Rotator cuff injuries
Fig. 1 shows a group of four muscles that cover the shoulder joint. These muscles originate on the scapula and insert on the humerus: the supraspinatus, infraspinatus, subscapularis and teres minor. The tendons of theses muscles form the rotator cuff (tendons connect muscles to bones). The most common injury to the rotator cuff is the impingement of one or more of these tendons. This may happen as a result of a trauma or sport related injury but more commonly as a result of aging. The tendons may rub against the acromion (a bony extension of the scapula that hangs over the cuff) every time the person raises an arm and become irritated, inflamed and ultimately torn.
Fig. 1: Rotator cuff muscles of the right shoulder. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.
Below is a narrated animation of arthroscopic rotator cuff repair. Click here to license this video and/or other orthopedic videos on Alila Medical Media website.
Impingement usually develops over a period of time. Treatment includes rest, shoulder exercise, physical therapy and surgery. In most cases surgical treatment is done through an arthroscope but open surgery may be needed for larger tears. During surgery the damaged tissue is removed, source of irritation (commonly bone spurs on the acromion) is identified and removed. If there is no tear, the treatment may stop here and the surgical procedure is called shoulder debridement. In case of tear sutures will be used to tight the tendon back down to the bone (Fig.2).
Fig 2. Rotator cuff injury (1) and repair: small holes are drilled (2) into the bone of the humerus to hold small suture anchors with threads (3). The threads are attached to the tendon (4) and pulled tightly to hold the tendon to the bone (5). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.
Separated shoulder
Separated shoulder is a condition affecting the “second” joint of the shoulder : the AC joint (acromioclavicular joint) between the acromion (an extension of the scapula) and the clavicle. This condition is commonly due to a direct blow to the shoulder as in a fall or sport injury. Fig. 3 shows the ligaments involved in stabilization of AC joint, injury to any of these ligament results in separated shoulder. Injuries are graded according to the extend of tears and number of ligaments involved. Grade I injury (partial tear in one of the ligament) may be treated with simple rest and ice, small tears heal themselves over time. Grade III injury where the clavicle is completely detached from the scapula requires surgery where a screw will be inserted to fix the clavicle to the coracoid process of the scapula.
Fig.3 : Shoulder separation grading. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.
Frozen shoulder (adhesive capsulitis)
The shoulder, like all synovial joint, has a capsule around it. The capsule encloses the two end surfaces of the bones involved in the joint and a joint cavity containing a lubricant called synovial fluid. In people with frozen shoulder condition this capsule is thicken and inflamed (Fig. 4) causing pain when they try to move an arm. The pain increases with time and the range of motion decreases, the shoulder becomes stiff or “frozen”.
Fig. 4: Frozen shoulder. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.
The causes of frozen shoulder are not fully established. People with diabetes and some other diseases show increased risk for frozen shoulder. It can also be resulted from a long-term immobilization of the shoulder (for example after a shoulder surgery). Treatments include pain management and physical therapy although in some cases surgery may be necessary. A procedure called arthroscopic capsular release is usually performed to cut through the tight area of the capsule.
