Biomechanics of posterior plating and screw fixation in tibial plateau fractures

INTRODUCTION: Recent experience with bicondylar tibial plateau fractures has led to concern over the stability of the posteromedial fragment when using standard lateral plating with anterior lag screws. Loss of reduction of this fragment has led to posterior subluxation of the femur in stance, and a stiff arthritic knee [1]. Historically fixation of these fragments has been performed with lateral plating combined with cannulated screws through a single anterior incision, or with combined medial and lateral plating [2-9]. In our hospital we have witnessed loss of fixation using these techniques resulting in posterior migration of the fragment which might have been avoided with more solid fixation. We have subsequently treated this fracture type using a posterior buttress plate with good results but data does not exists in the literature to show that this is better than anterior to posterior cannulated screws Bhatacharia [10] et al used posterior plating in a series of patients with posterior fragments and determined that posterior plating could be used with clinical success in these cases. Blokker et al [3] showed that quality of reduction was the dominant predictor of satisfactory outcome and that 5mm of articular step-off was associated with unsatisfactory results thus emphasizing the need for solid anatomic fixation that will resist postoperative forces. In this study we compared a technique using a lateral locking plate in combination with anterior lag screws to a technique that used a lateral locking plate in combination with a posteromedial ‘T’ plate in composite bones. We hypothesized that the posteromedial T plate would exhibit superior mechanical properties.