Wurzburg lag screw plate versus four-hole miniplate for the treatment of condylar process fractures.

PURPOSE: The purpose of this study was to compare the biomechanical stability of rigidly fixed condylar neck fractures using either a conventional four-hole miniplate system or the Wurzburg lag screw plate system.

MATERIALS AND

METHODS

Ten identical synthetic mandibles were used for this study. Simulated bilateral condylar neck fractures were fixed with the lag screw plate system on one side and the miniplate system on the other. The mandibles were loaded with an MTS servohydraulic testing machine at a rate of 1 cm/min until failure was reached. Data for resistance to motion and ultimate strength for each fixation device were compared by paired Student t-tests.

RESULTS

The mean resistance to motion for the four-hole miniplate was 64.0 kg/mm (SD = 10.1; range = 52-94) and for the lag screw system was 80.2 kg/mm (SD = 24.0; range = 55 to 126). The mean failure strength was 4.0 kg (SD = 0.9) (range = 2.6 to 5.5) for the miniplate system and 5.0 kg (SD = 2.5; range = 3.4 to 7.2) for the lag screw system. The lag screw system was significantly (P < .05) better than the miniplate for both parameters measured.

CONCLUSION

In laboratory testing using synthetic mandibles, the Wurzburg lag screw-plate fixation system proved superior to a four-hole miniplate system in regard to resistance to motion and failure strength. Clinical trials are necessary to substantiate these laboratory data and determine whether the system can be effectively applied by the surgeon.