Radiological and clinical comparison of kinematically versus mechanically aligned total knee arthroplasty

• Published in: The bone & joint journal Vol. 99-B; no. 5; p. 640
• Main Authors: Matsumoto, T, Takayama, K, Ishida, K, Hayashi, S, Hashimoto, S, Kuroda, R
• Format: Journal Article
• Language: English
• Published: England 01-05-2017
• Subjects: Aged; Aged, 80 and over; Arthroplasty, Replacement, Knee - methods; Arthroplasty, Replacement, Knee - rehabilitation; Biomechanical Phenomena; Bone Malalignment - prevention & control; Female; Humans; Knee Joint - diagnostic imaging; Knee Joint - physiopathology; Knee Joint - surgery; Knee Prosthesis; Male; Middle Aged; Orientation; Osteoarthritis, Knee - surgery; Prospective Studies; Radiography; Range of Motion, Articular - physiology; Recovery of Function; Treatment Outcome; Weight-Bearing - physiology; Mechanical alignment; Mechanical axis; Kinematic alignment; Total knee arthroplasty
• ISSN: 2049-4408
• DOI: 10.1302/0301-620X.99B5.BJJ-2016-0688.R2

The aim of this study was to compare the post-operative radiographic and clinical outcomes between kinematically and mechanically aligned total knee arthroplasties (TKAs).
A total of 60 TKAs (30 kinematically and 30 mechanically aligned) were performed in 60 patients with varus osteoarthritis of the knee using a navigation system. The angles of orientation of the joint line in relation to the floor, the conventional and true mechanical axis (tMA) (the line from the centre of the hip to the lowest point of the calcaneus) were compared, one year post-operatively, on single-leg and double-leg standing long leg radiographs between the groups. The range of movement and 2011 Knee Society Scores were also compared between the groups at that time.
The angles of orientation of the joint line in the kinematic group changed from slight varus on double-leg standing to slight valgus with single-leg standing. The mechanical axes in the kinematic group passed through a neutral position of the knee in the true condition when the calcaneus was considered. The post-operative angles of flexion and functional activity scores were significantly better in the kinematic than in the mechanical group (p < 0.003 and 0.03, respectively).
A kinematically aligned TKA results in a joint line which has a more parallel orientation in relation to the floor during single- and double-leg standing, and more neutral weight-bearing in tMA than a mechanically aligned TKA. Cite this article:
2017;99-B:640-6.