Shoulder replacement surgery was first introduced in the 1950s to treat shoulder fractures. Since then, there have been vast improvements in shoulder replacements, as well as an expansion of the indications for the procedure. Today, shoulder replacement is the third most common joint replacement, with over 60,000 Americans have shoulder replacement procedures each year. Shoulder replacement offers patients pain relief and improved function and a return to more active lifestyles.  Shoulder replacement is most commonly performed to treat degenerative joint disease (osteoarthritis) and has been highly successful in relieving pain and restoring function. It may also used to treat severe rotator cuff tears, rheumatoid arthritis, post-traumatic conditions, and avascular necrosis, among other problems.  Shoulder replacement has changed significantly over the last few years.  New technology such as the reverse shoulder and resurfacing are now available to treat shoulder pain due to arthritis or post traumatic degeneration.


The shoulder is made up of three bones: the upper arm bone (humerus), the shoulder blade (scapula), and the collarbone (clavicle). The shoulder joint is a ball-and-socket joint made up of the humeral head (ball) and glenoid (socket). Because the humeral head is much larger than the glenoid (like a golf ball on a tee) the shoulder is highly dependent on soft tissues (rotator cuff, labrum, capsule and ligaments) for stability. The rotator cuff is a group of four muscles and tendons that extend from the scapula to the humerus and surround the shoulder joint.. They keep your arm bone centered in your shoulder socket and are extremely important for normal shoulder motion, strength and stability.

Fig. 1 Diagram of shoulder anatomy

The shoulder is the most flexible and mobile joint in your body. Your shoulder allows you to move and rotate your arm in front, side, above your head and to the back of your body. In the normal shoulder, the humeral head (ball) and the glenoid (socket) are covered with smooth articular cartilage. This cartilage allows almost frictionless movement of the shoulder. It is this cartilage that is destroyed in shoulder arthritis.


There are several reasons why your doctor may recommend shoulder replacement surgery. People who benefit from surgery often have severe shoulder pain that interferes with everyday activities, such as reaching overhead, dressing, toileting, and washing. Some people also have moderate to severe pain at rest. This pain may be severe enough to prevent a good night’s sleep. Loss of motion and/or weakness in the shoulder is another common symptom. Finally, failure to improve with non-operative treatments such as anti-inflammatory medications, cortisone injections, or physical therapy is a reason your doctor may recommend shoulder replacement. The decision to have shoulder replacement surgery should be a cooperative one between you, your family, your family physician, and your orthopedic surgeon.

Fig.2 Pre-op Xray showing shoulder arthritis


Shoulder replacement surgery is highly technical and should be performed by a surgeon with experience in this procedure. There are different types of shoulder replacements. Currently there is total shoulder replacement, hemi arthroplasty replacement, reverse shoulder replacement, and humeral head resurfacing.  Your surgeon will evaluate your situation carefully before making any decisions and will discuss with you which type of replacement would best meet your health needs.

Total Shoulder Replacement

Most patients undergoing shoulder replacement have little or no damage to the rotator cuff. These patients benefit from an anatomic total shoulder replacement, in which the arthritic humeral head (ball) is replaced by a metal implant, and a plastic component resurfaces the glenoid (socket). These components come in various sizes in order to mimick the natural anatomy of the shoulder joint.

They may be either cemented or “press fit” into the bone. If the bone is of good quality, your surgeon may choose to use a non-cemented (press-fit) humeral component. If the bone is soft, the humeral component may be implanted with bone cement. In most cases, an all-plastic glenoid (socket) component is implanted with bone cement.

Fig.3 Post-op X-ray following Total Shoulder Replacement

Implantation of a glenoid component is not advised if the glenoid has good cartilage, the glenoid bone is severely deficient, or the rotator cuff tendons are irreparably torn.

Humeral Head Replacement

In certain situations, your surgeon may replace only the ball. This procedure is called a humeral head replacement. During this procedure, the head of the humerus is replaced with a metal ball and stem, similar to the component used in a total shoulder replacement. However, the glenoid (socket) is not resurfaced.

Some surgeons recommend humeral head replacement when the humeral head is severely fractured but the socket is normal. Other indications for a hemiarthroplasty include, arthritis that only involves the head of the humerus with a glenoid that has a healthy and intact cartilage surface, severe glenoid bone loss, or when there is a combined torn rotator cuff and arthritis

Occasionally a surgeon will make the decision between a total shoulder replacement and a humeral head replacement in the operating room at the time of the surgery, but should inform you of this plan before surgery.

Studies show that patients with osteoarthritis get better pain relief from total shoulder arthroplasty than from humeral head replacement.

Resurfacing Hemiarthroplasty

Resurfacing hemiarthroplasty involves replacing just the joint surface of the humeral head with a cap-like prosthesis without a stem. This procedure preserves the bone in the humerus and may be used as an alternative to the standard stemmed humeral head replacement. Resurfacing hemiarthroplasty may be an option for you if your glenoid still has an intact cartilage surface, there isn’t fracture of the humeral neck or head, or if there is a desire to preserve humeral bone

Fig.4 Post op X-ray after Resurfacing Hemiarthroplasty

Resurfacing hemiarthroplasty helps to avoid the risks of glenoid wear and loosening that may occur with conventional total shoulder replacements in patients who are young or very active. Also, because it conserves more bone, it may be possible to convert to total shoulder replacement, if necessary, at a later time.

