The Shoulder Labrum
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The labrum is a ring of soft tissue (cartilage) that surrounds the glenoid (socket). It deepens the glenoid and helps to contain the ball within the socket by acting like a ‘suction cup’.
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The Shoulder Capsule
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Surrounding the shoulder joint is a watertight sac called the joint capsule. The joint capsule holds fluid that lubricates the joint. It is comprised of strong connective tissue and has thickenings called ligaments. The capsule helps to stabilise the shoulder joint by preventing excessive movement of the ball within the socket.
Rotator cuff
The rotator cuff is comprised of four muscles:
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1) Supraspinatus
2) Infraspinatus
3) Teres Minor
4) Subscapularis
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The main function of the rotator cuff is to stabilise the ball within the socket (glenoid). The shoulder joint itself is inherently unstable due to the shallow socket. The rotator cuff muscles work together to contain the ball within the socket during movement of the arm.
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During elevation of the arm, if the rotator cuff is not functioning properly, the ball is pulled upwards towards the acromion, by the bigger deltiod muscle. This can result in painful compression of the structures within the subacromial space; the subacromial bursae and rotator cuff tendon itself. This is termed subacromial impingement. This is not a diagnosis of your problem but a symptom or a clinical sign.
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There are a number of conditions that can lead to dysfunction of the cuff:
- an acute injury or strain of the rotator cuff
- overuse injury or tendonopathy
- calcific tendonitis
- partial or full thickness tear of the rotator cuff
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Bankart Lesion
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When the shoulder dislocates the labrum can be torn as the ball is forced out of the socket. Sometimes a labral tear will result in the shoulder being less stable and more likely to dislocate. It is most common to dislocate out of the front (anterior) of the shoulder and, therefore, tear the anterior labrum. This is called a Bankart tear or lesion
Surgical treatment for this involves attaching the torn labrum to the edge of the glenoid using small implants called anchors. This is called a Bankart repair
Subacromial Bursa
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Bursae are small sacs of fluid which function to allow the gliding of muscles or tendons over bony surfaces i.e to prevent friction or rubbing of the tendons as they move. There are numerous bursae found throughout the body. The subacromial bursa is located in the subacromial space of the shoulder and separates the rotator cuff tendons and the acromion.
Subacromial Bursitis
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Bursitis is inflammation of a bursa. Subacromial bursitis can occur in the shoulder and often comes hand in hand with rotator cuff problems. Subacromial pain syndrome is an umbrella term used to describe these co-existing pathologies. For further details on the symptoms and treatment of this click here.
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