Objectives:
Tibial spine fractures (TSFs) most commonly occur in the skeletally immature population and are typically due to trauma or sports-related injuries. To our knowledge, no study has systematically described how often TSFs extend into weight bearing regions of the tibia plateau or how far anteriorly and posteriorly TSFs extend.
Methods
Fifty-four patients age 5-18 were identified from a search from 2012 to 2020, and they were classified according to the Green and Tuca TSF classification system on MRI. For fractures of grade 2 and 3, the anteroposterior dimensions of fracture beds as well as the mid epiphyseal length were measured on sagittal slices. Finally, the extensions (or lack thereof) of the fracture bed into the weight bearing surfaces of the tibial plateau were recorded as seen on coronal slices. The weight bearing surface was defined by: fractures in between the anterior and posterior horns of the meniscus on the sagittal view and fractures lateral or medial to the outer margin of the tibial eminence. ICC values (via two-way random effects model for single measures) and percent agreement were calculated for 10 patients selected at random.
Results
According to Green and Tuca’s classification system, 1 fracture was grade 1, 28 were grade 2, and 25 were grade 3.
In regard to the anteroposterior dimensions, on average, fracture beds spanned 45% of the mid-epiphyseal length. Surprisingly, 92% extended posteriorly past the halfway point of the epiphysis and 54% extended to the posterior third of the epiphysis.
Separating groups based on the median age (12.19 years), the younger patient group had significantly larger anteroposterior dimensions of fracture beds (P=0.017, t-test assuming unequal variance). However, the younger group did not have more fractures involving the medial or lateral weight bearing regions of the tibial plateau.
Tibial spine fracture beds extended into the weight-bearing surface of the medial and lateral tibial plateau 57% and 25% of the time, respectively.
The ICC values of 0.965 for mid epiphyseal width, 0.833 for anterior bed extension, and 0.866 for posterior demonstrate that these measurements are repeatable between different observers. The percent agreement was 80% weight bearing zones affected and 70% for classification grade.
Conclusion
This study demonstrates that tibial spine fracture beds are often large and extend in an anteroposterior dimension to the posterior third of the epiphysis 54% of the time. The “tibial spine” fracture often extends far more posterior than the anatomic footprint of the tibial spine.
Furthermore, it is not uncommon for them to extend into the weight-bearing surfaces of the tibial plateau, especially medially which was affected in 57% of fractures.
We believe that clinicians taking care of tibial spine fractures should be aware of the potential of a “tibial spine” fracture to extend posteriorly and into the weight bearing surfaces of the tibia plateau.