There are several diseases which can damage the hip joint as well as other joints of the body also. These diseases cause damage to the ball and socket taking part in the joint formation resulting in severe pain disability.

Causes are as follows 
OSTEOARTHRITIS: Osteoarthritis is most common cause for destruction of the most of the joints of the body including hip joint. As the age progresses the cartilages over the ends of bones gets distracted and degenerated due to the friction caused by the use of the joints. Once the cartilage is lost the surface of the bones beneath gets exposed. Due to the continuous rubbing and friction while walking the surface of the bone gets worsened and the individual cannot take even a single step without pain. Osteophytes formed at the margins of the joint restrict the movements of the joint. Due to severe pain and destruction of the joint one may start limping while walking and that will add problem to the spine.
For management of osteoarthritis one may use canes for support while walking, physiotherapy, and taking pain killer tablets or injections.

RHEUMATOID ARTHRITIS : Rheumatoid arthritis is a disease of connective tissues which involves inflammation of several joints. It starts in early age and can affect both men and women, more often women. The affected joints become swollen and tender. The bones become demineralised and muscles weak and atrophied.
The causes of all types of osteoarthritis are not always known. Some people suffer from haemophilia which is a bleeding disorder in which repeated bleeding into the joint results in swelling and inflammation, with subsequent destruction of the articular cartilage.  Infection to the joint, accidental injury, gout, death of the tissue of the bone due alcoholism, long term use of steroids or pain killers is some of the known causes.
Some people suffer from dislocation of the hip joint right from birth and other abnormalities put pressure on the joint causing excessive wear and tear to the joint.

TESTS AND EXAMINATIONS:
Once your doctor has decided that operation will benefit you, you will be asked to carry out some blood, urine tests, chest x-ray, and electrocardiogram to evaluate your physical fitness. If these tests reveal that there is some infection in your body that has to be treated first before going for operation. That’s why these tests should be carried out some weeks before the operation.

 PROSTHESIS:
Once you have decided that you will go for operation, your doctor will decide about the best material to be used in your particular case. This selection will depend upon factors such as your age and normal level of activity as well as on the degree of damage and deterioration of the bones of your hip joint. Although a replacement hip joint may continue to function successfully for 15 years or more, it will not last for ever. Careful consideration is therefore necessary before replacing the hip of someone in their forties or fifties, who is likely to require revision surgery at some time in future. In this instance, a cementless prosthesis which will preserve bone stock may be most appropriate.

 
THE FEMORAL COMPONENT:

The femoral component is the prosthesis which replaces the head of the femur. Apart from the ball – shaped head, the prosthesis usually also has a stem which is inserted into the shaft of femur itself; a neck between the head and the stem. There may also be a collar which rests on the inner aspect of the femur. The femoral component may be made of anyone of a variety of metals.
 Many different combinations have been tried over the years. Metal on plastic articulations are good for majority of people. Metal-on-metal designs currently seem to hold the best promise for younger more active people.

METALS: Titanium and Titanium Alloys are strong, light metals which are biocompatible i.e. they allow bone to grow relatively easily onto their surface.
COBALT CHROME: It is very strong alloy which has a high resistance to wear and corrosion.
POLYETHYLENE: Comprises a family of plastics with similar chemical composition but different structures & thus different mechanical & wear properties. The polyethylene used to make acetabular cups has very good wear properties.
CERAMIC: Ceramic materials such as zirconium oxide, aluminium oxide & titanium oxide are being used increasingly for one articular surface of replacement hip joints, particularly in young active people. Ceramic components are brittle but hard, do not scatter easily, are durable & have low friction.
CEMENT: Cement is used to fix prosthesis in place. Although some prosthesis are designed to be inserted without it. The choice depends in part on the decision of your surgeon & on factors such as the condition of your bone, age & activity profile.
UNCEMENTED: Various uncemented prosthesis are used in relatively younger people. The first condition of such prosthesis is that it should be biocompatible. Stability can be achieved by a good press-fit design.