The effect of distal radius locking plates on articular contact pressures.

PURPOSE: Fractures of the distal radius are among the most common injuries treated in hand surgery practice, and distal radius locking plates have become an increasingly popular method of fixation. Despite widespread use of this technology, it is unknown whether the subchondral placement of locking screws affects the loading profile of the distal radius. Our study was designed to determine whether subchondral locking screws change the articular contact pressures in the distal radius.

METHODS

Twelve cadaveric forearms underwent a previously described axial loading protocol in a materials testing machine. We used an intra-articular, real-time computerized force sensor to measure peak contact pressure, total pressure, and contact area in the distal radius. Internal validation of sensor placement and reproducibility was conducted. Each specimen was tested before fixation (control), after application of a palmar distal radius locking plate, and after simulation of a metaphyseal fracture.

RESULTS

We identified no statistically significant differences in maximum pressure, total pressure, and contact area among control, plated, and plated and fractured specimens. However, the contact footprint-represented by squared differences in force across the sensor-were significantly different between the control group and both plated groups.

CONCLUSIONS

The technique for measuring contact pressures produces highly repeatable values. Distal radius locking plates with subchondral hardware placement do not seem to significantly change articular contact pressures.