Kinematic Alignment Is All That Matters! Stephen M. Howell, MD - - PowerPoint PPT Presentation

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

Howell, Insall Scott 2017 Resections to Equal Thickness of Femoral Component after Compensating for Wear and Kerf

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

RESTORE ANTERIOR TIBIAL OFFSET FROM FEMUR

2 Caliper Measurements Set F-E (Slope) of Tibial Component Coincident to Native Tibial Joint Line

CALIPERED KINEMATIC ALIGNMENT MORE ACCURATELY ALIGNS TO NATIVE THAN ROBOTIC OR NAVIGATED MECHANICAL ALIGNMENT ALIGNS TO 00 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

Nedopil, Int Orthop, 2017

• At 2-9 year f/u, 0.3% (8 of

2725) had tibial component failure

• No varus loosening
• Posterior subsidence or

posterior insert wear caused by 50 greater posterior tibial slope than native

Posterior Subsidence

• f Tibial Component

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

Tibial Compartment Force (lbs)

20 40 60 80 100 Medial Force Lateral Force Medial - Lateral Force 11 7 18 8 6 14

Native Knee (Verstraete) Calipered KA TKA

J Biomech 2017

NS, p =0.2422 NS, p =0.6518 NS, p =0.4066 Shelton, BJJ, 2017

Kinematic Alignment Restores Lower Tibial Compartment Forces Than Mechanical Alignment

Tibial Compartment Force (lbs)

20 40 60 80 100 Medial Force Lateral Force Medial - Lateral Force 18 40 58 29 45 74 11 7 18

Calipered KA TKA MA Measured Resection (Nav) MA Gap Balancing

MA TKA 4 & 3x Higher MA TKA 6 & 5x Higher MA TKA 3 & 2x Higher

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 0o 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