What’s the Claim?
A retrospective, comparative study found that talar neck fractures with proximal extension into the talar body are more likely to:
- Develop osteonecrosis (49% versus 19%), even after controlling for confounding variables like smoking and diabetes (odds ratio for AVN of 3.5 after controlling for those variables)
- Collapse (14% versus 4%)
- Progress to nonunion (26% versus 9%)
How’s It Stack Up?
It’s surprising there isn’t more out there on this. Over 40% of the talar neck fractures in this study extended proximally. This pattern isn’t well captured by the Hawkins classification, and we’ve not seen a study specifically on this before, so we’ll share the authors exact words on how it looks:
Talar neck proximal extension (TNPE) was defined as a fracture that originates on the talar neck and extends proximal to a line subtended from the junction of the talar neck and the articular cartilage dorsal to the anterior portion of the lateral process of the talus. The fracture may traverse this line in an anterior-dorsal to posterior-plantar or an anterior-plantar to posterior-dorsal direction. Isolated talar neck (TN) fractures were defined as a fracture line confined to the talar neck with no extension proximally.
A nearly 30-year-old study about how we classify these injuries now has new relevance; CORRelations’ advisor in Foot & Ankle, Greg Guyton, MD, says: “We need to rethink how we classify talar neck fractures and base it on the inferior fracture line rather than the superior one. This is a useful exercise in rethinking the Hawkins classification in the era of CT (and long overdue).”