This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
Fractures of the ankle are usually the result of a force applied laterally, though sometimes a turning of the foot on the vertical axis of the leg may assist. The force applied causes fracture by inversion or eversion of the foot.
This is named after Sir Perci-val Pott, Surgeon to St. Bartholomew's Hospital, London, who described the injury, and was himself a victim of it. The French call it Dupuytren's fracture. It is produced by forcing the foot outward, or by having the foot firmly fixed and then bending the limb outward, thus breaking it at the ankle. The fibula is broken 4 to 7.5 cm. (1 1/2 to 3 in.) above its lower end and the ligamentum deltoideum (internal lateral) is either ruptured or the internal malleolus is torn off. Rarely the outer portion of the articular surface of the tibia may be torn off and displaced outward with the lower fibular fragment. It is to be noted that in this fracture the foot, with the small fragments of tibia and fibula, is practically loosened from the bones of the leg, and the muscles of the calf being unopposed pull the foot backward and upward. Therefore the displacement of the foot is not only outward, but also backward and upward (Fig. 573).
This is practically the opposite of the former and is not so frequent. The fibula is fractured by the traction of the external lateral ligaments which remain intact; it may break either above or below the strong inferior tibiofibular ligaments. The internal malleolus may also be torn off. The displacement is toward the inner side and upward and backward (Fig. 574).
In these fractures of the ankle replacement is often difficult and resultant deformities frequently cause considerable subsequent disability. For this reason especial efforts are to be made to reduce the displacement and maintain the fragments in proper position.
There are two main points of difficulty. The fractured ends of the fibula become displaced an-teroposteriorly and also in the fracture by ever-sion (Pott's) become pushed inward toward the tibia. The deep fascia of the leg is attached to the fibula and its sharp broken ends may get so fastened or caught in this fascia as to require an open incision before they can be freed sufficiently to allow of their proper replacement. Another difficulty is in the reduction of both the lateral and posterior displacement. Here it is necessary first to relax the muscles of the calf by flexing the leg on the thigh, then by pulling and direct pressure the foot can often be replaced. If this fails tenotomy of the tendo calcaneus (Achillis) is to be done, which relaxes the parts still more by releasing the pull of the soleus, the gastrocnemius and plantaris being already relaxed by flexion of the knee. This is sometimes necessary to prevent the persistent tendency of the foot to be drawn backward. After reduction not infrequently there is no further tendency to displacement, and the fracture box or any other simple means of retention is sufficient.
Fig. 573. - Pott's fracture of the fibula, showing eversion of the foot, point of fracture of the fibula, and tearing off of the point of the internal malleolus.
Fig. 574. - Illustrating fracture of the fibula by inversion of the foot.
In other cases it is better to place the leg in the Pott's position, viz., lying on its outer side with the knee flexed. For similar injuries, Dupuytren advised placing the leg on a straight internal lateral splint on a pad which extended from near the knee down to the seat of fracture. The leg was fastened near the knee to the upper part of the splint, and the foot which projected beyond the pad was drawn by bandages toward the lower part of the splint.