Rotator Cuff

Description

The rotator cuff (RC) is the general name for a group of 4 different muscles and their tendons that provide strength and stability during movement of the shoulder complex. They are also known as SITS muscles in reference to their initials (Supraspinatus InfraspinatusTeres minor and subscapularis, respectively). The muscle originates from the scapula and attaches to the head of the humerus, forming a cuff around the glenohumeral (GH) joint.

Anatomy

The rotator cuff muscles include:[1]

The main function that starts from the scapula and ends at the humerus M. The upper articular surface of supraspinous fossa greater tuberosity abduction Greater tuberosity external rotation (lateral/external rotation) M. Subscapularis subscapular fossa tubercle or humeral neck internal rotation (medial/internal rotation)

At the cranium of the rotator cuff is a bursa that covers and protects the muscles and tendons as they are in close contact with the surrounding bone.

Function

The RC muscles are used separately for various upper body movements, including flexion, abduction, internal rotation, and external rotation. They are essential players in almost every type of shoulder exercise. Balancing the strength and flexibility of the four muscles is critical to maintaining good health The function of the entire shoulder strap.

As a whole, the rotator cuff muscles are responsible for stabilizing the shoulder joint by providing fine-tuned movement of the humeral head within the glenoid socket. They are deeper muscles that are very active for the neuromuscular control of the shoulder complex during the upper extremity sports.

They hold the humeral head in the facet socket of the scapula to extend the range of motion of the GH joint and avoid mechanical obstruction (i.e., possible biomechanical impact during elevation). [1][2]

It is well documented that RC dysfunction leads to shoulder pain, functional impairment, and reduced quality of life. [3]

Image: Rotator Cuff Muscle Overview – Sagittal Plane [4]

Common Injuries to the Rotator Cuff

RC injuries are common injuries that can occur at any age. In younger subjects, most injuries were secondary to trauma or overuse due to overhead activities such as volleyball tennis pitching. Injury rates increase with age, but some people with rotator cuff lesions may Asymptomatic. [2][5] With age, the RC muscle can become a victim of muscle degeneration impingement and tearing. Poor biomechanics such as postural dysfunction (e.g. anterior posture of GH in the glenoid cavity) prematurely affects RC muscle mass and Tendon due to repetitive strain injury and tissue encroachment.

The most common injuries of the rotator cuff are commonly referred to as:

• Rotator cuff tear (micro or macro tear in muscle or tendon);
• Rotator cuff tendonitis (acute inflammation of the RC soft tissue);
• Rotator cuff tendinopathy (chronic irritation or degeneration of the RC soft tissue);
• Impingement syndrome (biomechanical dysfunction of the shoulder complex leading to abnormal wear of the RC soft tissues).

Common Symptoms

It is important to note that RC tears or injuries are not always associated with pain or patient-reported loss of function. [3] It is also worth noting that asymptomatic patients may develop symptoms within a shorter period of time.

The most common signs of a rotator cuff injury are:

• Pain (which may or may not be present). Can be localized to the front/outer side of the shoulder with referral pain down the upper arm (outer side).
• Painful range of motion
  • Painful arches (varies – usually above shoulder height)
  • Painful external/internal rotation/ABDuction
• Shoulder muscle weakness (especially ABduction and ER)
• Functional impairment (difficulty lifting weights overhead and dorsum (IR)).

These signs are primarily due to loss of glenohumeral joint stability due to rotator cuff muscle dysfunction. [6]

Diagnosis of Rotator Cuff Pathologies

The key elements in the diagnosis of RC pathology are:[7]

• History
  • Age/gender/comorbidities (diabetes/smoking/previous shoulder pain/cervical pain)
  • Participation in sports (contact sports/elevated sports)
  • Mechanism of injury (acute injury (i.e. fall on outstretched hand (FOOSH))/trauma or repetitive strain injury)
• Physical Examination
  • Visual inspection of the shoulder/cervical and thoracic spine
  • C-spine scan (to rule out referred pain and/or radiculopathy)
  • Palpation (pain/deformity/swelling)
  • Range of motion / functional movements
  • Strength testing (manual muscle testing or hand-held dynamometer)

Clinical Testing: Diagnosis of RC tendinopathy can be done in the clinic using cluster testing:

The following cluster tests were retrieved from Roy et al. (2015)[8]:

• Hawkins-Kennedy test
• Neer’s test
• Painful arch sign
• Empty can test
• Pain or weakness with external rotation.
• Diagnostic imaging of the shoulder:
  • X-rays (less accurate for RC diagnosis; unless avulsion fracture calcified arthritis or skeletal deformity is suspected)
  • MRI (best practice for soft tissue visibility) or
  • Ultrasound (US)

It is important to use the history and physical examination to differentiate shoulder pain from sources other than the shoulder, such as pain in the neck (referring to the cervical spine or chest) or elbow, from pain from other structures in the shoulder. Pain is mainly caused by overhead movements, Shoulder muscle weakness may occur.

The RC muscle is not visible on x-rays, but calcified arthritis or bone deformation may be seen – a common cause of rotator cuff disease. The most common imaging modality for evaluating rotator cuff lesions is MRI. It detects tears and inflammation and may help determine size and characteristics in order to establish an appropriate treatment plan.

Although MRI is the gold standard imaging method for rotator cuff lesions, US can be used because it has good diagnostic accuracy (evidence level 2a) [9] is more cost-effective and readily available [10][11].

Possible confounding factors:

• Increase in age;
• MRI tear characteristics;
• Worker’s compensation status.

Factors such as age-chronicity and severity of tendon unit injury were repeatedly associated with higher re-tear rates and poorer clinical outcomes. [3] [12]

Possible co-morbidities:

• Diabetes;
• Smoking;
• Prior shoulder infection;
• Cervical disease.

Strength of recommendation: Not sure [13]

Common Treatments for Rotator Cuff Lesions

Pain management

• NSAIDs are of moderate strength [13] (benefits outweigh potential harms) and are used in the absence of full-thickness tears.
• Active Modified Glacial Iontophoresis TENS PEMF Sonophoresis. Strength of recommendation: Not sure. [13]

Conservative treatments

• Physiotherapy/exercise prescription/modalities. Uncertain intensity. [13]
• Conservative treatment is effective for many rotator cuff injuries and includes corticosteroid (or sodium hyaluronate) injections into the subacromial space and physical therapy to increase the strength of the remaining muscles and improve shoulder stiffness.
• Corticosteroid injections. Strength of recommendation: Not sure. [13]

Surgical repair for acute RC tears

To achieve anatomic healing, the torn rotator cuff tendon must be repaired. Surgical repair showed moderate to excellent clinical outcomes in most studies. However, improved surgical management of chronic and large rotator cuff tears is needed, especially for those who continue Proven high failure rate. [6]

For irreparable rotator cuff tears, alternative treatments include:[6]

1. Superior capsule reconstruction;
2. Reverse total-shoulder arthroplasty;
3. Acromioplasty;
4. Partial RC repair debridement or muscle/tendon transfer (when irreparable RC tears);
5. Allographs and xenographs.

Strength of recommendation: limited. [13]

Other Helpful Links

• Rotator Cuff Tears
• Rotator Cuff Tendinopathy
• Chronic Rotator Cuff Tendinopathy
• Tendinopathy
• Western Ontario Rotator Cuff Index (WORC)