Talar necrosis

Introduction The talus is necrotic. When the ankle joint is severely damaged, the blood supply to the talus is completely destroyed and avascular necrosis occurs. Eventually, the talus body collapses and deforms, causing ankle joint osteoarthritis.

Cause

Avascular necrosis of the foot is more common. The talus is the only bone in the whole body that has no muscles to stop and attach. When the ankle joint is severely damaged, the blood supply to the talus is completely destroyed and ischemic necrosis occurs. Eventually, the talus body collapses and deforms, causing ankle joint osteoarthritis. Therefore, prevention and early treatment of avascular necrosis of the talus have an important role in its function. The talus fracture is the main cause of talus necrosis. The other causes of talus necrosis account for only about 10%. Talus necrosis is related to the type of fracture, ie the extent of the injury:

Type I

The talus neck fracture was without dislocation, the ligament was not damaged, the blood supply was intact, and the talus necrosis rate was less than 10%.

Type II

The talar neck fracture combined with the dislocation of the upper and lower joints, the interosseous ligament is damaged, and the blood supply to the talus is reduced, and the necrosis rate is increased to 20% to 40%.

Type III

The talus neck fracture combined with the dislocation of the upper and lower joints, that is, the distance between the ankle and the distance. This type is rare. After dislocation, there may be only a few soft tissues attached to maintain blood supply. If it is not repaired in time, it is prone to ischemic necrosis, and the necrosis rate is as high as 70% or more.

The rate of avascular necrosis of the talus increases with the severity of the injury, apparently due to the destruction of the blood supply.

an examination

Related inspection

Bone and joint MRI examination of serum osteocalcin (BGP)

In addition to the history of trauma and clinical symptoms, the imaging of the right, lateral and oblique X-ray films is extremely important for diagnosis and classification. Diagnosis of ischemic necrosis can be made by relying on dense X-ray films. However, it should be noted that on the lateral radiograph, part of the talus is overlapped by the shadows of the inner and outer iliac crests. Because the shadow of the talus is relatively dense, the diagnosis of ischemic necrosis can be made only if there is density deepening at the position without overlap.

Mainly due to pain and limited activity, due to talar collapse deformation, articular cartilage surface damage, osteoarthritis, pain during activity; patients with pain and joint space narrowing lead to ankle joint flexion and extension activities are limited. Its typical x-ray performance is an increase in talus density, which is more than twice the normal bone density. In the late stage, the talus collapses and deforms, the shape becomes smaller and flattened, the bone is hardened, and the joint space is narrowed.

Differential diagnosis

Differential diagnosis of talar necrosis:

Talus fracture and dislocation: talus fracture and dislocation is a common injury in the foot. Its prognosis is not very satisfactory. It is necessary to understand the damage mechanism and its anatomy in order to achieve satisfactory therapeutic results. The talus fracture is rare, and it is often injured by direct violent crushing or indirect compression by high ground. The latter often combined with calcaneal fractures. A talus fracture, easy to cause non-healing or ischemic necrosis, should be diagnosed early.

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