The lateral malleolar bony fleck classified by size and pathoanatomy: The IOFAS classification.

BACKGROUND: This study analyzes position of the peroneal tendons and status of the superior peroneal retinaculum (SPR) whenever a lateral malleolar bony flake fracture occurs. METHODS: Twenty-four patients had a lateral malleolar bony fleck on anteroposterior ankle radiographs, either in isolation or associated with other hindfoot injuries. We studied size of the bony flecks, presence or absence of peroneal tendon dislocation and pathoanatomy on CT scans. RESULTS: In 11 patients, a small bony fleck lies within the superior peroneal retinaculum and contiguous periosteum, which are stripped off the lateral fibula (Class II lesions). Tendons dislocate into the subperiosteal pouch thus formed, resembling Class I lesions without associated bony avulsion. Treatment for Class II is same as for Class I injuries. In 8 patients with a big bony fleck, tendons dislocate into the fracture site and SPR is intact (Class III lesions). In Class IV lesions, observed in 5 patients with 2-part calcaneal fracture/dislocation, SPR remains intact and peroneal tendons are not dislocated. The invariably large fleck results from the displacing lateral calcaneal fragment abutting against the fibula, whereas the dislocating tendons cause the bony avulsions in Classes II and III. CONCLUSIONS: Due to pathoanatomical differences, surgical approach and natural history of neglected lesions differ depending on size of the bony fleck. The SPR must not be incised in case of big Class III flecks.

Incidence and recognition of peroneal tendon dislocation associated with calcaneal fractures.

BACKGROUND: Questions abound regarding natural history and medicolegal implications of untreated peroneal tendon dislocation (PTD) associated with calcaneal fractures. METHODS: We retrospectively analyzed CT scans and anteroposterior ankle radiographs of 79 consecutive calcaneal fractures presenting over 4 years at a single institution. RESULTS: Nineteen patients (24%) had associated PTD, which was initially missed in 10 (53%). Bony fleck was present in 11 (13.75%). Soft tissue swelling at lateral malleolar level, present on radiographs of 18 tendon dislocators (95%), raises likelihood of PTD with increasing specificity the greater the swelling. In 6 patients, surgeons failed to identify on CT spontaneously relocated tendons that then peeped around the posterolateral fibula, a finding not appreciable on 3-dimensional volume-rendering. CONCLUSIONS: Despite a significant association of PTD with calcaneal fractures, it still passes unrecognized all too frequently. Anatomical fracture fixation does not guarantee stable tendon reposition. Further studies are required to elucidate functional outcome of untreated PTD.