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Fractures of the Lateral Talar Process

- Discussion:
    - two processes, lateral & posterior, project from body of talus;
    - either process may be fractured, either as isolated injury or assoc w/ other ankle or talar injuries;
    - it is frequently confused w/ an ankle sprain;
    - non union is a frequent complication of displaced lateral process frx;
    - lateral process:
           - broad based, wedge shaped prominence of lateral talar body with an articular surface dorsolaterally for fibula and inferomedially for anterior aspect of posterior facet;
           - lateral talocalcaneal, cervical, bifurcate, and anterior talofibular ligaments originate from tip of this process;
    - mechanism of injury:
           - occur when the foot is dorsiflexed and inverted (such as occurs with "snow boarding")
           - shearing stress is transmitted from calcaneus to lateral process, causing frx of variable size which may enter into posterior facet;
    - associated injuries:
           - subtalar dislocation
           - verticle frx of medial malleolus
           - talar neck frx
    - classification: (Hawkins)
           - non articular chip fracture;
           - single large fragment involving both talofibular articulation & subtalar joint;
           - comminuted frx involving both articulations;

- Clinical Findings:
    - point tenderness over lateral process just anterior & inferior to the tip of lateral malleolus;
    - may resemble an ankle sprain;
    - pt may note persistent pain and loss of motion, if frx extends into posterior facet of subtalar joint

- Radiographs:
    - frx may involve up to 1/3 of posterior facet of subtalar and/or ankle joint;
    - note that radiographs will frequently underestimate the size of the frx fragment;    
    - Broden's medial & lateral oblique axial views will help evaluate posterior facet;
    - mortise view:
           - help define size of fragment & amount of articular involvement;
           - taking the mortise view in plantar flexion along with 20-25 deg of internal rotation will place the lateral process in profile, and will flex the forefoot out of the way;

- CT scan: allows accurate sizing and assessment of articular displacement of posterior facet;

- Non Operative Treatment:
    - size of frx fragment & degree of displacement will determine clinical outcome;
    - larger fragments will be more likely to involvle posterior facet;
    - undisplaced fractures: treated w/ non wt bearing cast immobilization for approximately 4-6 weeks;
    - nonunion is frequent complication of displaced lateral process frx that are treated non operatively;

- Operative Treatment:
    - unreduced, displaced frxs may lead to nonunion, w/ residual malalignment of the subtalar joint & persistent pain;
    - large fragments are treated w/ ORIF;
           - fractures larger than 1 cm and frx w/ more than 2 mm displacement probably should be treated surgically;
    - small comminuted fragments: treated with excision of fragments;

- Complications:
    - nonunion is frequent complication of displaced lateral process frx that are treated non operatively;
    - sub talar arthrosis:
           - whether treated operatively or non operatively, many patients will develop subtalar arthrosis & may require late sub-talar arthrodesis

Fracture of the lateral process of the talus: a review of thirteen cases.

Fracture of the lateral process of the talus: a report of thirteen cases.