How Shoulder Replacement Surgery Is Performed — A Step-by-Step Guide

The shoulder is the most mobile joint in the human body. It rotates in almost any direction — above the head, behind the back, across the body. That extraordinary range of motion comes at a cost: the shoulder joint is inherently less stable than the hip or knee, relying heavily on the surrounding soft tissue (the rotator cuff) rather than bony constraint for its stability.

When the shoulder joint itself deteriorates beyond what physiotherapy, injections, and medication can manage, replacement surgery can restore function and eliminate the pain that has made ordinary activities — reaching overhead, dressing, sleeping on the side — genuinely difficult.

Less commonly performed than knee or hip replacement, shoulder replacement surgery has an 85%+ success rate in appropriately selected patients and modern implants that last 15–20 years or longer.

This guide explains what types of shoulder replacement exist, when each is used, and what actually happens during the operation.

The Shoulder Joint: Key Anatomy

The shoulder is a ball-and-socket joint. The ball (humeral head) is the rounded top of the humerus (upper arm bone). The socket (glenoid) is a shallow dish-shaped surface on the scapula (shoulder blade). The rotator cuff — four muscles and their tendons that wrap around the joint — is what keeps the ball centred in the socket and powers the shoulder's movements.

The shallow glenoid means the shoulder depends far more on soft tissue (labrum, ligaments, rotator cuff) for stability than the hip, where the deep acetabulum provides bony containment. This is why rotator cuff health is central to choosing the right type of shoulder replacement.

When Is Shoulder Replacement Recommended?

Surgery is considered when

• Severe glenohumeral (shoulder joint) osteoarthritis causes persistent pain and restricted movement that hasn't responded to non-surgical treatment
• Rheumatoid arthritis has significantly damaged the joint surfaces
• Avascular necrosis of the humeral head has destroyed the ball
• A severe proximal humerus fracture cannot be reliably fixed by internal fixation
• Rotator cuff tear arthropathy — severe arthritis combined with a massive, irreparable rotator cuff tear — limits function significantly

The decision involves imaging (X-ray and MRI), assessment of rotator cuff integrity, and evaluation of bone stock — all of which determine which type of replacement is appropriate.

Types of Shoulder Replacement

1. Total Shoulder Replacement (Anatomic)

The most commonly performed type when the rotator cuff is intact. The humeral head is removed and replaced with a metal ball fixed to a stem implanted into the humerus. The glenoid (socket) is resurfaced with a polyethylene (plastic) component fixed to the scapula.

The mechanics mimic the natural shoulder: the metal ball articulates against the plastic socket. The deltoid and rotator cuff muscles remain responsible for moving the arm.

Best suited for: Osteoarthritis, rheumatoid arthritis, or avascular necrosis with an intact rotator cuff.

2. Reverse Total Shoulder Replacement

In this design, the anatomy is deliberately reversed: the metal ball is placed on the scapula (where the socket normally sits), and the socket cup is placed on the humerus. This is why it's called "reverse."

The logic: in standard anatomy, the rotator cuff positions and powers the shoulder. When the rotator cuff is massively torn and irreparable, it cannot do this job — a standard total shoulder replacement would fail because the rotator cuff isn't there to stabilise it. By reversing the geometry, the centre of rotation changes. The deltoid muscle — which is largely intact in rotator cuff arthropathy — takes over the function of stabilising and elevating the arm.

Best suited for: Rotator cuff tear arthropathy, severe arthritis with irreparable rotator cuff, failed prior shoulder replacement, certain complex shoulder fractures.

Reverse shoulder replacement now accounts for the majority of shoulder replacements performed in many centres, because it works reliably even in challenging situations.

3. Hemiarthroplasty (Partial Shoulder Replacement)

Only the humeral head (ball) is replaced. The natural glenoid socket is left intact. Used primarily for severe proximal humerus fractures in older patients where reconstruction of the broken fragments is not feasible, and in selected cases of humeral head avascular necrosis.

