Purpose:
A shoulder replacement surgery may be performed in the following cases:

• Osteoarthritis or wear-and-tear arthritis (wearing down of the protective tissue at the bone ends, known as the cartilage)
• Rotator cuff (group of muscles and tendons that surround the shoulder joint) injuries
• Fractures of the humerus (due to the failure of previous surgery for fracture fixation or an injury)
• Rheumatoid arthritis (a chronic inflammatory disorder in which the immune system of the body attacks the joints and internal organs)
• Osteonecrosis (death of bone tissue due to reduced blood supply)
• Other inflammatory conditions 

Symptoms:
The following symptoms may indicate the need for a shoulder replacement surgery:

• Severe shoulder pain
• Shoulder stiffness
• Pain limiting everyday activities like bending or walking
• Inability to move or lift 
• Severe pain that is not relieved by the use of anti-inflammatory medications or drugs
• Shoulder joint fracture

The following tests and diagnostic methods are used in order to diagnose problems with the shoulder bone:

• Medical history- the orthopedic surgeon would ask questions about the patient’s general health, family history, severity and extent of pain, the extent to which the condition inhibits physical activity etc.
• Physical exam- the doctor would conduct a physical exam to check for shoulder alignment, strength or stiffness. Shoulder's mobility and range of motion will also be checked.
• X-rays- X-rays would help in determining the extent of damage or deformity by looking for structural changes, signs of joint erosion, cartilage loss or tissue tear, inflammation etc.
• Other tests- other tests such as a magnetic resonance imaging (MRI) scan may also be needed to determine the condition of the bone of the shoulder.

• The procedure is generally done under general anesthesia, that is, the patient is put to sleep during the procedure.
• A 4 to 10 inches long incision is made near the shoulder area.
• The damaged bone and attached cartilage are now cut out.
• The shoulder blade socket is then resurfaced.
• The shoulder joint is replaced using a plastic or metal prosthesis.
• The procedure takes approximately two to three hours to complete.

The following complications can occur due to a shoulder replacement surgery:

• Shoulder joint dislocation 
• Bone fracture
• Implant prosthesis loosening 
• Rotator cuff muscles failure 
• Nerve damage
• Blood clot formation
• Bleeding
• Infection 
• Allergic reaction to the anesthesia 
• Pain that does decrease or go away
• Need for another surgery

• The patient generally goes home one to three days after the surgery. 
• The patient is prescribed pain-relieving medications to ease the pain and discomfort after the procedure.
• Physiotherapy is provided to the patient in the hospital to prevent the stiffness of the muscles around the shoulder region.
• The patient will be taught how to move around the operated arm by using the non-operated arm.
• The operated arm needs to stay in a sling for two to six weeks after the surgery. 
• The patient is instructed to avoid lifting heavy objects and performing strenuous activities involving pulling or pushing after the surgery.
• Most patients are able to resume their daily activities two to six weeks after the procedure.
• The patient is instructed to avoid driving for about six weeks after the procedure.
• Home exercises are taught to the patient to aid in quick recovery.
• Vigorous activities like swimming or golfing can be resumed six months after the surgery.