- 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 upto 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 13 cases.
LG Hawkins.
JBJS-Am Vol 47. 1965. p 1170-1175.
Fracture of the lateral process of the talus: A report of 13 cases.
Mukherjee SK. et al.
JBJS. Vol 56-B. 1974 p 263-273.
