Complications of hip replacement surgery are not common, but can occur. When complications occur, a repeat hip replacement, called a revision hip replacement, may become necessary to fix a problem with the implanted joint. The most common reason for requiring a repeat hip replacement surgery is dislocation of the hip replacement. While the risk of hip replacement dislocation has come down over the past decade, this is still the most common reason for requiring revision hip replacement.
Hip Replacement DislocationHip replacement dislocations occur when the ball of the ball-and-socket replacement comes out of the socket. While it is often possible to reposition the hip replacement without a surgical incision, the chance of additional dislocations or damage to the implants is high. Therefore, hip replacement dislocation is the most common reason why a revision hip replacement is performed.
Determining why the hip joint dislocated is important to determine the appropriate treatment. Possible reasons for a hip replacement dislocation include the type of implant used, the positioning of the implant in the body, traumatic injury, or underlying medical conditions the patient has (for example, Parkinson's disease). Once the cause of the dislocation is determined, appropriate treatment can be recommended, which may include revision hip replacement.
Preventing Hip Replacement DislocationsRecent studies have investigated why a given patient may be more likely to experience hip replacement dislocation. Not all factors can be controlled; for example, a patient with Parkinson's disease cannot lower their risk of dislocation by changing their condition. Another factor that cannot be controlled is age; patients over the age of 85 had a higher chance of hip replacement dislocation. However, there are factors that have been shown to contribute to hip replacement dislocation that can be controlled:
- Implant Size
Femoral head size, or the size of the ball of the ball-and-socket, can be increased to help prevent dislocation of the hip replacement. Larger sized femoral heads are less likely to dislocate from the socket. Using special implants, such as metal-on-metal hip replacements, allows your surgeon to use a larger size femoral head, and thus lower dislocation risk. Femoral head size options have increased dramatically in the past decade.
- Surgeon Experience
Another factor to control hip replacement dislocation is surgeon volume. Surgeons who perform less than 5 hip replacements a year have a much higher chance of having a patient with a hip replacement dislocation. On the other hand, surgeons performing more that 50 hip replacements each year have a much lower chance of having a patient have a hip replacement dislocation.
Bottom Line: What Should I Do?Patients undergoing hip replacement should be aware of the potential risk of dislocation of the hip replacement. In patients who are most at-risk for sustaining a dislocation, special implants may be selected to help prevent the chance of this complication. If a hip replacement dislocation does occur, a careful assessment of the cause of this complication should be performed.
"Surgeon volume, femoral head size are factors in reducing dislocation risk" AAOS Now; February 2010.