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Current concepts in the treatment of anterior shoulder dislocations
Current Concepts in the Treatment of Anterior Shoulder Dislocations DENNIS Y. WEN, MD Anterior shoulder dislocations are commonly seen in emergency departments. With the recent proliferation of shoulder arthroscopy, the pathoanatomy has been better delineated. Arthroscopic series have confirmed the very high percentage of Bankart lesions (avulsions of the inferior glenohumeral ligament-labral complex), especially in younger patients. A high rate of recurrent dislocation in young patients has been noted in the literature with standard conservative treatment, consisting of immobilization with or without rehabilitation. This high recurrence rate is thought to be due to the Bankart lesion. Recently, investigations with the use of arthroscopic Bankart repairs have shown high success rates in preventing recurrences, with low surgical morbidity. A young, first-time, traumatic anterior dislocation patient should be referredfor consideration of possible early arthroscopic Bankart repair, rather than automatically being treated conservatively with immobilization. (Am J Emerg Med 1999;17:401-407. Copyright © 1999 by W.B. Saunders Company)
Shoulder dislocations are a common problem seen in emergency departments. Dislocations can occur anteriorly, posteriorly, or inferiorly (luxatio erecta), with the vast majority (96% in one series 1) occurring anteriorly.2 Although diagnosis and treatment can be relatively straightforward in most cases, newer treatment concepts are evolving. This article provides a brief review of the relevant anatomy and diagnosis of anterior shoulder dislocations, followed by a more detailed discussion of the pathology and treatment methods, with particular attention to the concept of early arthroscopic treatment in selected cases. Posterior and inferior dislocations will not be discussed. ANATOMY
The glenohumeral joint is inherently unstable, accounting for the frequency of dislocations. Unlike the hip joint with its deep acetabular socket, which was designed for weightbearing stability, the shoulder joint was designed for mobil~ ity, with stability being sacrificed to achieve this mobility. Glenohumeral instability encompasses a wide spectrum of clinical disorders, with frank dislocation representing the extreme end of the spectrum. Instability is commonly categorized3 based on degree (dislocation, subluxation, micro-subluxation), frequency (acute, recurrent), direction (anterior, posterior, inferior, multidirectional), and etiology (traumatic, atraumatic, microtraumatic, congenital). The restraints of the glenohumeral joint are divided into From the Department of Family and Community Medicine, University of Missouri, Columbia, MO. Manuscript received April 7, 1998, returned April 16, 1998; revision received May 6, 1998, accepted May 22, 1998. Address reprint requests to Dr Wen, Department of Family and Community Medicine, MA303 Medical Sciences Building, University of Missouri, Columbia, MO 65212. Key Words:Bankart lesion, arthroscopic surgery. Copyright © 1999 by W.B. Saunders Company 0735-6757/99/1704-0021 $10.00/0
static stabilizers and dynamic stabilizers. The static stabilizers consist of the glenoid fossa, the labrum, the joint capsule, and the glenohumeral ligaments. The dynamic stabilizers consist of the rotator cuff muscles and their tendons (supraspinatus, infraspinatus, teres minor, and subscapularis), the long-head of the biceps brachii, and the scapular stabilizing muscles. The bony glenoid fossa is a shallow concave structure and has a small surface area compared with the articulating humeral head. Thus, there is minimal contribution to stability from the bone structures, and a great reliance on soft-tissue restraints. The cartilaginous labrum circumferentially surrounds the glenoid, providing increased depth to the fossa and increasing the contact area of the glenohumeral articulation. The joint capsule and especially the glenohumeral ligaments provide additional restraints. The glenohumeral ligaments are specific thickenings of the joint capsule, consisting of the superior glenohumeral ligament, the middle glenohumeral ligament, and the inferior glenohumeral ligament (IGHL). The IGHL is further subdivided into an anterior band, a posterior band, and an axillary pouch, and it is the anterior band of the IGHL that is the most important soft-tissue restraint to anterior dislocations. 4,5 The rotator cuff and scapular stabilizing muscles serve to dynamically keep the humeral head centered in the glenoid fossa during various shoulder movements and, hence, are important in preventing minor degrees of glenohumeral instability. Their role in frank dislocation may be less important, especially in traumatic dislocations. In addition to the static and dynamic stabilizers of the glenohumeral joint, a negative intraarticular pressure exists within the joint capsule that provides a small amount of "suction," contributing to stability. 6 DIAGNOSIS
The clinical presentation of an anterior shoulder dislocation is usually fairly straightforward, often obvious to both the patient and the physician. The history may reveal the usual mechanism of injury, which is an indirect levering of the humeral head anteriorly with the shoulder positioned in some combination of abduction, hyperextension, and external rotation. A less common mechanism involves a direct blow to the shoulder with the force directed anteriorly. Information that may affect ease of reduction (and therefore decisions concerning anesthesia/analgesia) include the amount of trauma involved, whether the episode was a first-time dislocation or a recurrence, and the duration that the shoulder has been dislocated. 7 The physical examination generally reveals anterior fullness caused by the displaced humeral head. Patients often hold their affected shoulder in a slightly abducted, externally rotated position, cradling their forearm with the unaffected 401
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arm. The examination should also serve to detect any associated injuries. Although the occurrence of axillary artery injury is rare, distal pulses and perfusion should be checked. Neurological injuries are often difficult to detect in a very uncomfortable patient. Axillary nerve injuries are probably the most common nerve injury, but deltoid strength testing may be impractical with a dislocated shoulder. Instead, sensation can be tested in the posterolateral deltoid region. Other common nerve injuries include musculocutaneous nerve and brachial plexus stretching. Neurovascular injuries are generally not contraindications to attempted closed reduction. The other purpose of the physical examination is to diagnose possible multidirectional instability or evidence of generalized ligamentous laxity. This will generally not affect immediate treatment with attempted closed reduction, but could potentially alter postreduction management as is discussed below. Therefore, determination of unidirectional versus multidirecfional status is not urgent and could potentially wait until after radiographs and reduction of the dislocation. The examination is often best performed on the contralateral uninvolved shoulder since the involved shoulder may be too uncomfortable. A sulcus sign is looked for by placing caudal traction to the humerus with the shoulder adducted at the side with the patient sitting or standing. A sulcus may be created between the anterior acromion and the humeral head, which can be both visualized and palpated, possibly indicating laxity or instability in an inferior direction. Posterior instability is generally tested for with the posterior apprehension sign with the humerus passively forward flexed to 90 °, internally rotated and adducted, and with a posteriorly directed force. Individuals with generalized ligamentous laxity are thought to be more prone to multidirectional instability. Knee and elbow hyperextension, as well as the ability to extend the hand metacarpophalangeal joints past 90 °, are signs of possible generalized laxity. An additional sign for generalized laxity is the ability to touch the thumb to the forearm with the wrist volar-flexed. Radiographic studies serve to document the dislocation and to rule out associated osseous injuries, and are generally performed in the emergency department before attempts at reduction. At least 2 views are necessary at 90 ° to each other. Anterior and posterior dislocations may appear similar on anteroposterior views, so either lateral or axillary views are needed to confirm the direction of dislocation. Axillary views are often difficult to obtain in uncomfortable patients, and therefore true lateral (transscapular, Y) views can be useful in addition to the anteroposterior view. Humeral head and neck fractures should be ruled out since significant displacement may be a contraindication to attempted closed reduction. Other fractures that should be documented, but are not necessarily contraindications to closed reduction, include glenoid rim fractures (bony Bankart lesions), greater tuberosity avulsions, and posterolateral humeral head defects (Hills-Sachs lesions).
