Questions and Answers about Hip Replacement
What Does Hip Replacement Surgery Involve?
The hip joint is located where the upper end of the femur
meets the acetabulum. The femur, or thigh bone, looks like a long stem with a
ball on the end. The acetabulum is a socket or cup-like structure in the
pelvis, or hip bone. This "ball and socket" arrangement allows a wide
range of motion, including sitting, standing, walking, and other daily
During hip replacement, the surgeon removes the diseased
bone tissue and cartilage from the hip joint. The healthy parts of the hip are
left intact. Then the surgeon replaces the head of the femur (the ball) and the
acetabulum (the socket) with new, artificial parts. The new hip is made of
materials that allow a natural, gliding motion of the joint. Hip replacement
surgery usually lasts 2 to 3 hours.
Sometimes the surgeon will use a special glue, or cement, to
bond the new parts of the hip joint to the existing, healthy bone. This is
referred to as a "cemented" procedure. In an uncemented procedure, the
artificial parts are made of porous material that allows the patient's own bone
to grow into the pores and hold the new parts in place. Doctors sometimes use a
"hybrid" replacement, which consists of a cemented femur part and an
uncemented acetabular part.
Is a Cemented or Uncemented Prosthesis Better?
Cemented prostheses were developed 40 years ago. Uncemented
prostheses were developed about 20 years ago to try to avoid the possibility of
loosening parts and the breaking off of cement particles, which sometimes
happen in the cemented replacement. Because each person's condition is unique,
the doctor and patient must weigh the advantages and disadvantages to decide
which type of prosthesis is better.
For some people, an uncemented prosthesis may last longer
than cemented replacements because there is no cement that can break away. And,
if the patient needs an additional hip replacement (which is likely in younger
people), also known as a revision, the surgery sometimes is easier if the
person has an uncemented prosthesis.
The primary disadvantage of an uncemented prosthesis is the
extended recovery period. Because it takes a long time for the natural bone to
grow and attach to the prosthesis, people with uncemented replacements must
limit activities for up to 3 months to protect the hip joint. The process of
natural bone growth also can cause thigh pain for several months after the
Research has proven the effectiveness of cemented prostheses
to reduce pain and increase joint mobility. These results usually are
noticeable immediately after surgery. Cemented replacements are more frequently
used than cementless ones for older, less active people and people with weak
bones, such as those who have osteoporosis.