Anatomy of the Shoulder and Cause of Shoulder Arthritis

The normal shoulder comprises of the ball and socket joint, where each bone is covered in a smooth layer of cartilage. The gap you see between bones on an x-ray is the bones touching with the cartilage in between them.

The cartilage lines the end of the bones, cushions the impact of the bones and gives them a smooth gliding surface. A normal joint should slide smoothly around, letting us move, bend, lift and carry without pain.

As people age, and through a variety of conditions, you can get breakdown of that cartilage. You lose the smooth surface, so the bones don’t slide well. The space in the joint starts to narrow and you can get bone spurs, catching, clicking and popping.

When the cartilage is gone and the bones are touching with bone-on-bone arthritis, the surfaces don’t match as well: the bone is harder and rougher, and you have two rough surfaces that don’t quite fit together.

Over time, you get a progression of pain worsening with activity, especially with load and weight bearing. It tends to interfere with sleep, and due to pain you’ll stop using the joint as much. You start getting muscle wasting because you’re not using the joint. You may get clicking, cracking and popping (crepitus), swelling, and it may be painful to touch.

Treatments for Shoulder Arthritis

Non-Operative Treatments for Shoulder Arthritis

As with any arthritis, we do non-operative treatment first, especially when the arthritis is mild. Non-operative treatments include:

  • Non-steroidal anti-inflammatory medications like Motrin, Aleve, diclofenac, meloxicam, or Feldene.
  • Injections with a variety of different types of steroids depending on the joint condition, which can help decrease the inflammation that’s involved in arthritis.
  • Physical therapy to help with mobility, since an arthritic loose joint feels better than an arthritic stiff joint.
  • Activity modification to avoid doing things that hurt.

Surgery for Shoulder Arthritis

Deciding on Surgery for Shoulder Replacement

Surgery is a quality-of-life decision. Some questions to consider are:

  • Are the activities causing you pain the same ones that give you enjoyment of life (golf, swimming, etc.)?
  • Can you brush your hair, change clothes, bathe, wash your back, and do other self-care activities at home?
  • Can you do your job?
  • Can you get a good night’s sleep?

Talk with your shoulder surgeon if you’re having trouble doing these activities.

Steps for Surgery for Shoulder Replacement

A shoulder replacement begins with an incision on the front of the shoulder between the two main muscles above the shoulder, the pectoralis on your chest and the deltoid on the outside.

Then the surgeon goes toward the front of the shoulder and the rotator cuff muscles and opens up the front of the shoulder.

The surgeon exposes the worn out ball and socket and removes the top of the ball to resect that area of bone out.

On the cup side, the surgeon smooths it out to put a new cup in position. The cup is usually a plastic surface similar to the plastics used in hip and knee replacements. On the ball side, we use a stem or implant that goes down inside the upper arm bone, plus a new metal ball on top.

Some newer implants don’t go far down into the bone. If the bone quality is good, the smaller implant can be used and the bone will grow into the implant to make it solid.

The success rates on most arthritic surgeries like this is 90-95%. Most people have improved pain relief, function, range of motion, ability to perform their activities, better quality of life, and are able to return to independence and being able to do the activities they want to do.

Difference Between Anatomic and Reverse Shoulder Replacements

In an anatomic shoulder replacement, you’re replacing the ball with the ball and a socket with the socket. The other replacement option is a reverse replacement, where the ball is replaced with a socket and the socket is replaced with a ball.

The rotator cuff is the muscles that help hold the ball in the socket, keeping it centered and stabilized. If you have a large tear of the rotator cuff, the shoulder becomes unbalanced and the ball starts to rise up due to the pull of the deltoid muscle. As it becomes unbalanced, it’s like letting the air out of one tire of your car. Not only is that tire ruined, but if you drive for a while, you’ll start ruining the other tires faster because there is increased pressure and wear on them. Having a rotator cuff tear can degrade the cartilage in your shoulder because your shoulder is moving around more and you’ll get more wear at the top of the ball and on the socket as the ball lifts up.

As the ball rises up, it hits the bone above it and increases wear there as well.

Reversing the positions of the ball and socket creates a more stable construct that is different than how our shoulder is made, but it allows us to change the load and relationship, compensate for the lack of rotator cuff and rebalance the shoulder.

