Newer generation of proximal tibia locking plates demonstrate large variability in their ability to capture the posteromedial fragment in bicondylar tibial plateau fractures

Introduction: The early generations of proximal tibial locking plates demonstrated inferior results when compared to dual plating in bicondylar tibial plateau fractures with posteromedial fragments (PMF). Modern plates have multiple rows of locking screws and variable angle technology —which tote the ability to capture the PMF. The purpose of this study was to determine if the modern plates could capture the PMF in a large series of bicondylar tibial plateau fractures. Materials & methods: Axial computer topography (CT) scans of 114 bicondylar tibial plateau fractures with PMF were analyzed. Five proximal tibia locking plates—in seven total configurations—were applied to radiopaque tibiae models. All possible screws were placed. Templates of screw trajectories were created based on the model CT scans. These were superimposed onto patient CT scan images to assess for screw penetration into the PMF. Number of screws fully within the PMF were recorded. Capture of the PMF was defined as having at least two screws within the fragment. Results: On average, all plates were able to capture 81.6% of PMF with an average of 3.77 [95% Confidence Interval (CI): 3.47-4.07] screws. However, their ability to capture all fragments varied greatly, from 55.7%-95.2% in fixed angle constructs. Overall, variable angle constructs had a significantly higher capture rate (98.5% vs. 74.9%; p<0.0001) and more screws in the PMF (5.88 [95% CI: 5.58-6.17] vs 2.93 [95% CI: 2.62-3.24]; p<0.0001) when compared to fixed angle constructs. Conclusion: Newer generation locking plates vary greatly in their ability to capture the PMF. Variable angle technology dramatically increases the ability to capture the majority of PMFs. Prior biomechanical and clinical studies may yield substantially different results if repeated with these newer implants. Use of newer generation locked plates should not replace thorough preoperative planning.