Traction apophysitis of the fifth metatarsal base with an avulsion fracture
Iselin's disease is a traction apophysitis of the tuberosity of the fifth metatarsal. It occurs in physically active boys and girls between the ages of 9 and 14. It is caused by repetitive traction of peroneus brevis tendon at the site of its attachment. Clinically, there is a lateral midfoot pain aggravated by sports activities.
Differential diagnosis includes:
Normal apophysis: painless longitudinally oriented apophysis without fragmentation or widening of chondro-osseous junction.