Hip Replacement Dislocation

Hip replacement surgery is very successful; pain relief and increased ability to perform routine activities are among the best benefits of this procedure. Unfortunately, hip replacements have some potential complications. These complications are uncommon, but they do occur--sometimes in unforeseen circumstances. Among the most frequently seen complications of hip replacement surgery is dislocation of the hip replacement. Hip replacement dislocations occur in about 4% of first-time surgeries, and about 15% of revision hip replacements.

How do hip replacements work?

Hip replacements are most commonly performed in patients with severe arthritis of the hip joint. The hip replacement uses a metal and plastic implant to replace the normal ball-and-socket hip joint. By removing the worn out bone and cartilage of the hip joint, and replacing these with metal and plastic, most patients find excellent pain relief and improved motion of the hip joint.

Why do hip replacement dislocations occur?

Normal hip joints have many surrounding structures that help to stabilize the hip joint. These structures include muscles, ligaments, and the normal bony structure of the hip joint. Together, these structures keep the ball (the femoral head) within the socket (the acetabulum). When the hip replacement surgery is performed, the hip becomes less stable. By loosing some of these hip stabilizers, the metal and plastic hip replacement is prone to "coming out of joint," or dislocating.

What happens when a hip replacement dislocation occurs?

Patients who have a hip replacement are instructed on hip precautions. Hip precautions are various maneuvers a patient who has undergone a hip replacement needs to avoid. Hip precautions include:

• Do not cross your legs
• Do not bend our legs up beyond 90 degrees
• Do not sit on sofas or in low chairs
• Do not sleep on your side

Most physicians ease these precautions after rehabilitation, but total hip replacements are less stable than normal hips even years after surgery.

These activities place the hip joint in a position where the ball may fall out of the socket. Sometimes hip replacements are more prone to hip dislocation. Factors that can contribute to hip replacement dislocations include:

• Malpositioning of the hip replacement implants
• Revision hip replacements
• Excessive alcohol intake
• Neuromuscular problems (e.g. Parkinsons disease)
• Developmental hip dysplasia

Sometimes patients have no identifiable cause for their sustaining a dislocation of their hip replacement.

What is the treatment of a hip replacement dislocation?

Hip replacement dislocation treatment depends on several factors. The first step is usually to reposition the hip joint. This procedure, called a reduction of the hip replacement, is performed under anesthesia--either light sedation in the emergency room, or general anesthesia in the operating room. During the procedure, your orthopedic surgeon will pull on the leg to reposition the hip within the socket.

Most often the hip "pops" back into position. X-rays will be obtained to ensure the hip is repositioned and to see if there is any identifiable reason for the dislocation. If multiple dislocations occur, surgery may be necessary to prevent further dislocations. The implants can be repositioned, or special implants can be used to try to prevent further dislocations. You will need to discuss with your orthopedic surgeon the cause of your dislocation, and what treatments are available for the problem.

_Sources:

_{Soong M, et al. "Dislocation After Total Hip Arthroplasty" J. Am. Acad. Ortho. Surg., September/October 2004; 12: 314 - 321.}