Shoulder Replacement Surgery

Shoulder arthritis may occur in a number of different forms, including primary osteoarthritis (wear-and-tear arthritis), rheumatoid arthritis (inflammatory arthritis), post-traumatic arthritis (arthritis that occurs after a prior injury, such as a fracture or dislocation), or rotator cuff tear arthropathy (arthritis that develops after a long-standing rotator cuff tear). Regardless of the cause, shoulder arthritis results in a loss of the protective cartilage that lines the shoulder joint and allows it to move smoothly during shoulder motion. This results in an eventual “bone-on-bone” pattern in which the rough surfaces of the ball (humeral head) and socket (glenoid) that make up the shoulder joint are now in contact with each other causing pain, grinding, and limited motion. In some patients, the arthritic ball and socket of the shoulder have been grinding together for so long that the bone of the socket begins to wear away, resulting in glenoid bone loss.

Shoulder replacement surgery, also known as ‘shoulder arthroplasty’ is a safe and effective treatment option for patients with shoulder arthritis. In this surgery, the arthritic ball and socket of the shoulder joint are replaced, or “resurfaced”, with a prosthetic ball and socket, usually made out of a metal-alloy ball and plastic socket. This prevents the arthritic bones from rubbing together during shoulder motion and allows the metal ball and plastic socket to glide smoothly against one another, providing smooth, pain-free range of motion.

Indications for Shoulder Replacement

Although patients with shoulder arthritis often benefit from a shoulder replacement, treatment does not commonly begin with surgery. Many non-operative treatment options for shoulder arthritis exist and may provide pain relief and improved range-of-motion. This includes modification of painful activities, oral anti-inflammatory medications or NSAID’s (Non-Steroidal Anti-Inflammatory Drugs), physical therapy, and corticosteroid injections. Unfortunately, these treatment options may provide less benefit over time as shoulder arthritis continues to progress. In patients with advanced shoulder arthritis that are no longer experiencing relief from non-operative treatment strategies, or those who are unable to tolerate these treatment options, shoulder replacement surgery is typically indicated. The type of arthritis that the patient is suffering from, as well as the presence of glenoid or socket bone loss, can dictate the type of shoulder replacement that a patient should receive.

Types of Shoulder Replacements

The three types of shoulder replacements include:

• Hemiarthroplasty
• Anatomic total shoulder arthroplasty
• Reverse shoulder arthroplasty

As previously mentioned, the shoulder is a ball and socket joint. All types of arthritis commonly cause cartilage to wear away on both sides of the joint, including both the ball and socket. An anatomic total shoulder arthroplasty refers to a shoulder replacement in which both the ball and socket are replaced, since both sides of the joint are worn down. The arthritic ball is replaced with a metal ball, most commonly made out of a cobalt-chrome alloy (although other options exist including titanium and pyro carbon). The arthritic socket is then replaced with a plastic socket, typically made out of a material called “polyethylene.” This type of replacement is called “total” because it replaces the total joint, including both the ball and socket. It is called “anatomic” because it replaces the ball with another ball, and the socket with another socket, recreating normal anatomy.

In a hemiarthroplasty (hemi- meaning “half”), only the ball of the shoulder joint is replaced with a metal ball and the socket is typically left alone. This used to be done more often in the past for patients with arthritis before the development of the type of plastic socket that would last a long time before wearing out. Pain relief is often better with a “total” replacement because both the arthritic ball and arthritic socket are replaced. If the arthritic socket is left alone, like in a hemiarthroplasty, patients can sometimes experience continued symptoms from the arthritic socket interacting with the new metal ball. The metal ball commonly lasts a long time in patients before needing to be redone, or “revised”, but the plastic socket often does not last as long. For this reason, hemiarthroplasty may be done in a young patient whom the surgeon expects will use the shoulder for a long time and is very likely to wear out the plastic socket.

