Diagnostic Accuracy of Conventional Ankle CT Scan With External Rotation and Dorsiflexion in Patients With Acute Isolated Syndesmotic Instability.

BACKGROUND: Syndesmotic injury in an athletic population is associated with a prolonged ankle disability after an ankle sprain and often requires a longer recovery than a lateral collateral ligament injury. Although several imaging tests are available, diagnosing syndesmotic instability remains challenging. PURPOSE: To determine the diagnostic accuracy of conventional ankle computed tomography (CT) scans with the joint in external rotation and dorsiflexion and compare it with that of conventional ankle CT scans in a neutral position. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 2. METHODS: Between September 2018 and April 2021, this prospective study consecutively included adults visiting the foot and ankle outpatient clinic with a positive orthopaedic examination for acute syndesmotic injury. Participants underwent 3 CT scan tests. First, ankles were scanned in a neutral position. Second, ankles were scanned with 45° of external rotation, dorsiflexion, and extended knees. Third, ankles were scanned with 45° of external rotation, dorsiflexion, and flexed knees. Three measurements, comprising rotation (measurement a), lateral translation (measurement c), and anteroposterior translation (measurement f) of the fibula concerning the tibia, were used to diagnose syndesmotic instability in the 3 CT scans. Magnetic resonance imaging was used as a reference standard. The area under the curve (AUC) was used to compare the diagnostic accuracy, and Youden's J index was calculated to determine the ideal cutoff point. RESULTS: Images obtained in 68 participants (mean age, 36.5 years; range, 18-69 years) were analyzed, comprising 36 syndesmotic injuries and 32 lateral collateral ligament injuries. The best diagnostic accuracy occurred with the rotational measurement a, in which the second and third CT scans with stress maneuvers presented greater AUCs (0.97 and 0.99) than did the first CT scan in a neutral position (0.62). The ideal cutoff point for the stress maneuvers was 1.0 mm in the rotational measurement a and reached a sensitivity and specificity of 83% and 97% for the second CT scan with extended knees and 86% and 100% for the third CT scan with flexed knees, respectively. The ideal cutoff point for the first CT scan with a neutral position was 0.7 mm in the rotational measurement a, with a sensitivity of 25% and specificity of 97%. CONCLUSION: Conventional ankle CT with stress maneuvers has excellent performance for diagnosing subtle syndesmotic rotational instability, as it shows a greater AUC and enhanced sensitivity at the ideal cutoff point compared with ankle CT in the neutral position.

Posterior pilon fracture: Epidemiology and surgical technique.

OBJECTIVES: To review a case series of patients with posterior pilon variant fracture using a novel approach, focusing on demographic data, injury pattern, surgical results based on computed tomography (CT) scan, and short-term complications. DESIGN: Consecutive case series. SETTING: Level I trauma center. PATIENTS/PARTICIPANTS: Twenty-five patients with posterior pilon fracture. INTERVENTION: Posterior pilon fracture open reduction and internal fixation. MAIN OUTCOME MEASUREMENTS: Parameters measured included age, sex, type of fracture, surgical technique, anatomical reduction, and complications. RESULTS: Twenty-five patients sustained a posterior pilon fracture, accounting for 13.4% of all operatively treated ankle fractures with median follow-up of 21.7 months. The average age of patients was 42 years (22-62); 19/25 (76%) were female, and 6/25 (24%) were male. A modified posteromedial approach was used in 18/25 (72%) patients. Persistent syndesmotic instability was present in 11/25 (44%) patients after posterior malleolar stabilization. Quality of reduction was assessed under CT scan in 19 patients, with 15/19 (78.9%) having anatomic reduction. We report 2/25 (8%) patients with early wound problems and 7/25 (20%) with short-term complications during follow-up. CONCLUSION: Posterior pilon variant fracture appears to be less common than previously reported. Most fractures can be satisfactorily treated through a modified posteromedial approach. Albeit obtaining posterior malleolar fracture rigid fixation, syndesmotic instability was more prevalent than expected. The short-term complication rate was low. LEVEL OF EVIDENCE: Therapeutic level IV.