Reliability analysis of radiographic methods for determination of posterolateral lumbossacral fusion

OBJECTIVE: To analyze intra and interobserver agreement of two radiographic methods for evaluation of posterolateral lumbar arthrodesis. METHODS: Twenty patients undergoing instrumented posterolateral fusion were evaluated by anteroposterior and dynamic lateral radiographs in maximal flexion and extension. The images were evaluated initially by 6 orthopedic surgeons, and after 8 weeks, reassessed by 4 of them, totaling 400 radiographic measurements. Intra and interobserver reliability were analyzed using the Kappa coefficient and Landis and Koch criteria. RESULTS: Intra and interobserver agreement regarding anteroposterior radiographs were, respectively, 76 and 63%. On lateral views, these values were 78 and 84%, respectively. However, the Kappa analysis showed poor intra and interobserver agreement in most cases, regardless of the radiographic method used. CONCLUSION: There was poor intra and interobserver agreement in the evaluation of lumbosacral fusion by plain film in anteroposterior and dynamic lateral views, with no statistical superiority between the methods.