In a reverse shoulder arthroplasty, the bone of the ball is replaced with a metal and plastic socket and the bone of the socket is replaced with a metal ball held to the bone by a metallic baseplate and screws. This is commonly done in patients who have arthritis due to a chronic (long-standing) rotator cuff tear that can’t be fixed. An anatomic total shoulder arthroplasty can’t be used in patients with a chronic rotator cuff tear because the rotator cuff tear is needed to allow for normal, pain-free movement of the shoulder and to keep the ball centered on the socket, preventing the ball from sliding upward in the shoulder joint every time the patient lifts their arm. This puts patients at risk of the plastic socket loosening very early after surgery, requiring revision of their shoulder replacement. The reverse shoulder replacement changes the location of the center of rotation of the shoulder joint, allowing the patient to move the shoulder primarily using the deltoid muscle without the need for a rotator cuff. It also keeps the shoulder joint more stable in patients with a rotator cuff tear than an anatomic replacement is able to do, preventing that upward sliding of the joint from occurring. In addition, patients may be indicated for a reverse shoulder replacement when they have glenoid/socket bone loss, even if they have a normal rotator cuff. This is because the plastic socket of an anatomic shoulder replacement is fixed to the socket bone by plastic pegs surrounded by bone cement. These pegs and cement require adequate surrounding bone in order to be fixed to the socket, and this is compromised when bone is lost or worn away. The metal ball of the reverse shoulder replacement is fixed to the bone of the socket using large screws that are drilled into the bone, allowing it to be fixed very strongly even when a portion of it is worn away.

Surgical Procedures for Shoulder Replacement

Shoulder replacement is commonly performed through an incision over the front of the shoulder. The surgeon then navigates between the large muscle bellies of the deltoid and pectoralis muscles to expose the shoulder and rotator cuff tendons. The ball and socket of the shoulder are surrounded by 4 rotator cuff tendons; 2 in the back of the shoulder (teres minor and infraspinatus), 1 on top of the shoulder (supraspinatus), and 1 in front of the shoulder (subscapularis). The front rotator cuff tendon is commonly moved out of the way so that the surgeon can access and view the ball and socket of the shoulder. To do this, the surgeon will either peel the front tendon off of the humerus, cut the tendon with a sharp knife or cautery device (this is known as a “tenotomy”), or perform a Lesser Tuberosity Osteotomy. The lesser tuberosity osteotomy is when the surgeon takes a small piece of bone from the location at which the front rotator cuff tendon inserts onto the humerus and reflect the tendon with its attached bone out of the way. Once the front rotator cuff tendon is moved, bone spurs that commonly exist on the undersurface of the ball (humerus) are removed. Then, specifically designed guides are used to direct the surgeon regarding where to cut the arthritic ball from the shoulder. The arthritic socket is then examined, and if a patient is receiving an anatomic total shoulder arthroplasty or a reverse shoulder arthroplasty, the arthritis on the socket is then shaved away with a device called a “reamer”. Once that is complete, the surgeon then implants either a plastic socket (if performing an anatomic total shoulder arthroplasty) or a metal baseplate with screws followed by a metal ball (if performing a reverse shoulder arthroplasty). The surgeon then places a metal stem into the arm bone (the humerus) and replaces the arthritic ball that was removed with a new metal ball (if performing an anatomic total shoulder arthroplasty) or with a metal and plastic socket (if performing a reverse shoulder arthroplasty). After the new metal and plastic shoulder is placed, the front rotator cuff tendon that was moved out of the way must then be put back in place, which is typically done with a number of very high strength sutures. It is very important that the repair of the front rotator cuff tendon heal to make sure that the shoulder functions normally, and this is a major focus during the postoperative rehabilitation process.

