Peroneal tendon dislocation - is the fleck sign being overlooked?

D. Gibson, A. Tucker, D. O'Longhain, J. Wong

Introduction: Peroneal tendon dislocation (PTD) is frequently overlooked and missed. The presence of a lateral malleolar bony fleck is a pathognomonic sign. Classification systems only describe the presence of small bony flecks, and we aimed to see if a new classification with a large bony fragment should be included.

Method: All calcaneal fracture admissions were retrospectively identified from a prospectively collated Fracture Outcomes Research Database (FORD) between (insert dates). CT scans were reviewed by two of the authors, to identify PTD, and the presence of a fleck sign. Radiographs, multiplanar reconstructed (MPR) CT images were reviewed and the fleck sizes measured, as well as using an integrated software programme (Vitrea, Toshiba, Holland). Interobserver agreement by way of Cohens Kappa was calculated.

Results: A total of 79 patients were identified. PTD was present in 20/79. Plain radiographs identified 14/20 (70%), the remaining 6 were seen on CT imaging. All flecks were appreciated on CT. Mean fleck size was 3420mm³ (range 2-19,152 mm³). Cohens Kappa for coronal, axial and sagittal measurements demonstrated statistically significant (p< 0.001) interobserver agreement (0.721, 0.764, 0.706 respectively). Use of the Vitrea software to perform volumetric analysis demonstrated a fleck size < 100 - 21,000mm³, with significant interobserver agreement (k=0.688, p< 0.01).

Conclusions: Our results demonstrate that the fleck sign is pathognomonic of PTD. The presence of a large fragment, as opposed to a “fleck”, would direct the surgeon to have to repair ORIF of the distal fibula and anatomical restoration of the ankle joint in managing these injuries.