Post-traumatic arthritis is arthritis of the hip joint that develops after an injury. The injury can be a severe contusion to the hip or a fracture of one of the bones within or near the joint. A hard bruise to the hip joint or fall on the hip may not always cause a visible fracture in bone. It can, however, cause an injury to the surface or articular cartilage of the joint. The damaged surface no longer moves smoothly and the joint deteriorates and develops arthritis. Articular injuries are hard to diagnose because the joint surfaces cannot be seen on plain x-ray. Injuries to the joint may sometimes be diagnosed on MRI.
Other times, the joint injury can present as prolonged pain and stiffness with no positive radiologic findings at all. Months or years later, arthritis can develop and the severity of the joint injury is evident. Most often post-traumatic arthritis develops after a fracture in or around the hip. Fractures through the head of the femur are unusual but can occur either as an isolated injury or in combination with a dislocation. Fractures into the hip joint socket, the acetabulum, are more common. Either of these injuries results in a damaged joint surface and can lead to post-traumatic arthritis. Arthritis can also result from fractures that do not directly involve the joint.
Examples are an intertrochanteric fracture of the hip or a fracture of the long portion or shaft of the femur. Even though the fracture heals away from the joint, the shape of the femur may change and this can lead to altered mechanics in the joint. Some parts of the joint may develop abnormal pressure and subsequent arthritis. Since it results from injury, post-traumatic arthritis is most often unilateral or involves one hip only. Injuries to both hips are less common. They usually result from high velocity trauma such as an automobile accident. Post-traumatic arthritis can develop following a low impact osteoporotic fracture in the elderly.
The incidence is lower in these fractures because elderly people place less demand on their hips and have a shorter life span in which to develop the arthritic symptoms. Hip replacement in post-traumatic arthritis is different than a routine primary total hip. If there has been previous surgery, there may be hardware which needs to be removed. Scar tissue may be present which makes dis-section more difficult. A fracture deformity of the femur may make it harder to place standard components. A defect in the acetabulum may require a bone graft. In general, the symptoms of post-traumatic arthritis are similar to osteoarthritis, but the surgery can some-times be a little more difficult.