Advancements in Shoulder Replacement

Many advancements in shoulder replacement surgery have been made to help surgeons perform a more accurate and more personalized surgery for each patient. Surgeons commonly order a preoperative CT scan (CAT scan) of the shoulder and upload the images to a computer software program. This program allows the surgeon to perform the shoulder replacement through a computer simulation prior to performing the surgery on the patient. Doing this allows the surgeon to better plan the surgery, including the ability to decide what size and shape implants fit the shoulder best and to decide exactly where each implant should be placed in the shoulder to get the best outcome. To improve the accuracy of the surgeon, 3D-printed guides can be made using the planning software so that the surgeon can place the implants in the exact location they planned. Newer technology has been developed using augmented-reality glasses (i.e. the Hololens, Vision Pro, etc.) worn by the surgeon that can take the planned surgery performed on the computer software and project it onto the patients actual shoulder. This allows the surgeon to more accurately place the components of the shoulder replacement exactly as intended.

This surgical planning is also very useful for patients with glenoid (socket) bone loss. This bone loss leaves the socket with an abnormal shape that sometimes does not fit with normal shoulder replacement implants. Using this computer software allows surgeons to see the exact shape of the abnormal socket and decide if “standard” implants can be used. Over the last decade, many new implants (known as “augmented” implants) have been designed to fit the abnormal shape of the socket in patients with this type of bone loss, and this can be trialed through computer software before being attempted in a live patient during surgery. When the bone loss is too severe or the shape of the socket is too abnormal to fit standard or augmented implants, a personalized metal socket can be 3D-printed from the CT scan so that it fits the exact shape of the socket. This improves the chances that a shoulder replacement can be performed and provide the patient with a stable, functional shoulder.

Risks and Complications

All surgeries involve risk to a patient’s health to some degree, most of which commonly occur due to the risks of anesthesia. All open surgeries of the shoulder come with risks of damage to local anatomy like blood vessels, nerves, and bones, however, shoulder replacement surgery comes with its own unique potential complications.

The most common complication after anatomic total shoulder arthroplasty is loosening of the plastic socket. The plastic that is used to replace the arthritic socket can wear down over time causing it to loosen from the bone, which can sometimes result in shoulder pain. Alternatively, the metal ball and stem placed in the humerus can loosen, but this is much less common. Additionally, the front rotator cuff tendon (subscapularis) that is moved out of the way and eventually repaired again during surgery, can fail to heal. If this happens, the shoulder may become unstable and tend to slide forward (anterior) in the shoulder joint, causing pain and worsening function.

Finally, patients undergoing anatomic total shoulder arthroplasty may experience a tear of the superior rotator cuff tendon (supraspinatus) after surgery. This rotator cuff tear can lead to pain, decreased shoulder strength and range of motion, and earlier loosening of the plastic socket. Patients undergoing reverse shoulder arthroplasty may experience unique complications including instability or stress fracture. Instability occurs when the shoulder joint dislocates after a reverse shoulder replacement, this can be treated with immobilization in a sling, or with revision surgery depending upon the cause. Stress fractures may occur in the acromion or scapular spine, both of which are part of the shoulder blade, and typically cause pain and limited range of motion. These fractures are also commonly treated with immobilization in a sling to allow for healing to occur.

Recovery and Rehabilitation

After shoulder replacement surgery, you can expect to be discharged home in a sling. Patients undergoing anatomic total shoulder arthroplasty require a somewhat unique postoperative therapy plan in order to protect the front rotator cuff tendon that was repaired, and allow for it to heal. For this reason, patients are typically kept in a sling full-time for the first 2-3 weeks after surgery, which is often only removed for hygiene, range of motion exercises of the hand, wrist, and elbow, and pendulum exercises of the shoulder. After this time period, patients are often allowed to take the sling off when in a controlled environment, such as within their home.

