BICONDYLAR TIBIAL PLATEAU FRACTURES: AN EVALUATION OF OPTIMAL FIXATION CONSTRUCTS

Participants: E. P. Frankenburg, M. A. Karunakar, K. L. Mueller, D. S. Scott, S. Matuszak, P. Pazmino, B.T. Nolan, D. C. Kayner, J. Hall, E. T. Keller, S. A. Goldstein

Keywords: fracture fixation, tibial plateau fractures, mechanical properties

Introduction

Tibial plateau fractures are relatively common, and generally occur due to high-energy trauma. A review of the literature reveals that the gold standard for fixation of bicondylar tibial plateau fractures involves dual plating with large fragment buttress plates. This technique has been modified to minimize the soft tissue dissection involved in the placement of these plates. The classic medial large fragment plate has been replaced with a small fragment antiglide plate. Fixed angle devices have been used with success in the treatment of intraarticular fractures of the distal femur. However, this concept has not been extended towards the treatment of proximal tibia fractures. At present, the optimal fixation for bicondylar tibial plateau fractures remains controversial.

Materials and Methods

Twelve pairs of human cadaver lower extremities will be used in this study. The tibias will be dissected free of soft tissue, and radiographed to rule out any bony anomalies. Bone mineral density, measured by DEXA scanning, will then be determined to help quantify the bone quality. The distal diaphysis of each tibia will then be potted in PMMA, as is its matching distal femur. Each lower extremity will then be loaded in pre-yield compression (with an 11 degree of flexion at the knee joint).

A bicondylar tibial plateau fracture is then created with a bandsaw, with one large central fragment removed to create more instability. The fractures are reduced and fixed with one of three methods:

1.  
2. double plating with an eight hole 3.5 mm periarticular plate placed laterally and a 5 hole 3.5 DCP plate placed medially as an antiglide plate
3.  
4. double plating with an eight hole 3.5 mm periarticular plate placed laterally and a 5 hole one-third tubular plate placed medially as an antiglide plate
5.  
6. fixed angle plate (LISS) placed on the lateral side of the tibia

Three clip gages are then applied to each tibia to measure local displacements of the fracture fragments during compression testing. Each construct will be tested in compression (at 11 degrees flexion) until failure in an MTS machine under constant displacement. Construct stiffness, load to failure, energy to failure, and maximum local displacements (measured by the clip gages) will be determined. Finally, analysis of variance will be performed, where a p value < 0.05 will be considered significant.

Progress

All twelve pair of cadaver specimens have been collected and admitted to the study after radiographic and bone mineral density studies. Six pairs of specimens have been pre-tested, fractured, and fixed. The remaining six pairs have been potted and pre-tested, and are awaiting fracture creation and fixation. All mechanical testing protocols have been finalized.