REDUCTION METHODS A thorough discussion of methods of reduction is beyond the scope of this review. Numerus methods of reduction have been described in the literature, including several modifications of other techniques. Riebel and McCabe s reviewed several reduction tech-
niques and classified them into 4 major categories: (1) traction methods, (2) leverage techniques, (3) scapular manipulation, and (4) combinations. They found that most case series described similar success rates of 70% to 90%, regardless of technique used, but complication rates were more variable. Very few studies have compared different techniques with each other and it is difficult to draw firm conclusions based on the existing literature. The major consideration in deciding which technique to use is the experience and familiarity of the physician with certain techniques and their complications. Other practical considerations include time (and bed) availability (for example, the Stimson technique may require 20 to 30 minutes), and helper availability (some methods require more than one operator). The routine use of analgesia and/or anesthesia is variable and is usually determined by the experience of the physician. Degree of patient discomfort needs to be considered in decisions regarding both method of reduction and analgesia/anesthesia. Some reduction techniques are inherently more traumatic than others, and some patients are more anxious than others. Associated injuries, including fractures, need to be considered. Anticipated ease of reduction may depend on patient comfort, which in turn may depend on the amount of trauma involved to produce the dislocation, whether this was a first-time versus a recurrent dislocation, and time since the dislocation. Relatively atraumatic dislocations are generally easier to reduce and are often reduced by the patient or a helper before arrival to the emergency department. Similarly, recurrent dislocations often occur with less trauma and are often easier to reduce compared with first-time dislocations. If only minutes have elapsed since the dislocation occurred (rarely the case), often the reduction can be accomplished easily without analgesia/anesthesia because muscle spasm has not yet set in. In these cases, consideration can be given to attempting reduction before obtaining radiographs because of time constraints. Analgesics and anesthetics, when used, are generally administered intravenously in the emergency department, although inhaled general anesthetics are sometimes used. Usual regimens include some combination of narcotic analgesics and barbiturate or benzodiazepine sedatives. More recently, the use of intraarticular lidocaine has been advocated as a safe and effective analgesic for emergency department usage with few complications.9,1° Whether or not prereduction radiographs were taken, postreduction radiographs should be obtained both to document proper relocation of the humerus in the glenoid fossa, and to reassess for any associated fractures.
PATHOLOGY There is a range of pathology found in anteriorly dislocated shoulders. In some cases of atraumatic dislocations, little or no pathology may be present. Interstitial stretching and tearing of the anterior joint capsule can occur, but more commonly, especially in younger patients, detachment of the capsulolabral (IGHL-labral) complex from the anterior glenoid rim occurs, the classic Bankart lesion. 11 Capsular detachment at the humeral insertion is reported more often in older patients. Rotator cuff tears can occur in older individuals, but are relatively rare in younger patients. There exists some controversy about what the "essential" lesion is that allows anterior dislocation of the humeral head. Recent arthroscopic series implicate the Bankart lesion as being responsible. Matsen and Thomas 12 classified patients with anterior dislocations into 2 groups. Those with traumatic dislocations were represented by the acronym TUBS, standing for Traumatic, Unidirectional (ie, purely anterior), Bankart lesion present, Surgical treatment often necessary.
