Francis P. Bustos, MD; Jeremy K. Rush, MD, FAAP; and Stephen F. Brockmeier, MD
Shoulder instability or dislocation is a common condition seen in athletes. The team physician should be prepared for the expeditious evaluation and management of shoulder dislocation on the field, as well as the evaluation of shoulder complaints stemming from instability in the clinic setting. In one large epidemiologic study, the male incidence rate of shoulder dislocations presenting to the emergency department was 34.90 per 100,000 person-years.1 The maximum incidence rate occurred in those between age 20 and 29 years (47.8), and 46.8% of all dislocations were in patients between age 15 and 29 years. Shah et al, using a primary care database in the United Kingdom, noted an incidence rate of 40.4 per 100,000 person-years, with a rate of 80.5 in men between age 16 and 20.2 Kerr and colleagues noted that joint dislocations represented 3.6% (n = 755) of all injuries among high school athletes, with shoulder dislocations being most common (54.9%).3 This is due to the remarkable amount of mobility of the glenohumeral joint relative to other articulations. Anatomical considerations will be discussed in the following chapter.
In the clinic, shoulder instability can present in a clearer fashion, in the form of an overt dislocation event, or less overtly. Vague complaints of shoulder pain in a young athlete should alert the clinician to the potential of shoulder subluxation. In contrast to the unhurried clinic evaluation, the sideline physician may be challenged with the presentation of an acute dislocation with the expectation of providing prompt treatment in front of an audience of spectators, the team, and coaches. In lieu of radiographic confirmation, a systematic approach to assessing, obtaining reduction, and advising return to play is essential to the skillset of sideline physicians. Despite the frequency of encountering a shoulder dislocation, there is a paucity of literature regarding on-the-field management. Nevertheless, dislocations have been directly addressed since the days of Hippocrates, and the principles practiced have been handed down by practitioners of each generation of training.
ON–THE-FIELD EVALUATION AND TREATMENT OF SHOULDER DISLOCATION
History and Mechanism of Injury
In caring for an athlete presenting with shoulder instability, the sideline physician must gather an initial history to determine proper management. It is estimated that 96% of dislocation events are anterior, whereas 4% are the atypical posterior dislocation. Age, hand dominance, type of sporting activity, degree of participation, dislocation history, and shoulder laxity are important components of assessing instability. The mechanism of injury should be reviewed if witnessed, or perhaps video replay recordings can be referenced.4 If the physician was not able to see the injury, consulting the athletic trainer or involved athletes may yield valuable information if no confirmatory radiographs are available. Contralateral shoulder examination can provide information of baseline ligamentous laxity.
Shoulder dislocation is most prevalent in football and wrestling (relative risk 2.10 and 1.99, respectively), with competition play associated with 55% of events.3 Posterior shoulder dislocation is less prevalent, and although classically seen in seizure patients, may be seen in contact athletes. Again, football players, weightlifters, and gymnasts are susceptible to a posterior force and therefore are at higher risk because these sports demand that the shoulder be in the forward elevated, internally rotated, and adducted position.10 This cohort is therefore susceptible to posterior dislocation.5
With an acute injury, a survey of the totality of injuries should be undertaken with airway, breathing, and circulation first addressed in accordance with advanced trauma life support protocol. It is critically important to assess for cervical spine injury, and maintain appropriate precautions if spine injury is suspected. If no major injuries other than the shoulder can be identified, the focus can be narrowed and a systematic format of inspection, palpation, and passive and active range of motion specific to the shoulder should be undertaken. The physical examination on the field must include a careful and complete neurovascular exam of the suspected extremity. The clinician should pay special attention to the axillary nerve, which can be in a state of palsy following the dislocation. It is important to not only examine sensation in the axillary nerve distribution but to also ensure active firing of the deltoid muscle itself. The presence of active abduction does not rule out an axillary nerve injury because athletes with even a complete axillary nerve palsy may still have some active abduction using the periscapular muscles. Brachial plexopathies can be an infrequent accompaniment to shoulder dislocation. In a prospective database study of 3633 patients with glenohumeral dislocations, Robinson et al found that 13.5% of traumatic dislocations exhibited a persistent neurological deficit following reduction.6
The shoulder will frequently be held in a position of slight abduction and internal rotation in the setting of an anterior dislocation. Palpation may reveal a prominence anterior and inferior to the normal location of the humeral head with the deltoid appearing sunken because of its absence from the glenoid. The patient experiences immediate pain from the injury aggravated by muscle spasm, which is reactionary to the loss of concavity-compressive forces that normally maintain the humeral head in the glenoid.
