Extension of Tibial Spine Fractures Beyond the Tibial Spine: An MRI Analysis of 54 Patients

Background: To the authors’ knowledge, no previous study has thoroughly described the anteroposterior dimensions of tibial spine fractures (TSFs) on 3-dimensional imaging. The extension of TSFs into weightbearing regions of the tibial plateau, posterior extension within the epiphysis, and potential association between fracture size and patient age may have implications for treatment strategies and clinical outcomes. Hypothesis: TSF fragments would commonly involve weightbearing regions of the tibial plateau, would be larger in younger patients, and would extend more posteriorly than the anatomic footprint of the tibial spine. Study Design: Case series; Level of evidence, 4. Methods: Consecutive magnetic resonance imaging studies obtained between 2012 and 2020 in patients 5 to 18 years of age at the time of imaging for TSFs were included, measured, and classified via the Green and Tuca grading system. Anteroposterior fracture dimensions were measured and normalized to anteroposterior midepiphyseal length, as was fracture height to epiphyseal height. Extension into the weightbearing surface of the tibial plateau was recorded. Intraclass correlation coefficient and kappa values were calculated. Mean fracture bed size was compared using independent-samples t tests between older and younger patients based on median age and sex. Results: Of 54 TSFs, 1 (2%), 28 (52%), and 25 (46%) were grades 1, 2, and 3, respectively. Fracture beds spanned 45% of the anteroposterior midepiphysis, and 54% of the TSF beds extended to the posterior third of the epiphysis. Younger and female patients, on average, had larger anteroposterior dimensions to TSF beds (P = .018 and .006, respectively). The medial and lateral weightbearing surfaces of the tibial plateau were affected 57% and 25% of the time, respectively. Conclusion: This study demonstrated that TSF beds were larger in younger patients, extended to the posterior third of the epiphysis in 54% of cases, and should be examined carefully for extension into weightbearing regions of the tibial plateau. In pediatric patients, the TSF often involves more of the tibial plateau than the anatomic footprint of the tibial spine, and clinicians should be aware of the potential for extension posteriorly and into the weightbearing surfaces.