Application of Three-Dimensional Computed Tomography Improved the Interrater Reliability of the AO/OTA Classification Decision in a Patellar Fracture

We investigated whether interrater reliabilities of the AO/OTA classification of patellar fracture change with the imaging modalities applied, including plain radiography and two- and three-dimensional (2-D and 3-D) computed tomography (CT). Seven orthopedic specialists and four orthopedic residents completed a survey of 50 patellar fractures to classify the fractures according to the AO/OTA classification for patellar fractures. Initially, the survey was conducted using plain radiography only, then with 2-D CT introduced three weeks later and 3-D CT introduced six weeks later. Fleiss' Kappa coefficients were calculated to determine interrater reliability. The overall interrater reliability of the AO/OTA classifications was 0.40 (95% CI, 0.38-0.42) with plain radiography only and 0.43 (95% CI, 0.41-0.45) with the addition of 2-D CT. With the addition of 3-D CT, the reliability was significantly improved to 0.54 (95% CI, 0.52-0.56). In specialists, interrater reliability of the classifications was moderate with all three imaging modalities. With the use of 3-D CT, interrater reliability of the classification was 0.53 (95% CI, 0.50-0.56), which was significantly higher than that with the use of 2-D CT (kappa = 0.45; 95% CI, 0.42-0.48). In residents, interrater reliability of the classification was 0.30 (95% CI, 0.24-0.36) with plain radiography. The reliability improved to 0.49 (95% CI, 0.43-0.56) with the addition of 2-D CT, which was significantly higher than that with plain radiography only. The use of 3-D CT imaging improved interrater reliability of the classification. Therefore, surgeons, especially residents, may benefit from using 3-D CT imaging for classifying and planning the treatment of patellar fractures.