Hip Dislocation/Subluxation
Hip dislocations and subluxations are common in athletes and older adults, especially ones who have just undergone a total hip arthroplasty (THA), and can happen as a result of trauma. A hip dislocation occurs when the femoral head comes out of the acetabulum and a subluxation occurs when the femoral head does not completely translate out of the acetabulum. While it is very uncommon for the hip to completely dislocate, subluxations are more frequent but are inadequately recognized. Most of the hip dislocations are in the posterior direction, while anterior dislocations account for only 8% to 15% of the total dislocations. Dislocations and subluxations can occur by falling onto a flexed knee with the hip adducted or if the individual stops quickly and pivots on their weight bearing extremity. Individuals who have undergone a THA with a posterolateral approach are also more inclined to suffer a hip dislocation if the patient does not abide by the hip precautions. Individuals with a posterior dislocated hip usually present with a flexed, adducted, and internally rotated leg; whereas individuals with an anterior dislocation present with a leg that is externally rotated, abducted, and either flexed or extended. Treatment includes reducing the dislocated hip and then if there are no other complications, such as a fracture, the individual will be put on crutches until they are able to walk without pain. Physical therapy is also important to regain strength and normal function in the involved joint. This is a serious injury and the patient should be referred to a doctor in order to decrease complications or more injury to the joint and surrounding structures. Dislocations and subluxations many times result in fractures to the posterior acetabulum or the femoral so the individual should be referred for imaging.
Signs & Symptoms
Go to the hospital if this condition is suspected:
- Pain in the hip, thigh, or groin with movement
- Leg length discrepancy (involved leg will be shorter)
- Pain or numbness along the sciatic nerve distribution
- Leg may be internally or externally rotated and either flexed or extended depending on the direction of dislocation
Risk Factors
- Total hip arthroplasty
- Muscle weakness
- Involvement in contact or high impact sports
Important Questions
- Mechanism of injury
- Past surgeries
- Location of the pain
- If a pop or click was heard at the time of injury
- Sports involvement
Special Tests
- Leg length measurement
- Palpation
- Gait observation