Anatomy & Background
To the rotator cuff muscles compressing against the structures forming the upper portion of the shoulder. The region is referred to as the subacromial space and includes the acromio-clavicular joint, coraco-acromial ligament and the acromion (outer edge of the scapula or shoulder blade). This narrowing of the space that the rotator cuff muscle tendons pass through causes the muscles to become irritated and inflamed, resulting in pain, weakness and in severe cases, the loss of mobility.
One crucial aspect of the rotator cuff muscles daily functions is to act as a depressor of the humeral head. This in turn 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).
A mechanical dysfunction is said to occur when the rotator cuff does not properly perform its functions. As a result, the rotator cuff becomes pinched against the structures along the upper portion of the shoulder or coracoacromial arch. If left untreated, it can lead to chronic wearing, tendonitis and subsequent tearing of the rotator cuff tendons. In more advanced stages of the syndrome, bony spurs begin to form further limiting the size of the subacromial space.
Common triggers of Shoulder Impingement are inflammatory conditions like bursitis, tendonitis or anything that brings about a decrease in the subacromial space. Examples of high-risk activities or conditions that may 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 stemming from activities like overhead throwing, overhead exercise or work activities.
- Trauma, like falling on the shoulder.
Impingement Syndrome can be broken down into two basic classifications: primary impingement and secondary impingement.
- Primary impingement: The condition is inherent to the individual’s anatomy due to abnormal bio-mechanics in the shoulder. This predisposition in combination with primary factors may lead to narrowing of the subacromial space. Primary factors are usually congenital in nature manifesting usually later in life. An individual will begin to complain of anterior should and lateral arm pain combined with weakness in the shoulder. This pain will begin to become more frequent in occurrence and leads to difficulty completing overhead activities and preforming normal arm mobility.
- Secondary impingement: Occurs when one of the shoulder joints (gleno-humeral and/or scapula thoracic) experiences a decrease in stability. Secondary Impingement is more typically seen in younger individuals, specifically athletes, particularly those practicing sports characterized by overhead movements like baseball, volleyball, softball, swimming and tennis. Repetitive use of the arm without proper muscle rest can cause the posterior aspect of the shoulder to become agitated and tight. This limits the potential range of motion specifically having difficulty reaching across the body and behind the back.
Only a physician, physical therapist or other health care professional can properly diagnose Impingement Syndrome as it is important to rule out conditions that produce similar symptoms such as cervical spine defects or injuries.
Signs and Symptoms of Impingement
- In cases of Secondary Impingement, pain will often be acute due to the sudden severity of the injury. For Primary Impingement, the condition will gradually become more noticeable, as the onset of pain is often gradual.
- Pain and/or achiness at the tip and front of the shoulder that can radiate down the lateral arm even when the arm is at rest.
- Pain with lifting, throwing, and reaching motions across the body. This may include a painful arc of motion between 60-120 degrees of motion during overhead activities.
- Difficulty sleeping on the afflicted side of the body and performing daily activities, such as dressing or combing your hair.
- Restricted range of motion of the shoulder limiting the ability to reach for items.
- Weakness with motions or resisted activities above 90 degrees of flexion or abduction (reaching overhead).
- Some individuals experience a grinding or popping sensation when attempting to flex the arm.
Treatment includes a twofold process of reducing inflammation to increase the subacromial space in conjunction with strengthening the rotator cuff muscles to restore balance and stability. If left untreated and the condition is allowed to progress without intervention, Impingement Syndrome may progress to higher stages potentially causing serious medical issues.
Stages of Impingement Include
Stage 1: Edema and Inflammation: Early stage impingement is distinguished by pain during and after the attempt to perform certain positions and motions.
Stage 2: Fibrosis and Tendonitis: There is a marked loss of motion commingled with pain, weakness, inflammation and tendon involvement. It is difficult to lift the arm overhead independently. Joint noise, also know as grinding “crepitus,” may be present.
Stage 3: Bony Spurs and Tendon Ruptures: Painful bone spurs may form further reducing the range of motion with tendon ruptures happening in the worst cases. The severity of damage to the region will dictate the magnitude of weakness, degenerative changes, decrease of motion and pain felt by the individual.
Managing Your Pain
As discussed earlier, it is crucial to consult with a health care professional to get the correct diagnosis since the course of treatment is contingent on the underlying condition. In general terms, a conservative treatment plan should be implemented to see if symptoms can be alleviated by less intrusive measures such as physical therapy as opposed to invasive surgery. Each program should be tailored towards a patient’s individual needs as the ability to regain motion and ability differs from case to case. A treatment program may include:
- The use of NSAIDS (Non-Steroidal Anti-Inflammatory Drugs).
- Steroidal Injections to reduce inflammation.
- A pain management program, including medication, designed to reduce discomfort so the patient may be able perform recommended exercises.
- Surgical options may be investigated depending upon whether a primary or secondary impingement is present. Subacromial decompression is the surgical treatment of choice for a primary impingement while a surgical intervention that stabilizes the shoulder (GH) is indicated for secondary impingement.
Under a comprehensive physical therapy rehabilitation program, many patients with early stage Impingement syndrome will likely see a decrease in symptoms over a 3-month period. For patients with more advanced cases or if results are not realized after a 3-month period, surgical intervention may be considered.