The fate of Böhler's angle in conservatively-treated displaced intra-articular calcaneal fractures

Abstract

Purpose: Although the predictive value of Böhler's angle on outcome remains subject of debate, the initial angle at the time of trauma still guides treatment. Changes in Böhler's angle during follow-up are frequently reported following surgical treatment of displaced intra-articular calcaneal fractures (DIACF). The aim of the present study was to determine the changes in Böhler's angle as a measure of secondary fracture displacement following conservative management of DIACF.

Methods: Thirty-eight patients with a total of 44 displaced intra-articular calcaneal fractures treated conservatively with a minimum of two lateral radiographs during follow-up were analysed. Böhler's angle at different follow-up times was measured by three observers. The change in angle was compared with the angle at trauma, and influence of trauma mechanism and common calcaneal fracture classifications were determined.

Results: The results showed a significant decline over time of the Böhler's angle in conservatively-treated patients of more than 11° on average at a mean follow-up of 29.2 weeks. This decrease was not related to gender, the initial angle, or the Essex-Lopresti or Sanders classification. A statistically significantly higher decrease was detected in high energetic trauma compared with low energetic trauma.

Conclusion: The conservative treatment of displaced intra-articular calcaneal fractures is still a viable option, yet a significant secondary displacement in time should be taken into account, as reflected in a decrease of Böhler's angle of 11° up to one year following trauma.

Fig. 1

Change in Böhler’s angle over time. a Trend over 15 weeks. b Trend over 60 weeks. c Trend over 110 weeks

Fig. 2

Influence of various factors on the change in Böhler’s angle over time. a Initial Böhler on presentation (black line initial Böhler < zero, red line ≥ zero). b Trauma mechanism (black line LET, red line HET). c Gender (black line female, red line male)

Fig. 3

Influence of various factors on the change in Böhler’s angle over time. a Essex-Lopresti classification (black line joint-depression, red line tongue-type). b Sanders classification (black line without c-fracture line [2a, 2b, 3ab], red with c-fracture line [2c, 3ac, 3bc, 4])