Reverse Total Shoulder Replacement

A more recent procedure called reverse total shoulder replacement changes the structure so that the socket and ball are switched. A metal ball is placed onto the scapula and the socket is moved to the top of the humerus. This ultimately shifts the center of rotation, and the arm no longer needs to rely on the damaged rotator cuff tendons and muscles. Instead, movement will then rely on the stronger shoulder muscle known as the deltoid.

Fig. 5 Pre-op X-ray showing massive rotator cuff tear and arthritis combined

While an X-ray will clearly show the change, the general shape of the shoulder remains the same. Reverse total shoulder replacement is used for patients who suffer from severe arthritis combined with an irreparable rotator cuff (cuff tear arthropathy) or had a previous shoulder replacement that failed. In addition, some severe proximal humerus fractures that cannot be fixed can be treated with reverse total shoulder replacements.

Fig. 6 Post-op X-ray following Reverse total shoulder


IMG_0718Preop X-Rays of patient with severe disabling arthritis

IMG_0721 Post op X-Ray following TSA.

IMG_0720Post op patient showing ability to raise arm overhead after TSA



As with any surgical procedures, there are potential risks and complications of shoulder replacement. These can be related to the surgery itself or can occur over time after your surgery. These complications are rare, but when they occur, most are successfully treated. Possible complications include the following:


Infection is a complication of any surgery. In shoulder joint replacement, infection may occur in the wound or deep around the prosthesis. It may happen while in the hospital or after you go home. It may even occur years later. Minor infections in the wound area are generally treated with antibiotics. Major or deep infections may require more surgery and removal of the prosthesis. Any infection in your body can spread to your joint replacement.

Prosthesis Problems

Even though there continues to be advances in prosthesis designs and materials, as well as surgical techniques, the prosthesis may wear down and the components may loosen. The components of a shoulder replacement may also dislocate. These problems, while rare, may require revision surgery.  Patients who undergo a total shoulder replacement should be monitored for loosening of the glenoid component.  If you are going to have a total or reverse shoulder replacement be aware that your physical activity will need to be curtailed.  This issue is less of a problem with hemi-arthroplasty or resurfacing.

Nerve Injury

Nerves in the vicinity of the joint replacement may be damaged during surgery, although this type of injury is infrequent. If nerve injury occurs, you could experience numbness or weakness in the shoulder and arm. Over time, these nerve injuries often improve and may completely recover.  This and infection are probably the biggest concern for surgeons.


Patients who have a reverse shoulder replacement are at risk of dislocations.  Patients with total shoulder replacement are at risk of rupturing the repaired sub scapularis tendon.  This tendon is re attached to the proximal humerus after the implant is in place.  If not careful it can peel off the bone and cause significant problems.


Patients typically spend one night in the hospital after surgery. When you leave the hospital, your arm will be in a sling. You will need the sling to support and protect your shoulder for the first 6 weeks after surgery. However, during that time, you will remove the sling multiple times a day to perform exercises aimed at regaining your range of motion.

Rehabilitation after surgery is critical to the success of a shoulder replacement. You will start gentle physical therapy the first day after surgery. During total shoulder replacement, the front part of the rotator cuff, known as the subscapularis, is cut in order to gain access to the shoulder. After the components are implanted, the subscapularis is repaired. The goal of therapy after total shoulder replacement is to increase range of motion and strength while protecting the subscapularis repair. Patients with glenohumeral osteoarthritis usually have a good rotator cuff and can be expected to have excellent range of motion and strength.

Most patients are able to perform simple activities such as eating, dressing and grooming within 2 weeks after surgery. Some pain with activity and at night is common for several weeks after surgery.  By 3 months after surgery most patients have no pain, have good range of motion, and are able to comfortably perform most activities. Patients will continue to see improvement in range of motion and strength up to a year after surgery.


About Steve A. Mora MD:

Steve Mora MD Small

Dr. Mora is a native of Orange County. He graduated from Anaheim High School in Orange County CA. He completed his training at the UC Irvine where he earned top of his class honors with his induction into the Alpha Omega Alapha Medical Society honors. He completed his Orthopedic Surgery training USC. He then completed a Sports Medicine, Cartilage, Shoulder, and Knee Fellowship at Santa Monica Orthopaedic and Sports Medical Group. He is currently practicing Orthopedic Surgery in Orange County.  Dr. Mora’s practice focus on sports related trauma, knee ligament and cartilage repair, shoulder rotator cuff and instability, hip arthroscopy and partial knee replacement and ACL reconsctruction. He sees athletes of all levels including professional soccer and UFC/MMA. He is team doctor for the Anaheim Bolts pro indoor soccer team and Foothill High School. Some of the procedures he performs include Cartilage transplantation (Genzyme), partial custom knee replacement, OATS, tibial osteotomies, meniscus transplant, knee ligament reconstruction, shoulder reconstruction, elbow arthroscopy, hip arthroscopy, platelet rich plasma and adult stem cell injections. Dr. Mora’s family heritage is Peruvian. He speaks fluent Spanish.


Steve A. Mora MD, Orange County ACL Surgeon.  You can request an appointment with me by calling 714 639-3750 or going to my web page

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