Surface replacement for shoulder arthritis

Surgery with a CAP, a special type of conservative resurfacing joint replacement that resurfaces the ball of the ball and socket joint, can lessen pain and improve function

Last updated: December 12, 2013
Edited by:

Winston J. Warme, M.D. Winston J. Warme, M.D.,
Associate Professor,
UW Orthopaedics & Sports Medicine
Frederick A. Matsen III, M.D. Frederick A. Matsen III, M.D.,
UW Orthopaedics & Sports Medicine

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Arthritis of the shoulder is a devastating condition that can seriously compromises the comfort and function of the shoulder. This condition is characterized by the permanent loss of the normal smooth surface of the ball and socket of the shoulder joint. The cartilage that normally provides this smooth surface cannot be restored and resulting loss of comfort and function of the shoulder cannot be totally regained. When the symptoms of shoulder arthritis are severe, shoulder joint replacement arthroplasty becomes a consideration.

After performing a clinical exam, a shoulder surgeon experienced with shoulder arthritis  can suggest what type of joint replacement surgery is most likely to be helpful to the individual with the condition. Individuals are most likely to benefit from this surgery if they are well motivated and in good health.

Joint replacement with a resurfacing CAP prosthesis preserves the maximal amount of bone. This is a highly technical procedure and is best performed by a surgical team who has experience with this surgery. Such a team can maximize the benefit and minimize the risks.

The two-hour procedure is performed under general (or nerve block) anesthesia.

Use of the arm is started immediately after the procedure.  Extensive therapy is not needed.

Symptoms & Diagnosis

Characteristics of shoulder arthritis

Arthritis of the shoulder is a condition in which the shoulder has lost the cartilage that normally covers its joint surface.

This condition can result in shoulder pain, weakness, stiffness and grinding on movement.


Shoulder arthritis may result from an injury, but it commonly arises slowly over time. It may also be cause by conditions where the normal blood circulation to the ball of the ball and socket joint is disrupted, such as avascular necrosis.

Similar conditions

Shoulder arthritis must be distinguished from other conditions, such as rotator cuff tear, frozen shoulder, and from neck arthritis, each of which may produce somewhat similar symptoms. Arthritis usually gives rise to stiffness without weakness. Rotator cuff tears usually cause pain and weakness, but stiffness is less common. Frozen shoulder is characterized by shoulder stiffness, but the X-rays are usually normal. Neck arthritis may cause shoulder pain and weakness that is worse when the head is held in certain positions.

Incidence and risk factors

Shoulder arthritis can affect shoulders of either gender and at any age, but is more common in individuals over 40 years. Joint replacement with a resurfacing CAP prosthesis may be particularly attractive for younger individuals with arthritis.


Shoulder arthritis is diagnosed by a history of progressive loss of shoulder function, often without an injury, along with a physical examination showing stiffness and grinding on movement and a typical appearance on X-ray.  In these films the humeral head can be seen contacting the socket without the normal space occupied by articular cartilage.

Shoulder arthritis is best diagnosed by an orthopedic surgeon with experience in shoulder disorders. Certain surgeons specialize in shoulder replacement surgery for arthritis. Such individuals may be found in the shoulder services of major schools of medicine.


Mild analgesic medications may relieve some of the symptoms of shoulder arthritis.


If the symptoms of shoulder arthritis with are mild, the condition may be treated with gentle motion exercises and exercises to strengthen the deltoid and other muscles around the shoulder.

Possible benefits of shoulder replacement surgery with a cap resurfacing prosthesis

When exercises are not successful, most cases of shoulder arthritis are considered possible candidates for shoulder joint replacement arthroplasty with a hemiarthroplasty with non-prosthetic glenoid arthroplasty or a total shoulder arthroplasty. In cases where it is preferred to avoid a stem down the shaft of the humerus (arm bone) a resurfacing CAP prosthesis is considered.

Joint replacement surgery can improve the mechanics of the shoulder by providing a smooth joint surface, but cannot make the joint as good as it was before the onset of shoulder arthritis. The effectiveness of the procedure depends on the health and motivation of the individual, the condition of the shoulder, and the expertise of the surgeon. When performed by an experienced surgeon, shoulder joint replacement arthroplasty can provide improved stability along with improved shoulder comfort and function. The greatest improvements are in the ability of the individual to sleep and to perform some of the basic activities of daily living.