Considerations for Reduction on the Field, Sideline, or Locker Room
The ideal reduction maneuver is one that minimizes the use of force, can be executed with minimal pain, and produces a high degree of success. Numerous techniques exist for reducing the glenohumeral joint.7 Though no single reduction maneuver has clearly been shown to be superior, Amar et al noted in a prospective, randomized, controlled trial that the success rate and time to achieve reduction without sedation were superior for the Milch technique compared with the Stimson technique.8 Singh and colleagues demonstrated that the Milch technique was effective (96%) and led to a shorter emergency department stay and lower cost when compared to the traction-countertraction technique.9
There is some controversy regarding prehospital reduction before radiographs. However, most sports medicine physicians will attempt reduction in patients with a witnessed, classic mechanism of injury. It cannot be overemphasized that nerve and vascular function should first be assessed before reduction attempts. Multiple attempts at reduction on the athletic field may reflect poorly on the sideline physician. A single maneuver may be attempted on field by the experienced clinician, but the athlete should be taken to the locker room or a sideline tent should the initial attempt prove unsuccessful. There is also some controversy regarding initial management in a skeletally immature athlete. Some authors advocate radiographs before reduction if possible, noting a higher incidence of associated fracture.10 Reid et al, however, noted only a 3% incidence of associated fractures in patients younger than 21 years.11
The on-the-field reduction is accomplished with longitudinal traction and gentle forward elevation. Relief of pain and apprehension is often dramatic if reduction is achieved. Should this prove unsuccessful, the athlete is quickly taken to the training tent or locker room. We then routinely use the Stimson method for reduction. If reduction remains unachievable, the athlete is promptly transferred directly to the emergency department for shoulder radiographs (anteroposterior, axillary or Velpeau view, and scapular Y views).
As noted previously, myriad techniques are described in the literature, but common principles include unlocking the humerus from the lip of the glenoid, using judicious traction when necessary, and directing the humeral head back to its anatomic position. We provide a brief review of the most common reduction techniques as follows.
A benefit of the Milch method is that it does not rely predominantly on distraction for reduction and can be performed without sedation. The technique is typically performed with the patient supine but may also work with the patient prone (Figure 3-1). The clinician stands on the athlete’s affected side and grasps the shoulder with one hand and the athlete’s wrist/forearm with the other hand. The clinician slowly moves the shoulder into abduction and external rotation while reassuring the patient. The movement is paused if the athlete has pain or increased muscle spasm. Typically, shoulder reduction occurs before the shoulder reaches 90 degrees of abduction and external rotation. The clinician can use the hand holding the shoulder to gently guide the humeral head back into place. Alkaduhimi et al noted an overall 80% success rate in their systematic review of reduction techniques.7
Initially described in 1870 by Emil Theodor Kocher, a thyroid surgeon, this method is also conducted with the patient in supine position. The patient is positioned supine or seated with the elbow bent to 90 degrees. The athlete’s forearm should be externally rotated and the shoulder should be forward flexed. When resistance is met, the forearm should then be internally rotated until reduction is achieved. Gentle traction is maintained during the maneuver. Mechanically, this maneuver creates a lever between the humeral head and anterior glenoid. Reported complications include fracture of the neck of the humerus and pectoralis major rupture.7
This reduction technique involves positioning the athlete in a prone position on the edge of an examining table (Figure 3-2A). A 5- to 10-pound weight is then held by the athlete or suspended from the affected arm. This is maintained for approximately 15 to 20 minutes to provide traction to the upper extremity to fatigue the surrounding musculature and alleviate spasm. Reduction is achieved through longitudinal traction provided by gravity. When the weight is removed, the humeral head is allowed to reduce back into the glenoid fossa. Although reported reduction time is increased, the benefit of this technique is that gentle traction limits the risk of iatrogenic injury.
This technique may be performed seated or prone, though the authors’ preference is to use this as an adjunct to the Stimson method (Figure 3-2B).7 The aim is to reorient the scapula so the glenoid can accept the dislocated humeral head. The clinician is positioned on the side of the affected shoulder and pushes the inferior angle of the scapula medially and inferiorly. This rotation promotes glenoid positioning to the inferiorly displaced humeral head.
