Weight-Bearing Restrictions With Distal Radius Wrist-Spanning Dorsal Bridge Plates.

PURPOSE: The fixation of comminuted distal radius fractures using wrist-spanning dorsal bridge plates has been shown to have good postoperative results. We hypothesized that using a stiffer bridge plate construct results in less fracture deformation with loads required for immediate crutch weight bearing.

METHODS

We created a comminuted, extra-articular fracture in 7 cadaveric radii, which were fixed using dorsal bridge plates. The specimens were positioned to simulate crutch/walker weight bearing and axially loaded to failure. The axial load and mode of failure were measured using 2- and 5-mm osteotomy deformations as cutoffs. Bearing 50% and 22% of the body weight was representative of the force transmitted through crutch and walker weight bearing, respectively.

RESULTS

The load to failure at 2-mm deformation was greater than 22% body weight for 2 of 7 specimens and greater than 50% for 1 of 7 specimens. The load to failure at 5-mm deformation was greater than 22% body weight for 6 of 7 specimens and greater than 50% for 4 of 7 specimens. The mean load to failure at 2-mm gap deformation was significantly lower than 50% body weight (110.4 N vs 339.2 N). The mean load to failure at 5-mm deformation was significantly greater than 22% body weight (351.8 N vs 149.2 N). All constructs ultimately failed through plate bending.

CONCLUSIONS

All constructs failed by plate bending at forces not significantly greater than the 50% body weight force required for full crutch weight bearing. The bridge plates supported forces significantly greater than the 22% body weight required for walker weight bearing 6 of 7 times when 5 mm of deformation was used as the failure cutoff.

CLINICAL RELEVANCE: Elderly, walker-dependent patients may be able to use their walker as tolerated immediately after dorsal bridge plate fixation for extra-articular fractures. However, patients should not be allowed to bear full weight using crutches immediately after bridge plating.