Types of surgery recommended

Several types of surgery can be helpful in the management of shoulder arthritis (arthritis of the glenohumeral joint). The surgical procedures can range from a replacement of the humeral head with a resurfacing CAP prosthesis [Figures 1 and 2], a humeral hemiarthroplasty with a non-prosthetic glenoid arthroplasty, a total shoulder arthroplasty. If the rotator cuff is deficient, a rotator cuff tear arthropathy (CTA) prosthesis may be considered. Finally, if the shoulder is unstable a reversed prosthesis, such as the Delta may be needed.

Who should consider shoulder replacement surgery with a cap resurfacing prosthesis?

Individuals with shoulder arthritis should consider shoulder joint replacement arthroplasty with a resurfacing (CAP) prosthesis if

  • the shoulder arthritis is a major problem for the individual,
  • the individual is sufficiently healthy to undergo the procedure,
  • the individual understands and accepts the risks and alternatives,
  • there is sufficient bone to permit the surgery,
  • the surgeon is experienced in shoulder replacement surgery, and
  • the features of the arthritis and the shoulder favor a resurfacing prosthesis rather than a prosthesis with a stem that passes down the shaft of the bone.
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Figure 1
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Figure 2

Shoulder replacement surgery with a resurfacing (CAP) prosthesis is most effective when the individual follows a simple exercise program after surgery and understand the limitations of the procedure. Thus, the individual ‘s motivation and cooperation are important elements of the partnership.

What happens without surgery?

The rate of progression of shoulder arthritis is usually slow, thus surgery is not urgent.

Surgical options

Several types of surgery can be helpful in the management of shoulder arthritis (arthritis of the glenohumeral joint). The surgical procedures can range from a replacement of the humeral head with a resurfacing CAP prosthesis [Figures 1 and 2], a humeral hemiarthroplasty with a non-prosthetic glenoid arthroplasty, a total shoulder arthroplasty. If the rotator cuff is deficient, a rotator cuff tear arthropathy (CTA) prosthesis may be considered. Finally, if the shoulder is unstable a reversed prosthesis, such as the Delta may be needed.

Not all surgical cases are the same, this is only an example to be used for patient education.

Not all surgical cases are the same, this is only an example to be used for patient education.


In the hands of an experienced surgeon, shoulder arthroplasty with a resurfacing (CAP) prosthesis can be helpful in restoring  stability, comfort and function to the shoulder of a well-motivated individual with shoulder arthritis. The greatest benefits are often the ability to sleep on the affected shoulder and the ability to perform activities of daily living. As long as the shoulder is cared for properly and subsequent injuries are avoided, the benefit can last for years.


In that shoulder arthritis  progresses slowly, consideration of surgery is not urgent. Before surgery is undertaken, the individual needs to be in optimal health, understand and accept the risks and alternatives of surgery, and understand the postoperative rehabilitation program.


Shoulder replacement surgery for shoulder arthritis using a resurfacing (CAP) prosthesis carries significant risks that are important for the individual to consider. The risks of this surgery include but are not limited to the following:  infection (which can be sufficiently serious to require revision surgery, including removal of the prosthesis), injury to nerves and blood vessels, fracture, stiffness or instability of the joint, dislocation, loosening of the prosthesis, pain, failure of tendon or muscle attachment, and the need for additional surgeries – any or all of which may result in major loss of function to the arm. There are also risks of anesthesia and blood transfusion (although transfusions are not usually necessary). An experienced shoulder joint replacement team will use special techniques to minimize these risks, but cannot totally eliminate them.

Managing risk

Some of the risks of shoulder replacement surgery with a resurfacing (CAP) prosthesis can be effectively managed if they are promptly identified and treated. Infections may require a wash out in the operating room—sometimes complete removal of the prosthesis is necessary. Blood vessel or nerve injury may require repair. Fracture may require surgical fixation. Stiffness or instability may require exercises or additional surgery. Loosening of the prosthesis may require surgical revision. If the individual has questions or concerns about the course after surgery, the surgeon should be informed as soon as possible.


