Shoulder Arthritis and Replacement

What is it?
Arthritis is the loss of the cartilage lining the joint surface (articular cartilage). Normally this is a soft glistening smooth white tissue which acts as a bearing surface to allow the joint to move freely. If the cartilage is damaged the surface becomes rough and no longer glides. This causes pain and stiffness within the joint.

The most commonly affected joints are the hip and the knee. The shoulder is rarely affected.

What are the causes?
The most common cause leading to a shoulder replacement is osteoarthritis, or wear and tear arthritis. Osteoarthritis can occur without any injury to the shoulder, but it is uncommon. This is in large part because the shoulder is not a weight bearing joint. Wear and tear arthritis is more common in the hip and knee.

More commonly, osteoarthritis occurs many years after an injury to the shoulder. A shoulder dislocation can result in instability of the shoulder that leads to chronic instability. Repeated dislocations over many years damage the joint leading to arthritis. Some fractures of the shoulder can also lead to arthritis. The problem with aseptic necrosis described above can lead to osteoarthritis too. Other types of arthritis affect the shoulder joint as well. Systemic diseases, such as Rheumatoid Arthritis, affect all the joints of the body. The result is much the same as osteoarthritis. The shoulder is painful and difficult to use due to the pain.

Other causes include:

Trauma: If the shoulder joint has been broken (fractured) at some point the cartilage may have been damaged

Instability: If the shoulder has dislocated a number of times the cartilage may have been damaged with each dislocation

Idiopathic: Arthritis of unknown cause. It may be genetic (inherited) or may be due to heavy manual work but a specific cause is usually not found.

What are the symptoms?
Pain is usually the first complaint. It is often felt deep in the shoulder and may be difficult to locate precisely. The shoulder may feel stiff and weak. There may be a sensation of grinding or catching within the shoulder. On occasion there may be crunching which can be heard.

How is the diagnosis made?
The diagnosis of osteoarthirits of the shoulder begins with a complete history of the problem, followed by a physical examination of the shoulder. Your doctor will ask you about old injuries of the shoulder. He will ask about any other medical conditions and surgical conditions. A physical examination will be performed to try and determine how much strength and motion you have in the shoulder. You doctor may look at other joints for other signs of systemic arthritis.

X-rays of the shoulder will be necessary to make the diagnosis of osteoarthritis of the shoulder. X-rays will show the degree of changes in the bones of the shoulder and give some idea how much wear and tear is present. If your doctor is concerned that you also have a rotator cuff tendon tear, he may also suggest either an arthrogram or a MRI scan of the shoulder. (Still Graphic: X-ray Shoulder w/Osteoartritis - Colorized)

An arthrogram is a test where a special dye (contrast) is injected into the shoulder joint. X-rays are taken to see if the dye leaks out of the shoulder joint. If it does, then a tear of the rotator cuff tendons is present.

A MRI scan of the shoulder is a newer test. The MRI Scan can also be used to actually look at the rotator cuff tendons and determine whether or not they are torn. An MRI scan is a special radiological test where magnetic waves are used to create pictures that look like slices of the shoulder. The MRI scan shows more than the bones of the shoulder. It can show the tendons as well, and whether there has been a tear in those tendons. The MRI scan is painless, and requires no needles or dye to be injected. The arthrogram is an older test. Both tests are still widely used.

What is the initial treatment?
Like any arthritic condition, osteoarthritis of the shoulder may respond to anti-inflammatory medications such as aspirin or ibuprofen. The pain may also respond to acetaminophen, (Tylenol). Orthopaedic surgeons are using some of the newer oral medications or supplements such as glucosamine and chondroitin sulfate more commonly today. These medications seem to be effective in healing reduce the pain in osteoarthritis of all joints. There are also new injectable medications that lubricate the arthritic joint . These medications have been studied mainly in the knee. It is unclear if they will help the arthritic shoulder.

