Anatomic and Reverse Total Shoulder Replacement
The shoulder is a highly movable body joint that allows various movements of the arm. It is a ball and socket joint, where the head of the humerus (upper arm bone) articulates with the socket of the scapula (shoulder blade) called the glenoid. The two articulating surfaces of the bones are covered with cartilage, which prevents friction between the moving bones. The cartilage is lubricated by synovial fluid. Tendons and ligaments around the shoulder joint provide strength and stability to the joint.
What is Osteoarthritis?
When the cartilage is damaged, the two bones rub against each other resulting in pain, swelling and stiffness of the joint (osteoarthritis).
What is Shoulder Joint Replacement?
Total shoulder replacement surgery is performed to relieve these symptoms. In this surgery, the damaged articulating parts of the shoulder joint are removed and replaced with artificial prostheses. Replacement of both the humeral head and the socket is called a total shoulder replacement.
What are the Indications for Shoulder Joint Replacement?
Total shoulder joint replacement surgery is indicated for conditions such as osteoarthritis or rheumatoid arthritis when medication, injections, physical therapy, and activity changes do not help relieve pain. Your doctor recommends surgery when you have the following symptoms:
- Severe shoulder pain that restricts daily activities
- Moderate to severe pain during rest
- Weakness and/or loss of motion
Preparation for Shoulder Joint Replacement
To decide whether total shoulder replacement is a good option for you, your surgeon will evaluate your condition thoroughly.
Your surgeon reviews your medical history and performs a physical examination of your shoulder to assess the extent of mobility and pain. Imaging tests such as X-ray or MRI (magnetic resonance imaging) are ordered.
Shoulder Joint Replacement Procedure
The surgery is done under regional or general anesthesia. An incision is made over the affected shoulder and the underlying muscles are separated to expose the shoulder joint. The surgery may be performed as open surgery, where a large incision is made, or minimally invasive, where small incisions are made to insert an arthroscope (a thin tube with a camera and light source) and surgical tools.
The upper arm bone (humerus) is separated from the glenoid socket of the shoulder bone. The arthritic or damaged humeral head is cut and the humerus bone is hollowed out and filled with cement. A metal ball with a stem is gently press- fit into the humerus.
Next, the arthritic part of the socket is prepared. The plastic glenoid component is fixed in the shoulder bone.
After the artificial components are implanted, the joint capsule is stitched and the wound is closed.
Postoperative Care for Shoulder Joint Replacement
After the surgery, pain medications and antibiotics are prescribed to control pain and prevent infection. Your arm may be secured in a sling or cast. The rehabilitation program includes physical therapy, which is started soon after the surgery and is very important to strengthen and provide mobility to the shoulder. You may be able to perform gentle daily activities two to six weeks after surgery.
Risks and Complications of Shoulder Joint Replacement
As with any major surgery, there may be potential risks involved:
- Anesthetic complications such as nausea, dizziness and vomiting
- Infection of the wound
- Dislocation, requiring repeat surgery
- Damage to blood vessels, nerves or muscles
- Failure to relieve pain
- Pulmonary embolism
- Wear and tear of prosthesis
What is Reverse Shoulder Replacement?
Reverse total shoulder replacement, is an advanced surgical technique specifically designed for rotator cuff tear arthropathy, a condition where the patient suffers from both shoulder arthritis and a rotator cuff tear.
The shoulder joint is a ball and socket joint formed by the union of the head of the upper arm bone (humerus) and the shoulder socket (glenoid). The rotator cuff is a group of four tendons that join the head of the humerus to the deeper shoulder muscles to provide stability and mobility to the shoulder joint.
Rotator Cuff Arthropathy
When the rotator cuff is torn, it can cause wear and tear to the shoulder joint and lead to shoulder arthritis. Conventional surgical methods such as total shoulder joint replacement have been shown to be significantly ineffective in the treatment of rotator cuff arthropathy.
Symptoms of Rotator Cuff Arthropathy
Patients with rotator cuff arthropathy may feel pain (usually at night) and weakness within the involved shoulder. Patients may have had a prior rotator cuff repair or a history of multiple repairs. The most common symptom is the inability to raise the arm above the shoulder to perform overhead activities.
Differences between Conventional and Reverse Shoulder Replacement
Conventional shoulder replacement surgery involves replacing the ball of the arm bone (humerus) with a metal ball and the socket (glenoid cavity) of the shoulder blade (scapula) with a plastic socket. If this surgery is used to treat rotator cuff arthropathy, it may result in loosening of the implants due to the torn rotator cuff. Therefore, a specifically designed surgery was developed called reverse total shoulder replacement to be employed in such cases.
In reverse total shoulder replacement, the placement of the artificial components is essentially reversed. In other words, the humeral ball is placed in the glenoid cavity of the shoulder blade (scapula) and the plastic socket is placed on top of the arm bone. This design makes efficient use of the deltoid muscle, the large shoulder muscle, to compensate for the torn rotator cuff.
Ideal candidates for Reverse Shoulder Replacement
Reverse total shoulder replacement may be recommended for the following conditions:
- Completely torn rotator cuff that is difficult to repair
- Presence of cuff tear arthropathy
- Previous unsuccessful shoulder replacement
- Severe shoulder pain and difficulty in performing overhead activities
- Continued pain despite other treatments such as rest, medications, cortisone injections, and physical therapy
Reverse Shoulder Replacement Procedure
Reverse total shoulder replacement surgery is performed with the patient under general anesthesia.
- Your surgeon makes an incision over the affected shoulder to expose the shoulder joint.
- The humerus is separated from the glenoid socket of the scapula (shoulder blade).
- The arthritic parts of the humeral head and the socket are removed and prepared for insertion of the artificial components.
- The artificial components include the metal ball that is screwed into the shoulder socket and the plastic cup that is cemented into the upper arm bone.
- The artificial components are then fixed in place.
- The joint capsule is stitched together, the tissues approximated and the wound is closed with sutures.
Postoperative care for Reverse Shoulder Replacement
Patients can get out of bed on the same day of the surgery, but usually stay in the hospital for 1-2 days. General post-operative instructions include:
- Take all prescribed medications as instructed
- Undergo gentle range of motion exercises to increase your shoulder mobility
- Physical therapy will be recommended to strengthen the shoulder and improve flexibility
- Avoid overhead activities for at least 6 weeks
- Don’t push yourself up out of a chair or bed using your shoulder muscles
- Avoid lifting heavy objects
Risks and complications of Reverse Shoulder Replacement
Possible risks and complications associated with reverse total shoulder replacement surgery include:
- Dislocation or instability of the implanted joint
- Fracture of the humerus or scapula
- Damage to nerves or blood vessels
- Blood clots (deep vein thrombosis)
- Wound irritation
- Arm length discrepancies
- Wearing out of the components