Shoulder joint replacement surgery with a resurfacing (CAP) prosthesis is considered for healthy and motivated individuals with shoulder arthritis that interferes with the individual’s comfort and function. Successful shoulder replacement depends on a partnership between the individual and the experienced shoulder surgeon. Individuals should optimize their health so that they will be in the best possible condition for this procedure. Smoking should be stopped a month before surgery and not resumed for at least three months afterwards. Any heart, lung, kidney, bladder, tooth, or gum problems should be managed before surgery. Any infection may be a reason to delay the operation. The shoulder surgeon needs to be aware of all health issues, including allergies and the non-prescription and prescription medications being taken. Some of these may need to be modified or stopped. For instance, aspirin and anti-inflammatory medication may affect the way the blood clots. The incision used for a shoulder replacement with a resurfacing (CAP) prosthesis is usually made across the front of the shoulder between the deltoid and pectoralis muscles. The area of the skin incision must be clean and free from sores and scratches. Before surgery, the individual should consider the limitations, alternatives and risks of surgery. Individuals should also recognize that shoulder replacement cannot restore normal function to the shoulder damaged by arthritis. The individual needs to plan on carefully protecting the arm for three to six weeks after the procedure. Driving, shopping and performing usual work or chores may be difficult after surgery. Plans for necessary assistance need to be made before surgery. For individuals who live alone or those without readily available help, arrangements for home help should be made well in advance.


Shoulder replacement arthroplasty can be delayed until the time that is best for the individual’s  overall health and convenience. However, excessive delays can result in the loss of bone making the reconstruction more difficult for the surgeon and the individual.


The surgeon's office should provide a reasonable estimate of the surgeon's fee and the hospital fee.

Surgical team

Shoulder replacement arthroplasty with a resurfacing (CAP) prosthesis is a technically demanding procedure that should be performed by an experienced surgeon in a medical center experienced in performing similar shoulder joint replacements. Individuals should inquire as to the number of shoulder arthroplasty procedures that the surgeon performs each year and the number of these procedures performed in the medical center each year.

Finding an experienced surgeon

Because relatively few shoulder arthroplasties are performed in the United States each year, it is unlikely that every community has an experienced shoulder arthroplasty surgeon who frequently performs arthroplasties for  cuff tear arthropathy . Surgeons specializing in shoulder joint replacement may be located through university schools of medicine, county medical societies, or state orthopedic societies. Other resources include local rheumatologists or professional societies such as the American Shoulder and Elbow Surgeons society.


Shoulder replacement arthroplasty is usually performed in a major medical center that performs these procedures on a regular basis. These centers have surgical teams and facilities specially designed for this type of surgery. They also have nurses and therapists who are accustomed to assisting individuals in their recovery from shoulder replacement surgery.

Technical details

Shoulder replacement surgery  with resurfacing (CAP) prosthesis [Figure 3] for shoulder arthritis is a highly technical procedure; each step plays a critical role in the outcome. Before surgery the x-rays are used to plan the procedure [Figure 4].

After the anesthetic has been administered and the shoulder is specially prepared to minimize the risk of infection, an incision is usually made across the front of the shoulder between the deltoid and the pectoralis muscle. One tendon (that of the subscapularis) is cut to allow access to the inside of the joint and to release the limitation of external rotation [Figure 5]. With the subscapularis released, the arthritic ball is exposed [Figure 6]. The bone spurs (osteophytes) are removed [Figure 7]. The diameter and height of the ball of the shoulder (humeral head) is measured  [Figure 8]. The upper aspect of the humeral head is marked for orientation  [Figure 9]. A ‘sizer’ is then used to confirm the size of the humeral head  [Figure 10] and to mark the four quadrants  [Figure 11] using the sizer windows  [Figure 12] and a cut out guide [Figure 13]. These orienting marks guide the precise placement of a guide wire  [Figure 14].  The shaper reamer is assembled [Figure 15] and used to ream the head to fit the prosthesis precisely [Figure 16] using its triple reaming geometry [Figure 17]. A trial resurfacing (CAP) prosthesis is placed [Figure 18].  A punch is used to create the central fixation hole [Figures 19 and 20].  With the trial in place, the ball is put back into the joint [Figure 21]. Once the excellence of fit of the trial is ascertained, the definitive humeral head prosthesis is inserted [Figure 22] and driven into place [Figure 23]. The desired fit is shown in cross section [Figure 24]. The ball is placed back in the joint [Figure 25]. The figures show a case where the portion of the humeral head damaged by a condition known as avascular necrosis [Figure 26] is replaced with a resurfacing (CAP) prosthesis [Figures 27 and 28]. At the conclusion of the procedure, the subscapularis tendon is repaired [Figure 29].

