Shoulder Instability???
There are two main types of shoulder related instability problems. The first occurs at the acromioclavicular joint (ACJ), and results from an injury called a “shoulder separation”. The second occurs at the ball and socket joint, or glenohumeral joint (GHJ) and may follow a “shoulder dislocation”. These are very different conditions and have different implications for shoulder function.
ACJ:
AC Separation:
Resulting usually from a fall or blunt injury to the corner of the shoulder, a shoulder separation occurs as an injury to the joint between the collar bone and shoulder blade felt as a prominence on the top outside edge of the shoulder. This injury is common in football, hockey, and lacrosse, but can occur as the result of any fall or blow to the shoulder. The injury causes pain and difficulty moving the arm, and depending upon severity may produce a bump or “step-off” which is seen to increase with downward pull on the arm, such as when holding a weight by the side.
Severity is usually divided into three grades, but additional grades are reserved for special and more severe variants. Generally, the higher the grade, the worse the injury, and the greater the bump or “step-off”. Generally the grade also correlates with length of recovery, and potential for future problems.
Evaluation of the injury reveals signs of tenderness and swelling at the end of the collar bone with potential instability at this site. This means that the shoulder blade may display excessive motion in relation to the end of the collar bone, either in an up and down or back and forth manner.
In general, as part of the evaluation, x-rays to exclude a fracture of the collar bone. X-rays are also helpful in grading the severity of the injury, especially if done in conjunction with weighted views, wherein a weight is placed in the hand and an x-ray is taken for comparison to the uninjured side.
Treatment of an AC Separation:
Although historically many of these injuries have been treated with surgery, the mainstay of treatment in this day and age, is usually conservative, or non-operative. Treatment usually includes rest, a brief period of immobilization with a sling, application of ice, and use of anti-inflammatory medication.
Early exercises done at home or under the supervision of a therapist may also be useful, especially for the active athletic patients.
Surgery is usually reserved for the unusual case that results in persistent pain or a sense of instability despite conservative care. Exceptions to this general rule would be the dominant arm of a throwing athlete or laborer.
It can be expect that the vast majority of these sprains, rather grade I, II or III, will result in minimal if any long-term problems or late sequelae. Rare late problems would include: pain and swelling and a perception of weakness or gross motion at
the ACJ.
Surgical correction of this problem is aimed at relieving pain and restoring stability to this joint. When done for late symptoms, this usually includes removing a small section of the end of the collar bone, and reconstruction/repair of the stabilizing ligaments of the end of the collar bone. This can be accomplished in a number of weighs, which usually involves transfer of a local ligament called the “coracoacromial ligament” into the end of the remaining collar bone, and augmentation of this transfer with a loop of synthetic suture material to provide stability while the transferred biologic ligament heals. This is called a Weaver/Dunn Repair. In general, the use of metal in this are is avoided if possible.
Like any surgery this procedure has risks which include, but are not limited to: infection, loss of motion, tender scars, and potential wound healing problems. Unique problems at this site includes regrowth of the collar bone.
Post-Operative course is highlighted by a short period of sling immobilization, rehabilitation with the goal of gradual return of range of motion and strength, allowing full return to function usually in three to four months post-op.
ACJ Arthritis:
Occasionally arthritis can result a long interval after the original injury. This typically results in pain without any sense of instability. A bump may appear as a result of bone spur formation. Swelling may occur on an intermittent basis.
Although non-operative care such as anti-inflammatory medication, cortisone injections, and rest may result in relief of symptoms, persistent symptoms may indicate the need for removal of the end of the collar, which is usually very successful in solving the problem. Ligament reconstruction is not necessary in these cases.
Dan Wnorowski, M.D.
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