Hip Replacement Dislocation

A Possible Complication of Hip Replacement Surgery

hip replacement dislocation
X-ray of a dislocated hip replacement. Jonathan Cluett, M.D.

Hip replacement surgery is very successful; pain relief and increased ability to perform routine activities are among the significant benefits of this procedure. Unfortunately, hip replacement surgery has 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 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 (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.

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 becomes less stable.

By loosing some of these stabilizing hip structures, the metal and plastic hip replacement is prone to "coming out of joint," or dislocating.

People who have a hip replacement may be 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 dislocation. Factors that can contribute to hip replacement dislocations include:

In some circumstances patients have no identifiable cause for their sustaining a dislocation of their hip replacement.

People who sustain a hip dislocation will know immediately that something has gone wrong with their implant. Typically, any movement or effort at weight bearing is painful and difficult to perform. While pain relief is almost immediate after the hip implants have been repositioned, many people who have sustained a hip dislocation complication are bothered by the anxiety and uneasiness about this problem occurring again.

Treatment of Hip 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.

New Approaches to Prevent Dislocation

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. Changes in implant design need to be approached with caution, as there can be problems with newer implants that may not have a long track record of having be used in patients. While these implants may lower the chance of dislocation, you also want to be sure they don't cause other problems. There have been some recent high profile implant recalls that affected implants that were specifically designed to last longer with less chance of dislocation. Ultimately, these implants were shown to be less successful.  The most common design changes of implants that help prevent dislocation include:

  • Using larger implants. When the ball of the ball-and-socket hip joint is larger, it is less likely to come out of the socket. Older hip implants typically used a ball that was less than 3 cm in diameter. Some newer implants used a ball that is over 3 cm, making them less likely to come out of position. The downside of using a larger ball may be some trade-off in the longevity of the implants.
  • Using 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 joints, increasing the mobility needed for the ball to come out of the socket.
  • Using 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 longevity of the implants and the risk of significant failure is increased.

In addition, there are some new approaches to performing hip replacement. Specifically, 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. As a result of this lower likelihood of dislocation, often surgeons will recommend against using any hip precautions after anterior hip replacement.

A Word From Verywell

Hip dislocation is a major complication of total hip replacement surgery. Preventing this complication can be accomplished with certain precautions and the use of specialized implants and surgical techniques. However, dislocation can still occur, and when it does additional surgery may become necessary to prevent repeated dislocations. Fortunately, the chance of dislocation after hip replacement is quite small, but when it does occur it may require additional surgical intervention.

Sources:

Jones SA. "The prevention and treatment of dislocation following total hip arthroplasty: efforts to date and future strategies" Hip Int. 2015 Jul-Aug;25(4):388-92.

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