You may have heard this a thousand times, but do you know what exactly is this “rotator cuff” everyone seems to be talking about?
The rotator cuff is a group of 4 muscles surrounding the glenohumeral joint in the shoulder. These muscles originate in the scapula and attach on the head of the humerus and their function is to rotate the humerus, as well as lift the arm, but they play a crucial role in the stability of the joint. The tendons on these muscles all attach around the head of the humerus and therefore the balance in the strength of these muscles is crucial for centralizing the head of the humerus on its socket.
The 4 rotator cuff muscles are Supraspinatus, originates at the top of the scapula and passes under the acromion and attaches to the top part of the humeral head. Its function is to lift the arm in abduction. Due to its anatomy and function the supraspinatus is the most commonly affected muscle of the rotator cuff. Infraspinatus originates on the bottom part of the scapula and attaches on the middle and back part of the head of the humerus. Its function is to rotate the arm externally (outwards) along with the Teres Minor muscle, that originates on the outer border of the scapula and attaches to the bottom part of the head of the humerus below the infraspinatus. Lastly, we have Subscapularis, which originates in the anterior surface of the scapula, contrary to the first 3, and attaches to the anterior part of the head of the humerus, thus functioning in internal (inwards) rotation of the arm. (We will look at a more detailed anatomy of these muscles when we discuss Rotator Cuff impingement).
The most common injuries of the rotator cuff are impingement, inflammation (tendonitis an tendinopathies), tears and instability. We will discuss these each of these injuries in more detail later. Common symptoms of injury at the rotator cuff are pain or discomfort, stiffness, decreased range of motion, muscle weakness or difficulty on performing previously easy movements.
Let’s zoom in to rotator cuff tears, shall we?
Rotator cuff tears range from partial to full thickness tears where the whole tendon is ruptured. Different classifications are used to describe tears such as which tendons are torn, how many tendons are torn, the location of the tears and the size of the tears. Generally, it is accepted as a rotator cuff tear of more than one tendon is affected, otherwise it is just called a muscle tear (named after the specific muscle).
This sort of injuries may happen all at once through trauma, this can be a blow to the area, a fall or an accident. Alternatively, they may have a more gradual onset. This can happen through poor stability or mechanics that may then cause an impingement (where a muscle is squeezed between bony structures), inflammation of tendon/bursa, commonly caused by repetitive action and overuse. The inflammation then decreases the available space even further and the muscles moving on the area are pinched increasingly more until it results in a tear. Sometimes there are bony spurs in the area, under the acromion (part of the scapula) that pinches the tendon and sets out the injury as described above.
The risk factors to tears may be extrinsic (ones we can change) and intrinsic (ones we cannot change). Extrinsic factors are movement mechanics, repetitive load for long periods of time, impingements. Intrinsic factors are age, weight, health status, activity level, blood supply to the area, etc.
Symptoms of rotator cuff tears are:
- Pain at the time of injury;
- Pain during the night (especially one that interferes with sleep);
- Painful arc of movement, especially worse with overhead movement;
- Muscle weakness;
- Referral pain going down the arm or to the shoulder blade.
Rotator cuff tears are diagnosed through a physical examination, where a record of the history of the injury is taken, as well as special tests that put specific muscles under tension to identify the muscles involved. Imaging techniques such as ultrasound and MRI may be used to confirm a diagnosis. These tests and exams are also important to distinguish between a rotator cuff tear and a rotator cuff tendinopathy or bursitis which may present similarly.
Upon diagnosis the treatment options will be conservative, through physical therapy and rehabilitation exercises, in combination with ice, anti-inflammatory medication, activity modification and at times steroid injections are used. Alternatively, surgical repair may be advised, this is especially true for complete tears as they do not heal on their own.
The correct diagnosis is crucial to identify the most appropriate treatment. Treatments are not only designed according to diagnosis but should also be tailored according to individuals.
