[Illustration: FIG. 90.--Radiogram of Oblique Fracture of both Bones of Leg by indirect violence.]
There is usually considerable displacement, the weight of the lower portion of the limb causing it to fall backwards and to roll away from the middle line, and the traction of the calf muscles pulling up the heel and pointing the toes. The proximal fragment forms a projection on the front of the limb.
On account of the superficial position of the tibia and the pointed character of the fragments, this fracture is frequently rendered compound by the bone being forced through the skin. The projecting piece of bone is usually the distal end of the proximal fragment. This fracture is often comminuted. It has been observed that when the line of fracture forms the letter V on the subcutaneous surface of the tibia, there is invariably a fissure passing down along the back of the bone into the ankle-joint--a complication which adds to the risk of subsequent stiffness and impaired usefulness of the limb. Apart from this, the ankle is usually sprained in fractures by indirect violence, and we have frequently found the superior tibio-fibular articulation torn open in severe fractures of both bones of the leg from indirect violence.
_Clinical Features._--The tibial fracture is readily recognised by detecting an irregularity on running the fingers along the crest of the shin, and at this point abnormal mobility, tenderness, and crepitus can usually be elicited. It is often difficult to detect the fibular fracture, and it is not always advisable to attempt to do so, especially if the manipulations cause pain or tend to increase the displacement. The condition of the fibula is usually to be inferred by noting the amount of displacement and the extent of mobility of the tibial fragments. Not infrequently the seat of fracture may be recognised by locating a point at which pain is elicited on making pressure over the bone at a distance--pain on distal pressure.
On account of the close connection of the skin to the periosteum on the subcutaneous aspect of the tibia, the tension caused by extravasated blood is often extreme; blisters frequently form over the area of ecchymosis, and when these become infected, sloughing of the skin may take place and the fracture thus be rendered compound.