Hip Disorders

Treatment Options

Hip Resurfacing
Total hip resurfacing arthroplasty is a type of total hip replacement where the femoral component is placed upon the femoral neck. This is in contrast to standard hip replacements where the femoral neck is cut and a stem is placed into the proximal femur. The bearing surfaces (the pieces that contact one another) for current resurfacing total hip replacements are metal and are machined to very high tolerances to minimize the amount of debris in the joint. These so called “metal on metal” bearings are also used with some standard total hip replacements. Metal on metal bearings have been used in total hip replacement for greater than 30 years.

Studies have shown that metal on metal bearings produce detectable amounts of ions in the liver, kidney, and urine. In spite of this, there have been no cases of cancer reported as a result of the metal on metal hip replacements up to now. Metal on metal bearings allow the surgeon to use larger diameter femoral and acetabular components which leads to a improved range of motion and potentially a lower dislocation rate.

The additional benefit (and more important benefit) of resurfacing total hip replacement is the preservation of native bone in the femur. This would minimize the risk of debris traveling down the bone leading to bone digestion (osteolysis). Also, if a patient with a resurfacing total hip has a fracture of the neck of the femur, in many cases, the hip can be treated with conversion to a standard total hip replacement. However, this benefit does come at a cost.

The major problems with resurfacing include the requirement of using a metal on metal bearing, the risk of loosening of the femoral component (in cases of large cysts or inadequate bone), and the technical difficulty of the surgery. The surgery is more challenging since the femoral neck remains intact and can obstruct the view of the hip socket (acetabulum).

Not all patients are candidates for resurfacing total hip replacement. In particular, patients who have large cysts in the femoral head or hip socket, low bone density, those with a great degree of deformity, or extensive bone spurs around the hip socket would be best treated with a standard hip replacement. In house research center has made dramatic advances in computer aided custom instrumentation designed to clip onto the individual patient anatomic structure and act as a reference guide to implement the pre-surgical plan.



FAQ - Hip Resurfacing

• What is the difference between a standard hip replacement and a resurfacing total hip replacement?
• Most contemporary metal hip replacements are made of titanium alloys or cobalt-chromium alloys. The best way to understand the implants used in current replacements is to divide them into two parts. First is the metallic components that are directly fixed to the bone. These can be either through the use of cement (mostly on the femur or thigh-bone) or through a cementless or ingrowth process where the bone actually grows onto the metal. The second part of the hip replacement is made of the parts that actually move relative to one another (the bearing). These can be made of either metal on polyethylene plastic (most common) or other bearings such as ceramic-on-ceramic or metal-on-metal.
  
  
• How long will I be in the hospital?
• In most cases, patients remain in the hospital at our facility for a minimum of 2 days and usually 3-4 days.
  
  
• Can I put my full weight on the leg after a resurfacing total hip replacement?
• In most cases of ingrowth prostheses, we restrict the amound of weightbearing on the leg for 4 to 6 weeks. This has been shown to lead to decreased risk of the stem collapsing into the femur
  
  
• What are the advantages of the resurfacing total hip replacement ?
• The greatest advantage to the resurfacing hip replacement is the preservation of the patient's bone. By maintaining as much bone as possible in the femoral neck, there is a potential for the bone to continue to be loaded mechanically. This is theorized to lead to increase mineralization in the bone and avoid a complication known as "stress shielding" where the bone that is bypassed with a metal implant is not loaded and can ultimately lose its mineralization as seen by radiographs. Additionally, in the young patient, preservation of the bone can provide increased options in the future in the event of implant failure over the years or in case of trauma.
  
  
• What are its disadvantages?
• The biggest disadvantage of resurfacing hip replacement is the exposure of patients to increased levels of metal ions as a result of the metal on metal joint. In spite of higher measured levels of the metal ions, no cases of cancer have been reported directly related to metal on metal hip replacements in spite of greater than 30 years of clinical use.
  
  
• Do resurfacing total hip replacements wear out?
• Metal on metal hip replacements such as resurfacing total hip replacements can wear out. Their rate of wear is lower than that measured from standard metal on polyethylene hip replacements. At the current time, it is not known how long the expected implant survival would be for a resurfacing total hip replacement.
  
  
• What kind of activity level can I resume after the resurfacing total hip replacement?
• Patients with resurfacing hip replacements are not given any specific activity restrictions. However, just like a standard hip replacment, damage can be done to the hip by excessive activity and impact loading activities. These may ultimately lead to a shorter survival of the implant.
  
  
• Do I have to follow any other precautions after my surgery?
• You will be kept on crutches or a walker for the first 3-4 weeks after the surgery unless specified differently by your physician.
  
  
• Do resurfacing hip replacements dislocate?
• A dislocated hip can occur during activities in which the precautions are not followed or as a result of soft-tissue laxity or impingement. Impingement is a situation where the component or bony structures contact each other in such a way that they push the hip out of socket. Although resurfacing total hip replacements are very stable and not prone to dislocation, they still can dislocate if the patient goes into a very high degree of bending or twisting at the hip.
  
  
• What about the metal ion issue?
• Metal ions are released from every type of hip replacement. Metal on metal bearings such as those used in resurfacing hip replacements are associated with higher levels of metal ions. However, there have never been any cases of cancer directly related to the metal on metal prosthesis in spite of over 30 years of use. We would not recommend metal on metal total hip replacements for patients with liver or kidney disease or the potential for developing such disease.
  
  
• What are the long term results with the resurfacing total hip replacement compared to standard hip replacements?
• A number of reports have shown no difference in the early term results between the resurfacing and standard hip replacements. However, resurfacing is technically more demanding and may be associated with more complications. At this point, it is not clear if the benefits of resurfacing outweigh the risks associated with the procedure.