Comparison of different pseudotumor grading systems in a single cohort of metal-on-metal hip arthroplasty patients.
OBJECTIVE
Follow-up of pseudotumors observed with metal-artefact reducing sequence (MARS)-magnetic resonance imaging (MRI) following metal-on-metal total hip arthroplasty (MoMTHA) depends on how severe these pseudotumors are graded. Several pseudotumor grading systems for MARS-MRI have emerged but little is known of their validity. We studied the intra- and interobserver reliability of three different pseudotumor grading systems in a single cohort of MoMTHA.


METHODS
Two experienced musculoskeletal radiologists independently used three different pseudotumor grading systems for classifying MARS-MRI results of the same cohort of 42 MoMTHA patients (49 hips, mean follow-up 5.2 years). Intraobserver and interobserver reliability for each grading system was measured using Cohen's kappa (κ). Variance in pseudotumor severity grading between systems was analyzed.


RESULTS
Intraobserver reliability on grading pseudotumor severity with the Anderson, Matthies, and Hauptfleisch grading system scored 0.47, 0.10, and 0.35 (observer 1), and 0.75, 0.38, and 0.42 (observer 2), respectively. Interobserver reliability scores for pseudotumor severity were 0.58, 0.23, and 0.34, respectively.


CONCLUSIONS
Intraobserver reliability for grading pseudotumor severity on MARS-MRI ranged from poor to good, dependent on observer and grading system used. Interobserver reliability scored best with the Anderson system. A more succinct pseudotumor severity grading system is needed for clinical use.
Department of Orthopaedic Surgery, St. Anna Hospital, Bogardeind 2, 5664 EH, Geldrop, The Netherlands, kog@st-anna.nl.
W
W
van der Weegen
K
K
Brakel
R J
RJ
Horn
J A
JA
Wullems
H P
HP
Das
P
P
Pilot
R G
RG
Nelissen
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006104:Granuloma, Plasma Cell / Q000209:etiology* / Q000473:pathology*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008875:Middle Aged; D015588:Observer Variation; D010000:Osteitis / Q000209:etiology* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index