Anterior-Posterior (AP) Calcaneal Profile View: A Novel Radiographic Image to Assess Varus Malalignment

Abstract

Background: Assessing and correcting malalignment is important when treating calcaneus fractures. The Harris axial view is commonly utilized to assess varus deformity but may be inherently inaccurate due to its tangential nature. The anterior-posterior (AP) calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. Methods: Five nonpaired ankle cadaveric specimens were used in this investigation. Oblique osteotomies were created in relation to the long axis, and varus deformities were produced by inserting solid radiolucent wedges into the osteotomies to create models of 10, 20, and 30 degrees of angulation of the calcaneal tuberosity. Specimens were imaged using both the Harris axial view and the AP calcaneal profile view. Results: For cadavers with 10 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 10.9 ± 4.8 (range, 5.5-16.0) degrees and 13.0 ± 5.5 (range, 7.3-20.9) degrees, respectively. For cadavers with 20 degrees of actual varus angulation, the mean Harris view angle and the AP calcaneal profile view angle were 11.5 ± 2 (range, 8.2-13.6) degrees and 18.1 ± 4.8 (range, 11.7-23.5) degrees, respectively ( P = .005). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle ( P = .012) and actual angulation ( P = .011). For cadavers with 30 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 18.3 ± 4.3 (range, 13.3-23.6) degrees and 28.3 ± 2.9 (range, 24.4-31.1) degrees, respectively ( P < .001). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle ( P = .001) and actual angulation ( P < .001). There was no significant difference between the AP calcaneal profile view angle and actual angulation ( P > .999). Conclusion: The AP calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. While both views demonstrated similar measurement error for lesser degrees of varus malalignment, the AP calcaneal profile view demonstrated more accurate measurement of increasing heel varus compared with the Harris view. Clinical Relevance: The AP calcaneal profile view could be used in addition to other radiographic views when treating displaced, intra-articular calcaneus fractures to help optimize correction of hindfoot alignment.