DENNIS Y. WEN • SHOULDER DISLOCATIONS
The second group was an atraumatic group with the acronym AMBRI, standing for Atraumatic, Multidirectional (ie, instability in some combination of anterior, posterior, or inferior directions), Bilateral (ie, these patients often exhibit generalized ligamentous laxity), Rehabilitative treatment is preferred, Inferior capsular shift as the preferred surgical operation for those few who do need operative treatment. They found that in 63 traumatic dislocations, 97% had the presence of a Bankart lesion. Similarly, Norlin 13 found that 100% of 24 mostly young patients (median age, 22 years) with first-time anterior dislocations had Bankart lesions. Baker et a114 reported their arthroscopic findings in 45 patients under the age of 30 after initial anterior dislocations. Sixty-two percent had complete capsulolabral detachments (ie, Bankart lesions) from the anterior glenoid and all of these shoulders were unstable on examination under anesthesia. Another 24% had partial capsulolabral detachments with varying degrees of instability under anesthesia. The other 13% were found to have capsular injuries without labral detachment; these were all stable under anesthesia. They concluded that arthroscopy may be useful in determining the intraarticular pathology, and therefore predicting chances of recurrence. A more recent arthroscopic series by Taylor and Arciero 15 lends further support that the Bankart lesion may very well be the "essential" lesion. The results were part of a prospective study at the United States Military Academy where subjects with first-time traumatic anterior dislocations were allowed to choose between conservative management with sling immobilization followed by rehabilitation, or arthroscopic Bankart repair. All patients were age 24 years or younger. The results reported were for the 63 subjects in the arthroscopy arm of the study. They found that 97% of these subjects had Bankart lesions without evidence of intracapsular injury. Only one subject had an interstitial capsular tear. No rotator cuff tears were found. They concluded that in a young patient population, the Bankart lesion appeared to be the primary pathological lesion, and that this lesion was likely to be strongly associated with future recurrent dislocations. In contrast to these arthroscopic studies, 2 recent cadaveric studies lead to different conclusions regarding the essential lesion. Bigliani et all6 stretched isolated bone-IGHLbone specimens to failure. They found that the IGHLcapsule complex stretched significantly before failure and that, therefore, significant capsular injury was probably involved with anterior dislocations in addition to capsular detachment. Speer et a117 created Bankart lesions in cadaveric specimens and found that this resulted in only minimalty increased anterior translations of the humeral head. Their conclusion was that the capsulolabral detachment alone was not enough to allow anterior dislocation, and that stretching or elongation of the IGHL-capsular structure must also occur. Reeves 18 reported a cadaveric study that consisted of loading the glenohumeral joint to determine the weakest points. They found that the weakest point in young cadavers was at the glenoid labrat attachment, and the weakest points in older cadavers were the capsule itself and the subscapularis tendon. The pathology found in older patients appears to be quite
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different from that in younger patients. Hawkins et a119noted physical examination findings consistent with rotator cuff tear in 35 of 39 patients over the age of 40 years. Most of these tears were confirmed arthrographically. Similarly, Neviaser et al20 found rotator cuff tears to be a common complication of anterior dislocation in patients over age 40. No Bankart lesions were found, and they postulated that tears of the subscapularis and the anterior capsule from the lesser tuberosity was a frequent cause of recurrent instability in this age group. Although the issue is not totally resolved, most authorities believe that the capsulolabral detachment from the anterior glenoid rim is the primary pathological lesion in young active patients with traumatic dislocations. It is believed that this Bankart lesion is what predisposes to the high redislocation rate in younger patients, perhaps because of its poor spontaneous healing potential. In older individuals there may be a greater component of interstitial capsular tearing and stretching, with capsulolabral detachments occurring rarely. The rotator cuff tears found in older patients, although a potential cause of continued pain and disability, are not necessarily a cause of recurrent instability. The arthroscopic studies reported have been performed predominately on younger patients. In contrast, most cadaveric studies have used older individuals: age range of 56 to 87 years in Bigliani et al, 16 and age range of 56 to 85 years in Speer et al. 17Even in young patients, interstitial capsular injury likely exists, but detecting these injuries arthroscopically may be difficult or impossible.
POSTREDUCTION MANAGEMENT The traditional treatment of anterior glenohumeral dislocations after successful closed reduction and assuming no major associated injuries or complications, generally consists of some form of immobilization. This immobilization may take the form of a sling, a sling and swathe, or any of several commercially available immobilizers. The recommended duration of immobilization varies widely, but generally falls in the range of 3 to 6 weeks, depending on age of patient, first-time versus recurrence, traumatic versus atraumatic, and associated injuries. Immobilization theoretically allows the pathological lesions to heal, and the injured anterior tissues to "scar" in order to provide some resistance to excessive external rotation, and thereby prevent redislocations. Postimmobilization rehabilitation to restore motion and strength is also often recommended. The major long-term sequela after traumatic anterior shoulder dislocation is recurrent instability, ie, redislocation or subluxation. Other long-term sequelae include persistent pain, weakness, decreased range of motion, and glenohumeral degenerative arthritis. The long-term sequelae, with the exception of recurrence, are generally uncommon and generally not severe. Several factors have been implicated to contribute to the natural history in terms of redislocation, including age at time of first dislocation, level of activity, traumatic versus atraumatic (ie, TUBS versus AMBRI), duration of immobilization, postimmobilization rehabilitation, and presence of a Hills-Sachs lesion. Although the traditional treatment of immobilization with or without postimmobilization rehabilitation may effectively decrease
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the recurrence rate in older individuals, this treatment method does little to alter the high incidence of redislocation in younger patients. In 1950, McLanghlin and Cavallaro 21 reported a case series of 101 patients with shoulder dislocations. The recurrence rates for patients under age 20 was 90%, for ages 20 to 40 it was 60%, and for patients over 40 it was 10%. These results were confirmed in the large case series presented by Rowe and Sakellarides, first in 1956, 22 and then a continuation in 1961.23 Their retrospective analysis of 324 first-time dislocations showed that age at the time of initial dislocation was the most important factor relating to the risk of recurrence. Ninety-four percent of patients under age 20 had recurrences, 79% in ages 21 to 30, 50% in ages 31 to 40, and 14% in patients over 40. They found that immobilization, postreduction exercises, and humeral head defects were not clearly related to the rate of recurrence. Kiviluoto et a124 recommended 1 week of immobilization for patients older than 30 years, due to their low inherent redislocation rate. For patients younger than 30 years, those immobilized for 3 weeks had lower redislocation rates than those immobilized for only 1 week, 22% v 56%. In contrast, Henry and Genung 25 found no effect of immobilization or length of immobilization on recurrence rates in young athletic patients. Simonet and Cofield 26 in 1984 reported a retrospective series of 116 first-time anterior dislocations and found a lower rate of recurrence than the previous