stress reaction calcaneus LSBU

Description: Clinical presentation: 30 year old woman with pain in the right ankle after her aerobics class.
There is a line of density that crosses the calcaneum a little anterior to the calcaneal tuberosity and roughly parallel to it. This line forms the line that lies just anterior to the tuberosity in the axial view. The tuberosity itself is thickened and irregular, although the tendon insertion will tend to reduce any lamellar periosteal bone reaction at the margin.
There are also normal lines of condensed cancellous bone that mark normal stress. These are of greater than normal density. These cross roughly at a obtuse angle. The first crosses from the upper part of the tuberosity to the lower anterior margin, just behind the cuboid. The second line crosses from the talo-calcaneal articulation to the lower end of the calcaneal tuberosity, the weight bearing part of the calcaneum. These lines indicate the varius forces resulting from a combination of compression forces through the talus and the pull of the long plantar fascia and achilles tendon, when the foot is extended or flexed.