Two joints in our body—the shoulder and the hip—are special. These joints allow for an amazing range of motion thanks to their unique ball-and-socket configuration.
In the case of the shoulder, the ball is attached to the top of the humerus, or arm bone, and the socket is formed by a depression in the scapula, or shoulder bone.
- Learn more: Shoulder Joint Structure
When the shoulder joint has degenerated as a result of arthritis, the ball and socket can be replaced with synthetic parts. But sometimes the surgeon may recommend reversing the joint, so the ball is attached to the shoulder and the socket moves to the arm. This is called a reverse shoulder replacement.
Why reverse the joint?
What would motivate a surgeon to want to change the positions of the ball and socket in the shoulder joint?
There are a few reasons that this type of joint replacement is the better choice for a patient:
- Severe or irreparable damage to the rotator cuff
The rotator cuff is a group of four muscles that connect the scapula to the humerus and surround the shoulder joint. The rotator cuff can become damaged or torn either from a sudden acute injury or from years of gradual wear and tear. This damage causes the shoulder joint to become unstable and too weak to support the movement of the shoulder and arm. In severe cases, the shoulder may even feel paralyzed.
However, reversing the joint can take pressure off the rotator cuff, because the muscles powering the movement of the arm transfer to the shoulder’s deltoid muscles rather than the rotator cuff muscles.
- A traditional shoulder replacement that has failed
A traditional shoulder replacement can fail if, for example, the artificial components come loose from the bone. Rather than redo a traditional replacement, the surgeon may recommend a reverse shoulder replacement.
- Fractured shoulder
If the shoulder is fractured, it could cause instability and weakness the same way a rotator cuff injury can. This makes a reverse shoulder replacement a better option.
Possible drawbacks and complications
On the whole, reverse shoulder replacement is a successful surgery—90% of reverse shoulder replacements last at least 10 years. But like any surgery, there are risks and complications from the procedure.
These can include the following:
- Activity limitations
Reverse shoulder replacement helps relieve the stress on the rotator cuff muscles, but these muscles are still damaged. The joint is still vulnerable to instability and possible dislocation.
This means patients may have some activity limitations after surgery, especially for activities that involve extra force on the shoulder. For example, often they can still swim, but will be instructed to avoid tennis or other racquet sports.
- Problems with the prosthetic parts
The prosthetic parts may cause problems if they are not aligned correctly or come loose after surgery. These problems can usually be corrected successfully through a revision surgery.
- Nerve or blood vessel damage
Just about any surgery carries a risk for accidental damage to the nerves or blood vessels surrounding the surgical site. However, the risk is low.
Nearly all surgical procedures involve some risk for infection too. Most post-surgical infections can be treated with antibiotics.
- Blood clots
Whenever you are in bed for an extended period following surgery, you’re at risk for blood clots due to deep vein thrombosis. Healthcare workers help lower this risk by having patients wear compression stockings, getting them out of bed and active as soon as possible, and prescribing blood thinners as needed.