Reverse shoulder replacements aren’t just used for arthritis, but also for massive rotator cuff tears that are non-repairable, failed rotator cuff surgery, failed fractures, acute fracture repairs, failed other replacements and other severe bony deformities where an anatomic shoulder replacement can’t help.

Frequently asked questions

At what age do people start experiencing symptoms of shoulder arthritis?

It can be at any age, but generally it’s when you’re in the fifth or sixth decade of life. Most arthritis is from the wear and tear of age, and everything wears out at some point.

It can happen earlier if it’s the result of a traumatic injury: shoulder dislocations when you’re in your twenties can lead to arthritis in your forties, or after fractures where the blood supply has been compromised. Or power lifters in their early forties who were bench pressing 300 or 400 pounds may have symptoms earlier than you would expect just based on age.

How can you tell what your shoulder pain is from?

You can’t always tell based on history. One of our first steps when you come in for an evaluation is getting an x-ray. If the x-ray shows narrowing of the joint, bone spurs, uneven or rough bone, that gives us a clue that the pain is from arthritis. You can’t see the rotator cuff on the x-ray, but you can see changes to the ball and to the socket. If there are bumps on the ball but the socket looks smooth, especially if the ball is sitting high in the socket, it’s likely a rotator cuff issue. The best way to look at the rotator cuff is with an MRI, which we may also order.

What function do you have after a reverse shoulder replacement? Are you more limited than after an anatomic shoulder replacement?

The function can be very good. Older studies showed that people with an anatomic shoulder replacement had about 20-30% more motion than people with a reverse shoulder replacement, but those initial studies were done on patients where the anatomic replacements were done on people who had a good rotator cuff and the reverse replacements were done on people without a rotator cuff. Therefore, the people with reverse replacements were already in a worse starting position.

As technology and techniques have improved, reverse replacements can now have equivalent or similar results as an anatomic replacement in the right patient. You can get people back to near full range of motion with both types of replacement.

Can exercise or physical therapy help relieve pain from shoulder arthritis? And if they can, how does somebody know which exercises to do?

Yes, they can help with decreasing some pain. With bone-on-bone arthritis, sometimes exercise works and sometimes it doesn’t. We always recommend some physical therapy as a first line treatment because there are no major side effects other than potentially pain when you’re doing exercises. A goal is to always try to gain as much range of motion as you can because the shoulder joint wants to tighten up as it gets arthritic.

What is the recovery process like after a shoulder replacement?

Recovery is dependent on the patient. Like hip and knee replacements, increasing amounts of shoulder replacements are being performed in outpatient settings, as we are better with pain control, local nerve blocks and multimodal pain strategies. One nice thing about the shoulder, as opposed to the hip and knee, is you don’t have to walk on it. If your shoulder is numb and feels good and you’re healthy, you can go home the same day as your surgery. However, each patient is different. If you have a history of heart disease, COPD, lung disease or similar conditions, the surgery is more likely to take place in a hospital setting and you’re more likely to spend the night. Most people who spend the night only stay for one night.

If you’re dealing with bone-on-bone arthritis before the surgery, within a week or two after the surgery you will already feel less pain than before the surgery because the sharp gnawing pain from bones grinding is gone. You’ll spend about six weeks in the sling because the metal parts of the implant are coated to allow the bone to grow into them, and reducing the motion allows the bone to grow into the implant and form a solid connection. While you have a few at-home exercises to do initially, physical therapy begins in earnest about six weeks after surgery, starting with range of motion. You may have a little more pain as you start physical therapy since you haven’t moved the joint in several weeks. By three to four months, you’re feeling much better, and it can take six months to feel really good. It’s not a quick process, but usually between three and four months after surgery you’re glad you did the surgery. It can take up to a year after surgery to get all the improvements, with the last bit of motion and strength in the last four to six months.

Do shoulder braces or massages help with shoulder arthritis pain?

There aren’t any shoulder braces that can help with the pain. Some people want a sling or brace because the movement of the shoulder causes pain. However, the less you use your shoulder, the stiffer and weaker it will become. A brace will help some with pain, but you’ll end up with a less functional shoulder. While there are braces that can help knees, there aren’t ones that can help with shoulders.

There’s no harm in a massage. If your muscles are tight, stiff and sore and a massage helps them feel better, you can get a massage.