Kinematic Alignment Is All That Matters! Stephen M. Howell, MD Professor of Biomedical Engineering University of California at Davis Lodi Memorial Hospital, Sacramento, CA
DISCLOSURES ▪ Consultant Medacta ▪ Consultant and research support from Zimmer-Biomet ▪ Consultant Think Surgical ▪ On Editorial Board of American Journal of Sports Medicine, Orthopedics
WHAT IS KINEMATIC ALIGNMENT (KA)?
KA Restores the Coronal and Sagittal Alignment of the Native Knee and Limb
HOW IS KINEMATIC ALIGNMENT PERFORMED?
10 Caliper Measurements Set Components Coincident to Native Joint Lines of the Knee Howell, Insall Scott 2017
4 Caliper Measurements Set Femoral Component Coincident to Native Femoral Joint Line Resections to Equal Thickness of Femoral Component after Compensating for Wear and Kerf Howell, Insall Scott 2017
2 Caliper Measurements Set V-V of Tibial Component Coincident to Native Tibial Joint Line RESECT EQUAL THICKNESS AT BASE OF TIBIAL SPINES
2 Caliper Measurements Set Patella Component Coincident to Native Patella Joint Line RESTORE NATIVE PATELLA THICKNESS
2 Caliper Measurements Set F-E (Slope) of Tibial Component Coincident to Native Tibial Joint Line RESTORE ANTERIOR TIBIAL OFFSET FROM FEMUR
CALIPERED KINEMATIC ALIGNMENT MORE ACCURATELY ALIGNS TO NATIVE THAN ROBOTIC OR NAVIGATED MECHANICAL ALIGNMENT ALIGNS TO 0 0 HKA ANGLE
JOA, 2017
KINEMATIC ALIGNMENT RESTORES BETTER PATIENT SATISFACTION, FUNCTION, AND KNEE FLEXION THAN MECHANICAL ALIGNMENT
Three Meta-Analysis Conclude KA is Better than MA ▪ Functional outcome as measured by Knee Society Score favored KA over MA (Courtney, J Arthro, 2017) ▪ KA provided better function and flexion (Li, J Knee Surg, 2017) ▪ KA oriented the joint line more parallel to the floor similar to the native knee, with limb and knee alignment similar to MA (Lee, KSSTA, 2017)
KINEMATIC ALIGNMENT HAS NEGLIGIBLE AND LESS VARUS TIBIAL LOOSENING THAN MECHANICAL ALIGNMENT
Kinematic Alignment Has Negligible Varus Tibial Loosening at 9 Years Posterior Subsidence • At 2-9 year f/u, 0.3% (8 of of Tibial Component 2725) had tibial component failure • No varus loosening • Posterior subsidence or posterior insert wear caused by 5 0 greater posterior tibial slope than native Nedopil, Int Orthop, 2017
KINEMATIC ALIGNMENT RESTORES NATIVE TIBIAL COMPARTMENT FORCES THAT ARE MANY TIMES LOWER THAN MECHANICAL ALIGNMENT
Compartment Forces of KA TKA are Comparable to Native Knee 100 Native Knee (Verstraete) Tibial Compartment Force Calipered KA TKA 80 60 (lbs) 40 NS, p =0.2422 NS, p =0.6518 NS, p =0.4066 20 18 14 11 6 7 8 0 Medial Force Lateral Force Medial - Lateral Force J Biomech 2017 Shelton, BJJ, 2017
Kinematic Alignment Restores Lower Tibial Compartment Forces Than Mechanical Alignment Calipered KA TKA 100 MA Measured Resection (Nav) Tibial Compartment Force MA TKA MA Gap Balancing 4 & 3x Higher 80 60 MA TKA (lbs) 6 & 5x Higher MA TKA 40 74 3 & 2x Higher 58 45 20 40 29 18 18 11 7 0 Medial Force Lateral Force Medial - Lateral Force J Arthro 2016 Overview | Correction of Varus & Valgus Deformities | Tibial Compartment Forces| Summary
KINEMATIC ALIGNMENT REDUCES KNEE ADDUCTION MOMENT MORE THAN MECHANICAL ALIGNMENT
• KA is a promising option for patients with large coronal bowing of the tibia because the low knee adduction moment lowers the risk of varus tibial loosening Niki, KSSTA, 2017
WHAT CAN PATIENTS DO AFTER KINEMATIC ALIGNMENT?
Anything They Want!!!
SUMMARY F-E Plane of Knee | Kinematic Tibial Template | Virtual Feasibility I In Vivo Validation | Summary
KA IS All That Matters When Science and Not Dogma Decides! • 10 caliper measurements more accurately restore native alignment than robotics and nav restore a 0 o HKA angle • KA provides better clinical outcomes, less varus tibial loosening, lower compartment forces, and a lower knee adduction moment than MA • Make your patients happy-give KA a try!
THANK YOU
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