Traction-Countertraction Method and Hippocratic Method
The traction-countertraction technique is one of the most commonly used techniques. The success rate has been reported to be approximately 95%, though the technique requires the use of an assistant and frequently administration of sedation.7 The clinician stands on the side of the dislocated shoulder with the patient lying supine. A sheet can be draped around the body of the athlete with an assistant on the contralateral side, prepared to pull on both sides of the sheet for countertraction. Longitudinal in-line traction is focused on the affected shoulder to reseat the humeral head. Flexing the affected elbow to 90 degrees allows the practitioner to have appropriate grip to pull traction along the axis of the humerus (approximately 45 degrees of flexion). The Hippocratic method, described as early as 460 BC, uses a similar concept. The countertraction is provided by a covered heel placed in the patient’s axilla. This technique is not as frequently used in the emergency department setting, though it may be appropriate for a swift sideline reduction. Sayegh et al reported a 72.5% success rate with the Hippocratic maneuver in a study that compared this technique with other traction methods.12
Reduction of a Posterior Shoulder Dislocation
Though comprising only 2% to 5% of all shoulder dislocations, the posterior shoulder dislocation is associated with high-energy trauma.13 This injury is associated with impaction fractures at the anteromedial humeral head and posterior glenoid. Reduction often requires “unlocking” by manipulating the shoulder into 90 degrees of flexion, adduction, and internal rotation.14 This is followed by gradual external rotation and application of an anterior guiding force to the humeral head. This should be performed gently because there is risk of fracture to the humeral head. An alternative to manipulation is to allow the shoulder to hang with traction using the Stimson method and 5- to 10-pounds of traction.
TRANSFER TO THE EMERGENCY DEPARTMENT
If the attempted methods are unable to obtain reduction on the field, a direct transfer to the emergency department is warranted. Standard trauma series of shoulder films should be obtained to confirm type of dislocation and assess for concomitant fracture. Emergency department care allows for patient monitoring if intravenous sedation is desired. However, an intra-articular injection of 10 to 20 mL of 1% lidocaine has been successfully applied with a lateral approach with no significant difference in patient-reported pain and time to reduction when compared to intravenous sedation.15 A theoretical concern about intra-articular injection is infection in the shoulder, though this complication has yet to be reported. Once appropriate analgesia is obtained and X-rays have been scrutinized to rule out fracture, any of the reduction maneuvers that the practitioner is familiar with and comfortable conducting may be attempted in the emergency department.
Following reduction, the axillary nerve should be reassessed by checking sensation to the lateral deltoid and ensuring motor function in a small amount of abduction. Radiographs, including an axillary lateral or Velpeau view, are obtained to assess for glenoid of humeral head fracture and confirm a concentric reduction. Typically, patients are placed in a sling for immobilization in adduction and internal rotation for a period of 3 to 4 weeks to allow the soft tissues to heal. This is followed by judicious physical therapy to gradually reintroduce range of motion to prevent postimmobilization stiffness. Surgical management for the first-time dislocation is controversial and will be discussed in subsequent chapters.
The position of immobilization has had some controversy since Itoi et al espoused that a position of adduction and external rotation may be a position of greater stability in the setting of acute anterior dislocation.16 The rationale was to better tension the anterior soft tissues, which become stretched during dislocation. Although exciting, multiple, additional randomized controlled trials have been unable to recapitulate Itoi’s findings.17–19 Whelan and colleagues noted in a recent meta-analysis of randomized controlled trials that immobilization in external rotation was not significantly more effective in reducing the recurrence rate after primary anterior shoulder dislocation than immobilization in internal rotation.20
PHYSICAL EXAMINATION IN CLINIC
The physical examination of the athlete with suspected shoulder instability is critically important in developing an appropriate future treatment plan. A multitude of special tests and provocative examination maneuvers for shoulder instability exist. However, a thorough and complete physical examination begins with inspection, palpation, and range of motion and strength testing. Given the numerous available tests, the clinician must develop his or her own methodical approach to shoulder examination. Following a step-wise approach will ensure critical findings are not overlooked.
Though this chapter focuses on the clinical examination of the shoulder, it is also important to assess the cervical spine when evaluating any patient with shoulder complaints. Cervical spondylolysis and resultant radiculopathy or myelopathy can manifest as shoulder or arm pain. It should also be noted that cervical radiculopathy often presents in a nonstandard or nondermatomal pattern.21 Cervical range of motion should be assessed in all planes, including flexion, extension, rotation, and lateral bending. Cervical provocative tests include the Spurling test, the shoulder abduction test, Valsalva maneuver, neck distraction, and Elveys upper limb tension test.22 The most commonly used cervical provocative maneuver is the Spurling test. In this test, the clinician rotates the patient’s head toward the affected side while extending the neck and applying downward pressure to the top of the head. A positive test occurs when the athlete has a reproduction of pain. A systematic review of physical examination maneuvers found that the Spurling test using rotation and extension was the most sensitive and specific test for cervical radiculopathy, whereas axial compression alone had a low sensitivity and specificity.23
We most typically perform the seated examination maneuvers initially (inspection, palpation, range of motion, strength testing, sulcus sign, and hyperabduction sign). The patient is then placed supine and the load and shift, apprehension series, jerk test, and Kim test are performed.
