Correlation Between the Talar Tilt Angle and Hindfoot Varus in Medial Ankle OA

Abstract

Category: Ankle Arthritis Introduction/Purpose: Radiographically medial ankle osteoarthritis shows different features according to talar tilt which is known to an important determining factor in low tibial osteotomy surgery. However, little is known about the reason of this presentation. We hypothesized that the talar tilt angle and degree of hind foot varus might be correlated. Methods: We reviewed radiographs of 184 patients diagnosed with medial ankle osteoarthritis between May 2006 and February 2015. A total of 126 ankles in 97 patients diagnosed as Takakura stage 1–3b medial ankle osteoarthritis, were reviewed. We measured tibio-talar angle, talar tilt angle, tibial-anterior surface angle, and hindfoot alignment angle We divided the ankles into 4 groups according to tibio-talar angle by 10 degrees, and each group was further divided into 2 subgroups based on median talar tilt angle. We analyzed the correlation between talar tilt and hindfoot alignment angle in each group. We analyzed the differences in the hind foot alignment between the subgroups. Ankle radiographs of selected patients were measured by two observers to determine the interobserver reliability. One of the observers evaluated all radiographs twice to determine the intraobserver reliability. Results: The tibiotalar angle was strongly correlated with the talar tilt angle (r=−0.845), while there was no correlation between tibio-talar angle and hindfoot alignment angle(r=-0.595). Among the groups, tibio-talar angle of 70-80 showed a significantly different hindfoot alignment between the 2 subgroups (p=0.0187). In the rest groups, there was no significant difference between tibio-talar and hindfoot alignment angle. The interobserver and intraobserver reliability for all radiographic measurements was good to excellent Conclusion: We could find out a definite correlation between talar tilt and hindfoot alignment angle in certain degree of varus ankle OA, and no correlation between tibio-talar angle and hindfoot alignment, which might have a clincal relevance in determining the method of osteotomy surgery.