T Iranpour-Boroujeni1, J Li2, J A Lynch2, M Nevitt2, J Duryea3. 1. Brigham and Women's Hospital, Boston, MA, USA. 2. University of California San Francisco, San Francisco, CA, USA. 3. Brigham and Women's Hospital, Boston, MA, USA. Electronic address: jduryea@bwh.harvard.edu.
Abstract
OBJECTIVE: To develop and validate a new and improved software method to rapidly determine femur-tibia angle (FTA). METHODS: Three readers, two skilled and one unskilled, without any formal medical training, measured FTA in 142 subjects from the Osteoarthritis Initiative (OAI). The reader reliability was assessed using the intra-class correlation coefficient (ICC), root mean square standard deviation (RMSSD), and Bland-Altman plots, comparing the existing and new FTA methods. Gender-specific linear regression assessed the relationship of FTA with the hip-knee-ankle angle (HKA). RESULTS: The ICC (RMSSD) for intra- and inter-reader reproducibility of the existing FTA method was 0.96 (0.77°) and 0.92 (1.38°), respectively, and for the new technique was 0.98 (0.25°) and 0.98 (0.37°), with similar results for all three readers. Bland-Altman 95% limits of agreement were greater than ±2° for the existing, and ±1° for the new method. The r-value for the relation of FTA to HKA was 0.68 and 0.72 for the existing and new methods, respectively. Varus (HKA ≤ -2°)/neutral (-2° < HKA < 2°)/valgus (HKA ≥ 2°) alignment based on predicted HKA agreed moderately with measured HKA (weighted kappa = 0.53), and had moderate sensitivity (73%) and specificity (84%) for varus malalignment. The new FTA was related to HKA using a linear equation with a slope of 0.98 and an offset of 4.0°. CONCLUSIONS: Since it is largely automated and uses unambiguous anatomical landmarks, the new method is highly reproducible and can be made on a standard posteroanterior (PA) knee radiograph by a relatively unskilled reader.
OBJECTIVE: To develop and validate a new and improved software method to rapidly determine femur-tibia angle (FTA). METHODS: Three readers, two skilled and one unskilled, without any formal medical training, measured FTA in 142 subjects from the Osteoarthritis Initiative (OAI). The reader reliability was assessed using the intra-class correlation coefficient (ICC), root mean square standard deviation (RMSSD), and Bland-Altman plots, comparing the existing and new FTA methods. Gender-specific linear regression assessed the relationship of FTA with the hip-knee-ankle angle (HKA). RESULTS: The ICC (RMSSD) for intra- and inter-reader reproducibility of the existing FTA method was 0.96 (0.77°) and 0.92 (1.38°), respectively, and for the new technique was 0.98 (0.25°) and 0.98 (0.37°), with similar results for all three readers. Bland-Altman 95% limits of agreement were greater than ±2° for the existing, and ±1° for the new method. The r-value for the relation of FTA to HKA was 0.68 and 0.72 for the existing and new methods, respectively. Varus (HKA ≤ -2°)/neutral (-2° < HKA < 2°)/valgus (HKA ≥ 2°) alignment based on predicted HKA agreed moderately with measured HKA (weighted kappa = 0.53), and had moderate sensitivity (73%) and specificity (84%) for varus malalignment. The new FTA was related to HKA using a linear equation with a slope of 0.98 and an offset of 4.0°. CONCLUSIONS: Since it is largely automated and uses unambiguous anatomical landmarks, the new method is highly reproducible and can be made on a standard posteroanterior (PA) knee radiograph by a relatively unskilled reader.
Authors: Leena Sharma; Alison H Chang; Rebecca D Jackson; Michael Nevitt; Kirsten C Moisio; Marc Hochberg; Charles Eaton; C Kent Kwoh; Orit Almagor; Jane Cauley; Joan S Chmiel Journal: Arthritis Rheumatol Date: 2017-11 Impact factor: 10.995
Authors: Jeffrey B Driban; Timothy E McAlindon; Mamta Amin; Lori L Price; Charles B Eaton; Julie E Davis; Bing Lu; Grace H Lo; Jeffrey Duryea; Mary F Barbe Journal: J Orthop Res Date: 2017-08-21 Impact factor: 3.494
Authors: Lori Lyn Price; Matthew S Harkey; Robert J Ward; James W MacKay; Ming Zhang; Jincheng Pang; Julie E Davis; Timothy E McAlindon; Grace H Lo; Mamta Amin; Charles B Eaton; Bing Lu; Jeffrey Duryea; Mary F Barbe; Jeffrey B Driban Journal: J Orthop Res Date: 2019-07-29 Impact factor: 3.494
Authors: Gabby B Joseph; Charles E McCulloch; Michael C Nevitt; Jan Neumann; Alexandra S Gersing; Martin Kretzschmar; Benedikt J Schwaiger; John A Lynch; Ursula Heilmeier; Nancy E Lane; Thomas M Link Journal: J Magn Reson Imaging Date: 2017-11-16 Impact factor: 4.813
Authors: Grace H Lo; Mehveen G Merchant; Jeffrey B Driban; Jeffrey Duryea; Lori Lyn Price; Charles B Eaton; Timothy E McAlindon Journal: Arthritis Rheumatol Date: 2018-01-09 Impact factor: 10.995
Authors: Jeffrey B Driban; Julie E Davis; Bing Lu; Lori Lyn Price; Robert J Ward; James W MacKay; Charles B Eaton; Grace H Lo; Mary F Barbe; Ming Zhang; Jincheng Pang; Alina C Stout; Matthew S Harkey; Timothy E McAlindon Journal: Arthritis Rheumatol Date: 2019-05-21 Impact factor: 10.995