reports. After a mean 4.63 years of follow-up, recurrence rates were 66% for under age 20, 40% for ages 20 to 40, and 0% for those over 40. However, 82% of patients with dislocations occurring during athletic activity had recurrences, compared with 30% of patients with dislocations not occurring during athletic activity. In the only large-scale prospective study on first-time anterior dislocations, Hovelius et a127 recently reported on their 10-year follow-up for the cohort. Patients under the age of 40 were randomly assigned to 1 of 2 treatment groups: immobilization for 3 to 4 weeks versus sling until comfortable. The results indicated that immobilization made no significant difference in rate of recurrence, and that age still stood as the primary prognostic factor. The strict immobilization group had recurrence rates of 70% in age 12 to 22, 63% in ages 23 to 29, and 21% in ages 30 to 40. The sling only until comfortable group had recurrence rates of 63%, 53%, and 29%, respectively, for the same age categories. Shoulder rehabilitative exercises are often prescribed after anterior shoulder dislocations, generally after some period of immobilization. As mentioned, Rowe and Sakellarides 23 did not find exercises to be helpful in preventing recurrences. Similarly, Simonet and Cofield's 26 study could document no significant benefit from rehabilitative exercises. More recently, Wheeler et al28 and Arciero et a129 found recurrence rates of 92% and 80% in young active patients despite an exercise program. Contrary to these studies citing no benefit from postreduction rehabilitation, Aronen and Regan 3° showed a recurrence rate of only 25% of 20 young active patients after a strengthening program, with a follow-up period averaging 35.8 months. Yoneda et al, 31 in abstract form, reported a recurrence rate of 17.3% in
104 young patients after a postimmobilization exercise program. In a related study concerning exercises, Burkhead and Rockwood 32 reported on a series of 140 patients with subluxations, but without dislocations, who were treated with a supervised rehabilitative program. They found that only 16% of patients with a traumatic cause of subluxation had satisfactory response to the exercise program, compared with 80% with atraumatic subluxations. They concluded that it was helpful to classify patients as to the etiology of their instability, similar to the TUBS versus AMBRI classification of Thomas and Matsen, 9 to optimize treatment. To summarize the data concerning immobilization with or without postimmobilization rehabilitation, it appears that neither immobilization nor rehabilitation has a significant effect on the high rate of recurrent dislocation in young individuals with traumatic dislocations. Their youth, and probably therefore their higher level of physical activity, athletic and otherwise, makes them prone to redislocation, despite postreduction immobilization and/or rehabilitation. The data for older individuals is less clear. Their redislocation rate is lower at baseline, and it may be that immobilization is helpful. Most authorities advise against prolonged (over 3 to 4 weeks) immobilization in older patients (over age 50) because of the risks of iatrogenic adhesive capsulitis. Rehabilitative exercises do appear to be helpful in patients with atraumatic dislocations who may have multidirectional instability or generalized ligamentous laxity. Based on the available and somewhat conflicting data, immobilization is recommended as long as necessary to treat symptoms, and may be discontinued when symptoms allow. Despite these data suggesting lack of efficacy of immobilization and rehabilitation in young active patients with traumatic anterior dislocations, this very treatment remains the traditional standard of care. One possible reason that this remains the case is that, until recently, no effective alternative with acceptable complications has been shown to be clearly superior. Another reason may be that, although the traditional treatment may not prevent recurrences, it may be effective in treating the pain and other potential complications of shoulder dislocations, such as loss of range of motion or loss of strength, although limited data are available on these issues.
SURGICALTREATMENTS Over 250 operative techniques have been described for the treatment of anterior instability. These can be classified into four basic groups33: (1) procedures that limit external rotation by tightening the anterior structures such as the Magnuson-Stack 34 and Putti-Platt 35 procedures, (2) bony blocks to prevent anterior humeral head translation such as the Bristow procedure, ~6 (3) osteotomies to either the glenoid or the humerus to change the rotational alignment, and (4) anatomic reconstruction of the disrupted anteroinferior capsulolabral complex, such as the Bankart procedures Because of its success in preventing recurrences (generally 95% success rates with less than 5% recurrences 2) the open Bankart repair and its modifications are generally considered the gold standard procedure. The procedure involves repairing the "essential lesion."
DENNIS Y. WEN • SHOULDER DISLOCATIONS
The traditional indications for surgical procedures have been subject to debate, but generally include recurrent instability, pain, or activity limitation, usually after a trial of nonsurgical treatment. Because of the recognized high incidence of recurrent instability after traumatic anterior dislocation, especially in young patients, some authorities have advocated earlier surgical intervention to prevent these recurrences. However, potential surgical complications, along with potential loss of range-of-motion, especially external rotation, have limited the role of open operative procedures. With the development and advances in arthroscopic surgical techniques for treating shoulder pathology, many arthroscopists now advocate arthroscopic Bankart repairs for treating shoulder instability. Arthroscopic surgery has many potential advantages over comparable open procedures. Arthroscopy is relatively atraumatic, does not involve splitting the subcapularis, and can often be performed as an outpatient procedure. The quicker recovery from surgery allows earlier return to work and other activities. However, higher failure rates compared with open procedures have been noted in arthroscopic series, with redislocation rates between 14.7% and 49% .38-44 In a retrospective comparison of arthroscopic versus open reconstruction of Bankart lesions in patients with at least 3 episodes of dislocation or subluxation, Guanche et a145found recurrent instability in 5 of 15 patients after arthroscopic stabilization, compared with 1 of 12 patients after open procedures. They concluded that open stabilization should remain the procedure of choice. Geiger et a146prospectively offered 34 patients the choice between open versus arthroscopic Bankart repair. All patients had recurrent instability and had failed physical therapy. After an average follow-up of 34 months, the 18 patients in the open repair group had 83% good to excellent results, with no recurrent dislocations. In contrast, in the 16 patients in the arthroscopic repair group, only 50% had good to excellent results, with 3 recurrent dislocations and 4 recurrent subluxations. In contrast to the previously mentioned investigators reporting inferior results of arthroscopic Bankart procedures, Wheeler et a128 reported a series of 9 young patients who had arthroscopy after initial anterior dislocations, with Bankart lesions in all 9. The recurrence rate was only 22% in this group, compared with 92% (35 of 38) in patients treated nonoperatively. This same group of investigators (Arciero et a129) from the United States Military Academy reported the results of a nonrandomized prospective study. Thirty-six young (ages 18 to 24 years), active cadet-athletes who suffered traumatic first-time anterior shoulder dislocations were offered the choice between nonoperative treatment with immobilization for 4 weeks followed by supervised rehabilitation, or arthroscopic Bankart repair followed by identical immobilization and rehabilitation. After an average follow-up period of 23 months, 80% (12 of 15) of those treated nonoperatively developed recurrent instability. In contrast, after an average of 32 months of follow-up in the arthroscopy group, only 14% (3 of 21) developed recurrent instability. All 21 arthroscopic procedures were performed within 10 days of the injury, and all 21 had confirmed Bankart lesions which were repaired. Similarly, Uribe and Hechtman 47 reported 11 of 11 good or excellent results in a prospective study of young athletes
