provides stability on the inner side of the knee through a ball-in-socket design, while leaving the outer side free to move the way each patient’s knee naturally moves.
Stability matters for everyday activities such as going up and down stairs, standing up from a chair, getting into a car, and more demanding activities like shopping and gardening. The ball-in-socket design helps replicate the function and stability normally provided by the natural ligaments of the knee, most of which are removed during total knee replacement. Many patients prefer a stable knee design with a medial ball-in-socket compared to other conventional knee designs, as they feel more natural, more stable, and stronger during common daily activities.
Designed to fit more knees
Because kinematic alignment follows each patient’s own anatomy instead of forcing every knee into one standard position, the implant itself needs to accommodate more variation. The SpheriKA design is based on research using a database of more than 150,000 knee CT and MRI scans. Its funnel-shaped groove for the kneecap accepts a wider range of natural kneecap angles, and its shape is designed to better fit the bone cuts used in the kinematic alignment technique.
References
[1] C. Rivière et al. Alignment Options for Total Knee Arthroplasty: A Systematic Review. OTSR 2017-Nov; 103(7): 1047–56.
[2] Dossett, et al. A Randomised Controlled Trial of Kinematically and Mechanically Aligned Total Knee Replacements: Two-Year Clinical Results. BJJ 2014-Jul; 96-B(7): 907–13.
[3] P.A. Vendittoli. et al. Kinematic Alignment in Total Knee Arthroplasty Better Reproduces Normal Gait than Mechanical Alignment. KSSTA 2019-May; 27(5): 1410–17.
[4] P. Schütz et al. “Kinematic Evaluation of the GMK Sphere Implant During Gait Activities: A Dynamic Videofluoroscopy Study.” JOR 2019-Nov; 37(11): 2337–47.
[5] S. Banks et al. “Can a Total Knee Arthroplasty Be Both Rotationally Unconstrained and Anteroposteriorly Stabilised?: A Pulsed Fluoroscopic Investigation.” Bone Joint Res 2016-Mar; 5(3): 80–86.
[6] Pritchett, James W. “Patients Prefer A Bicruciate-Retaining or the Medial Pivot Total Knee Prosthesis.” JOA 2011-Feb; 26(2): 224–28.
Implant imagery and product information courtesy of Medacta International.