Mechanical characteristics of locking and compression plate constructs applied dorsally to distal radius fractures.

PURPOSE

Locking plates are thought to have many advantages such as a decreased incidence of loss of reduction secondary to screw toggling and improved bone healing due to an increased periosteal blood supply. We hypothesized that locking plates will also provide increased stiffness and increased load to failure when they are applied dorsally to stabilize dorsally comminuted distal radius fractures. This study compared the stiffness and strength of dorsally applied locking and standard (nonlocking) T-plates applied to a dorsally comminuted distal radius fracture model.

METHODS

Sixteen pairs of embalmed cadaveric human radii were potted, and a standard wedge osteotomy was performed simulating a dorsally comminuted distal radius fracture. The radii were randomized into 2 groups, so that 8 pairs received a 3.5-mm dorsal locking T-plate over the osteotomy on the right radius and 8 pairs received the same on the left radius. A dorsal 3.5-mm standard T-plate was placed over the osteotomy on the contralateral radius in each group. An axial load was used to test the strength and stiffness of each construct. Paired t tests were then used to compare the strength and stiffness of the locking plate with those of the standard plate.

RESULTS

A significant difference was found in both the stiffness and the strength between the locking and standard nonlocking plates. The locking T-plate was 33% stiffer than the standard T-plate. The locking T-plate had a 91% increase in the load to failure. Failure for both locking and standard T-plates occurred via volar cortex bone fracture.

CONCLUSIONS

Locking T-plates increased both the stiffness and strength of dorsally comminuted distal radius fractures compared with standard nonlocking T-plates by a statistically significant margin.