Comparison of five percutaneous pinning methods for unstable extra-articular distal radius fractures: A mechanical study using sawbones.

OBJECTIVES

This study aims to mechanically compare five different extra-focal bi-cortical pin configurations (using two and three pins) employed for fixation of a simulated unstable extra-articular distal radius fracture with dorsal comminution using a sawbone model.

MATERIALS AND METHODS

This in vitro mechanical study was conducted between June 2019 and July 2019. A standard fracture model (Arbeitsgemeinschaft für Osteosynthesefragen [AO] type 23-A3.3) was created using a fourth generation composite artificial radius bone. Five groups with two- and three-pin configurations were tested under axial, volar, and dorsal loading with a universal test device. Mean stiffness values were compared statistically.

RESULTS

Comparison of stiffness values from axial and volar loading tests between groups in paired comparison showed no statistically significant difference (p=0.194 and p=0.086, respectively). Dorsal loading tests showed statistically significant difference between the groups in pairwise comparison (p=0.002). Three-pin groups (Groups 3, 4, and 5) had higher stiffness values compared to two-pin groups (Groups 1 and 2) in dorsal loading tests (p=0.001). Three-pin configuration test groups with two divergent or convergent pins from the radial styloid performed better compared to both two-pin groups (p=0.01, p=0.002) in dorsal loading tests.

CONCLUSION

Our data demonstrated that the three-pin configuration with two divergent or convergent Kirschner wires from the styloid and a third wire from the dorsal/ulnar cortex had higher stiffness values compared to two-pin configurations in dorsal loading tests. When indicated, we suggest the use of a three-pin construct. Particularly in cases with a risk of volar angulation, we recommend a three-pin configuration with two divergent or convergent bi-cortical Kirschner wires.