Clinical and Health Affairs
Shoulder Pain: A Common-but-Challenging Problem
By Abigail Hamilton, M.D., and Jonathan P. Braman, M.D.
Abstract
Although shoulder pain is a common complaint among patients presenting to primary care physicians, many clinicians are unfamiliar with how to diagnose and treat many shoulder ailments. This article reviews the basic approach to diagnosis and management of shoulder pain in adult patients.
Shoulder pain is an extremely common and disabling problem. A systematic review of studies shows that the one-month prevalence populationwide is 18% to 31%, with some studies showing a lifetime incidence of up to 67%.1 Shoulder pain is a frequent concern among patients who present for primary care evaluations, and complaints of shoulder pain are third only to complaints of back and knee pain among patients with musculoskeletal problems.2 It is more frequently reported by female patients, especially those over the age of 65, than male patients.3 Increased rates of shoulder disorders and disability have been correlated with occupational exposures such as carrying heavy weights, working with the arms above shoulder level, repetitive actions, and working in a cold or damp environment; they have also been associated with performing monotonous work and having a high reported stress level at work.4
The underlying pathology giving rise to shoulder pain can be many things, and it is important that the evaluating physician has a sound understanding of the common causes of shoulder pain as well as the ability to differentiate among them using history, physical examination, and diagnostic studies. In most cases, shoulder pain can be evaluated and treated in a primary care clinic; referral for specialist evaluation is warranted in certain settings.
Working Up the Patient with Shoulder Pain
There are two major types of shoulder pain: acute and chronic. Acute shoulder pain most often occurs immediately following an injury event such as a fall. The patient can recall the exact time of onset, and the pain is described as lasting for days or weeks. Chronic pain usually is described as having an atraumatic onset and gradually worsening over a period of months. The duration of symptoms and associated injuries are important to address during the initial patient interview because the work-up of a patient with acute shoulder pain is distinctly different from that of a patient with chronic shoulder pain.
■ Acute Pain
Often when patients seek medical evaluation for pain caused by an acute shoulder injury, they present to an emergency room or urgent care setting. There, other patients with more critical injuries and illnesses take precedence. Thus, even acute shoulder injuries are often worked up later outside the emergency setting. However, a number of shoulder injuries such as dislocations must be dealt with immediately.
All patients who present to the clinic or emergency department with acute shoulder pain must undergo a good clinical examination as well as a thorough history. After a patient is assessed for any potentially life-threatening injuries or any other injuries that require more urgent attention, he or she should undergo a full shoulder evaluation. The history should focus on the nature of the complaint and cover the type of injury/impact, location of pain, severity of pain, any radiation of pain, associated neurovascular dysfunction, signs or symptoms of infection, and pertinent medical comorbidities. This often can be abbreviated so examination and radiographic evaluation can be expedited.
Physical examination must include a thorough evaluation of the cervical spine and neurologic function as well as evaluation of the entire shoulder girdle including the clavicle, scapula, and proximal humerus. This requires a thorough understanding of the nerve supply to the dermatomes and muscles of the upper extremities. Deformity should be noted; if the patient has deformity, range of motion and muscular strength evaluations may be deferred. It is important, however, to evaluate motor and sensory function of the axillary, radial, median, and ulnar nerves and compare the radial pulse on the affected side to that on the uninjured side.
Once an appropriate history has been taken and physical examination done, radiography should be done to rule out acromioclavicular separation, glenohumeral dislocation, or fracture. Orthogonal views of the injured joint (views in which two X-ray beams that are perpendicular to each other are directed at the joint) should be performed. Orthogonal views of the shoulder include an AP of the shoulder and the scapular Y, usually in conjunction with either a Grashey (an AP in the plane of the scapula) and an axillary lateral or axillary view.
If a fracture or dislocation is identified, it should be treated according to the usual care provided in the setting to which the patient presented. If the level of care required is too advanced for the setting (such as an outpatient clinic), most shoulder fracture patients can have their shoulder safely placed in a sling and be transferred to an orthopaedic surgeon or emergency department for care. Prompt reduction of any dislocation should be performed. The injured shoulder should be immobilized, and, depending on the facility protocol, an orthopaedic surgery consultation obtained. Follow-up should be arranged in the next few days to determine further management.
If fractures and dislocations have been ruled out, acute shoulder pain can often be treated with less urgency. An exception to this is the patient who has significant weakness. A patient who is unable to raise his or her arm away from the injured side after a fall or other injury may have an acute rotator cuff tear. In these patients, particularly those who are young and active, MRI scanning to evaluate the rotator cuff tendons for evidence of a tear is indicated. Patients with suspected rotator cuff tears (inability to raise the arm is frequently a sign of a larger rotator cuff tear)should be referred for specialist evaluation immediately, as they will likely require surgical intervention.
Acute septic infection of the glenohumeral joint is uncommon but should always be ruled out. It is most often seen in patients who are immunocompromised, are on chronic dialysis, have had recent severe systemic infection, or have had a recent shoulder surgery. Laboratory studies are typically abnormal with elevated WBC, ESR, and CRP levels. If there is clinical concern about a septic joint, aspiration should be performed and appropriate surgical consultation made immediately.
Calcific tendonitis, which can present with acute flare-ups, is another source of acute shoulder pain. The abnormal growth of calcium in the tendons of the rotator cuff causes a profound inflammatory response and can lead to pain and weakness in the shoulder. Patients present with acute pain most often during the resorptive phase, which is associated with the surrounding inflammation.5 Motion is usually very painful, and patients will have give-way weakness secondary to discomfort. There is usually no history of acute injury, and pain is severe and acute in nature; however, patients may describe a chronic waxing and waning of less severe and more severe pain over the past few months. Radiographic evaluation aids in making this diagnosis.
