Association of Talar Neck Fractures With Body Extension and Risk of Avascular Necrosis.

Background: The objective of this study was to determine whether talar neck fractures with proximal extension (TNPE) into the talar body are associated with higher rates of avascular necrosis (AVN) compared to isolated talar neck (TN) fractures.

Methods: A retrospective review of patients sustaining talar neck fractures at a level I trauma center from 2008 to 2016 was performed. Demographic and clinical data were collected from the electronic medical record. Fractures were characterized as TN or TNPE based on initial radiographs. TNPE was defined as a fracture that originates on the talar neck and extends proximal to a line subtended from the junction of the neck and the articular cartilage dorsal to the anterior portion of the lateral process of the talus. Fractures were classified according to the modified Hawkins classification for analysis. The primary outcome was the development of AVN. Secondary outcomes included nonunion and collapse. These were measured on postoperative radiographs.

Results: There were 137 fractures in 130 patients, with 80 (58%) fractures in the TN group and 57 (42%) in the TNPE group. Median follow-up was 10 months (interquartile range, 6-18 months). The TNPE group was more likely to develop AVN as compared to the TN group (49% vs 19%, P < .001). Similarly, the TNPE group had a higher rate of collapse (14% vs 4%, P = .03) and nonunion (26% vs 9%, P = .01). Even after adjusting for open fracture, Hawkins fracture type, smoking, and diabetes, AVN still remained significant for the TNPE group as compared to the TN group with an odds ratio of 3.47 (95% CI, 1.51-7.99).

Conclusion: We found a higher rate of AVN, subsequent collapse, and nonunion in patients with TNPE compared to isolated TN fractures.

Level of evidence: Level III, retrospective cohort study.