Hip Replacement Purpose
Hip replacements are most often performed in patients with severe arthritis of the hip joint. The hip replacement uses a metal and plastic implant (sometimes ceramic) 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.
Hip replacement surgery is generally very successful. Pain relief and increased ability to perform routine activities are among the consistent benefits of this procedure.
Dislocations of Hip Replacements
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 can become less stable. By losing some of these stabilizing hip structures, the metal and plastic hip replacement can, in some cases, be prone to “coming out of joint,” or dislocating.
People who have a hip replacement may be instructed to take hip precautions. Hip precautions are various maneuvers a patient who has undergone a hip replacement needs to avoid and are based on the type of surgery they had. These physical activities place the hip joint in a position where the ball could fall out of the socket.
Most physicians ease these precautions after rehabilitation, but total hip replacements can be less stable than normal hips even years after surgery.
Do not cross your legsDo not bend your legs up beyond 90 degreesDo not sit on sofas or in low chairsDo not sleep on your side
Risk Factors
Sometimes hip replacements are more prone to dislocation. Factors that can contribute to hip replacement dislocations include:
Malpositioning of the hip replacement implants Revision hip replacements Excessive alcohol intake Neuromuscular problems (such as Parkinson’s disease)
In some circumstances, patients have no identifiable cause for sustaining a dislocation of their hip replacement.
While pain relief is almost immediate after the hip implants have been repositioned, many people who have sustained a hip dislocation complication are anxious the problem may occur again.
Treatment
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 dislocations. You will need to discuss with your orthopedic surgeon the cause of your dislocation and what treatments are available for the problem.
New Prevention Approaches
Recent developments in the design of hip replacement implants and the surgical technique of performing a hip replacement may also lower the chance of developing this complication. Implant design can be changed to create a more stable implant.
Implant Design
The most common design changes of implants that help prevent dislocation include:
Larger implants: When the ball of the ball-and-socket hip joint is larger, it is less likely to come out of the socket. Some newer implants use a ball that is over 3 centimeters in diameter. The downside of using a larger ball may be some trade-off in the longevity of the implants. More mobile implants: There are implants designed to allow for a broader range of motion of the ball and socket. One of these implants is called a dual mobility cup. These implants allow motion at two separate segments, increasing the mobility needed for the ball to come out of the socket. More constrained implants: Constrained implants are seldom used, but in situations where dislocation is a recurrent problem, they may be helpful. These implants are linked together so that the ball is connected within the socket. The downside of these implants is that the risk of significant failure is increased.
Changes in implant design need to be approached with caution, as there can be problems with newer implants, which may not have a long track record of use in patients. While these implants may lower the chance of dislocation, you’ll also want to be sure they don’t cause other problems.
There have been some high-profile implant recalls affecting implants that were specifically designed to last longer with less chance of dislocation. Ultimately, unfortunately, these implants were shown to be less successful.
Anterior Approach
Anterior approach hip replacement is a surgery performed to minimize the trauma to some of the structures that stabilize the hip joint. Many surgeons feel that the risk of dislocation may be lower after this surgery compared to a traditional posterior hip replacement.
A Word From Verywell
Hip dislocation can be a major complication of total hip replacement surgery. Minimizing the risk of this complication can be accomplished with certain precautions and the use of specialized implants and surgical techniques.
However, dislocation can still occur. Fortunately, the chance of dislocation after hip replacement is quite small, but when it does occur it may require additional surgical intervention.
