Influence of bone quality on the strength of internal and external fixation of tibial plateau fractures

Abstract

We studied the influence of different parameters of bone quality on the fixation strength of bicondylar tibial plateau fractures and examined the relationship between these parameters. Bone quality was measured in the plateau of 16 cadaveric tibias using three modalities: dual-energy X-ray absorptiometry (DXA), peripheral quantitative computer tomography (pQCT), and spectral analysis of digitized radiographs (SADR). The tibias were divided into two groups by the median bone mineral density (BMD) and randomized to receive either dual plating or external fixator for the stabilization of a standardized bicondylar tibial fracture. The fixed fractures were subjected to axial compression until failure. DXA BMD correlated most significantly with the failure load (r>or=0.79, p<0.001), followed by the pQCT parameters of cancellous bone (0.52>or=r>or=0.73, p<0.01). Similar strong correlations were also evident in both fixation methods. For parameters derived from SADR, only those including both longitudinal and transverse trabecular orientations had modest correlation with the fixation strength (0.53>or=r>or=0.71, p<0.01). The failure loads of the two fixation techniques were not significantly different (mean+/-SD=3522+/-1386 N and 3710+/-1356 N, respectively, p=0.78). However, BMD in the dual-plating group influenced the failure load significantly (p=0.03), whereas in the external fixation group this was less evident (p=0.100). The majority of bone quality parameters that correlated with fixation strength were also strongly correlated with each other, particularly the BMDs measured by DXA and pQCT. This is the first study that relates fixation strength of bicondylar tibial plateau fractures to bone quality assessed at the same anatomical site. BMD around the fracture site had the best correlation with the failure load regardless of the fixation technique. The two fixation methods tested performed equally well, and the choice between them depends on the soft tissue condition and surgeon preference.