Rotator Cuff Syndrome rotator cuff tear/tendinitis shoulder impingement syndrome shoulder bursitis
The rotator cuff is a group of muscles in the shoulder that act to rotate and raise the arm.  The rotator cuff tendons attach the muscles to the humeral head (the ball of the ball and socket joint of the shoulder).  Pain associated with damage or injury to the rotator cuff is known as rotator cuff syndrome.
“Impingement” is when the rotator cuff is pinched underneath a bony process on the scapula known as the acromion.  Each time the arm is raised, the rotator cuff rubs underneath the acromion.  Over time, the rotator cuff can become irritated and inflamed (tendinitis).  A bursa is present over the rotator cuff that helps to limit the friction between the rotator cuff and the acromion.  The bursa itself can become inflamed and swollen--a condition known as bursitis.
The chronically impinged and inflamed rotator cuff can begin to wear down (tendinopathy).  This may result in a degenerative tear.  It may also weaken the rotator cuff so that it tears with a minor injury.  The tear may be a partial thickness or full thickness tear.
Rotator cuff disorders are diagnosed based on a history, physical exam, and MRI.  Patients with degenerative tears usually report gradually worsening shoulder pain.  Patients with acute tears report an injury to the shoulder.  Pain is typically worse with overhead activity and lifting the arm up to the side.  Rotator cuff syndrome is also notorious for keeping people awake at night when they attempt to lay on the affected shoulder.
Physical exam findings may include tenderness over the rotator cuff.  There is usually weakness and pain with raising the arm overhead.  If the condition has been present for long, the shoulder may be very stiff and range-of-motion limited.  The Hawkins and Neers tests involve moving the shoulder in such a way as to recreate impingement.  If this causes pain, impingement syndrome is suspected.  Other tests, such as the empty-can test and lift-off test have been developed to test the strength of the individual rotator cuff tendons.  If they demonstrate notable weakness or pain, a rotator cuff tear may be suspected.
The rotator cuff is not visible on x-rays, but they are often obtained to look for clues of rotator cuff syndrome.  A hooked acromion or a bone spur is evidence that there is impingement.  Calcium deposits may also be visible in the rotator cuff tendon (calcific tendinitis).  X-rays are also helpful in identifying other causes of shoulder pain such as fractures and arthritis.
First-line treatment for impingement, bursitis, tendinitis, and many partial tears is non-surgical.  Anti-inflammatory medications can reduce pain and inflammation.  Steroid (cortisone) injections can also help with pain and inflammation.  Physical therapy helps to improve shoulder mechanics and allow the rotator cuff to heal.  It may take the shoulder weeks or months to improve.
If shoulder pain does not respond to non-surgical treatment, shoulder surgery may be considered.  Surgery for rotator cuff syndrome is usually done arthroscopically (shoulder scope).  If there is impingement from a bone spur or hooked acromion, the bottom of the acromion can be shaved away to open up space for the rotator cuff.  This is known as a subacromial decompression or acromioplasty.  The rotator cuff is examined during surgery for a significant tear that may need to be repaired.
shoulder arthritis
normal rotator cuff MRI
normal shoulder x-ray
infraspinatus teres minor
rotator cuff
The space beneath the acromion (subacromial space) may become too tight because of a bone spur, a hooked acromion, or an inherently tight space.  Inflammation often begins with repetitive overhead activity that repeatedly presses the humerus up against the acromion, pinching the rotator cuff between them.
bone spur
rotator cuff tear
If a rotator cuff tear is suspected, an MRI of the shoulder may be obtained.  The rotator cuff can be visualized on an MRI.
rotator cuff tear
Shoulder Arthroscopy
Full-thickness rotator cuff tears do not have very good potential to heal without surgery.  They require a rotator cuff repair.  This is typically done by debriding the unhealthy tissue and fixing the healthy part of the tendon to the bone using anchors (small screws with sutures).  After surgery, the repair must be protected for a few weeks to allow the tendon to scar down and begin healing to the bone.  Physical therapy is very important to keep the shoulder from becoming too stiff.  For the first few weeks, only passive range-of-motion (using another person or object to move the arm rather than the shoulder muscles) is allowed.  Later, active range-of- motion and strengthening can begin.  3-4 months of rehabilitation is usually necessary after a rotator cuff repair.