Assessment of Patellar Height Measurement Methods from Digital Radiography.

OBJECTIVE To analyze the most common methods for measuring patellar height and the impact of observer experience in correlations with the other observers using digital radiography. METHODS Sixty digital radiographs of the knee in lateral view were analyzed by four observers: a physician in the second year of medical residence in orthopedics (R2); a physician in the third year of medical residence in orthopedics (R3); an orthopedic surgeon who was a specialist in knee surgery (SK); and a radiologist who was a specialist in musculoskeletal radiology (SR). The indices used were: Insall-Salvati (IS), Blackburne-Peel (BP), Caton-Deschamps (CD) and modified Insall-Salvati (ISM). The interobserver agreement was calculated using the kappa coefficient (κ). RESULTS The highest correlation coefficients were found when using the IS method followed by the CD method. The worst correlation was observed in the ISM method. The highest interobserver agreement was found between the orthopedic surgeon specializing in knee surgery and the radiologist specializing in musculoskeletal radiology, for the four measurement methods used. CONCLUSION Using digital radiography, the Insall-Salvati and Caton-Deschamps indexes presented the highest interobserver agreement, and this was also positively influenced by the observer's level of experience.