Review
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Rheumatol. Jul 12, 2015; 5(2): 69-81
Published online Jul 12, 2015. doi: 10.5499/wjr.v5.i2.69
Radiographic assessment of leg alignment and grading of knee osteoarthritis: A critical review
Lisa Sheehy, T Derek V Cooke
Lisa Sheehy, Bruyère Research Institute, Ottawa, ON K1N 5C8, Canada
Lisa Sheehy, School of Rehabilitation Sciences, University of Ottawa, Roger-Guindon Hall, Ottawa, ON K1H 8M5, Canada
T Derek V Cooke, School of Rehabilitation Therapy, Queen’s University, Perth, ON K7H 3A5, Canada
Author contributions: Sheehy L designed and wrote the initial draft of the paper and revised it; Cooke TDV conceived the paper and revised it for critically important content. Both authors approve the final version.
Conflict-of-interest statement: Cooke TDV is the president and shareholder of Orthopedic Alignment and Imaging Systems (OAISYS) Inc.; Cooke TDV has received salary support from OAISYS Inc.; Sheehy L declares no conflicts of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Lisa Sheehy, PT, PhD, Bruyère Research Institute, 43 Bruyère St., Ottawa, ON K1N 5C8, Canada. lsheehy@bruyere.org
Telephone: +1-613-5626262-1593 Fax: +1-613-5624256
Received: November 18, 2014
Peer-review started: November 19, 2014
First decision: February 7, 2015
Revised: February 25, 2015
Accepted: May 5, 2015
Article in press: May 6, 2015
Published online: July 12, 2015
Abstract

Knee osteoarthritis (OA) is a progressive joint disease hallmarked by cartilage and bone breakdown and associated with changes to all of the tissues in the joint, ultimately causing pain, stiffness, deformity and disability in many people. Radiographs are commonly used for the clinical assessment of knee OA incidence and progression, and to assess for risk factors. One risk factor for the incidence and progression of knee OA is malalignment of the lower extremities (LE). The hip-knee-ankle (HKA) angle, assessed from a full-length LE radiograph, is ideally used to assess LE alignment. Careful attention to LE positioning is necessary to obtain the most accurate measurement of the HKA angle. Since full-length LE radiographs are not always available, the femoral shaft - tibial shaft (FS-TS) angle may be calculated from a knee radiograph instead. However, the FS-TS angle is more variable than the HKA angle and it should be used with caution. Knee radiographs are used to assess the severity of knee OA and its progression. There are three types of ordinal grading scales for knee OA: global, composite and individual feature scales. Each grade on a global scale describes one or more features of knee OA. The entire description must be met for a specific grade to be assigned. The Kellgren-Lawrence scale is the most commonly-used global scale. Composite scales grade several features of knee OA individually and sum the grades to create a total score. One example is the compartmental grading scale for knee OA. Composite scales can respond to change in a variety of presentations of knee OA. Individual feature scales assess one or more OA features individually and do not calculate a total score. They are most often used to monitor change in one OA feature, commonly joint space narrowing. The most commonly-used individual feature scale is the OA Research Society International atlas. Each type of scale has its advantages; however, composite scales may offer greater content validity. Responsiveness to change is unknown for most scales and deserves further evaluation.

Keywords: Osteoarthritis, Mechanical axis angle, Knee, Radiography, Alignment, Grading scales, Assessment, Hip-knee-ankle angle, Femoral shaft-tibial shaft angle, Anatomic axis angle

Core tip: Radiographs are commonly used for the clinical assessment of knee osteoarthritis (OA) and to assess for risk factors. One risk factor for knee OA is malalignment of the lower extremities (LE). LE alignment is ideally measured from a full-length LE radiograph. While knee radiographs are sometimes used, the resulting angle is much more variable and should be used with caution. Knee radiographs are also used to assess the severity of knee OA. Global, composite and individual feature grading scales may be used. Each type of scale has its advantages; however composite scales may offer greater content validity.