Types of Total Hip Replacements
Total hip replacement is one of the major and most popular treatments for hip arthritis, with osteoarthritis being the main degenerative condition for which the operation is performed. The hip arthroplasty definition is the reconstruction or replacement of a joint. Further reading is available at About.com:Orthopedics and MedicineNet.com.
There are two major types of hip replacement or hip replacement methods, the cemented technique and the porous surface technique, each with different indications for surgery and each supported by particular orthopaedic surgeons.
Cemented hip prosthesis types include the Exeter, the Charnley and the Stanmore. In this hip replacement surgery the bony surfaces are prepared and the marrow cavity of the femur is drilled out and cleaned. Then cement is pressurised into the cavity and pushes into the surrounding bone, forming a micro interlock. Once the cement has set to a certain degree the metal component bearing the ball is inserted down the femur and held in the correct position until the cement sets. The socket is also pressurised and the cup pressed into the cement until it's set.
Once the hip replacement surgery has been performed the hip should last for a long time, with the main problems being loosening of the interface between the cement and the bone and difficulty of removing the cement when a revision operation needs to be performed.
Porous implant types are inserted into the prepared canal of the femur without cement, being push fitted tightly into it. The surfaces of the implant are designed to encourage the bone to grow into the porous surface of the implant, stabilising the hip replacement further. These replacements are easier to revise but may not do quite as well as cemented ones, with a higher incidence also of thigh pain.
Other types hip replacement prosthesis exist for different types of operation. The Birmingham Hip Resurfacing prosthesis replaces the arthritic surfaces with two hemispherical metal caps, removing much less bone in the process than normal hip replacement.
For different hip replacement causes such as trauma in a elderly person, a high fracture of the femoral neck may be treated by one of the other types of hip replacement joints, such as the Austin Moore hemiarthroplasty. This replaces the femoral head but leaves the socket undisturbed and is a big ball joint so is less likely to dislocate than the normal replacement. However, hip pain may persist after this operation, necessitating a full replacement eventually.