When undergoing shoulder replacement surgery, which type should be chosen?

When a patient has shoulder joint degeneration, severe fracture of the humeral head, or avascular necrosis of the shoulder joint head and requires shoulder replacement surgery, the doctor will conduct a thorough examination to plan and select the appropriate type of shoulder prosthesis for the patient.

Preoperative Examination and Evaluation

• The doctor will ask about the patient’s underlying diseases, regular medications, including the use of steroids and blood thinners. Regarding the shoulder, the doctor will inquire about pain, stiffness, and daily use of the shoulder joint.
• During the physical examination, the doctor will assess the shoulder joint’s range of motion, stability, muscle strength around the shoulder, and check for any pathology of the surrounding related organs.
• X-rays help determine the severity of degeneration, showing narrowed joint space, rough joint surfaces, bone spurs, or loose bodies within the joint, etc.
• Other tests include blood tests to detect arthritis, infections, and abnormalities of various internal diseases, as well as imaging such as MRI and CT scans to evaluate the condition of bones and soft tissues around the shoulder joint.

After all examinations and evaluations, the doctor will explain and consult with the patient about the most suitable treatment method to reduce shoulder pain and improve shoulder joint function.

Types of Shoulder Prostheses

There are several types of shoulder prostheses, each suitable for different patients. Therefore, the specialist doctor can explain the types of prostheses available and which type is most appropriate for each patient, along with the reasons.

• Conventional Total Shoulder Arthroplasty

This surgery replaces the damaged surfaces of both sides of the shoulder joint, the humeral head and the glenoid. The humeral head prosthesis is a metal head with a stem inserted into the humeral canal, which may be fixed with or without cement. The glenoid side is made of plastic-like material fixed to the original glenoid base with cement.

This double-sided prosthesis replacement is the most commonly performed surgery and yields good results in elderly patients with shoulder joint degeneration. It is also effective in shoulder degeneration caused by chronic inflammatory arthritis, such as rheumatoid arthritis.

• Hemiarthroplasty

This surgery replaces only the humeral head surface using a prosthesis with a metal head and a stem inserted into the humeral canal, similar to the prosthesis used in Conventional Total Shoulder Arthroplasty, but without replacing the glenoid. It is often used in cases of severe humeral head fractures unsuitable for metal fixation, cases where the glenoid is still good and does not require replacement, or cases where the glenoid is severely damaged and the original glenoid bone is too deteriorated to support a prosthesis.

Most reports indicate that in elderly patients with degenerative osteoarthritis of the shoulder, Total Shoulder Arthroplasty reduces pain and improves shoulder function better than Hemiarthroplasty.

• Surface Replacement Arthroplasty

This surgery replaces only the surface of the humeral head without inserting a stem into the humeral canal. There are two subtypes: replacing the entire surface of the humeral head and replacing only part of the humeral head (Anatomic Focal Resurfacing).

This surface replacement surgery is used when the humeral head damage is minimal, when preserving humeral bone mass is desired, or to avoid risks associated with stem insertion and loosening around the prosthesis stem. For example, in younger patients who may require revision surgery in the future, this procedure is beneficial because there is still substantial bone mass and no previous stem prosthesis has been implanted.

However, this type of prosthesis cannot be used in cases of severe humeral head damage, severe osteoporosis, or acute fractures of the humeral head or neck, or non-union fractures of the humeral head or neck.

• Reverse Total Shoulder Arthroplasty

This surgery replaces both the humeral head and glenoid surfaces, but the prosthesis design differs from Conventional Total Shoulder Arthroplasty. The spherical prosthetic head is fixed to the original glenoid bone, and the glenoid prosthesis is fixed to the humerus. The purpose is to mechanically advantage the deltoid muscle to lift the arm instead of the rotator cuff muscles, which are severely and chronically damaged.

This type of prosthesis is commonly used in shoulder degeneration caused by severe chronic rotator cuff tears (Rotator Cuff Tear Arthropathy) in patients over 70 years old who have weakness, inability to lift the arm (pseudoparalysis), and damage to the superior shoulder structures (Incompetent Coracoacromial Arch). It is also used as a revision surgery after failed shoulder surgeries such as failed massive rotator cuff repair, failed resection arthroplasty, or failed glenohumeral arthrodesis.