- 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;
-
diff dx of posterior ankle pain:
-
embryology:
- posterior process arises from 2ndary ossification center that fuses w/ talar body at about age 12;
- os trigonum is relatively frequently seen accessory bone of foot found just posterior to lateral tubercle of posterior process;
- it may be considered a non united portion of the lateral tubercle;
-
anatomy of posterior process:
- comprised of 2 tubercles: medial & lateral;
- undersurface of tubercles comprise posterior 25% of posterior facet of the subtalar joint;
-
FHL runs between these tubercles, and can be have synovitis in this area (ballet dancers);
-
lateral tubercle serves as attachment of posterior talo-fibular ligament;
- lateral tubercle has an articular surface, & frx thru this tubercle is often associated w/ arthrosis;
-
medial tubercle:
- serves as attachment for posterior 1/3 of deltoid ligament;
- serves as the medial limb of the bifurcate talocalcaneal ligament inferiorly;
- Frx of Lateral Tubercle of Posterior Process (Sheppard's Frx):
- inversion of ankle may avulse tubercle leaving
PTFL intact;
- frx may also occur when ankle is forced into extreme equinus;
-
clinical findings:
- patients will present with ankle sprain symptoms:
- posterolateral ankle tenderness may be elicited;
- decreased & painful motion of ankle and subtalar joints;
- active flexion of great toe may also produce pain as
FHL moves over fracture site (between medial & lateral tubercles;)
- lateral tubercle has an articular surface, & frx thru this tubercle is often associatted w/ arthrosis;
- Frx of Medial Tubercle:
- look for tenderness and perhaps a mass just posterior to medial malleolus and pain w/ motion of great toe (due to motion of FHL);
- treatment may involve excision of the the fragment;
- Radiographs:
-
lateral x-ray:
- postero-lateral tubercle is seen in profile;
-
os trigonum may be seen just posterior to lateral tubercle
of posterior process (bilateral in 60%);
- Treatment:
- minimally displaced fractures are treated w/ short leg cast for 4 to 6 weeks;
- some suggest casting in 15 deg of plantar flexion;
- Complications:
- nonunions are uncommon:
- pt will note persistent pain, esp w/ extreme plantar flexion & limitation of subtalar motion;
- surgical excision of the ununited fragment thru a posterolateral ankle arthrotomy may relieve the pain;
Excision of ununited fractures of the posterior process of the talus: a treatment for chronic posterior ankle pain.
BL Veazey et al. Foot Ankle. Vol 13. 1992. p 453-457.
Avulsion fractures of the medial tubercle of the posterior process of the talus.
Diagnosis of medial tubercle fractures of the talar posterior process using oblique views.
Use of a 30-Degree External Rotation View for Posteromedial Tubercle Fractures of the Talus.
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