A biomechanical comparison of conventional versus an anatomic plate and compression bolts for fixation of intra-articular calcaneal fractures

The purpose of this study was to compare the biomechanical stability obtained by using our technique featured an anatomical plate and compression bolts versus that of the conventional anatomic plate and cancellous screws in the fixation of intraarticular calcaneal fractures. Eighteen fresh frozen lower limbs of cadavers were used to create a reproductive Sanders type-III calcaneal fracture model by using osteotomy. The calcaneus fractures were randomly selected to be fixed either using our anatomical plate and compression bolts or conventional anatomic plate and cancellous screws. Reduction of fracture was evaluated through X radiographs. Each calcaneus was successively loaded at a frequency of 1 Hz for 1000 cycles through the talus using an increasing axial force 20 N to 200 N and 20 N to 700 N, representing the partial weight bearing and full weight bearing, respectively, and then the specimens were loaded to failure. Data extracted from the mechanical testing machine were recorded and used to test for difference in the results with the Wilcoxon signed rank test. No significant difference was found between our fixation technique and conventional technique in displacement during 20-200 N cyclic loading (P=0.06), while the anatomical plate and compression bolts showed a great lower irreversible deformation during 20-700 N cyclic loading (P=0.008). The load achieved at loss of fixation of the constructs for the two groups had significant difference: anatomic plate and compression bolts at 3839.6 +/- 152.4 N and anatomic plate and cancellous screws at 3087.3 +/- 58.9 N (P=0.008). There was no significant difference between the ultimate displacements. Our technique featured anatomical plate and compression bolts for calcaneus fracture fixation was demonstrated to provide biomechanical stability as good as or better than the conventional anatomic plate and cancellous screws under the axial loading. The study supports the mechanical viability of using our plate and compression bolts for the fixation of calcaneal fracture.