Inter- and intraobserver reliability of the Rockwood classification in acute acromioclavicular joint dislocations.
OBJECTIVE
The reliability of the Rockwood classification, the gold standard for acute acromioclavicular (AC) joint separations, has not yet been tested. The purpose of this study was to investigate the reliability of visual and measured AC joint lesion grades according to the Rockwood classification.


METHODS
Four investigators (two shoulder specialists and two second-year residents) examined radiographs (bilateral panoramic stress and axial views) in 58 patients and graded the injury according to the Rockwood classification using the following sequence: (1) visual classification of the AC joint lesion, (2) digital measurement of the coracoclavicular distance (CCD) and the horizontal dislocation (HD) with Osirix Dicom Viewer (Pixmeo, Switzerland), (3) classification of the AC joint lesion according to the measurements and (4) repetition of (1) and (2) after repeated anonymization by an independent physician. Visual and measured Rockwood grades as well as the CCD and HD of every patient were documented, and a CC index was calculated (CCD injured/CCD healthy). All records were then used to evaluate intra- and interobserver reliability.


RESULTS
The disagreement between visual and measured diagnosis ranged from 6.9 to 27.6 %. Interobserver reliability for visual diagnosis was good (0.72-0.74) and excellent (0.85-0.93) for measured Rockwood grades. Intraobserver reliability was good to excellent (0.67-0.93) for visual diagnosis and excellent for measured diagnosis (0.90-0.97). The correlations between measurements of the axial view varied from 0.68 to 0.98 (good to excellent) for interobserver reliability and from 0.90 to 0.97 (excellent) for intraobserver reliability.


CONCLUSIONS
Bilateral panoramic stress and axial radiographs are reliable examinations for grading AC joint injuries according to Rockwood's classification. Clinicians of all experience levels can precisely classify AC joint lesions according to the Rockwood classification. We recommend to grade acute ACG lesions by performing a digital measurement instead of a sole visual diagnosis because of the higher intra- and interobserver reliability.


METHODS
Case series, Level IV.
Department of Orthopaedic Surgery, Traumatology and Sports Medicine, Cologne Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany. marco.schneider@orthopia.com.|Orthopaedic Surgery, Schulthess Clinic, Zurich, Switzerland. marco.schneider@orthopia.com.
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Schneider
Sportsclinic Cologne - Practice for Sportstraumatology, Cologne Merheim Medical Center (CMMC), Witten/Herdecke University, Ostmerheimer Str. 200, 51109, Cologne, Germany.
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Balke
Department of Orthopaedic Surgery, Traumatology and Sports Medicine, Cologne Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
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Koenen
Department of Orthopaedic Surgery, Traumatology and Sports Medicine, Cologne Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
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Fröhlich
Department of Orthopaedic Surgery, Traumatology and Sports Medicine, Cologne Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
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Wafaisade
Department of Orthopaedic Surgery, Traumatology and Sports Medicine, Cologne Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
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Bouillon
Department of Orthopaedic Surgery, Traumatology and Sports Medicine, Cologne Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
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Banerjee
D000173:Acromioclavicular Joint / Q000000981:diagnostic imaging* / Q000293:injuries; D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012783:Shoulder Dislocation / Q000145:classification* / Q000000981:diagnostic imaging*; D055815:Young Adult
Ac joint; Acromioclavicular joint; Acute; Dislocation; Intra- and interobserver reliability; Rockwood classification; Separation