Fibular displacement does not predict instability in type B ankle fractures

Area of Science:

• Orthopedic Surgery
• Radiology
• Sports Medicine

Background:

• Ankle fractures are common, yet optimal imaging for medial ligament injury in isolated type B fibular fractures remains debated.
• Accurate diagnosis is crucial for determining appropriate treatment and preventing long-term complications.

Purpose of the Study:

• To assess the utility of fibular fracture displacement on standard radiographs in predicting medial clear space widening on gravity stress views.
• To evaluate fibular displacement as a predictor of ankle instability in isolated type B fibular fractures.

Main Methods:

• Retrospective cohort study of 192 patients with isolated type B fibular fractures.
• Radiographic measurements included medial clear space (MCS), superior clear space (SCS), and fibular displacement on mortise and gravity stress views.
• Instability defined as MCS ≥ SCS + 3.0 mm on gravity stress radiographs; Receiver Operating Characteristic (ROC) curve analysis used.

Main Results:

• 29% of patients had unstable ankle fractures.
• Fibular displacement showed an Area Under the Curve (AUC) of 0.68 for predicting instability.
• A correlation coefficient of 0.41 was found between fibular displacement and MCS.

Conclusions:

• Fibular displacement on regular mortise views is an unreliable indicator of instability in type B fibular fractures.
• Fracture displacement should not be the primary parameter for diagnosing medial injury or deciding on operative treatment.
• Gravity stress radiographs are essential for accurate assessment of ankle instability.