The "patellar ratio" in hemophilia and juvenile rheumatoid arthritis

Radiology. 1975 Jul;116(1):137-8. doi: 10.1148/116.1.137.


The ratio of patellar length to width was analyzed in comparison with subjective examination using radiographs of the affected knees in patients with hemophilia, juvenile rheumatoid arthritis (JRA), and controls to determine the usefulness of this measurement in differentiating the two diseases. A statistically significant difference was found between the proportion of JRA patients, controls, and patients with hemophiliac arthritis involving the knee. It was difficult to distinguish hemophilia from JRA by subjective analysis of the appearance of the knee using standard criteria. The patellar ratio is a more objective criterion which should be helpful in the radiological differentiation of JRA from hemophilia affecting the knee.

MeSH terms

  • Anthropometry
  • Arthritis, Juvenile / diagnostic imaging*
  • Diagnosis, Differential
  • Hemophilia A / diagnostic imaging*
  • Humans
  • Patella / anatomy & histology
  • Patella / diagnostic imaging*
  • Radiography