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Comparison of Quadriceps Angle Measurements Using Short‐Arm and Long‐Arm Goniometers: Correlation With MRI
Author(s) -
Draper Christine E.,
Chew Kelvin T.L.,
Wang Roberta,
Jennings Fabio,
Gold Garry E.,
Fredericson Michael
Publication year - 2011
Publication title -
pmandr
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.617
H-Index - 66
eISSN - 1934-1563
pISSN - 1934-1482
DOI - 10.1016/j.pmrj.2010.10.020
Subject(s) - goniometer , intraclass correlation , medicine , nuclear medicine , magnetic resonance imaging , orthodontics , radiology , physics , optics , clinical psychology , psychometrics
Objective To compare the reliability of quadriceps‐angle (Q‐angle) measurements performed using a short‐arm goniometer and a long‐arm goniometer and to assess the accuracy of goniometer‐based Q‐angle measurements compared with anatomic Q angles derived from magnetic resonance imaging (MRI). Design An intra‐ and interobserver reliability study. Setting University hospital. Participants Eighteen healthy subjects with no history of knee pain, trauma, or prior surgery were examined. Methods Two physicians, blinded to subject identity, measured Q angles on both knees of all subjects using 2 goniometers: (1) a short‐arm goniometer and (2) a long‐arm goniometer. Q angles were derived from axial MRIs of the subjects' hip and knees. Main Outcome Measurements The intra‐ and interobserver reliabilities of each goniometer were assessed using the intraclass correlation coefficient (ICC). The comparison between clinical and MRI‐based Q angles was assessed by using the ICC and a paired t ‐test. Results Intra‐ and interobserver reliabilities of the long‐arm goniometer (intraobserver ICC, 0.92; interobserver ICC, 0.88) were better than those of the short‐arm goniometer (intraobserver ICC, 0.78; interobserver ICC, 0.56). Although both goniometers measured Q angles that were moderately correlated to the MRI‐based measurements (ICC, 0.40), the clinical Q angles were underestimated compared with the MRI‐based anatomic Q angles ( P < .05). Conclusion The results of this study suggest that, although reproducible Q‐angle measurements can be performed using standardized patient positioning and a long‐arm goniometer, methods to improve the accuracy of clinical Q‐angle measurements are needed.