Anatomic Risks with Overpenetration of the Volar Locking Plates' Proximal Holes.

Area of Science:

• Orthopedic surgery
• Anatomy
• Biomechanics

Background:

• Volar locking plate fixation (VLP) is a standard treatment for distal radius fractures (DRF).
• The risk of dorsal structure injury from distal screw placement in VLP is known.
• The risk associated with proximal screw hole fixation in VLP remains understudied.

Purpose of the Study:

• To evaluate the anatomical risk of dorsal structure injury.
• Specifically investigate injury from screws placed in holes proximal to the distal rows of VLP.

Main Methods:

• Nine cadaveric forearms were utilized for the study.
• A long VLP was applied after volar distal radius exposure.
• Kirschner wires were inserted through proximal screw holes to identify dorsal compartment penetration, with measurements taken from the dorsal cortex.

Main Results:

• Penetration occurred in the muscle bellies of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB), but not in extensor tendons.
• The likelihood of muscle penetration increased with more proximal screw holes.
• Extensor structures were an average of 2mm from the dorsal cortex, a distance unaffected by forearm compression.

Conclusions:

• This study is the first to assess the anatomical risk of extensor structure injury from proximal VLP screw hole penetration.
• Proximal VLP screws did not penetrate extensor tendons; however, overpenetration may irritate first dorsal compartment muscle bellies.
• Proximal VLP screws do not require downsizing if their prominence does not exceed 2mm from the dorsal cortex.