How to choose hip Joint Prostheses?
How to choose hip Joint Prostheses is very important for patients who are going to have hip replacement or who are going to have hip replacement later.
The process of hip replacement
In hip joint replacement, the femoral head should be removed first. Then put the cup into the filed acetabulum. Sometimes the cup is fixed on the acetabulum bone with 1-3 screws.
Then place a piece of "plastic" (this "plastic" is called polyethylene), metal or ceramic lining inside the acetabulum cup.
The femur (thigh bone) is inserted with a metal handle, and then a ball is installed at the top. The ball can range in diameter from 28mm to 58mm and is made of metal or ceramic. The ball is put into the cup and a new joint is created.
In terms of fixation, the orthopedic doctor may choose to fix the hip joint prosthesis on your own bone safely by using bone cement or biological fixation of "bone growth".
Orthopedic surgeons will choose the design of prosthesis and the size of femur ball before operation to meet the maximum range of motion and the best joint function of patients after operation!
At present, there are several different kinds of hip joint prosthesis implants available in the world. Each joint prosthesis uses different materials with different advantages and disadvantages.
Types of hip joint prosthesis
The vast majority of hip joint replacement prostheses belong to fixed bearing connection devices. This means that there is a femoral stalk inserted into the femur (thighbone), a ball head that replaces the femoral head or the top of the femur, and a fixed acetabulum shell arranged on the hip fossa (acetabulum).
The main differences between different implants are the materials used (metal, polyethylene and ceramics) and the fixation.
In terms of fixation, your orthopedic surgeon will use two methods: bone cement fixation or "bone lengthening" fixation (cementless fixation), to fix the hip prosthesis implant on the bone, or both.
Implant materials for hip replacement
One of the most common problems after the replacement of hip joint prosthesis is the wear of the joint prosthesis caused by the normal use of the joint prosthesis.
Depending on the patient's specific conditions (such as age, body type, activity level, and experience of using special implants by surgeons), the patient's hip joint replacement implant prosthesis may be made of metal, polyethylene (plastic) or ceramics.
1. Metal ball head and polyethylene (plastic) liner
Standard metal balls and polyethylene cup liners have been in use since the early 1960s. Scientific research shows that the wear rate of the implant can be greatly reduced by using the improved polyethylene liner, the so-called "high cross-linking" polyethylene liner.
Because of its durability and other related properties, since the first implementation of hip replacement surgery, metal polyethylene material has been the main component material chosen by orthopedic doctors. The metal ball is made of cobalt chromium alloy and lined with polyethylene.Because the price is cheap, there are many places to use at present.
2. Ceramic ball head and polyethylene (plastic) liner
Ceramic head is harder than metal and is the most scratch resistant implant material.At present, the hard, scratch resistant and super smooth surface of ceramics used in joint replacement can greatly reduce the wear rate of polyethylene friction interface. The potential wear rate of this implant is less than that of metal to polyethylene.
3. Metal ball joint and metal bush
Metal to metal friction interface (Co-Cr alloy, sometimes stainless steel) was used as early as 1955, but it was not approved by FDA for use in the United States until 1999.
Later, with the progress of technology, the wear is greatly reduced, and there is less inflammation and bone loss. Metal bearings are available in a variety of sizes (28 mm to 60 mm); several neck lengths are also available.
4. Ceramic ball head and ceramic lining
Since the 1980s, total ceramic hip joint has been used in Europe, but it was only recently approved by FDA for sale in the United States. Ceramic hip joint has the reputation of ultra-low wear performance. However, with the advantages of high quality and low wear, it is bound to have the disadvantages of high price.