If you have been experiencing pain in your shoulder or down the side of your arm, you may have a rotator cuff tear. However there are other shoulder conditions with similar symptoms including sub-acromial impingement and the early stages of a frozen shoulder. A tear of one of the rotator cuff muscles will lead to weakness and pain. It may be difficult to lift or rotate your arm, and you will experience pain at night, especially when lying on the injured side.
What is the rotator cuff and why is it so important?
The rotator cuff is a group of four muscles which wrap around the head of the humerus (this is the ball part of the upper arm bone, which articulates with the socket in the scapula or shoulder blade). The shoulder joint is very unstable because its socket is shallow to allow a greater range of movement. Therefore the rotator cuff muscles play an important part in stabilising the joint and they help to guide and direct the head of the humerus during movements of the arm.
Of the rotator cuff muscles, the supraspinatus muscle is the most liable to injury. It passes along the top of the shoulder blade an underneath a bony arch known as the acromion to insert into the humerus just on the outer side of the shoulder. Supraspinatus has three functions: it lifts your arm to the side (aided by the much more powerful deltoid muscle), it rotates the arm outwards and it helps to position the head of the humerus correctly as the arm is lifted.
Unfortunately the supraspinatus is liable to irritation and damage as it passes under the arch of the acromion. This can lead to tears in its tendon where it attaches to the humerus.
The other rotator cuff muscles are used to rotate the arm inwards and outwards, and are also important for positioning the head of the humerus. All of these muscles originate on the scapula (shoulder blade), with two of them, the infraspinatus and teres minor, turning the arm outwards (so as to bring the palms of the hands to face forwards), and the third, the subscapularis turns the arm inwards. The tendon of the supraspinatus muscle attaches between the subscapularis at the front of the humerus and the infraspinatus behind. Thus the tendons of the four muscles are arranged around the top of the humerus to form a cuff.
Why do rotator cuff tears occur?
The cause of a rotator cuff tear depends partly on the age of the person. In a young person, the tear is more likely to happen suddenly and may be due to an injury such as might occur while lifting a heavy object over head, to a fall on an outstretched arm, or to breaking of the collar bone.
Repetitive movements can affect younger and older people. For instance tennis players who serve overhead are prone to rotator cuff tears, as are rowers. Similarly there is a higher risk among those who work with their arms above the head, such as painters and carpenters.
Among older patients, a rotator cuff tear may be the result of a gradual process of deterioration of the tendons. This can be due to poor blood supply or to irritation of the tendon where it passes under the acromion. In this case, the problem may have developed slowly and insidiously, rather than suddenly.
How can a rotator cuff tear be distinguished from other shoulder problems?
In a partial tear of the rotator cuff, the arm is weak, and it may be difficult for the patient to hold her arm out to the side. In a full tear (ie a tear of the full width of the supraspinatus tendon), it will be impossible for the patient to lift her arm, but it may still be possible for the doctor or other practitioner examining the patient to lift her arm for her.
In a case of impingement syndrome where there is inflammation of the structures underneath the acromial arch, it may be possible for the patient to lift her arm most of the way, but the pain starts at about 90 degrees and continues to 120 degrees, at which point the pain will stop. In a frozen shoulder, movement is usually reduced to less than 90 degrees, no matter whether the patient tries to lift her arm, or the examining practitioner.
What can I do about a rotator cuff tear?
The answer depends on how serious the tear is. A full tear will need a surgical repair, and surgery may also be needed in the case of a more serious partial tear. However if you have a more minor tear or if the problem is more one of degeneration (fraying) of the tendon, it should be possible to get a good result with more conservative treatment such as osteopathy or physiotherapy and suitable stretches and exercises. Remember the body has amazing healing resources and very often all it needs is some gentle manipulation to unlock those resources and put them to work.
Sorrel Pindar, Registered Osteopath, email: firstname.lastname@example.org; tel: 01234 409538