4. Shoulder Resurfacing

A metal cap is placed over the humeral head rather than replacing the entire ball with a stemmed implant. Preserves more native bone. Used in younger patients with good bone stock who want to preserve options for later.

Pre-operative Assessment

Before surgery, the patient undergoes:

• X-rays of the shoulder in multiple planes to assess joint destruction, alignment, and bone quality
• MRI to evaluate the rotator cuff (critical for deciding between anatomic and reverse replacement)
• CT scan in some cases to assess glenoid bone stock and version (angle)
• Blood tests, ECG, and medical clearance

Medications affecting bleeding (aspirin, anticoagulants) are stopped before surgery. Dental clearance is recommended, as oral bacteria can seed the new implant through the bloodstream.

The Operation: Step by Step

Anesthesia

Shoulder replacement is performed under general anesthesia combined with a regional nerve block (interscalene block) that numbs the arm and shoulder. The nerve block provides excellent post-operative pain control for 12–24 hours, significantly reducing opioid requirements in the early recovery period.

The surgery takes 1.5 to 2.5 hours depending on complexity.

Positioning

The patient is positioned in a beach-chair position — sitting at approximately 45–60 degrees, with the operative shoulder at the edge of the table. This provides excellent access to the front of the shoulder and allows the arm to be moved freely during the procedure.

The Deltopectoral Approach

The most commonly used approach. An incision is made over the front of the shoulder, typically 8–12 cm. The surgeon works through the interval between the deltoid muscle and the pectoralis major, without cutting either muscle — a tissue plane that naturally separates the two muscles.

The subscapularis (one of the rotator cuff muscles at the front of the shoulder) is carefully detached from the humerus to expose the joint, then meticulously repaired at the end of surgery.

Exposing and Preparing the Humeral Head

The shoulder is dislocated by bringing the arm into extension and external rotation, exposing the humeral head. The arthritic humeral head is cut with a saw at the predetermined angle (based on pre-operative planning), and the canal of the humerus is prepared with a sequence of rasps to accept the stem.

In resurfacing, the humeral head is not cut — only the articular surface is shaped.

Preparing the Glenoid (in Total Shoulder Replacement)

For anatomic total replacement, the glenoid surface is carefully reamed and shaped to accept the plastic glenoid component. Placement angle and version are critical — a malpositoned glenoid component is a major source of failure. The glenoid component is fixed with pegs or a keel cemented into the scapula.

In reverse replacement, a baseplate is fixed to the glenoid with screws, and a metal hemisphere (the ball) is attached to the baseplate.

Trial Components and Final Implants

Trial components are placed to check that the joint feels stable through a full range of motion, that the shoulder doesn't impinge in any position, and that soft tissue tension is appropriate. Adjustments are made as needed.

The permanent implants are then fixed — typically with cement for the humeral stem (or press-fit in cementless designs) and cement for the glenoid component.

Subscapularis Repair and Closure

The subscapularis is carefully repaired back to the humerus — either through bone tunnels or with suture anchors. This repair is critical: a failed subscapularis repair leads to instability and poor function. The wound is closed in layers, a drain placed, and a sling applied.

Recovery

Days 1–3: Hospital stay. Arm in a sling. Pain is managed with the combination of the nerve block (wearing off gradually) and oral medication. Passive shoulder movements begin.

Weeks 1–6: Sling worn most of the time. Gentle pendulum exercises and physiotherapy-guided passive range of motion. No active use of the shoulder.

Weeks 6–12: Active range of motion exercises begin. Strengthening starts gradually.

3–6 Months: Most daily activities restored. Light lifting possible.

6–12 Months: Full recovery, including more demanding shoulder activities.

Shoulder replacement implants typically last 15–20+ years with modern designs.

Shoulder Surgery at Prakash Hospital, Noida

Dr. Mayank Chauhan performs shoulder replacement surgery at Prakash Hospital, Sector 33, Noida, for patients with severe arthritis, rotator cuff arthropathy, and complex shoulder fractures. A thorough pre-operative assessment determines the most appropriate procedure for each patient.

To book a consultation, call the number listed on the website.