The subscapularis is a muscle in your shoulder that helps you internally rotate your arm. When your arm is internally rotated, it means that your palm is facing back, behind your body. The subscapularis is the largest muscle in the rotator cuff, which is a group of muscles that attaches your upper arm to your shoulder. These muscles help you lift and rotate your arm. The subscapularis connects from your shoulder blade to your humerus, or upper arm bone.
All the muscles of the rotator cuff, including the subscapularis, can tear from overuse, trauma, or age-related conditions. Tears can be small or can go through most of the muscle. The size of the tear determines what treatment is needed.
Subscapularis tears are most common near the end of the tendon that connects to the humerus. They can also cause issues with the bicep muscle.
The most common symptom of a subscapularis tear is shoulder pain, especially in the front of the shoulder. You might also hear or feel “clicking” in your shoulder when you rotate your arm.
Some symptoms of a subscapularis tear are very similar to symptoms of other rotator cuff tears. These include:
- pain that gets worse at night
- shoulder or arm weakness
- pain that gets worse when you lift your arm
Other symptoms of a subscapularis tear are unique to this injury. These include:
- bicep weakness
- having a hard time reaching for something in your back pocket or reaching for your back
- pain in the space under your collarbone
- your affected arm rotating outwards (palm facing forwards) without you moving it
In young people, an injury is the most common cause of a subscapularis tear. This usually happens when your arm is overextended. In older people, subscapularis tears are usually caused by age-related degeneration.
Shoulder impingement can also cause a subscapularis tear. This happens when impingement of other rotator cuff muscles puts pressure on the subscapularis and causes them to tear.
First, your doctor will take a full history. They’ll ask if you hurt your arm or shoulder recently, what specific symptoms you have, and if there’s anything you’re having trouble doing.
They’ll then do tests to help narrow down what might be causing your pain. There are several tests that your doctor might do to help diagnose a subscapularis tear. These include:
- Lift-off test. Your doctor will ask you to put your hand on your lower back and then try to lift it. If you can’t lift your hand, that’s a sign you have a subscapularis tear.
- Bear hug test. You’ll put the hand of the affected arm on the opposite shoulder. Your doctor will try to pull your hand off your shoulder by rotating your forearm outwards. If you can’t hold your palm on your shoulder or have a lot of trouble holding it on, you might have a tear in your upper subscapularis.
- Belly press test. You’ll put your hand on your stomach and press down, using only your hand (not your wrist or elbow). If this hurts, you might have a subscapularis tear.
After these tests, your doctor will probably do an MRI. The above tests can help your doctor narrow down possible conditions, but an MRI can help them more definitively diagnose the tear, as well as see how serious the tear is.
Treatment for a subscapularis tear usually depends on the tear size and how much the tear negatively impacts your life. If the tear is small and you can perform your daily life activities, your doctor might recommend a conservative course of treatment. This would include icing, heat, and pain medication such as ibuprofen or other nonsteroidal anti-inflammatory drugs. It might also include physical therapy, especially if you’re older.
If the tear goes through the full thickness of the muscle, you have significant disability from the injury, or the tear doesn’t get better after three to six months of conservative treatment, your doctor will probably recommend surgery.
Most surgery for a subscapularis tear is done arthroscopically, which means your doctor inserts a camera into your shoulder through a small slit and uses the camera to guide the surgery. The surgery is done using small instruments that are also inserted through small slits.
In some cases, the space near the tear might be too small for arthroscopic surgery. In these cases, your doctor can do a more traditional surgery, where they make a larger incision in your arm. This method gives them a better view and allows them to move their surgical instruments more easily.
After surgery, you’ll wear a brace that will keep you from rotating your arm outwards for about six weeks. After that, you’ll start physical therapy and gradually increase your range of motion. You can usually start doing exercises to strengthen your arm and shoulder about ten weeks after surgery.
Surgery is often slightly less successful in people who are older. In most cases, you’ll regain full use of your shoulder after surgery. Be sure to take it slow during your recovery and avoid activities that cause you pain or can lead to further injury.
Your doctor or physical therapist will give you exercises you can do to improve your range of motion and strengthen your subscapularis. These may include:
- Lean forward with one arm on a table for support and the affected arm hanging at your side. Without rounding your back, swing the free arm back and forth. Then try moving it side-to-side and in small circles.
- Hold a stick or other long object behind your back, with the affected arm only lightly holding on to one end. Pull the stick to the side so your affected arm is stretched across your back. This shouldn’t hurt. Hold for 30 seconds, then release.
- Lie on your back and bend your elbow so that your fingers are pointing up and your elbow is on the ground next to you. Keep your elbow bent and rotate your forearm forwards until it touches the ground, then backwards. You can stop before you touch the ground if this hurts.
In some cases, especially when the muscle has started to atrophy, a small tear can turn into a larger tear without surgery. Muscle atrophy can occur because of age.
A tear in the subscapularis muscle can also lead to tears in other rotator cuff muscles or issues in your bicep. This is because other muscles need to compensate for a tear in the subscapularis and can be put under a lot of stress.
A subscapularis tear can often be managed and fully heal without surgery. If a tear is large or causes significant pain, you might need surgery. However, with rest and physical therapy, you should regain full use of your shoulder after surgery.