CHAPTER 43 Management of chronic shoulder dislocations

Geoffrey S. Van Thiel, MD, MBA, Neil S. Ghodadra, MD, Anthony A. Romeo, MD, Matthew T. Provencher, MD, CDR, MC, USN

Chronic dislocation of the shoulder should be suspected in patients with shoulder pain and decreased range of motion in the context of dementia, alcoholism, obesity, seizure disorders, or multiple trauma.

A patient with a posterior dislocation is most comfortable in a standard sling and should be fully evaluated.

A quality axillary lateral radiograph is necessary to rule out dislocation.

Closed reduction of a chronic shoulder dislocation after 3 weeks can be very difficult, and open reduction should be considered.

Extensive bone loss should be addressed to improve postoperative stability.

Posterior dislocations result in anteromedial humeral head impaction injuries, and anterior dislocations can cause both posterolateral humeral impaction injuries and anteroinferior glenoid bone loss.

Arthroplasty should be considered in patients with greater than 50% humeral head destruction, preexisting arthritis, and low functional status.

Introduction

The definition of a “chronic” shoulder dislocation is not clear in the contemporary literature. Various authors have used different cutoff values in the description of chronic dislocations, ranging from 24 hours to 6 weeks.¹ For the purposes of this chapter, we agree with Griggs and Iannotti,² in the use of 3 weeks as the defining time point. Furthermore, a “locked” shoulder dislocation often presents the same management dilemmas and requires similar treatment decisions. This chapter addresses the management of chronic shoulder dislocations; however, parallels with the treatment of a locked shoulder dislocation are acknowledged and can be applied.

Unrecognized glenohumeral dislocations leading to chronic cases are relatively uncommon, with anterior dislocations occurring more frequently than posterior.¹ However, in the context of posterior dislocations, a larger percentage is missed because of the difficulty in diagnosis on “standard” radiographs. In addition, patients with a posterior dislocation present to the treating physician in a position of comfort with a sling worn on the abdomen (internal rotation at the side). This adds to the potential for a missed diagnosis with a posterior shoulder dislocation. Fractures also can be present in many of these cases; in fact, Schulz et al³ reviewed 61 chronic dislocations and concluded that 50% had an associated fracture, 33% had neurologic injury, and 28% of these chronic dislocations were posterior. Rowe et al⁴ also explored the prevalence of chronic dislocations seen by the practicing orthopaedist; 50% of surgeons in practice for 5 to 10 years had seen a chronic dislocation, 70% in practice for 10 to 20 years, and 90% above 20 years. Although it is a rare problem, the orthopaedic surgeon should be comfortable with the diagnosis and potential management options.

Patients with a chronic dislocation often have similar characteristics, including a history of significant multiple trauma, alcoholism, obesity, seizure disorder, or dementia. These conditions create distracting variables with a potentially decreased baseline functional status. Additionally, associated conditions such as rotator cuff tears (often massive) and glenoid and humeral head bony injuries may make the management decision-making complex. Thus, patient functional demands, outcome expectations, and rehabilitation potential must be taken into consideration when developing a treatment plan.

Coexistent shoulder pathology must be recognized in the management of a patient with a chronic or locked shoulder dislocation. Often, these patients will develop osteoporosis of the humeral head and softening of the articular cartilage. Significant soft tissue contractures can be present and adhesions may develop between the humeral head the adjacent neurovascular structures with an anterior dislocation. Concomitant rotator cuff tears (sometimes massive) can influence shoulder stability, and subscapularis ruptures with biceps dislocations also may occur. Glenohumeral bone deficiencies can significantly influence joint stability with anteroinferior glenoid bone loss common in anterior dislocations. Defects in the humeral head can create engaging lesions that also impact shoulder stability; these include posterolateral and anteromedial lesions associated with anterior and posterior dislocations, respectively. Overall, an unrecognized shoulder dislocation creates a difficult treatment paradox with functional status, surgical morbidity, and coexisting pathology defining the overall treatment plan.

