Comparison of Radiography and Histopathologic Analysis in the Evaluation of Hip Arthritis

OBJECTIVE. The purpose of this study was to establish the correlation of radiography findings with findings of gross and microscopic histopathologic analysis to assess the usefulness of radiography in preoperative assessment for hip arthroplasty. MATERIALS AND METHODS. Radiology and pathology reports from 953 consecutive femoral head resections were reviewed to establish the correlation of radiography and pathology findings as used in routine clinical practice. In 83 cases MR images were also available for review. Both radiologists and pathologists prospectively used a four-grade scale of absent, mild, moderate, or severe osteoarthritis. The grades established by radiologists and pathologists were compared by means of both the four-grade system and a simplified two-grade system of none-to-mild versus moderate-to-severe osteoarthritis. RESULTS. The mean patient age was 60 years (range, 18-94 years). Resection was performed for osteoarthritis in 941 cases and for infection, inflammatory arthritis, avascular necrosis, fracture, or tumor in the others. Radiographs showed severe osteoarthritis in 62.3% of patients and no or mild osteoarthritis in 17.7%. Observed agreement between radiology and pathology findings was 90% for both the four-grade and two-grade osteoarthritis scales. Findings on standing radiographs were more concordant with pathology results than findings on supine radiographs (odds ratio, 1.4). Observed agreement between radiography and MRI was 78%. There were significant discrepancies between radiography grade and pathology grade in 2.2% of cases. Observed agreement of MRI and pathologic analysis was 76% (κ = 0.64). CONCLUSION. Radiography findings are a reliable indicator of severity of osteoarthritis. This is important because previous studies have shown that patients with no or mild osteoarthritis are less likely to benefit from arthroplasty. If evidence of moderate or severe osteoarthritis is not present on radiographs, further investigation is warranted before proceeding to arthroplasty.