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(average age, 20 years) after first-time traumatic anterior dislocations treated with arthroscopic surgery. All procedures were performed within 36 days of the injury. After an average 24.5 months of follow-up, only 1 patient had a recurrent subluxation episode without dislocation. The success of Arciero et al, 29 and Uribe and Hechtman, 47 with arthroscopic stabilization with minimal postoperative morbidity represents strong evidence that perhaps arthroscopy should be considered early in the treatment of anterior shoulder dislocations in certain populations. In these studies, all were young (less than 26 years), all were active, all had first-time dislocations without previous instability, and all dislocations had resulted from trauma. Additionally, all arthroscopies were performed early after dislocation, and Bankart lesions were clearly evident in all the surgical patients. In previous series of arthroscopically treated patients, 38-44as well as comparisons between open and arthroscopic Bankart repairs, 45,46populations were often mixed in terms of age, activity level, degree of instability (subluxation v dislocation), cause of dislocation/subluxation, number of previous dislocations/subluxations, and time between injury and surgery. Green and Christensen48 reported results from 37 patients with anterior instability treated with arthroscopic repair and correlated these results to the severity of the labral lesion found at arthroscopy. After an average follow-up of 37 months, only 1 failure was noted among 22 patients with simple detachment of the anteroinferior capsulolabral complex from the glenoid rim (ie, Bankart lesion). However, of the 15 patients in the group with significant degeneration of the capsulolabral complex, there were 13 failures. Most of the patients in the study had had several recurrences of anterior instability, and there was a trend toward more severe labral pathology with more recurrences. Technical differences between the various arthroscopic reports deserves brief mention. Stabilization techniques in the earlier reports were generally either by a staple technique or by transglenoid sutures. More recently, bioabsorbable tacks have become more popular. Capsular tensioning to reduce redundancy and laxity is technically difficult arthroscopically, and the degree to which this was performed also varied from study to study. Recent reports specifically studying technical advances by Resch et a149 and by Marcacci et al 5° have demonstrated excellent results with low recurrence rates even among patients with multiple preoperative recurrences. Most of the reports on Bankart repairs, whether open or arthroscopic, either exclude patients with multidirectional instability or have found poor surgical results on these individuals. Capsular shift procedures are more appropriate if multidirectional instability is present despite nonoperative treatment. To summarize the recent literature concerning surgical treatment of anterior shoulder dislocations, open Bankart repairs seem superior compared with arthroscopic procedures overall for reducing recurrent episodes of instability. However, because of the invasiveness and potential morbidy associated with open procedures, these operations are generally reserved for those with recurring instability symptoms after nonoperative treatment. Most of the reports of inferior results for arthroscopic Bankart repairs have included patients with chronic recurring instability. Age ranges have
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also been variable. In contrast, studies by Arciero et a129 as well as other investigators on populations with young, acute first-time dislocators have had favorable results with early arthroscopic repair. Appropriate patient selection appears to be the critical factor. As discussed earlier, the pathology involved in anterior glenohumeral dislocation may differ between different age groups. Younger individuals with traumatic anterior dislocations for the most part have anteroinferior capsulolabral (IGHL-labral) avulsions from the glenoid rim, ie, Bankart lesions. Although controversial, these patients usually seem to have minimal or no interstitial capsular injury. In contrast, older patients may have more intracapsular stretching and tearing. Capsulolabral detachments may not spontaneously heal, or may heal very poorly. This, along with the generally overall higher level of activity in younger populations, may explain their high redislocation rates. Based on the likely pathology present, the young patient with a pure Bankart lesion and no intracapsular tearing or stretching would appear to be the ideal candidate for an arthroscopic Bankart repair. Patients who have chronic recurring instability episodes, even though young, are more likely to have concommitant intracapsular laxity with attenuation and degeneration of the IGHL-labral complex in addition to the Bankart lesion, possibly explaining the inferior arthroscopic results in treatment of recurrent instability. Time between injury and surgery may also be an important factor, although this has not been well studied. It may well be that the acutely dislocated shoulder with a fresh hemarthrosis and associated inflammatory mediators provides the optimal environment for wound healing following a Bankart repair.
SUMMARYAND RECOMMENDATIONS (1) Shoulder dislocations occur commonly because of the inherent instability of the glenohumeral joint. The majority occur anteriorly and are traumatic in origin. (2) Diagnosis is generally straightforward, but radiographs at orthogonal angles should be obtained to document the direction of dislocation and to diagnose associated injuries. (3) Physical examination should also determine if multidirectional instability may be present. (4) Multiple techniques of reduction exist and most have documented high success rates. The method chosen, as well as the decision to use analgesia/ anesthesia, may need to be individualized. (5) The traditional postreduction treatment involves some sort of immobilization for a period of 3 to 6 weeks, possibly followed by physical therapy. Older patients (over age 50 years) should generally be immobilized toward the shorter duration range to prevent the occurrance of adhesive capsulitis. (6) Young age at the time of initial dislocation is the most important factor predicting future recurrences. In these patients, especially active ones,
the traditional method of treatment is ineffective for preventing redislocations, and immobilizations is recommended mainly for treatment of symptoms. (7) Surgical treatments are generally reserved for patients who have failed the nonsurgical treatments of immobilization and/or physical therapy, and have had recurrent episodes of instability. The open Bankart repair remains the gold standard procedure and is currently believed to be superior to arthroscopic Bankart repair in this population of patients. (8) Although controversial and considered by some to be experimental, there is a growing body of literature supporting earlier arthroscopic Bankart repairs in certain well-defined populations. The ideal candidate appears to be a young, active, a first-time dislocator with a traumatic etiology of dislocation, anterior in direction with no evidence of multidirectional instability, and acute in duration before recurrences have occurred. These individuals should be referred promptly to an arthroscopist for consideration of an early arthroscopic Bankart repair. This procedure in the properly selected patient greatly reduces the redislocation rate with minimal surgical morbidity. (9) Patients who have had previous dislocations, as well as those with multidirectional instability, should be treated with traditional methods. Many will need future surgery for recurrences, but should initially be treated with nonoperative means. (10) As technical advances are further developed and experience is gained among arthroscopists, indications and patient populations for early arthroscopic stabilization will likely expand in the near future, possibly to include older patients and those with recurrences.
