The value of MR imaging in the diagnosis of the os trigonum syndrome.

Objective: The objective of this study was to evaluate the value of magnetic resonance (MR) imaging in the diagnosis of the os trigonum syndrome.
Design: Sagittal and coronal spin echo MR sequences of the ankle were acquired along with sagittal images in both dorsiflexion and plantar flexion.
Patients: Three consecutive patients presenting with posterior triangle pain were assessed.
Results and Conclusions: MR imaging delineated the anatomical site of the abnormality and demonstrated coexisting pathology in all patients. Flexion/extension MR images yielded additional information regarding the mobility of the os trigonum in one patient. MR imaging is the technique of choice for investigating the os trigonum syndrome.