If the socket is damaged by the arthritis, resurfacing of the humeral head (ball of the shoulder joint) alone may be insufficient. In such cases a humeral hemiarthroplasty with a non-prosthetic glenoid arthroplasty or a total shoulder arthroplasty may be necessary.

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Figure 3
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Figure 5
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Figure 7
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Figure 8
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Figure 9
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Figure 10
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Figure 14
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Figure 17
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Figure 21
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Figure 22
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Figure 23
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Figure 24
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Figure 25
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Figure 26
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Figure 27
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Figure 28
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Figure 29


Shoulder joint replacement surgery may be performed under a general anesthetic or under a brachial plexus nerve block. The individual should discuss his or her preferences with the anesthesiologist before surgery.

Length of shoulder replacement surgery with a cap resurfacing prosthesis

The procedure usually takes approximately one and a half hours, however the preoperative preparation and the postoperative recovery may add several hours to this time. Individuals often spend two hours in the recovery room and two to four days in the hospital after surgery.

Pain and pain management

Recovery of comfort and function after humeral prosthetic arthroplasty with a resurfacing (CAP) prosthesis is progressive after the surgery. Often the benefits become apparent to the individual after two to six weeks.   This joint replacement procedure is a major surgical procedure that involves cutting of skin, tendon and bone and removal of scar tissue, as well as resuturing of tendon back to bone. The pain from this surgery is managed by the anesthetic and by pain medications. Immediately after surgery, strong medications (such as morphine or Demerol) may be given by injection and by mouth as needed. Within a day or so, oral pain medications (such as hydrocodone or Tylenol with codeine) are usually sufficient. On the other hand, some individuals need surprisingly little pain medication after this procedure. In older individuals it is often safer to use relatively less pain medication.

Use of medications

Initially after surgery pain medication can administered by mouth, in the vein (intravenously), or in the muscle (intramuscularly). Sometimes patient controlled analgesia (PCA) is used to allow the individual to administer the medication as it is needed. Hydrocodone or Tylenol with codeine are taken by mouth. Intravenous pain medications are usually needed only for the first day or two after the procedure. Oral pain medications are usually needed only for the first two weeks after the procedure. Some individuals need surprisingly little pain medication after this procedure. In older individuals it is often safer to use relatively less pain medication.

Effectiveness of medications

Pain medications can be very powerful and effective. Their proper use lies in the balancing of their pain relieving effect and their other, less desirable effects (such as slowed breathing, sleepiness, nausea, constipation, or difficulty urinating). Good pain control is an important part of the postoperative management.

Important side effects

Pain medications can cause drowsiness, slowness of breathing, difficulties in emptying the bladder and bowel, nausea, vomiting and allergic reactions. Individuals who have taken substantial narcotic medications in the recent past may find that usual doses of pain medication are less effective. For some individuals, balancing the benefit and the side effects of pain medication is challenging. Individuals should notify their surgeon if they have had previous difficulties with pain medication or pain control.

Hospital stay

After surgery the individual spends an hour or so in the recovery room. A drainage tube is usually used to remove excess fluid from the surgical area. The drain is usually removed on the second day after surgery. Bandages cover the incision. They are usually changed the second day after surgery.

Individuals are discharged as soon as the incision is dry, the shoulder is comfortable with oral pain medications, the individual can care for the shoulder, and the home support systems for the individual are in place. Discharge is usually on the third or fourth day after surgery.