Chronic posterior dislocation

Posterior dislocations comprise approximately 1.5% of shoulder dislocations. Fifty percent of these dislocations are associated with tuberosity, humeral head, or glenoid fractures.⁵ Posterior capsular tears are invariably present and do have the potential to heal without treatment, as do small posterior glenoid rim fractures. However, posterior dislocations are frequently missed in the initial treatment setting because of an association with distracting variables such as seizures, alcoholism, and severe trauma. This fact, coupled with the subtlety of findings on an anteroposterior radiograph (Fig. 43-1), increases the potential for a posterior dislocation to become a chronic unrecognized problem. In addition, patients also present in a position of comfort with the arm in an internal rotation sling held against the abdomen. However, clinical suspicion and a thorough examination will reveal a decreased range of motion (ROM) and a diagnosis of a locked glenohumeral joint dislocation (Fig. 43-2).

FIGURE 43-1 A, Anteroposterior (AP) radiograph of a posterior dislocation demonstrating the subtly of findings on this view. B, Axillary radiograph confirming the diagnosis of a locked posterior dislocation.

(From Kowalsky MS et al: Traumatic posterior glenohumeral dislocation: classification, pathoanatomy, diagnosis, and treatment. Orthop Clin N Am 39(4):519–533, 2008.)

FIGURE 43-2 The patient with a locked posterior dislocation demonstrating the presence of an internally rotated shoulder that lacks external rotation.

(From Kowalsky MS et al: Traumatic posterior glenohumeral dislocation: classification, pathoanatomy, diagnosis, and treatment. Orthop Clin North Am 39(4):519–533, 2008.)

In fact, Rowe et al ⁴ noted that the initial treating physician failed to diagnose a posterior dislocation in up to 79% of cases. Checchia et al⁶ also reviewed 66 patients with a total of 73 posterior fracture dislocations of the shoulder and found that over 50% of the chronic cases were initially misdiagnosed. Thus, an appropriate workup with an axillary lateral radiograph and physical examination is mandatory in the context of shoulder pain or decreased motion involving the patient populations noted above. Specifically on examination, the shoulder will be locked when trying to externally rotate a posterior dislocation (see Fig. 43-2).

In the setting of a chronic or locked posterior dislocation there is almost invariably a large anteromedial humeral head defect or impression fracture, as well as posterior glenoid bone loss or erosion ⁷ (Fig. 43-3). The size of these defects and the stability of the shoulder will dictate treatment in conjunction with the functional demands of the patient. Treatment can range from nonoperative management to prosthetic replacement with a variety of intermediate options.

FIGURE 43-3 Anteromedial humeral head defect with a locked posterior dislocation.

(Modified from Rockwood CA et al: The shoulder, ed 4, Saunders, Elsevier, 2009.)

Indications/contraindications

The initial evaluation of a patient with a chronic dislocation should begin with a comprehensive history and physical examination. Many of these patients will have other medical issues that significantly affect treatment planning. The majority will benefit from operative intervention or reduction; however, multiple factors must be taken into account in order to balance surgical morbidity. Including:

• Functional status

• Outcome expectations

• Coexistent medical conditions

• Rehabilitation potential

Once the determination is made that the patient will benefit from operative intervention, there are numerous procedures available including soft tissue, osseous, and prosthetic options. The decision also is influenced by the following set of patient factors and concomitant pathology:

• Age of patient

• Time from injury

• Functional demands

• Glenoid bone loss and quality

• Humeral bone loss and quality

The following section outlines and describes the available alternatives. There is a discreet decision analysis that occurs during the development of a treatment plan (Fig. 43-4).

FIGURE 43-4 Flowchart for the management of a chronic posterior dislocation

Preoperative history, examination, and radiographic findings

Preoperative history

Patients with chronic posterior dislocations will often segment into specific populations. Elderly patients with severe dementia and alcoholics do have a greater propensity to present with a posterior dislocation. They also may not be able to give a clear history, which may contribute to an initial misdiagnosis. Furthermore, patients with a history of seizures or that present with multitrauma should be thoroughly evaluated.

To complicate the matter, the initial shoulder pain can dissipate and waist level activities may be resumed. However, these patients will continue to lack external rotation. Given the unique patient population, other medical problems, functional status, and expectations also should be ascertained because they will factor into the eventual treatment plan.

Examination findings

It is important to expose both shoulders during the physical examination. The examiner should then begin by standing behind the patient and observing the contour of the normal shoulder in comparison to the affected shoulder. With a posterior dislocation, there will be a loss of anterior fullness, and the coracoid of the dislocated shoulder will be more prominent. On palpation, there will often be an asymmetry noted in the anterior deltoid or in the area around the coracoid. It should be noted that in large patients these findings may be more subtle and not immediately obvious.

