This method involves placing an artificial metal ball and a plastic socket into the humerus and scapula to treat a deformed shoulder joint. The main types of surgery are total shoulder arthroplasty and reverse total shoulder arthroplasty.

 

　
Shoulder arthroplasty is performed when a normal joint has developed osteoarthritis or cuff tear arthropathy.
 

Osteoarthritis of the shoulder: The cartilage of the humeral head and the glenoid cavity is worn down.

Cuff tear arthropathy: Due to a rotator cuff tear, the space between the humeral head and the acromion is lost, and the cartilage of the humeral head is worn down.
 

 
Total shoulder arthroplasty: The humeral head is removed and replaced with a metal ball (head), and a glenoid component is placed in the worn glenoid cavity to restore smooth joint movement.
 

 
Reverse total shoulder arthroplasty: The humeral head is removed, a metal ball (called a glenosphere) is placed on the scapula, and a stem and liner are placed in the humerus to create a smoothly moving joint.