Abstract
Background Volar ulnar corner fractures are a subset of distal radius fractures that can have
disastrous complications if not appreciated, recognized, and appropriately managed.
The volar ulnar corner of the distal radius is the “critical corner” between the radial
calcar, distal ulna, and carpus and is responsible for maintaining stability while
transferring force from the carpus.
Description Force transmitted from the carpus to the radial diaphysis is via the radial calcar.
A breach in this area of thickened cortex may result in the collapse of the critical
corner. The watershed ridge (line) is clinically important in these injuries and must
be appreciated during planning and fixation. Fractures distal to the watershed ridge
create an added level of complexity and associated injuries must be managed. An osteoligamentous
unit comprises bone–ligament–bone construct. Volar ulnar corner fractures represent
a spectrum of osteoligamentous injuries each with their own associated injuries and
management techniques. The force from the initial volar ulnar corner fracture can
propagate along the volar rim resulting in an occult volar ligament injury, which
is a larger zone of injury than appreciated on radiographs and computerized tomography
scan. These lesions are often underestimated at the time of fixation, and for this
reason, we refer to them as sleeper lesions. Unfortunately, they may become unmasked
once the wrist is mobilized or loaded.
Conclusions Management requires careful planning due to a relatively high rate of complications
after fixation. A systematic approach to plate positioning, utilizing several fixation
techniques beyond the standard volar rim plate, and utilizing fluoroscopy and/or arthroscopy
is the key strategy to assist with management. In this article, we take a different
view of the volar ulnar corner anatomy, applied anatomy of the region, associated
injuries, and management options.
Keywords
distal radius fracture - lunate facet - carpal instability - osteoligamentous unit
- watershed line - watershed ridge - volar ulnar corner - volar rim
