Intraobserver and interobserver agreement of Goutallier classification applied to magnetic resonance images.
BACKGROUND
Fatty infiltration of the muscle bellies is an important prognostic factor in rotator cuff tears. It was described initially in computed tomography examinations, and there is an ongoing debate about whether magnetic resonance (MR) is a reliable method for staging fatty infiltration. This study sought to determine intraobserver and interobserver agreement for Goutallier's classification of fatty infiltration of the rotator cuff as evaluated through MR imaging.


METHODS
Twenty MR examinations of the shoulder showing full-thickness tear of the supraspinatus tendon, with or without associated lesions, were evaluated by 3 radiologists with experience in musculoskeletal system imaging and 3 fellowship-trained shoulder surgeons. The evaluators classified the fatty infiltration of the supraspinatus muscle according to the guidelines proposed by Goutallier et al. After 8 weeks, they re-evaluated the examinations, without access to their previous reports. Weighted κ index values were determined for intraobserver and interobserver agreement analyses, and intraobserver agreement κ values are reported with 95% confidence intervals (CIs).


RESULTS
The mean intraobserver agreement was 0.832 among the orthopedists (CI > 95%) and 0.741 among the radiologists (CI > 95%). Interobserver agreement was 0.8214 (evaluation 1) and 0.7231 (evaluation 2) among the orthopedists (P < .0001) and 0.6627 (evaluation 1) and 0.6067 (evaluation 2) among the radiologists (P < .0001). Intraobserver agreement was not associated with length of experience or frequency of routine evaluations.


CONCLUSIONS
When it is applied to MR images of rotator cuff musculature, Goutallier's fatty infiltration staging rubric yielded highly significant intraobserver and interobserver agreement.
Department of Orthopaedic Surgery, Center of Shoulder and Elbow Surgery, National Institute of Trauma and Orthopaedics, Rio de Janeiro, Brazil. Electronic address: marcioschiefer@hotmail.com.
Marcio
M
Schiefer
Department of Radiology, Hospital Barra D'Or, Rio de Janeiro, Brazil.
Renato
R
Mendonça
Collective Health Study Institute, Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Monica Maria
MM
Magnanini
Department of Orthopaedics, Clementino Fraga Filho University Hospital (HUCFF), Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
César
C
Fontenelle
Department of Radiology, Faculty of Medicine, Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Antonio Carlos
AC
Pires Carvalho
Department of Orthopaedics, Clementino Fraga Filho University Hospital (HUCFF), Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Mariana
M
Almeida
Department of Orthopaedics, Clementino Fraga Filho University Hospital (HUCFF), Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Ana Cláudia
AC
Chu
Department of Orthopaedics, Clementino Fraga Filho University Hospital (HUCFF), Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Sérgio Maurício
SM
Silva
Department of Orthopaedics, Faculty of Medicine, Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Filipe
F
Visconti
Department of Orthopaedics, Faculty of Medicine, Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
Gabriel A M
GA
Ferreira
Department of Orthopaedics, Faculty of Medicine, Rio de Janeiro Federal University (UFRJ), Rio de Janeiro, Brazil.
José Sérgio
JS
Franco
D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012372:ROC Curve; D017006:Rotator Cuff / Q000473:pathology; D000070636:Rotator Cuff Injuries; D012421:Rupture / Q000473:pathology; D020069:Shoulder Pain / Q000145:classification* / Q000175:diagnosis* / Q000209:etiology; D013708:Tendon Injuries / Q000145:classification* / Q000150:complications / Q000175:diagnosis
Goutallier classification; MRI; Rotator cuff tear; fatty infiltration