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J Knee Surg 2023; 36(03): 254-260
DOI: 10.1055/s-0041-1731720
Original Article

The Effect of Aberrant Rotation on Radiographic Patellar Height Measurement Using Canton-Deschamps Index: A Cadaveric Analysis

Hailey P. Huddleston
1   Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, Illinois
,
Michael L. Redondo
1   Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, Illinois
,
William M. Cregar
1   Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, Illinois
,
David R. Christian
1   Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, Illinois
,
Charles P. Hannon
1   Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, Illinois
,
Adam B. Yanke
1   Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, Illinois
› Author Affiliations
Funding This study received its financial support from CONMED Linvatec personal fees, JRF Ortho personal fees, Olympus personal fees, Organogenesis grant, Patient IQ stock/stock options, Smith & Nephew nonfinancial support, Sparta Biomedical nonfinancial support, grants from Vericel, grants from Arthrex, Inc. and Aastrom Biosciences Inc. outside the submitted work. Medical Device Business Services Inc. $2100–(2019).
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Abstract

The Caton-Deschamps Index (CDI) is a measurement used to evaluate patella alta based on true lateral radiographs; however, no prior study has investigated how altering the degree of radiograph aberrancy affects CDI measurement. The primary and secondary purpose of this study was to evaluate effects of rotational radiographic changes on patella height measurements and compare these findings to MRI measurements, respectively. Five cadaver knees (n = 5) were utilized in this study. True lateral radiographs were obtained for each specimen by using a fluoroscopic C-arm machine. The C-arm was then altered in two planes (axial and coronal) in both the clockwise and counterclockwise direction and radiographs were taken at 5, 10, and 15 degrees of error from the true lateral position. A CDI measurement of each specimen was performed based on sagittal magnetic resonance imaging (MRI) slices and compared with radiographic CDI measurements. Three orthopedic surgeons measured the CDI for each radiograph and MRI performed. Interrater reliability and changes in CDI were analyzed. Clinically significant difference in CDI was set to 0.1. Mean intraclass correlation coefficient was high (≥0.7) at true lateral and at all varying degrees of error. When performing a pairwise comparison of mean CDI from the true lateral position to increasing degrees of error, statistically significant differences were observed in the axial plane. The largest change in CDI measurements was seen with rotational malposition in the axial plane and counterclockwise direction. No statistically significant differences in mean CDI were observed in the coronal plane. The change in CDI from the true lateral position reached an absolute maximum of at least 0.1 in all four scenarios at each tested degree of error. This study found that aberrant radiographic rotation in the axial plane resulted in a significantly different mean CDI measurement when compared with true lateral radiographs. All degrees of error in both directions and in both planes could have a clinically significant effect on CDI (≥0.1). Our findings confirm the importance of a perfect true lateral radiograph when measuring patella height.

Keywords

Caton-Deschamps Index - perfect lateral radiograph - knee


Publication History

Received: 12 October 2020

Accepted: 31 May 2021

Article published online:
14 July 2021

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