Pathognomonically, these patients will have an external rotation deficiency with a mechanical block to anything past neutral (see Fig. 43-2). They also often will have a limitation in abduction to less than 60 degrees. However, in chronic cases, there is a potential that the humeral head has remodeled enough to permit limits beyond those cited, as well as allowing the patient a functional ROM.

Key Exam Pearls

Patients will present in a position of comfort with internal rotation at the shoulder and the arm held against the abdomen.

With shoulder ROM, there is a mechanical block to external rotation.

The coracoid can be more prominent on the affected side.

Radiographic findings

Plain radiographs can confirm the diagnosis of a posterior dislocation; however, the appropriate views must be taken. Often, the patient with an acute dislocation will present with a painful shoulder and the treating physician will fail to obtain correct diagnostic imaging. On an anteroposterior (AP) view the dislocated shoulder can appear normal (see Fig. 43-1). However, there are also subtle findings present on the AP radiograph. These include; the loss of normal joint space, overlap between the humeral head and the glenoid rim, the “light bulb” sign (Fig. 43-5, an internally rotated view of the humeral head), and a break in “Moloney’s line” (Fig. 43-6, analogous to Shenton’s line in the hip). Nonetheless, the best view in the evaluation of a posterior dislocation is the axillary lateral.

FIGURE 43-5 AP x-ray showing the outline of an internally rotated humerus characteristic of a posterior dislocation—the “light bulb” sign.

(From Bahu NJ et al: An unexpected posterior dislocation. J Emerg Med 21(4):435–436, 2001.)

FIGURE 43-6 ‘‘Moloney’s line’’ makes a continuous arc from the inferomedial humeral calcar to the inferior aspect of the glenoid. This line can be disrupted with a posterior dislocation, similar to the break in Shenton’s line with hip dysplasia.

(From Levine WN et al: Traumatic posterior glenohumeral dislocation: classification, pathoanatomy, diagnosis, and treatment. Orthop Clin N Am 39(4): 519–533, 2008.)

The axillary lateral view also will provide important information regarding the amount of glenoid involvement and any impaction of the humeral head. The degree of impaction can be quantified by estimating the size of the defect and comparing it to the arc of the articular surface (Fig. 43-7). All images also should be evaluated for any associated fractures. The associated fracture rate of the humerus and tuberosities has been reported to be as high as 50%.⁸ If any osseous involvement is noted on plain radiographs, a computed tomography (CT) scan is recommended to further evaluate the amount and location of bony involvement.

FIGURE 43-7 Estimation of the size of humeral impaction (X/Y × 100 = % impaction).

(From Chen AL et al: Management of bone loss associated with recurrent anterior glenohumeral instability. Am J Sports Med 33(6):912–925, 2005.)

Pearls

Posterior shoulder dislocations can be missed on the initial evaluation. Appropriate x-rays and a complete physical examination are mandatory.

Management of chronic posterior dislocations is driven by the size of the humeral head defect.

Defects greater than 20% commonly require a procedure to address the bony deficiency.

Description of technique(s)

Conservative management

Despite the anatomic deformity and severe losses in glenohumeral rotation, a chronic posterior dislocation can be surprisingly well tolerated, especially in the elderly or debilitated patient (Fig. 43-8).⁵ In these cases, the patient may regain enough ROM for activities of daily living with minimal pain. Thus, it is important to balance surgical morbidity with expected outcomes. Hawkins et al⁸ reported on 41 patients with locked posterior dislocations and 7 patients received no treatment. Of these patients, only two had enough function to raise the hand to the level of the head. On final follow-up, pain ratings did not worsen and the functional losses did not progress beyond the immediate postinjury losses. Schulz et al³ also noted that the 5 patients in his nonoperative group had a fixed internal rotation deformity and elevation averaged 40 degrees. These patients did not gain a significant increase in ROM with physical therapy.

FIGURE 43-8 Patient with a left chronic posterior dislocation managed without reduction. ROM is limited but may be functional in the patient with low demands.

(From Green A et al: Part III: Glenohumeral dislocations—posterior dislocations. In Browner BD et al: Skeletal trauma, ed 4, 2009, Saunders, Fig. 44–104.)

Conservative management should be considered in patients with uncontrolled seizures, those that are unable to follow postoperative rehabilitation, and those that present with low functional demands and pain-free activities. In these cases, the risks of surgery do not warrant the potential outcome.