Shoulder impingement occurs when soft tissues like tendons get compressed or "pinched" within the shoulder. This typically happens where the rotator cuff tendons pass through a narrow space under the acromion (shoulder bone).When the arm is lifted overhead, the tendons can get squeezed between the bone and the head of the upper arm bone (humerus). This pinching causes inflammation and pain.

Causes of Impingement Syndrome

There are a few potential causes that can lead to shoulder impingement:

Poor posture - Spending long hours hunched over a desk or computer can pull the shoulders forward and round them. This posture narrows the space for the rotator cuff tendons.

Overuse injuries - Repeated overhead activities like swimming, serving in tennis, throwing a baseball etc. put stress on the rotator cuff tendons over time.

Aging - As we grow older, the spaces in the shoulder joint narrow down making impingement syndrome more likely. The rotator cuff tendons also weaken with age.

Injury - Prior shoulder dislocations, fractures or labral tears can alter the shoulder mechanics and lead to impingement.

Bone spurs - Extra bone growths known as spurs can develop on the acromion and impinge on the tendons as the arm is lifted.

Symptoms of Impingement Syndrome

The main symptoms of shoulder impingement include:

- Pain in the front or side of the shoulder that worsens when lifting the arm overhead or behind the back.

- Pain that occurs at night, especially while lying on the affected shoulder.

- Weakness in lifting or rotating the arm.

- Possible tenderness when pressure is applied just behind or above the shoulder.

- Occasional shoulder stiffness, especially after periods of inactivity.

The symptoms usually start gradually and worsen over time. Some people may also experience pain that radiates down the arm.

Diagnosis and Tests for Impingement Syndrome

A doctor will first perform a physical exam to check shoulder range of motion and strength. They may also do tests like the Neer impingement sign or Hawkins sign to check if certain motions reproduce the symptoms.

Sometimes x-rays are done to rule out bony abnormalities. But x-rays often appear normal in impingement syndrome since the cause is soft tissue damage.

Magnetic resonance imaging (MRI) provides a clearer picture of tendons, muscles, ligaments and cartilage. It is very useful for detecting rotator cuff tears which can co-exist with impingement.

Treatment Options for Impingement Syndrome

Non-surgical treatments are usually the first line of defense. Some common options include:

Resting the shoulder - Avoiding painful overhead activities gives the tendons time to heal.

Physical therapy - Allows structured shoulder strengthening and stretching exercises to improve shoulder mechanics.

Cortisone injections - Steroids can reduce pain and inflammation in the tendons and bursa.

Oral anti-inflammatory medications - Drugs like ibuprofen help relieve pain and swelling.

Lifestyle modifications - Pay attention to posture, arm positioning, strengthening weak muscles, losing weight if overweight etc.

Surgery may be considered if symptoms persist longer than 6 months despite conservative care. Procedures include decompression surgery to enlarge the space under the acromion or acromioplasty to shave the bone spur. In some cases a shoulder dislocation or labral repair may also be performed.

Prognosis of Impingement Syndrome

The success rate of non-surgical treatments is quite high. Most people see improvements within 3 months of starting physical therapy or corticosteroid injections. Adhering to lifelong posture and activity modifications helps prevent recurrence.

Surgery has a good success rate for severe, persistent cases. Recovery takes longer than non-surgical treatments but over 90% of patients are satisfied with their outcomes. Prevention emphasizes taking stretch breaks when working and keeping active range by swimming or low-impact exercise.