Your Hip Surgery
There are many ways to treat the pain caused by arthritis. One way is total hip replacement surgery. The decision to have total hip replacement surgery should be made very carefully after consulting your doctor and learning as much as you can about the hip joint, arthritis, and the surgery.
In total hip replacement surgery, the ball and socket that have been damaged by arthritis are removed and replaced with artificial parts made of metal and a durable plastic material. We call these artificial parts "implants," or "prostheses."
Two Types of Hip Fixation
There are two main types of fixation philosophies-cemented and porous. Both can be effective in the replacement of hip joints. The physician (and the patient) will choose the best solution that is specific to the patient's needs.
Cemented Hip Implants
The cemented hip implant is designed to be implanted using bone cement (a grout that helps position the implant within the bone). Bone cement is injected into the prepared femoral canal. The surgeon then positions the implant within the canal and the grout helps to hold it in the desired position.
Porous Hip Implants
The porous hip implant is designed to be inserted into he prepared femoral canal without the use of bone cement. Initially, the femoral canal is prepared so that the implant fits tightly within it. The porous surfaces on the hip implant are designed to engage the bone within the canal and permit bone to grow into the porous surface. Eventually, this bone ingrowth can provide additional fixation to hold the implant in the desired position.
During Surgery
The patient is first taken into the operating room and given anesthesia. After the anesthesia has taken effect, the skin around the upper thigh is thoroughly scrubbed with an antiseptic liquid. An incision of appropriate size is then made over the hip joint.
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One type of implant that replaces the socket consists of a metal shell that is lined with a strong plastic liner. |
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Removing the Surface of the Socket
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The leg is maneuvered until the femoral head is dislocated from the socket. A special reamer is then used to remove the damaged cartilage and bone surface from the acetabulum, and to shape the socket so it will match the shape of the implant that will be inserted. |
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Inserting the Implant
The shell portion of the socket implant may be attached either by using a special kind of epoxy cement for bones, or by pressing the implant into the socket so that it fits very tightly and is held in place by friction. Some implants may have special surfaces with pores that allow bone to grow into them to help hold the implant in place. Depending on the condition of the patient's bone, the surgeon may also decide to use screws to help hold the implant in place.
When the shell portion of the socket implant is in place, the plastic liner is locked into place inside the shell.
Replacing the Ball Portion of the Joint
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The implant that replaces the ball consists of a long metal stem that fits down into the femur. The metal ball is mounted on top of this stem. |
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Removing the Ball
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A special power saw is used to remove the damaged femoral head. |
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Clearing and Shaping the Canal
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The upper leg bone has relatively soft, porous bone tissue around the center. This part of the bone is called cancellous bone. It surrounds the canal, which mainly contains blood vessels and fatty tissue. Special instruments are used to clear some of the cancellous bone from the canal, and then to mold the inside walls of the canal to fit the shape of the implant stem. |
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The stem implant may be held in place by either using the special cement for bones, or by making it fit very tightly in the canal. If cement is used, it is injected into the canal first, and then the implant is inserted into the canal. If cement is not used, the implant is simply inserted into the canal. Like the socket implant, the stem implant may have a special surface with pores that allow bone to grow into them.
On some implants, the stem and ball are one piece. On others, they may be two separate pieces. If the ball is a separate piece, it is usually secured to the top of the stem after the stem has been inserted.
When all the implants are in place, the surgeon places the new ball that is now part of the upper leg bone into the new socket that is secure within the pelvic bone. If necessary, the surgeon may adjust the ligaments that surround the hip to achieve the best possible hip function.
When the ligaments are properly adjusted, the surgeon sews the layers of tissue back into their proper position. A plastic tube may be inserted into the wound to allow liquids to drain from the site during the first few hours after surgery. After the tube is inserted, the edges of the skin are sewn together, and a sterile bandage is applied to the hip. Finally, the patient is taken to the recovery room.
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