Physical therapy is used during this time to begin passive range of motion of the shoulder, by being led by a therapist to improve shoulder range of motion and prevent stiffness. At approximately 6 weeks after surgery, patients are allowed to begin active range of motion under the guidance of a therapist in order to further improve range of motion and begin training the muscles surrounding the shoulder. External rotation (rotating the arm and shoulder outward away from the body) is limited during this time to protect the repair of the front rotator cuff tendon. At approximately 2-3 months after surgery, strengthening of the shoulder with resistance exercises is started. Sport- or work-specific training may be performed between 4 and 6 months after surgery if required. Return to unrestricted activities may then begin at around this time point. This time-line is not exact and may differ depending upon surgeon reference. Interestingly, new techniques to perform this surgery, known as “subscapularis-sparing”, are used by some surgeons to avoid having to take down the front rotator cuff tendon. This can allow for earlier range of motion and strengthening after surgery in hopes of speeding-up the postoperative recovery time.

Patients undergoing reverse shoulder replacement may undergo a somewhat different postoperative rehabilitation program. As the reverse shoulder replacement is not as dependent upon the rotator cuff, earlier rehabilitation may be initiated. Current research has shown that immobilization in a sling and delay of physical therapy for weeks after surgery does not provide significant benefit to patients after reverse shoulder replacement in comparison to early physical therapy. For this reason, patients may be placed in a sling for 2-4 weeks postoperatively depending upon surgeon preference, but range of motion exercises are often started immediately after surgery.

Preparing for Shoulder Replacement Surgery

Preparing for shoulder surgery typically consists of medical optimization and preparation of your home to accommodate your limitations after surgery. Medical optimization includes a visit to your primary care doctor to obtain preoperative clearance for surgery. This doctor will often perform blood work and a chest x-ray to ensure your heart and lungs, as well as your remaining organ systems, are functioning well and that you are healthy enough to undergo surgery and anesthesia. Patients with diabetes will undergo a hemolobin A1C test to ensure that their blood sugar is well-controlled prior to surgery. If the patient has a history of heart disease, they will often require clearance from their cardiologist prior to undergoing surgery. Finally, any patient on blood-thinner medications will be required to stop taking this medication a few days prior to surgery to limit the amount of bleeding during and after the surgery.

Patients are often discharged home on the same day or the next day after their shoulder replacement. You will need assistance by a relative or close friend to help get you into the car and to drive you home because your arm will be immobilized in a sling, making it difficult to drive. In addition, any patient taking narcotic pain medication cannot operate a vehicle while under the influence of this medication. It is also recommended that you have another person stay with you for a few days following surgery to assist you in getting in and out of bed or a chair and to help you with hygiene as the arm that underwent surgery will be in a sling at all times. Finally, sleeping in a bed and lying flat after shoulder surgery can often be uncomfortable. For this reason, it is recommended that you sleep in a recliner after surgery as this can help minimize your discomfort and make it easier to get up unassisted. 

Surgical Team and Expertise

Rothman Orthopaedics has employed a number of highly-trained shoulder specialists that perform hundreds of shoulder replacements every year. These shoulder surgeons went through additional training and certification specifically in shoulder surgery in order to specialize in these procedures. Along with a skilled team of experienced nurses, operating room staff, and shoulder therapists, our surgeons work with their patients to develop an individualized plan for success that is specific to each patient’s needs regarding their shoulder. This includes patients with all types of shoulder arthritis, no matter how complex their problem may be. Our team utilizes their specialized training, as well as up-to-date techniques and technology, to ensure that patients have the best possible outcome following shoulder replacement surgery.

Shoulder replacement surgery is a safe and effective way to improve pain and function in patients with advanced shoulder arthritis. No two patients with shoulder arthritis are the same, and each patient may have special needs regarding the type of shoulder replacement required or the type of implants that are used. It is important to seek help from a highly-trained shoulder specialist who has performed a number of shoulder replacements and is familiar with current techniques utilized to treat patients with complex shoulder problems.

Additionally, it is important to follow the instructions of your surgeon and therapist to ensure that your shoulder has the best possible outcome after a shoulder replacement. If you believe you may have shoulder arthritis and would like to know if a shoulder replacement is right for you, do not hesitate to make an appointment to see one of our shoulder specialists. Our surgeons will be able to give you a clear answer regarding the severity of your shoulder arthritis, if you would benefit from surgery, and what type of shoulder replacement would be best for you.