Reverse Shoulder Arthroplasty

Introduction

Shoulder pain and dysfunction can significantly impact one's life, limiting their ability to perform even the simplest tasks. Traditional shoulder arthroplasty, or total shoulder arthroplasty, has been a well-established procedure for decades. While traditional shoulder arthroplasty is highly successful in many cases, it may not yield optimal results for patients with complex issues, such as massive rotator cuff tears or irreparable joint damage. The glenohumeral joint is a type in which a ball-shaped bone fits into a socket-like bone. It is an important articulation in the shoulder joint complex. The rounded head of the upper arm bone (humerus) meets the shallow socket of the shoulder blade (glenoid) at this joint.

What Does Reverse Shoulder Arthroplasty Mean?

Reverse shoulder arthroplasty is a newer surgical technique known as reverse total shoulder arthroplasty (RTSA). It was developed to address the needs of patients with limited treatment options due to rotator cuff arthropathy, massive rotator cuff tears, and severe fractures. The glenohumeral joint is replaced in this procedure.

In RTSA, the shoulder's center of rotation changes, making it lower and more inward. In the body's natural shoulder joint, the ball is connected to the humerus and the socket to the shoulder blade. In a reverse shoulder arthroplasty, the ball is affixed to the shoulder bone, while the socket is anchored to the upper arm bone. This reversal in design essentially transforms the mechanics of the shoulder joint. Instead of relying on the rotator cuff for stability, the new joint leverages the strength and function of the shoulder muscles to provide support and functionality.

What Conditions or Symptoms Would Require Reverse Shoulder Replacement Surgery?

Reverse shoulder arthroplasty is indicated in the following conditions.

• Rotator cuff arthropathy is a condition stemming from a massive rotator cuff tear that leads to degenerative changes in the glenohumeral joint and the migration of the upper arm bone.

• Revision surgery following the failure of a previous anatomic total shoulder arthroplasty.

• Acute proximal humerus fractures involving three or four parts require surgical intervention for proper treatment.

• Pseudo-shoulder paralysis is caused by an irreparable massive rotator cuff tear severely limiting shoulder function.

• Glenohumeral arthritis resulting from traumatic injuries.

• Inflammatory joint conditions, such as rheumatoid arthritis that affects the shoulder, warrant surgical intervention.

• Chronic irreducible shoulder dislocation, a persistent dislocation issue in the shoulder joint.

• Revision surgery is needed due to the failure of a prior proximal humerus hemiarthroplasty.

What Are the Contraindications of Reverse Shoulder Arthroplasty?

Reverse shoulder arthroplasty should not be performed in patients with the following conditions.

• Active infection in the shoulder area, as surgery in the presence of infection, can lead to complications.

• Deficient deltoid muscle, which plays a vital role in shoulder movement and stability, may not provide the necessary support for arthroplasty.

• Axillary nerve palsy is a condition affecting the nerve responsible for the deltoid muscle's function, which can impair the procedure's outcome.

• Skeletal immaturity means the patient's bones have not yet fully developed, making them unsuitable for the procedure.

• A significant deficiency in the glenoid's bony stock may compromise the ability to anchor the artificial joint securely.

• Neuromuscular disorders increase the risk of prosthesis dislocation, potentially leading to less successful outcomes.

What Is the Surgical Procedure for Reverse Shoulder Arthroplasty?

Preoperative Preparation

Before undergoing reverse shoulder arthroplasty, patients will undergo a thorough evaluation by their orthopedic surgeon. This assessment includes medical history, physical examination, imaging studies, and discussions about the patient's goals and expectations.

Anesthesia

Reverse shoulder arthroplasty is typically performed under general anesthesia, though regional anesthesia may be an alternative. The choice of anesthesia depends on the patient's health and the surgeon's preferences.

Surgical Approach

The surgery begins with the patient positioned in a semi-seated or lateral decubitus position, allowing access to the shoulder joint. The surgeon will make an incision to expose the damaged shoulder joint.

Glenoid Component Placement

The first step is to prepare the glenoid (the socket) for implantation. The damaged cartilage is removed, and the glenoid is reshaped to receive the implant. The artificial component is then secured to the scapula with screws.

Humerus Component Placement

Next, the humerus is prepared for the implant. The damaged or arthritic head of the humerus is removed, and the humerus is reshaped to accommodate the humeral component.

Closure

The surgeon carefully examines the joint's function and stability, ensuring the components are aligned appropriately and the incision is closed.

Post-operative Care

After the surgery, the shoulder operated in a special arm sling made of a sturdy board. This keeps the shoulder from moving for two weeks. For the first four weeks, avoiding rotating the arm too far outward is best. Pendulum shoulder exercises can be starters early on. X-rays are taken to check the artificial joint parts, screws that hold them in place, and the bones of the upper arm and shoulder socket. A check-up should be scheduled two weeks after the surgery to examine the wound and ensure there are no problems.

What Are the Complications of Reverse Shoulder Replacement?

• Prosthesis Infection - Post-surgery infection rates range from one to ten percent. Rheumatoid arthritis increases the risk, and revisions have higher infection rates. Early infection can be treated with antibiotics and component retention, while late infections may need revision surgery.

• Axillary Nerve Palsy - Temporary nerve issues can occur during surgery.

• Prosthesis Instability and Dislocation - Approximately 3.6 percent experience prosthesis dislocation due to soft tissue tension, mechanical impingement, and nerve issues. Glenoid baseplate failure can occur due to increased motion at the plate-bone interface and insufficient bone integration.

• Scapular Notching - Mechanical contact between the humeral prosthesis and the scapula may lead to scapular notching. Adjusting component placement can reduce this risk.

• Other Complications - These may include intraoperative fractures, vascular injuries, heterotopic ossification, and surgical scar-related problems.

What Are the Recent Innovations in Reverse Shoulder Arthroplasty?

Pre-operative 3D Planning Software - Digital software has brought a new way of planning before surgeries. This program uses a CT scan to create a 3D digital version of the patient's shoulder. Doctors can use this model to study the details of the shoulder, find any problems with the bones, and plan for different sizes of parts, angles of certain components, and the alignment of the arm bone part. 3D preoperative planning is beneficial for creating personalized solutions for complex bone problems in the shoulder.

Stemless Humeral Component - This new and improved technology is also known as the canal-sparing humeral component. It is beneficial for patients with problems in their arm bones. This part helps keep the humeral bone intact, essential for future surgeries.

Conclusion

Reverse shoulder arthroplasty is a new way to treat complex shoulder problems. It gives patients with few choices in the past a chance for better results and less discomfort. While the surgery is complex and may require a long time and effort to recover, it also has the potential to reduce pain and improve function significantly.