■ Chronic Pain
Chronic shoulder pain is far more common than acute shoulder pain and, thus, is more often seen by primary care providers. Again, initial evaluation should focus on history and physical examination with adjunct radiography as indicated. A focused history should address the onset and duration of the pain, its location and nature, exacerbating and alleviating factors, prior treatments attempted, and pertinent comorbidities (eg, diabetes, cervical spine disease, or coronary artery disease).
After the patient’s history is obtained, a thorough physical examination should be performed. The physician should pay close attention to the cervical spine when evaluating any complaint of shoulder pain. Examination of the spine is particularly important if the patient has bilaterally symmetrical symptoms, if pain radiates below the elbow, or if the patient has weakness below the elbow or neurologic signs such as an abnormal Hoffman’s or asymmetric reflex. Additionally, neck pain or symptoms that are recreated with movement of the neck can be a sign that the neck is the culprit rather than the shoulder. After evaluation of the cervical spine, attention should turn to the shoulder girdle. Full examination of the SC joint, clavicle, AC joint, scapula, and glenohumeral joint should be done; scapulothoracic motion should be evaluated. Range of motion should be compared with the contralateral shoulder and evaluated in the planes of forward elevation, abduction, and external and internal rotation. The strength of the rotator cuff musculature should be tested, and a full distal neurovascular examination of the extremity should be done. Subtle differences in range of motion and strength are best determined by comparing the unaffected and affected shoulders if the patient does not have bilateral complaints.
Shoulder stiffness (“frozen shoulder”) can arise from idiopathic processes or from post-traumatic or surgical causes (secondary stiff shoulder). The first-line approach to treatment is gentle progressive stretching done several times a day. If pain does not improve with the return of range of motion or if range of motion deficits persist despite appropriate physical therapy, additional work-up may be necessary and referral to a surgical specialist should be considered.
Generally, patients with chronic pain who show no evidence of weakness on physical examination can be treated successfully with a course of physical therapy or judicious use of injections. Physical therapy should first focus on regaining full range of motion if it is absent and then transition to a strengthening program that addresses both the rotator cuff and parascapular stabilizing musculature. A full program can usually be designed by a physical therapist after evaluation. It should always include a home program, so that the patient does therapy on his or her own as well as at physical therapy appointments. Although there are no absolute indications for subacromial corticosteroid injections, when used in an appropriate setting, they can have both a diagnostic and therapeutic benefit. Patients who have pain on examination with Neer and Hawkins impingement maneuvers and no weakness that would suggest full thickness rotator cuff pathology are appropriate candidates for injections. After local anesthetic is injected in conjunction with a corticosteroid, the patient should be re-examined to determine the amount of pain relief with repeated impingement maneuvers.6
Additional work-up may be necessary if pain does not diminish after appropriate nonsurgical management. This would include radiographs to confirm or rule out arthritis and other diseases and conditions. Although arthritis is less common in the shoulder than in the hip and the knee, it is a significant cause of disability and discomfort.7 Shoulder osteoarthritis should be considered in the absence of other causes of pain. Primary osteoarthritis has no specific etiology and is more prevalent than secondary arthritis. Secondary osteoarthritis arises after a predisposing factor such as chronic instability, traumatic injury, infection, congenital malformations, or a rotator cuff tear.8 Arthritis of the shoulder appears on plain radiographs as changes in the shape of the humeral head, osteophyte formation, and narrowing of the glenohumeral joint space. Initial management of arthritis should consist of conservative measures such as activity modification, physical therapy to maintain range of motion and strength, and anti-inflammatory medications if they are not contraindicated. If conservative management fails, the patient should be referred to an orthopedic surgeon to discuss possible shoulder arthroplasty.
Additionally, plain radiographs can reveal changes associated with rotator cuff tears such as proximal migration of the humerus relative to the glenoid. This finding should prompt further evaluation with MRI and a surgical referral. Rotator cuff problems are by far the most common cause of chronic shoulder pain. Inflammation, bursitis, biceps tendonitis, rotator cuff full thickness tears, and suprascapular nerve impingement are all on the spectrum of rotator cuff disease. Patients will have differing presentations based on the severity of their disease, and not every patient with a full thickness rotator cuff tear will actually manifest with symptoms.
When patients have more significant weakness, particularly the inability to raise the arm away from the side or above shoulder height, an MRI can be indicated to evaluate the shoulder for evidence of a rotator cuff tear. Finally, we know that a significant number of patients without shoulder pain will have incidental full-thickness rotator cuff tears on MRI or ultrasound. Not every rotator cuff tear requires surgery. However, it is important to know that some tears get bigger with time, and sometimes the muscle atrophies when rotator cuff tendons are left torn for long periods of time. At this time, we cannot predict who will and will not progress to these problems. Consequently, patients about whom there is significant concern should be referred for evaluation by an expert in shoulder pathologies.
Conclusion
Shoulder pain is a common problem in patients presenting to primary care physicians. Taking a systematic approach that involves obtaining a detailed history, doing an appropriate physical examination, and judiciously using radiography can lead to the appropriate diagnosis of most shoulder pathologies. This approach can enable primary care physicians to determine indications for conservative management with physical therapy and corticosteroid injection therapy or more urgent referral to a surgical specialist. MM
Abigail Hamilton is a fellow in orthopedic surgery at TRIA Orthopaedic Center and Jonathan Braman is chief of shoulder surgery at the University of Minnesota’s department of orthopaedic surgery. He practices at TRIA Orthopaedic Center.
References
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