Radial head translation measurement in healthy individuals: the radiocapitellar ratio

Rouleau, Dominique M.; Sandman, Émilie; Canet, Fanny; Djahangiri, Ali; Laflamme, Y.; Athwal, George S.; Petit, Yvan

doi:10.1016/j.jse.2011.03.017

Cited by 16 publications

(7 citation statements)

References 21 publications

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“…For anterior and posterior radial subluxations, as little as 5°deviation in the inferior direction may lead to an RCR measurement beyond the acceptable threshold found in healthy subjects (4% ± 4%) [12]. A RCR of 10% corresponds, for example in a capitellum with a diameter of 25 mm, to 2.5 mm of anterior deviation.…”

Section: Discussionmentioning

confidence: 91%

“…It could be explained by the RCR itself which is a measure of the deviation of the axis passing through the center of the radial head compared with the center of the capitellum [12]; thus, this distance does not change on the radiograph when the C-arm turns on the same plane. Regardless, the difference between the mean RCRs is more important with anterior and posterior subluxations than with nonsubluxated elbows.…”

Section: Discussionmentioning

confidence: 99%

“…The evaluator was blinded for beam angulation and radial head translation. The minimal distance from the center of the capitellum to the center of the radial head was assessed following the method described by Rouleau et al [12]. As a reference value, the RCR (for the six arms in the three subluxation conditions) was measured in the 0°to 0°position (true lateral radiograph).…”

Section: Methodsmentioning

confidence: 99%

“…Radial head subluxations are commonly associated with Monteggia fractures [1,2] and most frequently with posterior subluxations compared with anterior subluxations [11]. To detect subluxations of the elbow, lateral radiographs are used and tools have been developed to gauge radial head subluxations: the radiocapitellar line (RCL) for the pediatric elbow [16] and the radiocapitellar ratio (RCR) for the adult elbow [12]. Both methods use lateral radiographs taken after trauma but the patient's position and the elbow's position are not always optimal.…”

Section: Introductionmentioning

confidence: 99%

“…In 2011, Rouleau et al [12] proposed a method to assess elbow stability. More specifically, they measured the radiocapitellum joint translation and the RCR and determined that, in the healthy (nonsubluxated) elbow, the radial head is aligned with the capitellum on the true lateral radiograph and that the RCR ranges from 13% anteriorly to À5% posteriorly (mean, 4%; SD, 4%).…”

Section: Introductionmentioning

confidence: 99%

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Does Radiographic Beam Angle Affect the Radiocapitellar Ratio Measurement of Subluxation in the Elbow?

McCann

Canet

Sandman

et al. 2013

Clinical Orthopaedics &Amp; Related Research

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Background Radial head alignment is the key to determine elbow reduction after treatment of subluxations or Monteggia fractures. The radiocapitellar ratio (RCR) quantifies the degree of subluxation, by evaluating radial head alignment with the capitellum of the humerus; this ratio is reproducible when measured on true lateral radiographs of nonsubluxated elbows. However, the impact of beam angulation on RCR measurement is unknown. Questions/purposes Our hypotheses were that the RCR of the nonsubluxated elbow would remain in the normal range as the beam angle changed and that the RCR variability would increase for the subluxated elbow with small deviations in the beam angle. Methods Radiographs were taken of six healthy cadaveric extremities using beam angles ranging from À20°to 20°a long the inferosuperior axis and from À20°to 20°along the dorsoventral axis. The same views then were taken of the six arms with anterior radiocapitellum subluxation followed by posterior radiocapitellum subluxation. RCRs were measured by one observer. As a reference value, the RCR was measured in the 0°to 0°position and the difference between each RCR in a nonreference position was subtracted from each RCR reference to obtain the delta-RCR. An ANOVA was performed to assess the main and interactive effects on the RCR measured in each C-arm position compared with the RCR measured on a true lateral radiograph. Results The RCR remained in the normal range even as the beam angle of the C-arm varied between À20°and 20°. The position of the beam did not affect the RCR in anteriorly subluxated elbows (p = 0.777), whereas RCR variation increased especially in the presence of posterior radial head subluxation when the C-arm position was 10°o r more out of plane (p = 0.006). The inferosuperior malposition of the C-arm had a greater impact on quantification of radial head alignment measurement. Despite that, the RCR measurement is reliable in reduced and subluxated elbows on lateral radiographs with a C-arm position deviation of as much as 20°.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%