Shoulder Arthritis – Shoulder Osteoarthritis

Shoulder osteoarthritis (OA) refers to the degeneration (wear and tear) of the cartilage covering the bones that make up the glenohumeral joint, which is the main ball-and-socket joint of the shoulder. In this joint, the humeral head (top of the upper arm bone) fits into the glenoid cavity of the scapula (shoulder blade). It is characterized by gradually increasing pain and restricted shoulder mobility. The onset of symptoms is often latent and patients initially may not pay sufficient attention.

The treatment option for the advanced stage of Shoulder Osteoarthritis is surgical intervention with shoulder joint replacement (total shoulder arthroplasty).

Timely and proper management of the condition can significantly delay its progression and reduce pain. The majority of patients with Shoulder Osteoarthritis are over the age of 65, and it occurs more frequently in men. Early diagnosis and treatment can delay disease progression. It also helps maintain function, reduce pain, and potentially delay or avoid surgery.

• Diffuse pain in the shoulder
• Limited range of motion – Joint stiffness
• Pain during shoulder rotation
• Pain during shoulder abduction
• Guarding – Avoidance of using the upper limb
• Grinding, clicking or cracking sounds (crepitus) due to friction between joint surfaces

• Degeneration and wear and tear of the joint surfaces
• Fracture of the humeral head
• Fracture of the glenoid (shoulder socket)
• Large tear of the rotator cuff tendons
• Inflammatory arthritis – Rheumatoid arthritis
• Bacterial infections

The exact cause of this condition remains unclear, but genetic predisposition and chronic stress play significant role.

Secondary shoulder arthritis refers to degenerative changes in the shoulder joint caused by an underlying condition or injury. Unlike primary arthritis, which arises from age-related wear and tear or idiopathic causes, secondary arthritis results from a known trigger that damages the joint’s structure and function.

Causes and Mechanisms:

• Rotator Cuff Tendon Tears (usually of the supraspinatus)

The rotator cuff is a group of muscles and tendons that stabilize the shoulder joint. The supraspinatus tendon is one of the most commonly injured. A tear leads to instability in the shoulder, meaning the joint is no longer well supported. This instability disrupts the normal mechanics of the joint, causing abnormal wear on cartilage surfaces. Over time, the damaged tendons and instability accelerate cartilage breakdown, leading to arthritis.

• Shoulder Injuries (Fractures, Dislocations, Subluxations)

Physical trauma like broken bones (fractures), complete displacement of the joint surfaces (dislocations), or partial displacements (subluxations). Such injuries can directly damage the cartilage that covers the ends of the bones (articular cartilage). Cartilage damage leads to rough joint surfaces, causing pain and stiffness.

• Bacterial Infections

Infection in the joint, usually caused by bacteria spreading through the bloodstream (hematogenous spread). Infection can cause inflammation and destruction of joint tissues, including cartilage and bone. Although very rare in the shoulder, bacterial infection can rapidly destroy the joint, resulting in secondary arthritis.

• Osteonecrosis of the Humeral Head

Osteonecrosis refers to the death of bone tissue due to a loss of blood supply. It is caused by long-term corticosteroid use, chronic alcoholism, or diseases like sickle cell anemia that impair blood flow. The humeral head (the ball part of the ball-and-socket shoulder joint) loses blood supply, leading to bone death and collapse. This causes the joint surface to become irregular and damaged, resulting in arthritis symptoms.

Each of these conditions disrupts the normal shoulder anatomy and mechanics, leading to progressive joint degeneration and arthritis.

At first, it is observed a characteristic joint space narrowing due to the loss of cartilage that cushions the joints as well as the presence of osteophytes (bone spurs). In advanced stages, there is a complete joint deformity. While X-rays show bone changes, MRI gives detailed images of soft tissues, including:

• Rotator cuff tendons
• Labrum
• Cartilage integrity

MRI is also useful to plan the appropriate treatment approach, providing reliable information about the condition of the tendons around the joint, especially if surgery is considered.

1. Conservative (Non-Surgical) Treatment:

It is recommended for early stages of OA.

Goals:

• It relievespain
• It preservesmotion
• It strengthens the shoulder muscles

Methods:

• Physical Therapy: Focused on range of motion, flexibility, and strengthening exercises.
• Medications:
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Analgesics for short-term use

Injections:

• Hyaluronic acid: Lubricates the joint
• Growth factors/biological treatments(like PRP – platelet-rich plasma): Aim to reduce inflammation and possibly promote healing.

These treatments help manage symptoms but do not cure osteoarthritis. They may delay progression and reduce the need for surgery in the short term.

2. Surgical Treatment: Total Shoulder Replacement (Arthroplasty):

When conservative treatment fails and OA severely impacts quality of life, joint replacement surgery (arthroplasty) is considered. 

• Anatomical Total Shoulder Arthroplasty:
• Used when the rotator cuff tendons are intact.
• Mimics the natural anatomy: A metal ball replaces the humeral head and a plastic socket replaces the glenoid.
• Reverse Total Shoulder Arthroplasty:
• Used when there is a massive rotator cuff tear.
• The ball-and-socket configuration is reversed to use the deltoid muscleinstead of the damaged rotator cuff to move the arm.