Validation of 9-Grid Scheme for Localizing Osteochondral Lesions of the Talus

• Main Authors: Kevin D. Martin DO, FAAOS, Trevor J. McBride BS, Dylan P. Horan BA, Amgad Haleem MD, PhD, Jeannie Huh MD, Adam Groth MD, Laura K. Dawson DO
• Format: Article
• Language: English
• Published: SAGE Publishing 2020-09-01
• Series: Foot & Ankle Orthopaedics
• Online Access: https://doi.org/10.1177/2473011420944925

Background: A 9-grid scheme has been integrated into the foot and ankle literature to help clinicians and researchers localize osteochondral lesions of the talus (OLTs). We hypothesized that fellowship-trained orthopedic foot and ankle surgeons would have a high rate of intra/inter-observer reliability when localizing OLTs, therefore validating the scheme. Methods: We queried our institution’s foot and ankle radiographic database for magnetic resonance images with OLTs. Each MRI was reviewed by the senior author, and 2 key images (widest OLT diameter) from each tangential view were copied and combined onto one slide. Fifty consecutive deidentified images of ankles were then sent to 4 practicing fellowship-trained foot and ankle surgeons. Each was asked to identify which zone the OLT was localized within. A radiologist’s report served as the control. Statistical analyses were performed using Cohen and Fleiss kappa tests. Results: The reviewers demonstrated majority consensus on 45/50 images with substantial agreement for zones 4 and 6. The interobserver reliability was moderate with a κ = 0.55. The mean intraobserver reliability was substantial, with a κ = 0.79. A musculoskeletal radiologist determined there were 3 lesions in zone 7, 18 lesions in zone 4, and 29 lesions in zone 6. Conclusion: This study is the first to critically evaluate the 9-grid scheme and its reliability among orthopedic foot and ankle surgeons. Our study found that the 9-grid scheme is an accurate method of localization for OLTs with high intra- and moderate interobserver reliability between surgeons. Level of Evidence: Level IV, retrospective diagnostic study.