Examination of the shoulder begins with visual inspection of the shoulder girdle, including the symptomatic and asymptomatic sides. It is important to preserve the patients’ modesty and place them at ease as much as possible. The provocative maneuvers performed later in the exam are potentially more accurate in the setting of a relaxed patient. Having female patients wear a tank top or a gown tied below the axilla is often helpful. Asymmetry of the deltoid, supraspinatus, and infraspinatus should be noted. Deltoid atrophy, presenting as “squaring of the shoulder,” may be secondary to axillary nerve palsy in the setting of a previous shoulder dislocation. The supraspinatus and infraspinatus are both supplied by the suprascapular nerve, which can be injured by compression or traction. Injury to the nerve at the suprascapular notch can cause atrophy of both muscles, whereas injury at the spinoglenoid notch affects only the infraspinatus muscle. Both muscles can also display atrophy in the setting of a chronic rotator cuff tear. The clinician should also assess for scapular winging, at rest as well as during active motion and during a “wall push-up.” Finally, the acromioclavicular (AC) and sternoclavicular joints should be assessed for asymmetry and deformity.
The bilateral shoulders are then palpated in entirety, focusing on tenderness, deformity, and crepitus. Tenderness at the AC joint can be seen in the setting of an AC joint injury, synovitis, or arthrosis. Likewise, tenderness, swelling, or deformity at the sternoclavicular joint is associated with sprain or instability. Rotator cuff tendinosis or partial-thickness tears are associated with tenderness just anterior or lateral to the border of the acromion. Tenderness at the lateral shoulder is frequently observed with a greater tuberosity fracture or Hill-Sachs lesion associated with a dislocation event.
Range of Motion
Passive and active range of motion is then assessed. Measurements should include forward flexion, abduction, external rotation in adduction and 90 degrees of abduction, and internal rotation behind the back and in 90 degrees of abduction. When assessing internal rotation behind the back, the clinician measures the most cranial vertebral segment reached. The superior scapular border is at approximately T4, the inferior scapular angle is at T7, and the iliac crest is at L4. As noted earlier, scapular winging should be assessed during active range of motion measurements. Athletes with a recent dislocation or subluxation event will often have decreases both in active and passive range of motion secondary to muscle guarding or inflammation. However, athletes with chronic instability often have normal or even increased range of motion compared to the contralateral side.
Muscle strength testing is then performed, with a focus on the rotator cuff musculature. The supraspinatus is evaluated with the supraspinatus isolation test or Jobe test. The arm is elevated 90 degrees in the scapular plane and internally rotated, and the athlete is asked to resist downward pressure. The infraspinatus is evaluated with resisted external rotation with the elbow at the side. An infraspinatus lag sign is present when the clinician passively externally rotates the arm and the athlete is unable to maintain the arm in that position. The teres minor is evaluated with the “Hornblower” test, or resisted external rotation with the arm in 90 degrees of elevation and external rotation in the scapular plane with 90 degrees of elbow flexion.
The subscapularis is evaluated with the “lift-off,” “belly-press,” and “bear hug tests.” In the lift-off test, the athlete places the hand on the lumbar spine and is asked to lift it off the body. In the belly-press test, athletes place their hand on their abdomen and are asked to press posteriorly into the abdomen without flexing their wrist or moving their arm posteriorly. It is critical that the elbow remain in front of the body to accurately assess the subscapularis. In the bear-hug test, the athlete places the arm in 90 degrees of forward flexion with the elbow flexed and the hand on the contralateral shoulder and is asked to maintain this position while the clinician tries to lift the hand away from the shoulder. Tokish et al demonstrated in an electromyogram study that although both the belly-press and lift-off tests were useful for assessing subscapularis strength, the belly-press test and lift-off tests provided greater challenges to the upper and lower subscapularis, respectively.24 Contrary to these results, Pennock and colleagues noted that the level of subscapularis muscle activation was similar among the bear-hug, belly-press, and lift-off tests.25
It is important to distinguish “laxity” from “instability” because these 2 terms are not synonymous. Matsen et al defined shoulder “laxity” as the ability of the humeral head to be passively translated on the glenoid fossa and “instability” as “a clinical condition in which unwanted translation of the head on the glenoid compromises the comfort and function of the shoulder.”26 Multiple physical examination tests have been described to assess shoulder laxity, including the drawer, load and shift, sulcus sign, and Gagey hyperabduction test. Gerber and Ganz described the anterior and posterior drawer tests in 1984.27 As initially described, the anterior drawer test is performed with the athlete supine and the clinician standing on the affected side. The clinician holds the brachium in 80 degrees to 120 degrees of abduction, 0 degrees to 20 degrees of forward flexion, and 0 degrees to 30 degrees of external rotation. The clinician holds the athlete’s brachium and provides an anterior directed force.