Guillaume Lux, Abstract Co-Author: Nothing to Disclose

Alain Gilbert Blum MD, Presenter: Nothing to Disclose

Milena Rocha Souza MD, Abstract Co-Author: Nothing to Disclose

Pedro Augusto Gondim Teixeira MD, Abstract Co-Author: Nothing to Disclose

Benoit Osemont, Abstract Co-Author: Nothing to Disclose

Sophie Lecocq, Abstract Co-Author: Nothing to Disclose

Guillaume Oldrini, Abstract Co-Author: Nothing to Disclose

Matthias Louis MD, Abstract Co-Author: Nothing to Disclose

To demonstrate the feasibility of dynamic CT in the exploration of the subtalar joint during foot inversion and eversion. To describe the finding of dynamic CT of the subtalar joint in inversion and eversion in healthy and pathologic subjects. To describe new imaging criteria in the diagnosis of subtalar instability.  

15 healthy volunteers and 15 patients with hind foot pain following a sprain underwent dynamic CT of the subtalar joint. The examinations were performed on an Aquilion One® (Toshiba®), with low doses (DLP = 160 mGy.cm). Acquisition was performed 9 times successively, using the intermittent mode, while the movement was achieved in the supine position in 12 seconds. Adaptative Iterative Dose Reduction (AIDR®) was used to increase image quality despite the low dose. Image post-treatment was performed on dedicated console, with dynamic multi-planar reconstructions and dynamic volume rendering. The examinations were interpreted by two radiologists independently. The following measurements were acquired : -Frontal talocalcaneal angle -Uncovering of the posterior articular surface of the calcaneus -Amplitude between sustentaculum tali and medial posterior tubercle of the talus -Maximal talocalcaneal distance in antero-lateral and posterior position The quality of the analysis of bone and soft tissues was evaluated. Finally, the overall movement of the subtalar joint was assessed subjectively. 

Dynamic CT of the subtalar joint is feasible in routine in healthy and pathologic patients. Frontal talo-calcaneal angle was 18° on average in healthy subjects, 22° in case of suspicion of subtalar instability. Uncovering of the posterior articular surface of the calcaneus was slightly increased in pathologic condition. The other measurements showed no significant change. Despite the low doses, it was possible to depict small anomalies in bone or soft tissues. 

Dynamic CT of the subtalar joint allows biomechanical evaluation of the subtalar joint, which is particularly complex. It provides more objective criteria for the diagnosis of the subtalar joint pathology, particularly subtalar instability. This condition is difficult to assess clinically, and so far, there are no reproductible and reliable imaging criteria described in the literature.  

Dynamic CT of the subtalar joint is recommanded in patients with chronic pain following ankle sprain.

Lux, G, Blum, A, Souza, M, Gondim Teixeira, P, Osemont, B, Lecocq, S, Oldrini, G, Louis, M, Dynamic Computed Tomography of the Subtalar Joint.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11014420.html