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Avascular Necrosis and Related Disorders

FOOT AND ANKLE

FOOT

METATARSAL HEAD

Due to the collapsed appearance, Freiberg originally termed the process an infraction of the second metatarsal head, therefore, it is now often termed Freiberg's infraction. It is now known that the process is that of true osteonecrosis resulting in collapse. While the second metacarpal head is the most common, involvement of the third is not uncommon.

The demographics of Freiberg's disease is quite distinct. It is much more commonly observed in females than males, approximately 3-4:1. The average age range seen is 13-18 years of age and is most commonly unilateral .

The cause of Freiberg's infraction is trauma, either acute or chronic. It is thought that the second metatarsal is most commonly involved because of its relative length and fixation as compared to the rest of the metatarsals. High heels, most commonly worn by females combined with the microtrauma that they cause to the heads of the metacarpals is often is blamed for the onset of Freiberg's disease.

Clinically, as with other forms of osteonecrosis, local pain, swelling, and redness are typical. Restriction of motion at the involved joint is also seen. The symptoms may start out as mild, but may progress to a chronic debilatating state eventually.

If you see one Freiberg's infraction, you've seen them all, as they say. The radiographic signs are very consistent and typical as seen below.

Freiberg's of the second metatarsal

Freiberg's

The radiographic signs of Freiberg's infraction seen here include increased sclerosis, fragmentation and collapse/flattening of the second metatarsal. Other signs specific for this location include widening of the metatarsal head and widening and cortical thickening of the metatarsal shaft.

Freiberg's of the third metatarsal

Figure 3 illustrates AP and medial oblique views of a foot revealing Freiberg's disease of the head of the third metatarsal head with very similar radiographic changes as described in figures one and two.

Treatment is difficult. Some treatment regimes may include a felt donut cushion to ease pressure off the metatarsal head, ice to reduce pain and swelling, and ultrasound if there is no fragmentation. Properly fitted new shoes may be suggested if there is a history of routine use of high heel shoes.

NAVICULAR

Kohler's disease was thought by many to be avascular necrosis of the tarsal navicular primarily based on the radiographic signs. It is now a much more controversial subject. Kohler's disease is can be a very confusing and ambiguous entity due to uncertain etiology and often times vague symptoms. A history of trauma is only elicited in approximately 35% of cases and symptoms that correlate with the radiographic signs are very sporadic.

When a diagnosis of Kohler's disease is made, the typical patient is a young male, typically between 3 and 7 years of age. It is unilateral approximately 75% of cases.

The controversy of Kohler's disease stems from the fact that many authorities feel that this process is not a "disease" at all, but rather a process of altered, but completely normal, ossification of the tarsal navicular which leads to the radiographic appearance.

There are two main reasons for the idea that this often times is not osteonecrosis is the fact that 1) there are a lack of symptoms and 2) it is a self-limiting condition.

The radiographic appearance is sclerosis, overall flattening and deformity of the navicular. But, again, it's the associated signs and symptoms, as described that must be present for a confident diagnosis. MRI or bone scan may help confirm the diagnosis, but because of its self-limiting nature, it most likely is not warranted.


 

SESAMOIDS

Avascular necrosis of the sesamoids do not have an eponym to memorize, thank goodness. This condition is most present in active individuals commonly involved with dancing or running. Symptoms consist of focal pain, swelling and restricted range of motion. When it becomes revascularized, normal function and resolution of symptoms are expected.

 
   
 

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