The clinical epicondylar axis is not the functional flexion axis of the human knee

• Published in: Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association 2014-05, Vol.19 (3), p.451-456
• Main Authors: Mochizuki, Tomoharu, Sato, Takashi, Watanabe, Satoshi, Koga, Yoshio, Blaha, John David, Tanifuji, Osamu, Yamagiwa, Hiroshi, Endo, Naoto, Kobayashi, Koichi, Omori, Go
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; Biomechanical Phenomena; Female; Humans; Imaging, Three-Dimensional; Knee Joint - diagnostic imaging; Knee Joint - physiology; Male; Medicine; Medicine & Public Health; Middle Aged; Original Article; Orthopedics; Range of Motion, Articular - physiology; Reference Values; Rheumatology; Tomography, X-Ray Computed
• ISSN: 0949-2658; 1436-2023
• DOI: 10.1007/s00776-014-0536-0

The functional flexion axis (FFA) is the principal axis around which the knee moves and thus, by definition, does not move in vertical displacement relative to the tibia. The transepicondylar axis (TEA) has been reported to coincide with the FFA. If that is not true, the TEA should show vertical displacement during motion, and this hypothesis was investigated. Three-dimensional knee kinematics of 20 healthy volunteers were determined during a squatting motion via a 3-dimensional to 2-dimensional image registration technique by calculating the vertical displacement of the clinical epicondylar axis (CEA) through the full range of motion. From 0° to 90° knee flexion, the average vertical displacement of the lateral end of the CEA was