By Ted Parks, MD
Posted on June 14, 2010
Common Shoulder ProblemsTo understand problems related to the shoulder joint, it is important to review the anatomy. The shoulder is a combination of three bones, the clavicle, humerus, and the scapula which is composed of four parts: the body, the scapular spine terminating in the acromion, the coracoid process, and the glenoid (Figure 1). These three bones come together to make two joints, the glenohumeral joint and the acromioclavicular joint. These joints are stabilized by two systems of ligaments, the glenohumeral joint ligaments, which are found in the capsule of the glenohumeral joint, and the AC joint ligaments, one set in the capsule of the AC joint; the other set going from the coracoid to the clavicle. The next layout in terms of anatomy is the rotator cuff muscle layer, and this is comprised of the subscapularis, the supraspinatus, and the infraspinatus. The teres minor contributes minimally to the pathology and physiology of the rotator cuff. More superficial to the rotator cuff is the subacromial bursa, and more superficial to that is the deltoid muscle.
Shoulder problems can be divided into three basic groups: impingement, glenohumeral joint problems, and AC joint problems.
Impingement (Figure 3) Rotator cuff impingement occurs because the space between the underside of the acromion and superior surface of the rotator cuff gets narrow when the arm is abducted or flexed forward. Structures that impinge include the bursa, the supraspinatus tendon, and the long head of the biceps tendon. Rotator cuff impingement can be thought of as a continuum:
Rotator cuff arthropathy, the most severe element on the continuum, is a chronic massive tear in the rotator cuff causing the humeral head to be translated superiorly against the acromion by superiorly directed deltoid forces.
History: Patients with impingement often have a history of pain with overhead activities and night pain. Pain can radiate to the distal third of the humerus and they may have pain reaching behind their back.
Physical examination: Impingement signs include tenderness over the greater tuberosity and pain and/or weakness with rotator cuff strength testing. Important radiographic studies are an AP and Y view x-ray with the Y view x-ray probably being the most important because it will show subacromial spurs in the subacromial space. If necessary, an MRI is obtained to confirm or dispute a rotator cuff tear.
Treatment: The first stage of treatment is typically oral anti-inflammatory medications and physical therapy, specifically physical therapy exercises to strengthen the subscapularis and infraspinatus muscles, which have a downward force effect on the humerus, opening the subacromial space. An order for PT might be: Diagnosis-L shoulder impingement, Treatment- ROM (avoid overhead positions until symptoms improve), scapular retraction, IR/ER PREs with arm at side, start supraspinatus PREs when symptoms improve. If that does not work, a subacromial space cortisone injection can be beneficial.
After the subacromial space injection, one of four scenarios will occur:
1. The patient gets better and stays better, the best scenario.
2. The patient gets better for a long time (greater than four months) and then the symptoms return, in which case reinjection may be the best treatment.
3. The patient gets better for a short time (less than four months) and then symptoms return. In this scenario, the shot works confirming impingement, but it is too soon to repeat an injection, so surgery is an option.
4. If the patient does improve at all, an MRI should be obtained to rule out occult sources of shoulder pain such as a labral tear.
Surgical treatment for this condition is subacromial decompression and if necessary, a rotator cuff repair.
Glenohumeral Problems
Glenohumeral instability may lead to shoulder dislocation. Because of the position of the glenoid, approximately 90% of these will be anterior with posterior and inferior dislocations occurring approximately 10% and 1-2% respectively. Posterior dislocations can occur after seizure and electrocution. The shoulder can usually be reduced using IV sedation. Once reduced, no further treatment is necessary if it does not dislocate again. Patients with repeat dislocations or those that have first dislocation at a young age may be candidates for surgery. Typically, the labrum is reattached and the capsule may be tightened.
Arthritis-The treatment of glenohumeral joint arthritis involves treating erosive changes to the articular cartilage of the glenohumeral joint. Patients with this condition are usually older patients, who exhibit poor glenohumeral joint rotation with their elbow at their side. A properly taken AP x-ray can demonstrate the joint space narrowing that is typically seen with glenohumeral joint arthritis.
The treatment of glenohumeral joint arthritis includes oral anti-inflammatory medications, supplements, cortisone injections and physical therapy. If these do not work, a shoulder replacement is an option.
AC joint problems
AC joint instability can come in one of seven different types: most commonly types I, II and III. In a type I AC joint injury, a lateral blow is delivered to the shoulder, compressing the space between the acromion and clavicle. This causes the joint to fill with blood, which can cause a prominence noted on physical examination. X-rays of the AC joint do not show any displacement of the AC joint. A type II injury is a downward force supplied to the acromion, which shears the AC ligaments, but allows the coracoclavicular ligaments to remain intact. In this clinical scenario, the patient will have a prominence over the AC joint and an x-ray which shows displacement of the AC joint with the acromion displaced inferiorly; however, there is still overlap between the clavicle and acromion. In a type III, all of the ligamentous connections are torn between the clavicle and the acromion and on clinical examination a more pronounced AC joint deformity is noted and on x-ray a 100% translational deformity is seen. (Figure 4)
AC joint arthritis can also exist. In this condition the patient is tender over the AC joint on physical examination. X-rays often show joint space narrowing, erosive changes and/or osteophytes. Treatment includes oral anti-inflammatory medications, supplements and cortisone injections. Surgical treatment consists of distal clavicle excision.
A final caveat, not all shoulder pain is indicative of disease in the shoulder. Referred pain from the cervical spine and elbow as well as internal organs (heart, liver) can present as shoulder pain.
Dr. Ted Parks is a practicing orthopedic surgeon in Denver, Colorado. He completed a fellowship in Sports Medicine and is a team physician for numerous high school, college, and professional athletes. He is a clinical professor at the University of Colorado School of Medicine where he has received numerous teaching awards.
