A dislocated hip occurs when the femoral head (the top of the thigh bone) is forcefully pushed out of its natural resting place in the pelvis. This joint functions as a ball-and-socket, with the “ball” of the femur fitting snugly into the “socket” of the hip bone, called the acetabulum. Because the hip is one of the body’s most stable joints, a dislocation is a severe orthopedic injury that requires immediate medical attention to prevent serious long-term complications.
Anatomy and Common Causes of Dislocation
The hip joint’s stability comes from the deep fit of the femoral head into the acetabulum, supported by strong ligaments and surrounding muscles. Significant mechanical force is required to overcome these natural restraints. High-energy trauma is the primary cause of hip dislocations, with motor vehicle accidents being the most frequent scenario.
A common mechanism in a car collision is the “dashboard injury,” where the knee strikes the dashboard, driving the thigh backward and forcing the femoral head out of the socket. High falls or impact sports injuries also cause dislocations. Approximately 90% of these injuries are posterior dislocations, where the femoral head is pushed backward. Less commonly, the displacement can be anterior, with the ball moving forward.
Identifying the Symptoms
A dislocated hip typically results in immediate and intense pain. The injured person will be unable to stand or bear weight on the affected leg due to the disruption of the joint structure. A clear and visible physical deformity is one of the most telling signs of the injury.
In the most common posterior dislocation, the leg usually appears shortened and is rotated inward toward the opposite leg. Conversely, an anterior dislocation often causes the leg to be rotated outward. Swelling and bruising may develop quickly, and some individuals may experience numbness or tingling down the leg if nerves have been compressed during the injury.
Emergency Response and Initial Treatment
A hip dislocation constitutes a medical emergency, and the immediate response involves calling emergency services. No one should attempt to move or reposition the injured person or the limb before medical professionals arrive. Any attempt to manually correct the dislocation could cause further damage to surrounding nerves and blood vessels. The injured person should be kept as still and calm as possible while waiting for transport to a hospital trauma center.
Upon arrival at the emergency department, imaging tests, typically X-rays and sometimes a CT scan, are performed to confirm the diagnosis and check for associated fractures. The definitive initial treatment is a closed reduction, the physical maneuver to guide the femoral head back into the acetabulum without surgery. This procedure requires deep sedation or general anesthesia to relax the powerful hip muscles. Timely reduction is essential, ideally within six hours of the injury, to reduce the risk of long-term damage.
Recovery Outlook and Managing Long-Term Risks
After a successful reduction, the recovery phase begins with a period of restricted weight-bearing, often followed by extensive physical therapy. Rehabilitation focuses on rebuilding the strength of the hip muscles and gradually restoring the joint’s range of motion. The initial recovery can take several weeks, but full return to activity may take months, depending on the severity of soft tissue damage.
The most significant long-term risk following a traumatic hip dislocation is avascular necrosis (AVN), which occurs when the blood supply to the femoral head is damaged. Interruption of this blood flow causes the bone tissue to die, potentially leading to collapse of the femoral head and debilitating arthritis. The risk of AVN is directly related to how long the hip remains dislocated. Another concern is injury to the sciatic nerve, which can cause weakness or partial paralysis in the foot or ankle, though some recovery of nerve function is often possible.