CONCLUSION Newer advances in the treatment of anterior shoulder dislocations have received increasing attention recently. It has long been apparent that recurrence rates are exceedingly high among young, athletic individuals, despite optimal nonoperative treatment. With the more widespread use of the arthroscope, increasing evidence exists implicating anteroinferior capsulolabral avulsions (Bankart lesions) as the "essential lesion" in young patients, predisposing to recurrent instability. Recent studies have shown that early arthroscopic Bankart repairs in these young individuals can markedly decrease recurrence rates with minimal surgical morbidity. Referral for consideration of early arthroscopic repair should be made in a timely manner for appropriate candidates. If recurrent dislocation is allowed before referral, the opportunity to successfully repair the lesion arthroscopically may be lost.
DENNIS Y. WEN • SHOULDER DISLOCATIONS
REFERENCES 1. McLaughiin HL: Posterior dislocation of the shoulder. J Bone Joint Surg Am 1952;34:584-590 2. Rowe OR: Acute and recurrent anterior dislocations of the shoulder. Orthop Olin North Am 1980;11:253-270 3. AItchek DW, Warren RF: Shoulder instability, In Reider B (ed): Sports Medicine: The School-Age Athlete. Philadelphia, PA, Saunders, 1991, pp 157-189 4. Bowen MK, Warren RF: Ligamentous control of shoulder stability based on selective cutting and static translation experiments. Olin Sports Med 1991;10:757-782 5. Turkel SJ, Panio MW, Marshall JL, et al: Stabilizing mechanisms preventing anterior dislocation of the glenohumeral joint. J Bone Joint Surg Br 1981;67:1208-1217 6. Speer KP: Anatomy and pathomechanics of shoulder instability. Clin Sports Med 1995;14:751-760 7. Rockwood CA Jr, Wirth MA: Subiuxations and dislocations about the glenohumeraljoint, In Rockwood CA Jr, Green DP, Bucholz RW, et al: Rockwood and Green's Fractures in Adults, fourth ed. Philadelphia, PA, Lippincott-Raven, 1996, pp 1193-1339 8. Riebel GD, McCabe JB: Anterior shoulder dislocation: A review of reduction techniques, Am J Emerg Med 1991;9:180-188 9. Suder PA, Mikkelsen JB, Hougaard K, et al: Reduction of traumatic primary anterior shoulder dislocation under local analgesia. Ugeskr Laeger 1995;25:3625-3639 10. Matthews DE, Roberts T: Intraarticular lidocaine versus intravenous analgesic for reduction of acute anterior shoulder dislocations: A prospective randomized study. Am J Sports Med 1995;23: 54-58 1t. Bankart ASB: The pathology and treatment of recurrent dislocation of the shoulder joint. Br J Surg 1938;26:23-29 12. Thomas SC, Matsen FA: An approach to the repair of avulsion of the glenohumeral ligaments in the management of traumatic anterior glenohumeral instability. J Bone Joint Surg Am 1989;71:506513 13. Norlin R: Intraarticular pathology in acute, first-time anterior shoulder dislocation: An arthroscopic study. Arthroscopy 1993;9:546549 14. Baker CL, Uribe JW, Whitman C: Arthroscopic evaluation of acute initial anterior shoulder dislocations. Am J Sports Med 1990;18: 25-28 15. Taylor DO, Arciero RA: Pathologic changes associated with shoulder dislocations: Arthroscopic and physical examination findings in first-time, traumatic anterior dislocations, Am J Sports Med 1997;25:306-311 16. Bigliani LU, Pollock RG, Soslowsky LJ, et al: Tensile properties of the inferior glenohumeral ligament. J Orthop Res 1992; 10:187-197 17. Spear KP, Deng X, Borrero S, et ai: Biomechanical evaluation of a simulated Bankart lesion. J Bone Joint Surg Am 1994;76:18191826 18. Reeves B: Experiments on the tensile strength of the anterior capsular structures of the shoulder in man. J Bone Joint Surg Br 1968;50:858-865 19. Hawkins RJ, Bell RH, Hawkins RH, et al: Anterior Dislocation of the shoulder in the older patient. Clin Orthop 1986;206:192-195 20, Neviaser RJ, Neviaser TJ, Neviaser JS: Anterior dislocation of the shoulder and rotator cuff rupture. Clin Orthop 1993;291:103-106 21. McLaughlin HL, Cavallaro WU: Primary anterior dislocation of the shoulder. Am J Surg 1950;80:615-621 22. Rowe CR: Prognosis in dislocations of the shoulder. J Bone Joint Surg Am 1956;38:957-977 23. Rowe OR, Sakellarides HT: Factors related to recurrences of anterior dislocations of the shoulder. Clin Orthop 1961;20:40-47 24. Kiviluoto O, Pasila M, Jaroma H, et al: Immobilization after primary dislocation of the shoulder. Acta Orthop Scand 1980;51:915919 25. Henry JH, Genung JA: Natural history of genohumeral dislocation-Revisited. Am J Sports Mad 1982;10:135-137
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26. Simonet WT, Cofieid RH: Prognosis in anterior shoulder dislocation. Am J Sports Med 1984;12:19-24 27. Hovelius L, Augustini BG, Fredin H, et al: Primary anterior dislocation of the shoulder in young patients. J Bone Joint Surg Am 1996;78:1677-1684 28. Wheeler JH, Ryan JB, Arciero RA, et al: Arthroscopic versus nonoperative treatment of acute shoulder dislocations in young athletes. Arthroscopy 1989;5:213-217 29. Arciero RA, Wheeler JH, Ryan JB, et al: Arthroscopic Bankart repair versus nonoperative treatment for acute, initial anterior shoulder dislocations. Am J Sports Med 1994;22:589-594 30. Aronen JG, Regan K: Decreasing the incidence of recurrence of first time anterior shoulder dislocations with rehabilitation. Am J Sports Med 1984;12:283-291 31. Yoneda B, Welsh RP, Macintosh DL: Conservative treatment of shoulder dislocation in young males. J Bone Joint Surg Br 1982;64:254-255 (abstr) 32. Burkhead WZ, Rockwood CA: Treatment of instability of the shoulder with an exercise program. J Bone Joint Surg Am 1992;74: 890-896 33. Payne LZ, Altchek DW: The surgical treatment of anterior shoulder instability. Olin Sports Med 1995;14:863-883 34. Magnuson PB, Stack JK: Recurrent dislocation of the shoulder. JAMA 1943;23:889-892 35. Osmond-Clarke H: Habitual dislocation of the shoulder: The Putti-Platt operation. J Bone Joint Surg Br 1948;30:19-25 36. Helfet AJ: Coracoid transplantation for recurring dislocation of the shoulder. J Bone Joint Surg Br 1958;40:198-202 37. Bankart ASB: Recurrent or habitual dislocation of the shoulderjoint. BMJ 1923;2:1132-1133 38. Ooughlin L, Rubinovich M, Johansson J, et al: Arthroscopic staple capsulorrhaphy for anterior shoulder instability. Am J Sports Med 1992;20:253-256 