Frontal and lateral characteristics of the osseous configuration in chronic ankle instability

¹ Department of Radiology, University of Basel, Switzerland
² Department of Orthopaedic Surgery, University of Basel, Switzerland
³ Department of Orthopaedic Surgery, Kantonsspital Liestal, Switzerland

^* To whom correspondence should be addressed. E-mail: mail{at}arnofrigg.com.

Accepted 3 June 2008

	Abstract

Objective: The osseous ankle configuration (tibiotalar sector, talar radius and height) has been discovered as intrinsic risk factor for chronic ankle instability (CAI). These measurements were done on lateral radiographs only. The aim of this study was to measure osseous characteristics in the frontal plane and further lateral values.

Design: Case control study, Level III.

Setting: Radiological measurement of frontal and lateral radiographs by one independent, blinded radiologist using a digital DICOM/PACS system.

Patients: A group of 52 patients with CAI was compared to an age- and gender-matched control group of 52 healthy subjects.

Main Outcome Measurements: In the frontal plane: the depth of the talar curvature (froCu), the lateral and medial malleolar length. In the lateral plane: the position of the center of rotation to the tibial axis (TibCOR) and the lateral tibial surface angle (TLS).

Results: The froCu was deeper in patients with CAI (1.8±1mm) than in healthy subjects (1.0±0.4mm; P<0.05). The TibCOR was more anterior in patients with CAI (2.4±1.9mm) than in healthy subjects (1.5±2.2mm; P<0.05). The distance from the fibular tip to the center of rotation was smaller in patients with CAI (3.5±3.4mm) than in healthy subjects (6.5±3.3mm; P<0.05). The TLS, the length of the lateral and medial ankle were not significantly different.

Conclusions: This study supports that the osseous joint configuration is an intrinsic risk factor for CAI. It could be shown that CAI is characterized by a deeper frontal curvature of the talus and a more anterior position of the talus to the tibia.