A forty-seven-year-old farmer felt being kicked in the left heel while he was running around a corner during an athletic event and he complained of difficulty in walking. He had always been healthy and there was no history of injury. On admission there was tenderness and a firm bean-sized mass palpated 5cm proximal to the Achilles tendon insertion. Squeezing the calf produced almost no plantar flexion of the foot. Roentgenographic examination of the left ankle revealed an area of ossification just at the site of the tumor about 0.5cm in diameter. There can be little doubt, in retrospect, that this was an avulsion fracture. Roentgenograms of the right Achilles tendon showed no ossification.
At operation the medial fibers of the tendon were ruptured partially and the avulsed fragments of the calcaneus were densely adherent to the lateral fibers of the tendon. The fracture was set in place and held with a wire. The ruptured tendon was repaired. With the knee in 40 degrees of flexion and the ankle in 20 degrees of plantar flexion, a cast of plaster was applied for four weeks, and followed by gradually increasing activity.
At review seven months after operation, he had no complaints regarding the left heel and no restriction of motion in any direction.
The avulsion fracture of the medial part of insertion of the calcaneal tendon may have been produced by a combination of muscle contraction, medial-sided stretch force produced by eversion stress and the existence of an osteophyte. After the avulsion fracture .the intact tendon fibers lateral to the fracture may have ruptured.