Talus Fracture

Talus fractures are an orthopaedic urgent case due to the precarious blood supply.  They are usually as a result of high energy trauma.  You need to keep a keen eye out for them! They can be commonly associated with other foot and ankle fractures common.

Q: You are the ortho spr the next patient comes to A&E after sustaining a fall from height and is complaining of left ankle pain. What would you do?

A: Read on!

Mechanism:

Typically hyperdorsiflexion: talar neck impacts on distal anterior tibia: fall from height/RTA.

NB: pain, decreased ROM, variable swelling/ecchymosis. Ankle sprains (inversion/eversion) – can mask lateral process fractures (classic  – snowboarding)

Posterior process fractures (Shepard’s fractures) – FHL irritated. Tenderness of talonavicular joints: talar head fractures.

Vascular supply:

Limited vascular perforation: therefore high risk of AVN.

Anastomotic sling along inferior neck formed by Artery of the sinus tarsi (from DP and Peroneal arteries) and artery of tarsal canal – supplies body (from PT). Deltoid artery (from PT) – supplies medial 1/3 body. Dorsa neck branches (from DP) supplies portion of head. Posterior process vessels (from Peroneal arteries) – minor contributions to posterior process.

Imaging:

Canale view: foot in max plantarflexion and beam 15 degrees from vertical.

Ct: assess articular incongruity +- degree of communition +- incarcerated fragment.

Hawkins sign: subchondral osteopenia implies viability of subchondral bone. (this is with follow up and shows that there is potential to heal)

MRI: occult fractures +  – osteonecrosis.

Classification:

Talar neck:

Hawkins 1: non displaced talar neck fracture.  (on ct). (15% risk of osteonecrosis)

Hawkins 2: 1 + subtalar subluxation/dislocation. (40 – 50% risk)

Hawkins 3: 1 + subtalar + ankle dislocation. (nearly 100% risk)

Hawkins 4: 1 + subtalar + ankle + talonavicular subluxation/dislocation (100% risk)

Management:

Immediate – Analgesia. Bloods. Fluids. Backslab. Ct. (if open; follow BOAST guidelines).

Hawkins 1: Conservative – non weight bearing cast. Xr/Ct to confirm Hawkins 1 and no displacement: NWB for 6 weeks with regular radiographic fu to ensure no displacement.  – then removable brace.

Hawkins 2: ORIF recommended: occasionally reduced closed: Manoeuvre: knee flexion (relaxes gastroc), Full plantarflexion and traction of foot – brings head and neck in line: varus and valgus can be corrected with inversion/eversion!

Hawkins 2,3, 4: ORIF with interfragmentory lag screw technique: anteromedial incision: AP screws: Landmarks anterior-inferior medial malleolus, TA and TP tendons: incision in between. Anterolateral approach (less destructive to vasc supply). Posterior approach: PA screw and perhaps more perpendicular to fracture line.

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