39. Grana WA, Buckley PD, Yates OK: Arthroscopic Bankart suture repair. Am J Sports Med 1993;21:348-353 40. Walch G, Boileau P, Levigne C, et al: Arthroscopic stabilization for recurrent anterior shoulder dislocation: Results of 59 cases. Arth roscopy 1995; 11:173-179 41. Youssef JA, Cart CF, Walther CE, et al: Arthroscopic Bankart suture repair for recurrent traumatic unidirectional anterior shoulder dislocations. Arthroscopy 1995; 11:561-563 42. Mologne TS, Lapoint JM, Morin WD, et al: Arthroscopic anterior labral reconstruction using a transglenoir suture technique: Results in active-duty military patients. Am J Sports Meal1996;24:268274 43. Pagnani MJ, Warren RF, AItchek DW, et al: Arthroscopic shoulder stabilization using transglenoid sutures: A four-year minimum followup. Am J Sports Med 1996;24:459-467 44. Manta JP, Organ S, Nirschl RP, et al: Arthroscopic transglenoid suture capsulolabral repair: Five-year followup. Am J Sports Med 1997;25:614-618 45. Gaunche CA, Quick DC, Sedergren KM, et al.: Arthroscopic versus open reconstruction of the shoulder in patients with isolated Bankart lesions. Am J Sports Med 1996;24:144-148 46. Geiger DF, Hurley JA, Tovey JA, et al: Results of arthroscopic versus open Bankart suture repair. Clin Orthop 1997;337:111-117 47. Uribe JW, Hechtman KS: Arthroscopically assisted repair of acute Bankart lesion. Orthopedics 1993;16:1019-1023 48. Green MR, Christensen KP: Arthroscopic Bankart Procedure: Two- to five-year followup with clinical correlation to severity of glenoid labral lesion. Am J Sports Med 1995;23:276-281 49. Resch H, Povacz P, Wambacher M, et al: Arthroscopic extra-articular Bankart repair for the treatment of recurrent anterior shoulder dislocation. Arth roscopy 1997; 13:188-200 50. Marcacci M, Zaffagnini S, PetittoA, et al: Arthroscopic management of recurrent anterior dislocation of the shoulder: Analysis of technical modifications on the Caspari procedure. Arthroscopy 1996; 12:144-149
Shoulder dislocations are a common problem seen in emergency departments. Dislocations can occur anteriorly, posteriorly, or inferiorly (luxatio erecta), with the vast majority (96% in one series 1) occurring anteriorly.2 Although diagnosis and treatment can be relatively straightforward in most cases, newer treatment concepts are evolving. This article provides a brief review of the relevant anatomy and diagnosis of anterior shoulder dislocations, followed by a more detailed discussion of the pathology and treatment methods, with particular attention to the concept of early arthroscopic treatment in selected cases. Posterior and inferior dislocations will not be discussed. ANATOMY
The glenohumeral joint is inherently unstable, accounting for the frequency of dislocations. Unlike the hip joint with its deep acetabular socket, which was designed for weightbearing stability, the shoulder joint was designed for mobil~ ity, with stability being sacrificed to achieve this mobility. Glenohumeral instability encompasses a wide spectrum of clinical disorders, with frank dislocation representing the extreme end of the spectrum. Instability is commonly categorized3 based on degree (dislocation, subluxation, micro-subluxation), frequency (acute, recurrent), direction (anterior, posterior, inferior, multidirectional), and etiology (traumatic, atraumatic, microtraumatic, congenital). The restraints of the glenohumeral joint are divided into From the Department of Family and Community Medicine, University of Missouri, Columbia, MO. Manuscript received April 7, 1998, returned April 16, 1998; revision received May 6, 1998, accepted May 22, 1998. Address reprint requests to Dr Wen, Department of Family and Community Medicine, MA303 Medical Sciences Building, University of Missouri, Columbia, MO 65212. Key Words:Bankart lesion, arthroscopic surgery. Copyright © 1999 by W.B. Saunders Company 0735-6757/99/1704-0021 $10.00/0
static stabilizers and dynamic stabilizers. The static stabilizers consist of the glenoid fossa, the labrum, the joint capsule, and the glenohumeral ligaments. The dynamic stabilizers consist of the rotator cuff muscles and their tendons (supraspinatus, infraspinatus, teres minor, and subscapularis), the long-head of the biceps brachii, and the scapular stabilizing muscles. The bony glenoid fossa is a shallow concave structure and has a small surface area compared with the articulating humeral head. Thus, there is minimal contribution to stability from the bone structures, and a great reliance on soft-tissue restraints. The cartilaginous labrum circumferentially surrounds the glenoid, providing increased depth to the fossa and increasing the contact area of the glenohumeral articulation. The joint capsule and especially the glenohumeral ligaments provide additional restraints. The glenohumeral ligaments are specific thickenings of the joint capsule, consisting of the superior glenohumeral ligament, the middle glenohumeral ligament, and the inferior glenohumeral ligament (IGHL). The IGHL is further subdivided into an anterior band, a posterior band, and an axillary pouch, and it is the anterior band of the IGHL that is the most important soft-tissue restraint to anterior dislocations. 4,5 The rotator cuff and scapular stabilizing muscles serve to dynamically keep the humeral head centered in the glenoid fossa during various shoulder movements and, hence, are important in preventing minor degrees of glenohumeral instability. Their role in frank dislocation may be less important, especially in traumatic dislocations. In addition to the static and dynamic stabilizers of the glenohumeral joint, a negative intraarticular pressure exists within the joint capsule that provides a small amount of "suction," contributing to stability. 6 DIAGNOSIS
The clinical presentation of an anterior shoulder dislocation is usually fairly straightforward, often obvious to both the patient and the physician. The history may reveal the usual mechanism of injury, which is an indirect levering of the humeral head anteriorly with the shoulder positioned in some combination of abduction, hyperextension, and external rotation. A less common mechanism involves a direct blow to the shoulder with the force directed anteriorly. Information that may affect ease of reduction (and therefore decisions concerning anesthesia/analgesia) include the amount of trauma involved, whether the episode was a first-time dislocation or a recurrence, and the duration that the shoulder has been dislocated. 7 The physical examination generally reveals anterior fullness caused by the displaced humeral head. Patients often hold their affected shoulder in a slightly abducted, externally rotated position, cradling their forearm with the unaffected 401
