The biomechanics of point contact-dynamic compression plate and its effects on bone perfusion.

OBJECTIVE

To compare the mechanical properties of point contact-dynamic compression plate (PC-DCP) and its effects on cortical bone perfusion with that of dynamic compression plates (DCP) in goat tibiae.

METHODS

Twenty pairs of matched fresh goat tibiae were used. A transverse fracture model was established. The fractures with a 3mm interspace between the fracture ends were subject to fixations with the DCPs and the PC-DCPs respectively, then the four-points bending tests and the torsion tests were conducted to compare the mechanical properties of the PC-DCP with that of DCP. Another 13 sexually mature goats underwent fixations with the DCPs and the PC-DCPs, respectively, at the mid-shafts of the intact bilateral tibiae. Ischemic zones were observed at four time points (1 day, 2, 6, and 12 weeks after operation) using disulphine blue staining technique.

RESULTS

There were no significant differences in mechanical properties, such as bend- and torsion-resistance, between the DCPs and the PC-DCPs. One day, 2, and 6 weeks after operation, on the side of DCP fixation, outer cortical bone ischemia under the plate persisted, and this condition did not reverse until 12 weeks after operation. However, on the side of PC-DCP fixation, cortical bone ischemia occurred only in the periphery of the screw holes and at the contact sites of the PC NUTs 1 day after operation, and it disappeared at 2 weeks after operation.

CONCLUSIONS

The PC-DCP has similar biomechanical properties of the DCP, but is less detrimental to local bone blood circulation than the conventional plates.