Physical therapy may be suggested to regain as much of the motion in the joint and strength in the shoulder muscles as possible before undergoing a shoulder replacement.

An injection of cortisone into the shoulder joint may give temporary relief. Cortisone is a powerful anti-inflammatory medication that can ease the inflammation and reduce the pain - possibly for several months.

If initial treatment fails, what's next?
Corticosteroid injection into the shoulder joint may provide substantial pain relief. The amount of benefit is variable as is the duration which may be as little as days or as long as months. Most surgeons will limit the number of cortisone shots in any joint to two or three.

Arthroscopy and debridement in which the arthroscope is introduced into the shoulder and the rough or loose cartilage is smoothed down also has variable results with benefits as variable as those seen with injection although usually longer lasting.

If conservative treatment fails to provide any lasting relief, your doctor may suggest considering something more permanent, like surgery to replace the shoulder joint. Shoulder replacement in which the arthritic shoulder joint is replaced with a new one of metal and plastic give relief of pain in 90% of patients. The replacements last on average 15 years.

What is Shoulder Arthroplasty (replacement)?
Shoulder replacement (or shoulder arthroplasty) can be performed in many patients who have pain which has not responded to other treatments. Though less common than hip or knee replacements, shoulder arthroplasty has been performed since the 1950's with good success. The results of replacement surgery depend greatly on the type of arthritis, the quality of the bone, and the condition of the muscles around the shoulder. The primary goal of replacement surgery is pain relief. Shoulder arthroplasty is generally effective in relieving pain. The secondary goal of replacement surgery is improvement in range of motion and function. The extent of improvement varies greatly depending on the severity of the preoperative condition, the preoperative range of motion, and the postoperative rehabilitation. A shoulder replacement consists of two major parts, a humeral component, which replaces the bone at the end of the upper arm, and a glenoid component, which replaces the shoulder blade socket. The humeral component is made of metal, and the glenoid component of plastic. In some circumstances, such as severe fractures, only the humeral component is used. This is referred to as a hemiarthroplasty.

Complications

As with all major surgical procedures, complications can occur. Some of the most common complications following artificial shoulder replacement are:

• Infection
• Loosening
• Dislocation
• Nerve
• Injury

This is not intended to be a complete list of the possible complications, but is the most common.

Infection

Infection can be a very serious complication following an artificial joint. The chance of getting an infection following artificial knee replacement is probably somewhere around 1%. Some infections may show up very early - before you leave the hospital. Others may not become apparent for months, or even years, after the operation. Infection can spread into the artificial joint from other infected areas. Your surgeon may want to make sure that you take antibiotics when you have dental work, or surgical procedures on your bladder and colon to reduce the risk of spreading germs to the joint.

Loosening

The major reason that artificial joints eventually fail continues to be a process of loosening where the metal or cement meets the bone. There have been great advances in extending how long an artificial joint will last, but most will eventually loosen and require a revision. Hopefully, you can expect 12-15 years of service from an artificial knee, but in some cases the artificial shoulder will loosen earlier than that. A loose prosthesis is a problem because it causes pain. Once the pain becomes unbearable, another operation will probably be required to revise the shoulder replacement.

Dislocation

Just like your real shoulder, an artificial shoulder can dislocate - the ball comes out of the socket. There is a greater risk just after surgery, before the tissues have healed around the new joint, but there is always a risk. The therapist will instruct you very carefully how to avoid activities and positions that may have a tendency to cause a shoulder dislocation. A shoulder that dislocates more than once may have to be revised (which means another operation) to make it more stable.

Nerve Injury

All of the large nerves and blood vessels that go to the arm and hand travel through the armpit (axilla). Due to the fact that the operation is performed so close to these important structures, it is possible to injure either the nerves or the blood vessels during surgery. The result may be temporary if retractors holding them out of the way have stretched the nerves. It is very uncommon to have permanent injury to either the nerves or the blood vessels, but it is possible.