Os trigonum/Stieda process

Findings

Active and passive plantar flexion is painful and the calcaneotibial compression test is positive.

Cause

The os trigonum, a separated ossification centre of the talus, is trapped between the upper surface of the calcaneum and the posterior tibia during forced plantar flexion. The Stieda process is a fused os trigonum that has produced an elongated posterior element of the talus.

Treatment

a)      Electrotherapeutic modalities to settle inflammation, such as interferential and pulsed shortwave.

b)      Cortisone to the posterior aspect of the talar joint and around the os trigonum.

c)      Surgery to remove the os trigonum or fragmented pieces.

Sports

a)      See posterior capsule

b)      Ballet dancers and high jumpers will require surgery to remove the os trigonum if this is a persistent problem. Other sports only need the acute episode treating conservatively.

Although not common, it can be very problematical for those requiring large degrees of plantar flexion, and surgery is probably the treatment of choice in these cases.

"Concise guide to sports injuries, 2^nd edition",Churchill Livingstone, Malcolm T.F. Read,  foreword by Bryan English