Many have heard of arthritis. But despite its straightforward definition – inflammation of a joint – there are more than 100 types of arthritis, each with different causes and treatments. They all have the same symptoms, though: inflamed joints that can lead to pain and stiffness.
Osteoarthritis (OA), the most common type of arthritis, is caused primarily by age-related wear-and-tear and can affect shoulders, knees, hips and other joints. Also known as “wear-and-tear” arthritis, OA is a condition that involves the deterioration of the smooth outer covering of bone (cartilage).
If people lived forever, everyone would develop osteoarthritis, since the loss of cartilage occurs from simply using the joint. Shoulders are less susceptible to wear-and-tear compared to other weight-bearing joints, but longer lifespans and an increase in sports participation have contributed to rising numbers of shoulder problems earlier in life.
The shoulder consists of the upper arm bone (humerus), the shoulder blade (scapula), and the collarbone (clavicle). The upper arm bone ends in what looks like a ball, which rests against a socket in the shoulder blade. Shoulder OA is the loss of the cartilage that allows this ball to glide smoothly against the socket, which can lead to the bones rubbing against each other.
What causes shoulder osteoarthritis?
Shoulder OA is caused by both genetic and behavioral factors.
“Genetics predisposes you to wear-and-tear, then it’s what you do with your life that makes osteoarthritis manifest,” explains Dr. Tamara Martin, an orthopaedic surgeon in the Department of Orthopaedic Surgery at Brigham and Women’s Hospital. Factors include:
- Gender: Shoulder OA is more common in women than men.
- Genetics: Hereditary factors determine the toughness and durability of cartilage, as well as how it attaches to bone. A person with weaker cartilage is more likely to develop OA than another individual, even when participating in similar activities.
- Repetitive stresses: People whose jobs call for repeated lifting or pushing, such as activities performed during manual labor, subject their joints to minor stresses that can accelerate the development of OA.
- Athletic participation, particularly sports that require a lot of shoulder movement. Athletes engaging in repetitive activities are more susceptible to cartilage loss. They are also more likely to injure their shoulder, which can lead to post-traumatic arthritis (a type of OA caused by injury rather than aging).
How is osteoarthritis in the shoulder diagnosed — and when?
The shoulder’s three bones and many tendons and muscles make the shoulder the most mobile joint in the body. But this combination of structures also makes the shoulder vulnerable to problems.
Five major types of arthritis commonly affect the shoulder: osteoarthritis, post-traumatic arthritis (a type of OA), rheumatoid arthritis (an autoimmune disease that can affect the whole body), avascular necrosis and rotator cuff tear arthropathy. Other common shoulder conditions include bursitis, tendonitis, frozen shoulder and rotator cuff injury.
All of these conditions can produce shoulder pain, but vary in their underlying causes. Because the conditions show similar symptoms, it’s difficult for a person to know what problem is causing their shoulder pain without a physician’s help.
A physical exam and X-ray can help diagnose the problem.
- During the physical exam, a doctor examines the shoulder joint for range of motion, involvement of other joints and tenderness. The exam also includes questions about personal and family medical history.
- X-rays are used to look for a narrowing joint space and damage related to the bones in the shoulder joint, as well as for the formation of bone spurs, which indicate arthritis.
- Other diagnostic tests may be used to rule out causes of joint pain. Blood tests and analysis of joint fluid can rule out rheumatoid arthritis or infection.
- An MRI may also be needed to gauge the condition of the rotator cuff (a combination of muscles and tendons in the shoulder).
Early diagnosis is important for OA specifically in the shoulder due to the possibility of having two conditions at once. In particular, a torn rotator cuff can limit the types of surgical treatments available to someone with osteoarthritis. It’s important that persistent shoulder pain be evaluated by a physician so that these conditions can be treated before they co-occur.
“Anybody with symptoms that persist for more than several weeks should be evaluated, especially if the pain is not responding to ice, anti-inflammatory medications, and rest,” says Dr. Martin.
Nonsurgical treatments can provide pain relief
There is currently no cure for OA, but nonsurgical treatments can slow its progress and help with pain management in the shoulder. These options include: activity modification, periodic rest, cold compresses, physical therapy, anti-inflammatory medications, such as aspirin or ibuprofen, and steroid injections.
“Some people never need to consult a surgeon,” says Dr. Martin. “We may start with injections, physical therapy, and anti-inflammatories. If their pain isn’t effectively managed, we will do an MRI to assess the rotator cuff. If it looks like they’re developing more arthritis over time, then we would suggest that they be evaluated for surgery.”
Dr. Martin reminds patients that the timing of surgery is important. “The sooner a person is evaluated, the better we can guide them on their medical journey,” she says.
When necessary, surgical treatment can be highly successful
Surgery on the shoulder is common, with a success rate of over 90 percent. Complications are few and uncommon. If you have advanced OA, however, the condition of your rotator cuff will determine your surgical options.
If your rotator cuff is intact, the best option is likely total shoulder replacement. In this surgery, the socket is resurfaced and the arthritic ball is replaced. The patient can have nearly normal shoulder function without pain.
If your rotator cuff is severely damaged, there is nothing holding the ball in the socket. This makes moving your arms above your shoulder blades difficult. Total shoulder replacement is not possible, but there are still three surgical options.
- Reverse shoulder: A ball is screwed into the socket’s original location and a socket is placed where the ball used to be. This eliminates most of the pain on both the ball and socket side, but doesn’t allow full overhead motion and strength.
- Hemiarthroplasty: The ball is replaced with a larger metal head to glide against the original socket. Overhead function is not fully restored, and some pain will continue due to friction between ball and socket.
- Resection arthroplasty: The ball is removed. The pain will improve, but overhead motion may be difficult. This procedure is becoming less common, because this result is not ideal.
It doesn’t always make sense for a person to undergo surgery. For instance, elderly people with complex medical problems may not be suitable candidates for surgery due to a higher risk of complications.
Recovery is a common concern among surgery candidates. Recovery can be lengthy, from two weeks to three months, and it’s difficult to navigate the world with one hand, especially if you live alone or are the sole caretaker of another.
Dr. Martin works closely with her patients to prepare them in advance. She advises patients to wear their arm in a sling around the house before surgery to discover where the challenges might be, such as securing a belt buckle, cooking, or opening a door. Then together they can work on a plan to make these challenges easier before the sling becomes reality.
“It takes some forethought and planning before embarking on surgery,” says Dr. Martin. In addition to making small changes at home, she recommends that you plan to have help with tasks that you can’t complete on your own, such as shopping for groceries.
She also reminds patients to set expectations in advance of surgery. Most patients will need physical therapy to recover their strength, motion and endurance. And healing will take time. The surgeon will work with the patient to determine when they should start physical therapy after surgery.
Taking care of our bodies can lead to healthier joints
Dr. Martin emphasizes the importance of taking care of our bodies.
“Be thoughtful,” she says. “Be aware of how you use your shoulders. Keep your muscles strong and make sure you’re using proper techniques, especially in sports training.”