Colles Fracture Classification
A Colles fracture is a specific type of distal radius fracture with dorsal displacement and angulation, but it does not have universally recognized subtypes with distinct names—rather, it is classified by displacement, stability, and articular involvement. 1
Definition and Mechanism
A Colles fracture results from a fall on the dorsiflexed and pronated hand, producing the characteristic "dinner-fork deformity" with dorsal displacement of the distal radius fragment. 2
Classification Approaches
Rather than having named subtypes, Colles fractures are categorized based on several key characteristics:
By Displacement Status
- Undisplaced or minimally displaced fractures: These show little to no displacement of the distal radius fragment 3
- Displaced fractures: These demonstrate significant dorsal and radial displacement with the classic deformity 3, 4
By Stability and Complexity
- Simple/stable fractures: Non-comminuted fractures without significant articular involvement 2
- Comminuted fractures: Multiple fragments present, indicating greater instability and potential for collapse 2
- Intra-articular fractures: Involvement of the radiocarpal joint surface 4
- Extra-articular fractures: No joint surface involvement 2
By Associated Injuries
- With ulnar styloid fracture: Frequently accompanies Colles fractures, though its presence does not necessarily affect functional outcome 5
- With distal radioulnar joint involvement: May occur but does not consistently predict worse functional results 5, 4
Clinical Significance of Classification
The severity of initial displacement is the most important predictor of functional outcome, more so than the specific fracture pattern or articular involvement. 4 Interestingly, radiographic findings correlate poorly with functional results—only final dorsal angulation correlates with loss of flexion, while radial shortening does not predict grip strength or range of motion loss. 5
Common Pitfall
Do not assume that involvement of the radiocarpal or distal radioulnar joints automatically predicts poor functional outcome—studies show these factors do not adversely affect rehabilitation when properly treated. 5, 4