The goal of hip replacement surgery is to help regain natural hip function. Hip replacement surgery involves replacement of the damaged hip joint with an implant. Hip joint resembles a ball and socket joint where acetabular cup forms socket and head of femur bone rotates within the acetabular cup. During hip replacement surgery worn out acetabular component, femur head, or both may be replaced and these implants may be made up of different materials.
The implant comprises of acetabular cup and femoral head. Acetabular cup contains a shell and a liner. The ball, replacement for femoral head, will be attached to the stem. This ball attached to stem will then be placed into the socket and this forms the artificial hip joint. The site at which the movable parts of new hip joint unite to form a movable joint is called as ‘bearing’.
Types
Bearing is made of different materials and selection of the type of material (bearing surface) is very important. Different materials used for these implants are metal, ceramic, and polyethylene. Combination of these materials may also be used. Each of these bearing surfaces has their unique advantages and disadvantages. Therefore your surgeon decides on which bearing surface would be best for you. Your surgeon considers various factors such as your age, standard of living and body weight for selecting the bearing surface. One or more than one type of bearing may be used by your surgeon depending upon the durability, level of performance, wear resistance, and your personal needs.
Cross-linked Polyethylene
Cross-linked polyethylene</strong> is usually used for lining the acetabular cup. The acetabular cup and the ball will be made up of stainless steel, cast or wrought cobalt, or metal-alloy.
Advantages Of Cross-linked Polyethylene
- Better durability
- Non-toxic
- Proven long-term success results
proven long-term success results
- Better toughness that suits people of different lifestyles
Better toughness that suits people of different lifestyles
Disadvantages Of Cross-linked Polyethylene
Wear out over time causing inflammation and bone loss necessitating revision surgery.
Metal On Metal
Metal on metal bearings was commonly used earlier and advent of polyethylene surfaces replaced the metal-on-metal surfaces. However with increase in demand for better designs, stronger and long lasting surfaces metal-on-metal bearings regained their importance. In metal on metal implants the acetabular cup, lining and femoral head will be made of metals
Advantages Of Metal On Metal
- Larger femoral heads can be used and offer the convenience of greater range -of-motion
Larger femoral heads can be used and offer the convenience of greater range -of-motion
- Greater stability and minimal risk of dislocation
Greater stability and minimal risk of dislocation
- Minimal risk of inflammation and loosening of implant
Minimal risk of inflammation and loosening of implant
- Durability and release of particles into the body are better compared to polyethylene surfaces
Durability and release of particles into the body are better compared to polyethylene surfaces
Disadvantage Of Metal On Metal
Not suitable for those with metal sensitivity.
Ceramic
These bearings are available in two forms, a ceramic femoral head with a polyethylene liner, or a ceramic femoral head with a ceramic liner.
Advantages Of Ceramic
- Better lubrication and minimal friction
Better lubrication and minimal friction
- Better performance compared to polyethylene and metal-on-metal bearings
Better performance compared to polyethylene and metal-on-metal bearings
Disadvantages Of Ceramic
- Risk of fracture
- Ceramic implants are hard and brittle, it can crack
Ceramic implants are hard and brittle, it can crack
- Loss of more bone tissue because of size limitations
Loss of more bone tissue because of size limitations
- Costlier compared to other bearing surfaces
Costlier compared to other bearing surfaces
A total hip replacement is one of the most successful operations that orthopedic surgeons perform. A hip replacement is an elective surgery, which means patients decide if and when to have their hip replaced. As a physician, I never tell patients they have to have a hip replacement surgery, but many times surgery may offer the only possibility for pain relief. Although the surgery is elective, it is covered by most insurance companies; however, depending on your policy you maybe required to make a small co-payment. My philosophy is to give my patients as much information as they need to make informed decisions regarding their health and hip pain and then treat their hip pain according to their wishes.
A hip joint is basically a ball and socket joint. A hip replacement involves removing the ball (femoral head) and replacing it with a metal prosthetic ball. The femoral prosthesis is inserted into the hollow part of the femoral shaft. The socket of the pelvis is machined into a hemisphere and a metal hemisphere is inserted into the socket. The new metal ball and new metal socket form the new hip joint and allow the same and often times more motion than the native hip joint. The femoral and acetabular prosthesis are attached to your bones by creating a space in the bone that is slightly smaller than the metal prosthesis and then pressing the metal prosthesis into this tight space. Occasionally, the metal prosthesis is attached to the bone with bone cement. The parts are made of stainless steel, titanium, ceramic and/or polyethylene. I typically make an incision about 3-4 inches long for a hip replacement.
The purpose of this web page is to educate patients about the major aspects of hip replacement surgery. Many studies have shown that an informed patient will have less surprises and more satisfaction with their surgery. I do not intend to scare people away from getting their hip pain treated. Although the following information is a reasonable overview of what I consider the major aspects of hip surgery, it is not a substitute for a clinical consultation where I can directly answer your questions. If you would like more information, please schedule an appointment to see me.
These bearings are available in two forms, a ceramic femoral head with a polyethylene liner, or a ceramic femoral head with a ceramic liner.
Not suitable for those with metal sensitivity
Metal on metal bearings was commonly used earlier and advent of polyethylene surfaces replaced the metal-on-metal surfaces. However with increase in demand for better designs, stronger and long lasting surfaces metal-on-metal bearings regained their importance. In metal on metal implants the acetabular cup, lining and femoral head will be made of metals
Wear out over time causing inflammation and bone loss necessitating revision surgery.
Cross-linked polyethylene</strong> is usually used for lining the acetabular cup. The acetabular cup and the ball will be made up of stainless steel, cast or wrought cobalt, or metal-alloy.
Cross-linked polyethylene
Bearing is made of different materials and selection of the type of material (bearing surface) is very important. Different materials used for these implants are metal, ceramic, and polyethylene. Combination of these materials may also be used. Each of these bearing surfaces has their unique advantages and disadvantages. Therefore your surgeon decides on which bearing surface would be best for you. Your surgeon considers various factors such as your age, standard of living and body weight for selecting the bearing surface. One or more than one type of bearing may be used by your surgeon depending upon the durability, level of performance, wear resistance, and your personal needs.
The implant comprises of acetabular cup and femoral head. Acetabular cup contains a shell and a liner. The ball, replacement for femoral head, will be attached to the stem. This ball attached to stem will then be placed into the socket and this forms the artificial hip joint. The site at which the movable parts of new hip joint unite to form a movable joint is called as ‘bearing’.
