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Impingement Syndrome

Background and Etiology

Impingement Syndrome occurs when the rotator cuff tendon is compressed against the structures that form the upper portion of the shoulder. These structures include the acromio-clavicular joint, coraco-acromial ligament, and the acromion (outer edge of the scapula, or shoulder blade). This region is referred to as the subacromial space.

The rotator cuff normally functions as a depressor of the humeral head, which contributes to keeping the humeral head and shoulder stable. The rotator cuff muscles also assist in actively raising the arm overhead (flexion and abduction) and turning the arm in and out (internal and external rotation).

When the rotator cuff does not perform its functions adequately, a mechanical dysfunction is created. This results in the rotator cuff becoming impinged (pinched) against the structures along the upper portion of the shoulder or coracoacromial arch. Over time, this can lead to chronic wearing, tendinitis and subsequent tearing of the rotator cuff tendons. Advanced stages of impingement syndrome can include narrowing of the subacromial space by the formation of a bony spur along the under surface of the acromion.

Causes

Shoulder Impingement is often triggered by inflammatory conditions like bursitis, tendinitis, or anything that can cause a decrease in the subacromial space. Other high risk activities or conditions that can lead to the development of impingement syndrome include:

  • A curved or hooked acromion (type 2 or type 3) that affects the subacromial space (instead of a flat acromion (type 1) which does not.)
  • Repeated stress or overuse activities like overhead throwing, overhead exercise or work activities.
  • Trauma like falling on the shoulder

There are two basic forms of impingement syndrome – primary and secondary:

Primary impingement is the result of abnormal biomechanics in the shoulder as discussed earlier. Additionally, there are “primary factors” that can lead to narrowing of the subacromial space. These primary factors are often congenital in nature, seen frequently in patients over 40 years old. The person often complains of anterior shoulder and lateral arm pain along with weakness at the shoulder that results in difficulty with overhead activities and reaching motions across the body.

Secondary impingement is generally the result of instability in one of the shoulder joints (gleno-humeral and/or scapula thoracic). Secondary Impingement typically occurs in younger individuals who participate in activities characterized by overhead movements like baseball, volleyball, softball, swimming and tennis. The posterior aspect of the shoulder can become tight, making reaching motions across the body and behind the back difficult.

A person who suspects they have impingement syndrome should see a physical therapist or other health care professional who can properly diagnose this injury. It is particularly important that the professional who screens for impingement syndrome rule out the likelihood of having pathology of the cervical spine instead of the shoulder.

Symptoms

Pain and/or achiness at the tip and front of the shoulder that can radiate down the lateral arm. This may include a painful arc of motion between 60-120 degrees of motion when performing overhead activities.

Pain with overhead activities, lifting, throwing, and reaching motions across the body.

Difficulty sleeping on the effected side of the body, and performing daily activities such as dressing or combing your hair.

Restricted range of motion of the shoulder making reaching for items or reaching behind the back more difficult.

Weakness with motions or resisted activities above 90 degrees of flexion or abduction (reaching overhead).

Treatment

When treating shoulder impingement it is important to reduce the inflammation that may decrease or compromise the subacromial space, and strengthen the rotator cuff muscles to restore balance and function. Left alone, impingement can progress through stage one to two and then three, causing more serious problems.

Stages of Impingement Include:

Stage 1: Edema and Inflammation or early stage impingement is characterized by pain when attempting certain positions and motions. Overhead motion restrictions and performing overhead activities may be difficult.

Stage 2: Fibrosis and Tendinitis characterized by marked loss of motion, pain and weakness, inflammation and tendon involvement. Actively lifting the arm overhead independently, and sometimes with assistance may become difficult. Joint noise, grinding “crepitus” may be present along with a feeling of catching when raising the arm overhead.

Stage 3: Bony Spurs and Tendon Ruptures The patient may present with significant weakness, degenerative changes, decrease or absence of active motion, significant or absent pain depending on the severity of the damage.

Physical Therapy Interventions

Physical Therapists are professionals, educated and trained to administer interventions. As defined by The Guide to Physical Therapist Practice, interventions are the skilled and purposeful use of physical therapy methods and techniques to produce changes consistent with the diagnosis, prognosis and the patient or client’s goals. Common interventions in the treatment of Shoulder Impingement include:

  • Manual Therapeutic Technique (MTT): hands on care by a physical therapist to regain mobility and range of motion of the shoulder and surrounding joints.
  • Therapeutic Exercises (TE) to restore range of motion and strengthen the shoulder and surrounding joints. Rotator cuff strengthening exercises to dynamically depress and stabilize the humeral head resulting in improved biomechanics that can possibly increase the subacromial space.
  • Neuromuscular Reeducation (NMR) to begin retraining the upper extremity and the patient overall to use the involved upper extremity in daily activities. Scapula stabilizing exercises are indicated for both primary and secondary impingement because the scapula is the base of support where the rotator cuff muscles originate.
  • Modalities including the use of ultrasound, electrical stimulation, ice, cold laser and others to decrease pain at the shoulder.
  • Home programs including exercises and instructions to help the person with shoulder impingement perform daily tasks and advance to the next functional level.

Medical Management

Treatment of impingement syndrome is dependent on the underlying cause that may create a primary or a secondary impingement. Initially, conservative treatment should be instituted. In addition to physical therapy, your physician may recommend medical management interventions. If conservative treatment is not successful in reaching the individual’s functional goals, surgical interventions may be necessary.

  • The use of NSAIDS (Non Steroidal Anti-Inflammatory Drugs)
  • Steroidal Injections to reduce inflammation
  • Pain medication to reduce discomfort and allow the patient to perform the recommended exercises
  • Surgery, dependent upon whether a primary or secondary impingement is present. Subacromial decompression is the surgical treatment of choice for a primary impingement and a surgical intervention that stabilizes the shoulder (GH) is indicated for secondary impingement.

Prognosis

For less severe impingement syndrome cases there will be a decrease in symptoms over a 3-month period using a comprehensive physical therapy rehabilitation program. However, if there is not improvement in function after a 3-month period then surgical interventions may be considered.

Reference: Brotzman SB, Wilk KE. Clinical Orthopaedic Rehabilitation. 2003, Mosby, Philadelphia, PA.