Recovery and rehabilitation in the hospital

Early protected motion is important after a shoulder replacement with a resurfacing (CAP) prosthesis to help achieve the best possible shoulder function.  The surgeon will provided detailed information on the optimal program after the particular surgical procedure.

During the hospitalization, the individual learns a simple rehabilitation program that will be used at home after discharge.  The arm is kept in a sling for several weeks after surgery to allow for early healing.

Hospital discharge

At the time of discharge, the individual should be relatively comfortable on oral medications, should have a dry incision, should understand their exercises and should feel comfortable with the plans for managing the shoulder. For the first month or so after this procedure, the operated arm may be less useful than it was immediately beforehand.

The specific limitations can be specified only by the surgeon who performed the procedure. It is important that the reconstructed shoulder not be challenged until it has had a chance to heal. Usually the individual is asked to lift nothing heavier than a cup of coffee for six weeks after the surgery.

Management of these limitations requires advance planning to accomplish the activities of daily living during the period of recovery.

Convalescent assistance

Individuals usually require some assistance with self-care, activities of daily living, shopping and driving for at least six weeks after surgery. They usually go directly home after this surgery, especially if there are people at home who can provide the necessary assistance, or if such assistance can be arranged through an agency. In the absence of home support, a convalescent facility may provide a safe environment for recovery.

Recovery of comfort and function after shoulder arthroplasty continues for many months after the procedure. Improvement in some activities may be evident as early as six weeks. With persistent effort, individuals can make progress for as long as a year after surgery.

Physical therapy

Limited use for six weeks after shoulder replacement  with a resurfacing (CAP) prosthesis is critical for protection during the early phases of healing.

Most individuals find the recovery of comfort and function can be accomplished without formal physical therapy.

Rehabilitation options

It is often most effective for the individual to carry out her or his own rehabilitation at home. Often no physical therapy is recommended.

Can rehabilitation be done at home?

In general the rehabilitation is best performed by the individual at home. Occasional visits to the surgeon or therapist may be useful to check the progress and to review the program.

Usual response

Individuals are almost always satisfied with the increases in comfort and function that are achieved with the rehabilitation program. If the exercises are uncomfortable, difficult, or painful, the individual should contact the surgeon promptly.


The rehabilitation program is safe with little risk.

Duration of rehabilitation

the rehabilitation goals are achieved, the exercise program can be cut back to a minimal level.

Returning to ordinary daily activities

In general, individuals are able to perform gentle activities of daily living with the operated arm at the side starting four weeks after surgery. Walking with the arm protected is strongly encouraged. Driving should wait until the individual can perform the necessary functions comfortably and confidently. This may take up to six weeks if the surgery has been performed on the right shoulder, because of the increased demands on the right shoulder for shifting gears.

With the consent of their surgeon, individuals may be able to return to progressive activities after their surgery. It is important to remember that shoulder arthroplasty does not make the shoulder normal. It will never totally regain full comfort, strength, range of motion or function. Stressful activities and activities with the arm in extreme positions may never be possible after this procedure.

Long-term patient limitations

Individuals should avoid activities that involve major impact (chopping wood, contact sports, activities with major risk of falls) or heavy loads (lifting of heavy weights, heavy resistance exercises) after  this surgery.  In this way the risk of re-injury is minimized.


The surgeon and therapist should provide the information on the usual cost of the rehabilitation program. The program is quite cost-effective, because it is based heavily on home exercises.

Summary of shoulder replacement surgery with a cap resurfacing prosthesis for shoulder arthritis

Shoulder arthritis can be a devastating condition that seriously compromises the comfort and function of the shoulder.  This condition is characterized by the loss of the normal surface of the shoulder joint. These tissues cannot be restored to their normal condition and the lost comfort and function of the shoulder cannot be totally regained.

However, in the hands of an experienced surgeon  and in a well-motivated individual, shoulder  replacement surgery along with careful post-surgical  rehabilitation can help restore substantial  comfort and function to shoulders damaged by arthritis.

Pre-planning and persistent rehabilitation efforts will help assure the best possible result for the individual with rotator cuff tear arthropathy.

Thanks to the DePuy Company, the distributor  of the  resurfacaing (CAP) prosthesis,  for their permission to use the illustrations.