Anteroposterior x-ray of a 90-year-old man who recently underwent revision left total hip replacement surgery
Lateral x-ray of the patient
A 90-year-old man presents to the emergency department with left hip pain and inability to bear weight on his left leg. He was sitting in a chair putting on his shoes when he felt a “pop” in the left hip. Three weeks previously, he underwent revision left total hip replacement surgery by the posterior approach. X-rays of the hip show a posterior dislocation.
This case has been brought to you in partnership with the Journal of Orthopedics for Physician Assistants.
Submit your diagnosis to see full explanation.
Dislocation is one of the most common complications seen in the emergency department in patients with a recent total hip replacement (THR). The incidence is estimated to be 1% to 4%, and up to 70% of dislocations occur within the first month following surgery. Revision total hip arthroplasty has an even higher dislocation rate of up to 16%.
Risk factors for dislocation after THR include neuromuscular and cognitive disorders, female gender, THR after fracture, poor surgical technique, and posterior approach. The dislocation rate is 3.23% when the posterior approach is used, 2.18% when the anterior lateral approach is used, and 0.55% when surgery is done using the direct lateral approach.1 Meticulous closure of the joint capsule, short external rotators, and gluteal muscles have been shown to reduce the risk for postoperative dislocations when the posterior approach is used.
Treatment of a dislocated THR involves closed reduction with the patient under sedation. The patient’s medical record must be reviewed to determine which surgical approach was used. The surgical approach, physical examination, and x-ray findings help determine the direction of the dislocation and the necessary reduction maneuver. If adequate anesthesia can be achieved in the emergency department, a closed reduction may be attempted there. Often general anesthesia is required in the operating room to relax the hip muscles fully to facilitate reduction. Fluoroscopy is used in the operating room to help guide the reduction and confirm implant stability through range of motion after reduction.
For posterior hip dislocations, patients are advised to avoid flexion greater than 90 degrees, adduction, and internal rotation. A hip abduction brace, abduction pillow, or knee immobilizer are often used for 6 weeks after reduction to avoid these positions.
Recurrence rates depend largely on when the first dislocation occurs; a recurrence rate of 40% has been reported when the first dislocation occurs within 5 weeks of surgery, whereas the rate is nearly 60% when dislocation occurs later. Revision surgery is often necessary if 2 or more dislocations have occurred.2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Soong M, Rubash HE, Macaulay W. Dislocation after total hip arthroplasty. J Am Acad Orthop Surg. 2004;12(5):314-321.
- McKean J, Badylak J. THA Dislocation. Orthobullets. http://www.orthobullets.com/recon/5012/tha-dislocation. Updated April 16, 2016. Accessed April 19, 2016.