Anatomically precontoured locked plates in pilon fractures: A computed tomography based and cadaveric study

Background: The treatment of comminuted tibia plafond fractures remains clinically challenging due to the complexity of the articular fracture pattern despite using the anatomically precontoured locked plates. This study describes the morphologic characteristics of the anterolateral fragment and to evaluate the fixability of the anterolateral fragment with the anatomically precontoured locked plate in the pilon fracture. Materials and Methods: One hundred and twenty five cases of AO 43-B and C fracture were evaluated using the computed tomography (CT) scan. The anterior-posterior distance in CT (APDc), medial-lateral distance in CT (MLDc), coronal and sagittal height, and articular surface area of the anterolateral fragment were measured in CT. Four types of anatomically precontoured locked plates were used for cadaveric measurement. Four cadaveric parameters were also evaluated; anteroposterior distance in plate (APDp), height of the screw in the medial plate, medial-lateral distance in plate (MLDp), and height of the screw in the anterolateral plate. Results: The anterolateral fragment was described with a mean surface area of 167.13 mm² (APDc: 10.89 ± 4.64 mm, MLDc: 15.02 ± 6.56 mm, sagittal height: 14.85 ± 6.25 mm, and coronal height: 17.27 ± 6.88 mm). The cadaveric measurement showed that the juxta-articular screw of the medial distal tibia plate was placed away from the anterolateral fragment. The anterolateral distal tibia plate did not purchase the anterolateral fragment due to the higher position of the most distal-lateral screw (Synthes 18.37 ± 1.86 mm and Zimmer 17.78 ± 2.37 mm of the height of screw in the anterolateral plate). Conclusion: Anatomical distal tibial locked plates did not take purchase on the anterolateral fragment in pilon fracture in the best anatomical fit. Preoperative CT measurement can be used for determining a fixation strategy for the anterolateral fragment. In addition, a newly designed anterolateral distal tibia plate can be another solution when the usual anatomically precontoured distal tibia locked plate fails to cover the anterolateral fragment.