a. What is Shoulder Instability?
Shoulder Instability occurs when the humeral head (ball of the shoulder) slides partially out of the glenoid (socket). It results from laxity of the glenohumeral ligaments that attach the ball to the socket. There are three directions of instability: anterior, posterior and inferior. Because the acromion overlies the humeral head and acts as a barrier to superior migration of the head, there can be no superior instability. There are two types of instability: unidirectional and multidirectional. Unidirectional instability occurs when the shoulder subluxes in a single direction, such as anterior. Multidirectional instability means the shoulder is unstable in more than one direction, such as anterior and inferior.
What causes Shoulder Instability?
Shoulder instability may result from an injury, such as a labral tear or dislocation. It may also be inherited, or result from a genetic disease known to cause loose joints.
What are the symptoms?
Patients with shoulder instability will feel their shoulder ‘pop in and out’ of the socket. They will have pain in the shoulder, feel a click or grind with shoulder motion and often have shoulder weakness. Patients with moderate to severe instability may be able to sublux their shoulder on demand, often boasting that they are ‘double jointed’.
How is Shoulder Instability diagnosed?
The surgeon will perform a physical exam of the shoulder and perform tests of other body parts to evaluate laxity. During the exam, anterior, inferior and posterior force is applied to the humeral head. If the surgeon is able to move the humeral head out of the socket, then instability is present. Patients who can pull their thumb to their forearm, hyperextend their elbows and knees, and pull their skin a significant distance away from the back of the hand, are at risk for shoulder instability.
How is it treated?
Physical therapy is the key to treating instability. Both unidirectional and multidirectional instability patients should be treated with an initial course of therapy, unless the instability resulted from an injury. Therapy strengthens the muscles of the shoulder and allows better control of the humeral head.
Patients with unidirectional instability who fail non-operative treatment should consider surgery to tighten the lining of the joint, or capsule and to repair associated labral injuries. Multidirectional instability patients should have surgery only after failing a year or more of physical therapy. In these cases, the entire shoulder capsule must be tightened. The surgeon accomplishes this by placing stitches through the capsule and tying the stitches to fold the lining of the joint over on itself.
b. Glenohumeral (shoulder) Dislocation
What is a Shoulder Dislocation?
A shoulder dislocation occurs when the humeral head (ball of the shoulder) is completely dislodged from the glenoid (socket). A subluxation occurs when the ball comes part of the way out of the socket, and then returns to the center without intervention.
What causes a Shoulder Dislocation?
Falls onto the shoulder or an outstretched hand, collision sports such as football and rugby, and sports where a sudden twisting injury may occur, such as skiing, are common causes of shoulder dislocations. Most of these injuries will cause the humeral head to be dislocated out of the front of the shoulder. Seizures and electrocutions can cause the humeral head to be dislocated out of the back of the shoulder.
What are the symptoms?
Patients complain of shoulder pain, and the inability to move the arm. A deformity will be present in the shoulder. Numbness and tingling may be present in the arm.
How is a Shoulder Dislocation diagnosed?
On physical exam, your surgeon will press on the shoulder and find a depression where the humeral head should be. Range of motion will be greatly reduced, and the shoulder will have a visible deformity. X-rays should be obtained to evaluate for associated injuries, such as fractures of the humeral head or glenoid. The labrum, or shoulder cartilage and the ligaments holding the humeral head in place are torn as a result of the dislocation. In older patients, the rotator cuff may be torn. An MRI should be obtained if a rotator cuff tear is suspected.
How is it treated?
The shoulder is reduced by providing traction to the arm, or elevating and rotating the arm. After the shoulder is back in place, it is initially immobilized in a sling. Consideration was recently given to immobilization of the shoulder in external rotation, but as of this time, scientific literature has not proven this to be of long-term benefit. Physical therapy should begin as soon as the patient can tolerate it to regain motion and strength in the shoulder. Anti-inflammatory medication and ice may be used to help with the initial pain and swelling. Return to activity may be allowed when the shoulder’s motion and strength has returned to normal.
In young patients, consideration should be given to surgical repair of the labrum and shoulder ligaments that are injured at the time of the dislocation. These structures are detached from the socket, and do not heal. This leaves the shoulder ‘loose’ and prone to further dislocations. The risk of future dislocation is inversely proportional to the patient’s age, with the risk of recurrent dislocation in young, active patients approaching 100%. With each dislocation, an indentation may form in the back of the humeral head, or the front of the glenoid as a result of the bones rubbing against each other. These indentations become larger with each subsequent dislocation, and further increase the risk of recurrent instability in the shoulder.
Surgery can be performed arthroscopically or through an open incision. The labrum and the shoulder ligaments are reattached to the glenoid using small, plastic devices called anchors. These devices have suture imbedded in them that allows the surgeon to sew the cartilage and ligaments down to the bone. A sling is worn postoperatively to protect the repair, and physical therapy is started to regain motion and strength.
If dislocations persist despite surgery or if the indentations on the humeral head and glenoid are too large to allow conventional repair, then the surgeon will transfer a bone block from the shoulder blade to the front of the glenoid to act as a bumper. This is called a Laterjet procedure.
c. AC Joint Sprains (Separated Shoulder)
What is a Separated Shoulder?
A Separated shoulder is a sprain of the acromioclavicular (AC) joint, where the collarbone meets the shoulder blade. The joint is stabilized by two sets of ligaments. These ligaments are stretched or torn in a Separated shoulder.
What causes a Separated Shoulder?
A Separated Shoulder occurs as a result of trauma, such as a fall directly onto the shoulder.
What are the symptoms?
The patient complains of pain in the AC joint and difficulty moving their shoulder. If any of the ligaments holding the joint together are completely torn, the weight of the arm will cause the clavicle to become more prominent, producing a bump under the skin.
How is a Separated Shoulder diagnosed?
History of a fall onto the shoulder is obtained. If a deformity is not obvious, the surgeon reproduces the patient’s pain by pushing on the AC joint. X-rays are obtained to rule out a fracture of the collarbone or shoulder blade.
How is it treated?
There are six types of Separated shoulders, identified by Roman Numerals. Types I, II, and sometimes III, can be treated non-operatively. In types I and II, ligaments supporting the joint are stretched but not completely torn. The surgeon will prescribe a sling for comfort. In Type III, the ligaments are torn, but a portion of the collarbone remains in the AC joint. The surgeon will prescribe either a sling or a figure eight brace to help push the collarbone back down into the joint.
Patients with a Grade III Separation who are unhappy with the deformity, have persistent pain, or are overhead athletes should consider surgical repair. Patients with types IV, V, and VI injuries require surgical repair because the collarbone is widely displaced from its original position. For recent injuries, the surgeon begins by reducing the collarbone into its original position. The collarbone is then stabilized to the shoulder blade by passing a device, a graft, or both around, or through, the portion of the shoulder blade called the coracoid and through the collarbone. For older injuries, the end of the collarbone is removed, and a ligament is harvested and transferred into the end of the collarbone to reconstruct the torn ligaments. The shoulder is placed in a sling post-operatively to protect the repair, and physical therapy is started to regain motion and strength.