Instability refers to laxity in the “ball and socket” or glenohumeral joint (GH joint). Instability can occur for several reasons. The severity and the direction of instability depends on the causal pathology. The GH joint may be unstable with the humeral head, or “ball” of the “ball and socket joint” having too much motion toward the front (anterior), back (posterior), top (superior) or bottom (inferior) of the glenoid, or socket. If the humeral head is loose in more than one direction, it is referred to as multidirectional instability.
Glenohumeral instability may result from an acute or chronic injury, causing damage to the ligaments, labrum, rotator cuff or capsule surrounding the joint. It may also be inherited and result from a genetic disease known to cause loose joints like Ehlers Danlos Syndrome or Marfan Syndrome.
Patients with glenohumeral instability have pain and inflammation associated with excessive motion of the “ball” on the “socket”. Patients complain of “looseness” or anxiety because their shoulder feels like it’s about to “pop out” of place. Clicking and grinding may occur, as well as weakness depending on the underlying cause of the instability. Some patients may be able to voluntarily dislocate their shoulders, which is an indicator that surgical repair may not restore proper shoulder function.
Your surgeon will perform a thorough history and physical exam with X-rays. During the exam, your surgeon will move the shoulder through a range of motion to test for instability in all planes, as well as attempt to keep the shoulder in place to see if symptoms resolve. X-rays may or may not show evidence of instability. CT/”CAT” scans are useful in determining whether there is damage to the bones and cartilage of the GH joint. MRI (with and without a special dye) is helpful in viewing damage to the labrum and rotator cuff that surround the GH joint.
Treatment depends on the cause of the instability. Physical therapy is the key to the treatment of instability. Both unidirectional and multidirectional instability patients should be treated with an initial course of therapy, unless the instability resulted from an injury (fracture or acute dislocation in an athlete). Physical therapy strengthens the muscles of the shoulder and helps stabilize the “ball” on the “socket”.
Patients with unidirectional instability who fail non-operative treatment should consider minimally-invasive arthroscopic or open incision surgery to repair the labrum and tighten the capsule surrounding the GH joint. 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. This procedure is usually performed through an open incision in the front of the shoulder.
A shoulder dislocation occurs when the humeral head (ball) no longer sits on the glenoid (socket). A shoulder subluxation occurs when the ball comes part of the way out of the socket and then returns without intervention. The ball can be disassociated from the socket in the front or back of the shoulder.
Shoulder dislocation occurs from trauma, like falling with the arm extended away from the body, collision sports such as football and rugby, and sports where the arm is forced away from the body. Most of these injuries will cause the ball to be dislocated out of the front of the shoulder joint. Seizures and electrocution can also cause shoulder dislocation, with the ball dislocating towards the back of the shoulder joint.
Patients complain of shoulder pain, the inability to move the arm and usually carry the hand and arm away from the body. A flattening of the side portion of the shoulder is present. The outside of the shoulder may be numb and tingling may be present in the arm and hand.
Your surgeon will perform a thorough history and physical exam, aided by X-rays. Range of motion will be greatly reduced, and the shoulder will have a visible deformity. X-rays will show the dislocated “ball and socket” joint. Your surgeon will also evaluate for associated injuries, such as fractures of the humeral head or glenoid. An MRI is typically obtained to assess the rotator cuff and other tissues that help stabilize the joint, as these are commonly injured during shoulder dislocation.
Your surgeon will place the ball back on the socket (reduce the shoulder) with or without pain medication. After the shoulder is back in place, it is initially immobilized in a sling. Anti-inflammatory medication, cryotherapy and activity modification may be used to help with the initial pain and swelling. Physical therapy may begin as soon as the patient can tolerate it to regain motion and strength in the shoulder. Return to activity may be allowed when the shoulder's motion and strength has returned to normal. Athletes may or may not undergo non-operative treatment based on their age, sport, time of year and risk of another dislocation.
Surgery is usually reserved for non-athlete patients that have failed non-operative treatment, resulting in chronic shoulder dislocations or athletes in high-risk sports. Once the shoulder dislocates, the risk of further dislocation is great, particularly in younger patients and athletes in overhead or collision sports. Multiple dislocations cause erosion of the bones of the “ball and socket”, making it easier to dislocate again. Surgery includes a minimally-invasive arthroscopic or open incision procedure that reattaches the ligaments and tightens the soft tissue surrounding the joint. If the initial surgery fails to relieve symptoms or bone erosion has occurred and dislocations continue, your surgeon may choose to add a bone block to the socket (Latarjet procedure) or tighten the rotator cuff (Remplissage procedure) to decrease the risk of dislocation.
An AC sprain is a stretching of the ligaments that join the clavicle (aka-collarbone) to the scapula (aka – shoulder blade). Research has identified several classifications of injury, but sprains are typically graded 1-5. If the damage to the ligaments is severe enough, the bones no longer touch each other. This is known as a Grade 5 AC sprain, also known as an AC separation, or “separated shoulder”.
AC sprains only occur because of trauma, either in sports or falls with a direct force to the side of the shoulder. The mechanism of injury is similar to the cause of clavicle fractures.
AC sprains cause pain specifically at the AC joint. Depending on the severity of the sprain, the collarbone may appear to be elevated compared to the shoulder blade. Patients will have pain with most motions of the shoulder, particularly moving the arm across the body.
Your surgeon will perform a thorough history and physical exam including X-rays. The exam will test the laxity at the AC joint. The surrounding structures of the shoulder will be examined to determine if there are other injuries, as rotator cuff tears and clavicle fractures can also occur during trauma. X-rays may or may not demonstrate looseness around the AC joint and are the basis for most classification systems. Clavicle fractures may also be seen on x-ray. MRI may be helpful if your surgeon suspects damage to the rotator cuff.
Treatment depends on the severity of the damage to the ligaments surrounding the AC joint. Grade 1 and 2 AC sprains are treated non-operatively with a sling, anti-inflammatory medication, cryotherapy and potentially a joint injection. Grade 3 AC sprains may be treated with or without surgery, depending on the patient’s age, activity level/sport and risk of non-compliance after surgery.
Some Grade 3 and all Grade 4 and 5 AC sprains are treated with surgery. Depending on the acute or chronic nature of the injury, multiple techniques can be employed to repair or reconstruct the ligaments in an effort to stabilize the AC joint. Surgery is followed by immobilization in a sling for a period of time determined by the surgeon, cryotherapy and physical therapy.