[Inadequate detectability of early stages of coxarthrosis with conventional roentgen images].
OBJECTIVE
The study was undertaken to determine the value of standard radiographs in the early stages of osteoarthritis.


METHODS
Standard radiographs and arthro-MRI's from thirty hips operated on for early arthrosis (age 25-57 years) were independently analyzed by two orthopaedic surgeons and one radiologist blinded from the intra-operative findings. The radiographs were read on two occasions two months apart. The radiographic findings were then compared to the intra-operative findings.


RESULTS
Intra-operatively, all cases had a labral lesion and, in all but three of the cases, there was a major acetabular cartilage lesion. Each investigator diagnosed all of the labral and/or cartilage lesions on the arthro-MRI. However, on average, the investigators judged 20% (10-35%) of the hips to be normal on the standard radiographs. The probability of detecting an abnormal hip joint was statistically significantly better with arthro-MRI in four of six readings (p < 0.05) and there was a trend in favor of the arthro-MRI in the other two readings (p < 0.1). Intra-observer agreement when using the Tönnis classification of arthrosis on standard radiographs was 0.26 (-0.1-0.62), 0.69 (0.42-0.96) and 0.83 (0.53-1) [kappa-statistic, (95% confidence interval)]. The interobserver agreement was 0.24 (-0.07-0.55).


CONCLUSIONS
Plain radiographs in the early stages of osteoarthrosis of the hip are neither reliable nor valid to diagnose the onset of disease. Therefore, in the case of a normal radiograph and clinical suspicion of arthrosis, a "normal" radiograph does not exclude the diagnosis and an artho-MRI should be obtained for further evaluation.
Locher
S
S
Universitätsklinik für Orthopädische Chirurgie, Inselspital, 3010 Bern, Schweiz.
Werlen
S
S
Leunig
M
M
Ganz
R
R
D000328:Adult; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000145:classification / Q000175:diagnosis / Q000000981:diagnostic imaging*; D011859:Radiography; D012680:Sensitivity and Specificity