A new computer-assisted method for measuring the tibio-femoral angle in patients with osteoarthritis of the knee

• Published in: Osteoarthritis and cartilage Vol. 12; no. 3; pp. 256 - 259
• Main Authors: Takahashi, T., Yamanaka, N., Komatsu, M., Ogawa, Y., Yoshida, S., Yamamoto, H.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2004
• Subjects: Adult; Aged; Aged, 80 and over; Computed radiography; Female; Femur - diagnostic imaging; Humans; Image Processing, Computer-Assisted - methods; Joint Deformities, Acquired - diagnostic imaging; Joint Deformities, Acquired - etiology; Joint Deformities, Acquired - pathology; Knee Joint - diagnostic imaging; Knee Joint - pathology; Male; Middle Aged; Observer Variation; Osteoarthritis, Knee - complications; Osteoarthritis, Knee - diagnostic imaging; Osteoarthritis, Knee - pathology; Radiographic measurement; Radiography; Reproducibility of Results; Tibia - diagnostic imaging; Tibio-femoral angle; Tibio-femoral angle; Radiographic measurement; Computed radiography
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2003.10.005

Objective: The purpose of this study was to evaluate the inter- and intraobserver variability in measuring the tibio-femoral angle using our new computer-assisted method, and to compare it with a conventional manual method. Methods: Radiography of all patients of osteoarthritis of the knee in outpatient were performed with standing on both legs, and with conventional antero-posterior weight bearing view of the knee fully extended. Three examiners measured the tibio-femoral angle with the computerized method in 52 subjects with osteoarthritis (73 knees). The tibio-femoral angle was measured using a computer-assisted method in which the observer must visually determine and select eight points on the margins of the femur and tibia on a radiographic image displayed on a computer monitor. The inter- and intraobserver Intra-class correlation (ICC) was analyzed. Results: The interobserver mean correlation of computer-assisted method was 0.970 with a mean difference of 0.38° ( s.d. 1.125°). The intraobserver mean ICC of computer-assisted method was 0.973, with a mean difference of 0.16° ( s.d. 1.12°). An analysis of the difference between conventional methods and our new system showed a mean ICC of 0.922, with an intersystem mean difference of 0.295° ( s.d. 1.82°). Conclusion: Our computer-assisted method of measuring the tibio-femoral angle was simple, easy, and quick, and should be considered as an alternate method for measurement.