FRACTURES OF THE TALUS

A i.e Avascular necrosis

A i.e. Osteoarthritis of ankle; C i.e. Avascular necrosis of body os talus

Fracture Talus (Neck)

–  Talus is the major weight bearing structure (the superior articular surface carries a greater load per unit area than any other bone in body), and it has a vulnerable blood supply and is a common site for post traumatic ischemic necrosis.

–  The body of talus is supplied mainly by vessels which enter the talar neck from the tarsal canal. In fractures of the talar neck these vessels are divided; if the fracture is displaced the extraoseous plexus too may be damaged and body of talus becomes ischemic.

–  Fracture of the talar neck is produced by violent hyperextension of ankle. Body of talus fracture is usually a compression injury due to fall from height.

Complications

• Avascular necrosis of body is most continonQ complication. The incidence varies with the severity of displacement: in type I < 10%, in type II – 40% , in type III >90%.
• Malunion predispose to osteoarthritis.
• Secondary Osteoarthritis of ankle and /or subtalar joint occurs some years after injury in over 50% of patients. There are several causes : articular damage d/t intial trauma, malunion, distortion of articular surface and AVN.

Hawkins Classification

Treatment

– Below knee cast with foot in plantar flexionQ X 4 weeks Further plaster change will allow the foot to be brought up slowly to plantigrade Close / open reduction & internal fixation

Proximal surface of cuboid articulates with calcaneum, distal surface with 4th and 5th metatarsal and medial surface articulates with lateral cuneiform bone.

Ans: D i.e. Talus

Because of the poor blood supply, after a fracture through the neck, the body of talus becomes avascular

Ans. B i.e. Talus fracture

Fracture through neck of femur, neck of talus and waist of Scapho d can lead to AVN

 Plantar calcaneonavicular ligament

• Spring ligament (Plantar calcaneonavicular ligament) connects the calcaneum with the navicular bone. o However, its principal job is to provide a sling for the talus, to support the head of talus (though it has no attachment to talus).
• This aids in supporting the weight of the body.
• Weaknes or lengthening along this ligament can cause flat foot.

Ans. A. Spring ligament 

Spring Ligament

• The plantar calcaneonavicular ligament (also known as the spring ligament) is a ligament on the underside of the foot that connects the calcaneus with the navicular bone.

Structure

• The plantar calcaneonavicular ligament is a broad and thick band of fibers, which connects the anterior margin of the sustentaculum tali of the calcaneus to the plantar surface of the navicular.
• This ligament not only serves to connect the calcaneus and navicular, but supports the head of the talus, forming part of the articular cavity in which it is received.
• The dorsal surface of the ligament presents a fibrocartilaginous facet, lined by the synovial membrane, and upon this a portion of the head of the talus rests.
• Its plantar surface is supported by the tendon of the tibialis posterior; its medial border is blended with the forepart of the deltoid ligament of the ankle joint.
• The plantar calcaneonavicular ligament helps to maintain the medial longitudinal arch of the foot, and by providing support to the head of the talus, bears the major portion of the body weight.