Why Hip Replacement Surgery

The hip joint is a ball and socket joint. The ball is called the “femoral head” and the socket is called the “acetabulum”. The ball glides smoothly in the socket and is capable of movement in all directions due to a covering of cartilage. The hip joint can be affected in a variety of ways producing pain, stiffness and lack of mobility. The femoral head itself can lose its blood supply leading to softening and collapse of the ball, the cartilage could wear out resulting in direct contact of the bony surfaces or there could be a fracture of the neck of femur and acetabular fracture. These are some of the disorders that result in a need for replacement of the ball and socket joint.

Hip replacement is a procedure in which the surgeon removes damaged or diseased parts of the patient’s hip joint and replaces them with new artificial parts. The operation itself is called hip arthroplasty. Arthroplasty comes from two Greek words, arthros or joint and plassein, “to form or shape.” It is a type of surgery done to replace or reconstruct a joint. The artificial joint itself is called a prosthesis. Hip prostheses may be made of metal, ceramic, plastic, or various combinations of these materials.

Each hip prosthesis is made up of several parts

• The acetabular component or cup replaces the acetabulum. The acetabular component can either be made of a metal alloy outer shell with a fitted plastic, metal or ceramic liner or it can be made of a one plastic component.
• The femoral component replaces the femoral head. The femoral component can be a single or a two piece design. The single piece is made of metal alloy, while the two piece design consists of the femoral stem, made of metal alloy and the femoral head that attaches to the stem which can be made of either ceramic or metal alloy. This is known as a modular prosthesis. Envelopes of tough ligaments connect the pelvis and femur, covering the joint and stabilising it. The hip joints’ movements are initiated and controlled by the thick muscles of the buttock at the back and the thick muscles of the thigh at the front.

In the past, joint replacement was principally carried out to relieve pain. Now, we perform surgery on increasingly younger people. The aim today is to give patients their life back and at the same time ensure that the prosthesis stands up to the test of time. Our modern patients would like a hip as good as their own, to enjoy absolutely all the activities they previously could and to get back to their usual work, recreation and sports.

Hence we are left with one choice – an artificial joint.

• Relieve your pain.
• Correct any deformity for example, leg length inequality.
• Restore any loss of function in your hip.
• Improve your quality of life.

• There are so many varieties of artificial joints on the market that it would not be wrong to say that there are as many prostheses as there are orthopaedic surgeons.
• There are also various materials that these joints are made from. The companies that make these joints all claim that their product or material is the best.

Is it better to have

• metal on metal or
• ceramic on ceramic or
• metal on polyethylene?
• Delta Ceramic (Miot hospitals has used Delta Ceramic for the first time in India and successfully replaced 372 hips with this technology. It is mainly for patients under the age of forty years who want to perform high impact activity (running, swimming, sports, etc) and it comes in various sizes. We feel that this is the artificial joint of the future for the young and active patient.

Is it better to go

• fully uncemented or
• fully cemented?

A lot of the time these decisions are taken based on

• availability,
• a personal surgical preference.

• What is the science?
• Is one better than the other?

The main factors that govern a surgeon’s decision are therefore :

• The quality of bone and the reason the joint wore out in the first place
• The age of the patient
• Co-existing factors – weak musculature, obesity, neurological disorders, etc
• Changes occuring to the bone
• Occupation / Activity

If, in a young patient, the ball was weak due to a reduction in blood supply, an uncemented ceramic on ceramic total hip replacement could be carried out. Ceramic on ceramic bearing surfaces have the least coefficient of friction. They produce the least amount of debris. Debris is produced in all joint replacements owing to movement between the ball and the socket. These particles affect the bond between the implant and the bone and produce loosening. This greatly reduces the longevity of artificial joints.

In an older person, suffering from Parkinsonism or obesity or a fractured neck of femur requiring total hip replacement, (conditions where there is a high chance of dislocation) it is ideal to use a big head (36mm or higher) to reduce the risk of dislocation. In the elderly, where one encounters weak bone, it may be necessary to use bone cement to ensure proper stability and fit. As they may also have weak musculature, a cemented component could be combined with a big head to reduce the chance of dislocation.

It is logical therefore that one has to choose carefully from an array of products to ensure each patient gets the best suited hip. But there is more. The angles in which the prostheses are placed affect their longevity and function. A badly placed prosthesis could result in a huge restriction in mobility, prove to be unstable and dislocate easily or even wear out quickly. Careful pre-operative planning using radiographic images ensures that leg length inequality is corrected and post operatively the limbs are the same length. This results in a normal gait pattern being quickly established.

The surgical approach plays an important role too. Minimally invasive surgery involves virtually no muscle cutting. The need for blood transfusion is nil and faster mobility and early discharge reduce the chance of deep vein thrombosis and shorten hospital stay. All this translates to a great saving in cost for the patient. Less muscle damage also reduces the risk of dislocation. The ideal hip inserted via an ideal approach results in the ideal result

A Joint for Life. This is the MIOT promise.