Freiberg's Infarction

This is a form of avascular necrosis. It is idiopathic (possibly post-traumatic). The process typically affects the second metatarsal head and is unilateral.
A AP radiograph of the foot. The typical appearance of Freiberg's infarction.

Links to online textbooks

Wheeless' Orthopedics: discussion of Freiberg's disease

References:

Freiberg AA, Freiberg RA: Core decompression as a novel treatment for early Freiberg's infraction of the second metatarsal head Orthopedics. 1995 Dec;18(12):1177-8. [See related articles]
Sproul J, Klaaren H, Mannarino F: Surgical treatment of Freiberg's infraction in athletes Am J Sports Med. 1993 May-Jun;21(3):381-4. [See related articles]