Shoulder Impingement Syndrome – Shoulder Tendonitis

The shoulder comprises three primary bones: the humerus (upper arm bone), the clavicle (collarbone), and the scapula (shoulder blade), which moves on the back. The acromion, a prominent edge of the scapula, forms the shoulder's top.

The round head of the humerus rotates within a shallow cavity on the scapula known as the glenoid. A collection of ligaments, called the joint capsule, stabilizes the head of the humerus in place. These ligaments connect the bones and provide essential support.

The shoulder's rotator cuff consists of four muscles and tendons that connect to the humerus, enabling arm rotation and upward movement. A lubricating membrane known as the bursa reduces friction between the rotator cuff tendons as they move.

You engage your rotator cuff muscles during overhead activities, such as reaching for objects or putting on clothing. These movements are prevalent in sports (e.g., tennis serves, baseball pitching, swimming strokes) and various job functions, particularly in construction.

Impingement syndrome generally arises from muscle imbalances around the shoulder, leading to increased stress on the rotator cuff tendons. Secondary impingement syndrome occurs when tendons and bursa rub against each other during repetitive overhead motions. The syndrome manifests when the space beneath the acromion becomes too tight for the rotator cuff tendons due to structural abnormalities, bone spurs, or thickened tissues.

As the tendons and bursa grind against each other during movement, friction, pain, and restricted motion can result. Degenerated tendons may become painful, leading to conditions like tendonitis, while the bursa may develop bursitis, both of which are distressing. Ongoing inflammation can further cause rotator cuff tendons to tear or detach from the humerus.

Individuals with shoulder impingement syndrome typically experience a persistent aching pain in the shoulder and upper arm. Activities requiring arm elevation, such as combing hair or dressing, may lead to weakness and discomfort. Nighttime pain is common and can disrupt sleep.

A doctor can diagnose shoulder impingement syndrome by assessing the patient's medical history and conducting a physical examination of the shoulder. X-rays may be ordered to identify bone spurs or abnormalities in the acromion. In some cases, a magnetic resonance imaging (MRI) scan is utilized to provide detailed images of the shoulder, particularly of the rotator cuff, muscles, and joint capsule.

Treatment options for shoulder impingement syndrome include resting from aggravating activities, applying ice packs, and using medications to alleviate pain and inflammation. Cortisone injections are also commonly employed. Physical therapy is often recommended to restore motion and strengthen weakened muscles, thereby reducing pain.

Surgery is considered when non-operative treatments yield minimal or no symptom relief. Surgical options may include enlarging the space beneath the acromion to facilitate tendon movement or trimming degenerated tendon tissue. Procedures such as acromioplasty involve removing bone spurs and the undersurface of the acromion, sometimes requiring the removal of part of the bursa or clavicle. This surgery is typically performed arthroscopically.

In contrast to open surgical repair, which requires a larger incision to access the joint, arthroscopic surgery is less invasive. It employs an arthroscope and specialized instruments introduced through small incisions. The arthroscope contains a lens and lighting system, allowing surgeons to visualize the joint's interior and capture magnified images on a video screen.