The Quadriceps Vector is Most Parallel to the Spherical Axis with Minimal Difference for Gender or Ethnicity

• Published in: The Journal of arthroplasty 2016-09, Vol.31 (9), p.2031-2037
• Main Authors: Mochizuki, Tomoharu, MD, Blaha, John David, MD, Tanifuji, Osamu, MD, Kai, Shin, PhD, Sato, Takashi, MD, Yamagiwa, Hiroshi, MD
• Format: Article
• Language: English
• Subjects: 3-dimensional quadriceps vector; Adolescent; Adult; Arthroplasty, Replacement, Knee - methods; Asian Continental Ancestry Group; Biomechanical Phenomena; ethnicity; European Continental Ancestry Group; Female; Humans; Japan; Knee Joint - surgery; Male; Models, Anatomic; Orthopedics; precision; Principal Component Analysis; Quadriceps Muscle - surgery; reproducibility; Tomography, X-Ray Computed; total knee arthroplasty; Young Adult
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1016/j.arth.2016.02.044

Abstract Background The extensor mechanism may be the key to kinematic alignment of total knee arthroplasty. The purpose of this study was to determine any differences in the direction of the quadriceps vector based on gender or ethnicity, and to determine which anatomically derived alignment axis is closest to the quadriceps vector. Methods CT scans and patient records for 14 Caucasians (9 men, 5 women) and 40 Japanese (19 men, 21 women) were evaluated. Three axes of alignment—anatomical, mechanical, and spherical—were identified, measured, and compared to the quadriceps vector in each case. Principal component analysis was used to determine the quadriceps vector by using three-dimensional models of muscles on CT scan. Results No statistically significant differences in the orientation of the quadriceps vector were found based on gender or ethnicity, and the quadriceps vector was most closely aligned with the spherical axis. Conclusion Because the quadriceps is the primary knee extensor, the spherical axis therefore may be a ubiquitous guide to alignment of the arthroplasty knee based on motion.