Types Hip Replacement Prosthesis
Hip replacement is a very popular operation for hip arthritis in the UK, with over 50,000 episodes of hip replacement surgery performed every year. The hip arthroplasty definition is an operation to reconstruct an abnormal joint or to replace the joint with artificial components.
Hip replacement causes are typically osteoarthritis, rheumatoid arthritis, avascular necrosis, trauma and congenital abnormalities of the hip. All these conditions may be suitable for a particular types of hip replacement joints.
Hip replacement methods vary with the presenting clinical problem and surgeons have many types of hip replacement joints to choose from in making their decision, although most surgeons will fall into one camp or another in preferring a particular technique.
Cemented Total Hip Replacements
There are several types of hip replacement in this category such as the Exeter Hip, the Stanmore and the Charnley. The Charnley was the original and development of this group of cemented implants has continued over the last 40 years, with very good long term results for people keeping their implants trouble free over fifteen years or more.
After problems with the loosening of implants over time the techniques of cementing have been changed to pressurise the cement into the reamed and cleaned cavity in the thigh bone, with the same method used in the socket. This allows a more intimate bond between the cement and the bone and has shown good long term results.
Impaction grafting of bone chips is the second major technique which has improved the ability of hip replacements to be revised and new bone to form in areas of deficiency which occur in hips which have loosening problems.
Overall, this technique has proved the best over time of all the types of total hip replacements.
Uncemented Types of Hip Replacement
In contrast to the above hip replacement methods, uncemented replacement relies on push fitting to locate the components firmly in the bone. These prostheses are coated with a special coating which is designed to promote bone growth up to and into the coating, forming a more secure lock between the bone and the metal.
The advantages are said to be that when the hip replacement has to be re-done the surgeon does not have to remove the cement, a long job which risks the integrity of the bone in the upper thigh. Problems are that there may be an increased incidence of thigh pain.
This is one of the different hip prosthesis types from the types of hip replacement joints mentioned above. Hip resurfacing removes very little bone from the socket and the head of the femur, replacing it with two hemispherical caps made of metal.
Provided the hip replacement causes are not due to gross abnormality of the joint, the resurfacing allows normal stresses to pass through the head and neck of the femur and maintains the bone stock of the upper femur. This allows the person to go back to most activities after the operation and the bone stock allows a total hip replacement to be easily performed in the future.
Overall the hip resurfacing approach looks good but the results may not yet approach the excellent results of cemented hip replacement.