MRI Characterization and Diagnosis of Individual Syndesmotic Structures in Asymptomatic and Injured Cohorts

OBJECTIVES: The purpose of this study was to characterize the MRI presentation of the distal tibiofibular syndesmosis in both asymptomatic volunteers and injured patients to define the optimal MRI sequencing image(s) for each structure and further improve clinical diagnostic sensitivity and reliability of common syndesmotic injuries. Additionally, we correlated the presentation of individual structures on MRI with anatomic investigations to assess the ability of MRI to reproducibly identify the individual syndesmotic structures and common pathology. METHODS: This study was IRB approved. Age-matched volunteers deemed asymptomatic by self-reported subjective measures, objective physical exam, and morphological MRI exam were analyzed to refine syndesmosis imaging and define the optimal MRI sequence(s) for the characterization of the individual articular structures. Twenty patients from the practice of one foot and ankle fellowship trained orthopaedic surgeon (initial blinded for review) between December 2009 through September 2013 were included. Preoperative 3.0 T ankle MR images (Magnetom Verio, Siemens Medical Solutions, Erlangen, Germany) from patients with suspected syndesmotic injuries and subsequent arthroscopic evaluation were retrospectively reviewed and analyzed. Patient MRI findings were correlated with arthroscopic surgery to calculate the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). To further the understanding of the distal tibiofibular syndesmosis and concomitant pathology, concurrent injuries to other structures of the ankle were recorded and reported. RESULTS: Analysis of asymptomatic volunteers allowed for the successful identification of optimal MRI sequences for the visualization of individual syndesmotic structures (Table 1). In the patient cohort, sequence-optimized MRI diagnosed pathology correlated strongly with arthroscopic surgery reports demonstrating excellent diagnostic sensitivity and specificity in the diagnoses of common clinically observed syndesmotic injuries (Table 1)(Figure 1). Rarely (20%), were isolated injuries to the syndesmosis reported either preoperatively on MRI or intraoperatively during arthroscopy. Concurrent fractures (medial/lateral/bi/tri malleolar, proximal/distal/maisonneuve fibular fractures, and attachment avulsions), additional ligamentous injury (deltoid sprains/tears), tendon tears (peroneus brevis), osteochondral lesions (distal tibia, dorsal/medial/lateral talus), and synovitis were frequently observed. CONCLUSION: Accurate diagnosis and subsequent treatment are paramount when dealing with syndesmotic injuries due to the chronic pain and instability that can result from misdiagnoses and inappropriate treatment. In this MRI characterization of syndesmotic structures and retrospective analysis of diagnostic accuracy, we demonstrate the capability of MRI to consistently visualize relevant individual syndesmotic structures and to diagnose frequently observed syndesmotic injuries with a high degree of sensitivity and specificity. We propose that the optimal MRI sequences/planes defined in this study be clinically implemented to aid in future pre-operative planning, to facilitate anatomic repair of the syndesmosis, and to assist in post-operative assessment of the ankle syndesmosis.