Evaluation of Communication between the Equine Tarsocrural and Talocalcaneal Joints Using Intra-articular Contrast Enhanced CT and Methylene Blue Stain

Introduction: The objective of the study was to examine communication of the tarsocrural and talocalcaneal joints using intraarticular contrast enhanced CT and methylene blue dye.

Materials and Methods: Plain CT was performed on six paired cadaveric limbs from horses euthanized for reasons unrelated to tarsal disease. Limbs from each specimen were randomly assigned to a high or low volume group for injection. The tarsocrural joints were injected with a mixture of iodinated contrast and methylene blue stain via a routine dorsomedial approach. One was injected with 60 mL (high) total volume and the other was injected with 7 mL (low). Repeat CT following injection and flexion of the limb was performed. The tarsi were dissected to assess the methylene blue staining of the talocalcaneal cartilage.

Results: On CT, contrast was noted to fill the tarsal sinus and surround the talocalcaneal joint facets in all 12 limbs. Discernable contrast between the articular surfaces of the talocalcaneal facets was only seen in 3/ 12 limbs and only within a single facet of each. Methylene blue staining of all talocalcaneal facets was present in 6/ 6 high volume limbs. For the low-volume limbs, the stain uptake was subjectively decreased when compared with the high-volume injection, 3/ 6 had minimal stain uptake in the medial facet.

Discussion/Conclusion: Methylene blue confirmed tarsocrural–talocalcaneal joint communication in all cases, the medial facet appears to have less direct communication. CT was poorly sensitive for detection of synovial communication within the talocalcaneal joint.

Acknowledgment: Funding was provided by the Center for Equine Health, University of California Davis.