The shoulder is a ball and socket joint; however the ball (humeral head) is relatively large, compared to the socket (glenoid). This gives the shoulder a large range of motion compared to other, more constrained ball and socket joints in the body, such as the hip joint. Attached to the humeral head is a group of four tendons that rotate the humeral head on the glenoid and therefore, move the arm. The four tendons are collectively called the rotator cuff. The functions of the tendons of the rotator cuff vary depending on where they attach to the humeral head. The supraspinatus tendon attaches to the top of the humeral head. When it pulls on the humeral head it elevates the arm. It is the most common tendon involved in rotator cuff tears. The subscapularis tendon attaches to the front of the humeral head and internally rotates the shoulder. There are two tendons, infraspinatus and teres minor, attached to the back of the humeral head which externally rotate the shoulder.
What Is A Rotator Cuff Tear?
A rotator cuff tear is detachment of one or more of the tendons of the rotator cuff, from the insertion into the bone of the humeral head. A tear can be a result of an injury to the shoulder (e.g. while lifting or during a fall), but many tears develop slowly and often patients cannot recall any specific injury to the shoulder. Rotator cuff tears are very common and usually occur in patients over the age of 40 years. The symptoms of rotator cuff tear vary from patient to patient, but usually involve weakness of the shoulder and pain. The pain is often felt during attempted elevation of the shoulder, lifting, driving or with overhead activities. Pain is often present at night and may disturb sleep. The tear may involve a part of the tendon (partial tear), all of the tendon (full thickness tear) or more than one tendon (massive rotator cuff tear). When the tendon is completely torn, the tendon end retracts away from the bone insertion due to the pull of the muscle attached to the other end. A massive, retracted tear may not be repairable if it has been present for a long time.
How Is A Rotator Cuff Tear Diagnosed?
A clinical examination may indicate a rotator cuff tear, however the diagnosis is usually confirmed with x-rays and a MRI scan. A MRI will also help determine the size of the tear and the amount of retraction of the tendon end. An ultrasound scan can also be used to diagnose a rotator cuff tear, however they are not as accurate as an MRI scan, nor can they be used to plan surgery. MRI will also be able to detect other common conditions associated with rotator cuff tear.
Other Common Conditions Associated With Rotator Cuff Tears:
Rotator cuff tears are commonly associated with:
Damage to the long head of biceps
AC Joint arthritis
The long head of biceps enters the shoulder joint adjacent to the supraspinatus tendon and is often damaged with the rotator cuff. Also, once the rotator cuff is torn, the torn tendon end can rub on the undersurface of the acromion (bone above the shoulder). This is called subacromial impingement and can be very painful. Arthritis of the AC Joint can also be seen on an MRI scan, and is common in patients with a rotator cuff tear, although it is usually not related to the development of rotator cuff tear. All these conditions can be treated at the same time as the rotator cuff tear.
How Is A Rotator Cuff Treated?
There are several treatment options available for rotator cuff tears. These include:
A period of rest in a sling, followed by physiotherapy.
Injections into the shoulder to treat pain and inflammation.
Arthroscopic surgery for rotator cuff repair
Joint replacement surgery (reverse shoulder replacement) for massive, irrepairable cuff tears.
The best treatment choice will be determined by several factors including the size of the tear, the retraction of the tear, how long the tear has been present (chonicity), your age, and the functional demand on the shoulder.
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