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arm. The examination should also serve to detect any associated injuries. Although the occurrence of axillary artery injury is rare, distal pulses and perfusion should be checked. Neurological injuries are often difficult to detect in a very uncomfortable patient. Axillary nerve injuries are probably the most common nerve injury, but deltoid strength testing may be impractical with a dislocated shoulder. Instead, sensation can be tested in the posterolateral deltoid region. Other common nerve injuries include musculocutaneous nerve and brachial plexus stretching. Neurovascular injuries are generally not contraindications to attempted closed reduction. The other purpose of the physical examination is to diagnose possible multidirectional instability or evidence of generalized ligamentous laxity. This will generally not affect immediate treatment with attempted closed reduction, but could potentially alter postreduction management as is discussed below. Therefore, determination of unidirectional versus multidirecfional status is not urgent and could potentially wait until after radiographs and reduction of the dislocation. The examination is often best performed on the contralateral uninvolved shoulder since the involved shoulder may be too uncomfortable. A sulcus sign is looked for by placing caudal traction to the humerus with the shoulder adducted at the side with the patient sitting or standing. A sulcus may be created between the anterior acromion and the humeral head, which can be both visualized and palpated, possibly indicating laxity or instability in an inferior direction. Posterior instability is generally tested for with the posterior apprehension sign with the humerus passively forward flexed to 90 °, internally rotated and adducted, and with a posteriorly directed force. Individuals with generalized ligamentous laxity are thought to be more prone to multidirectional instability. Knee and elbow hyperextension, as well as the ability to extend the hand metacarpophalangeal joints past 90 °, are signs of possible generalized laxity. An additional sign for generalized laxity is the ability to touch the thumb to the forearm with the wrist volar-flexed. Radiographic studies serve to document the dislocation and to rule out associated osseous injuries, and are generally performed in the emergency department before attempts at reduction. At least 2 views are necessary at 90 ° to each other. Anterior and posterior dislocations may appear similar on anteroposterior views, so either lateral or axillary views are needed to confirm the direction of dislocation. Axillary views are often difficult to obtain in uncomfortable patients, and therefore true lateral (transscapular, Y) views can be useful in addition to the anteroposterior view. Humeral head and neck fractures should be ruled out since significant displacement may be a contraindication to attempted closed reduction. Other fractures that should be documented, but are not necessarily contraindications to closed reduction, include glenoid rim fractures (bony Bankart lesions), greater tuberosity avulsions, and posterolateral humeral head defects (Hills-Sachs lesions).
REDUCTION METHODS A thorough discussion of methods of reduction is beyond the scope of this review. Numerus methods of reduction have been described in the literature, including several modifications of other techniques. Riebel and McCabe s reviewed several reduction tech-
niques and classified them into 4 major categories: (1) traction methods, (2) leverage techniques, (3) scapular manipulation, and (4) combinations. They found that most case series described similar success rates of 70% to 90%, regardless of technique used, but complication rates were more variable. Very few studies have compared different techniques with each other and it is difficult to draw firm conclusions based on the existing literature. The major consideration in deciding which technique to use is the experience and familiarity of the physician with certain techniques and their complications. Other practical considerations include time (and bed) availability (for example, the Stimson technique may require 20 to 30 minutes), and helper availability (some methods require more than one operator). The routine use of analgesia and/or anesthesia is variable and is usually determined by the experience of the physician. Degree of patient discomfort needs to be considered in decisions regarding both method of reduction and analgesia/anesthesia. Some reduction techniques are inherently more traumatic than others, and some patients are more anxious than others. Associated injuries, including fractures, need to be considered. Anticipated ease of reduction may depend on patient comfort, which in turn may depend on the amount of trauma involved to produce the dislocation, whether this was a first-time versus a recurrent dislocation, and time since the dislocation. Relatively atraumatic dislocations are generally easier to reduce and are often reduced by the patient or a helper before arrival to the emergency department. Similarly, recurrent dislocations often occur with less trauma and are often easier to reduce compared with first-time dislocations. If only minutes have elapsed since the dislocation occurred (rarely the case), often the reduction can be accomplished easily without analgesia/anesthesia because muscle spasm has not yet set in. In these cases, consideration can be given to attempting reduction before obtaining radiographs because of time constraints. Analgesics and anesthetics, when used, are generally administered intravenously in the emergency department, although inhaled general anesthetics are sometimes used. Usual regimens include some combination of narcotic analgesics and barbiturate or benzodiazepine sedatives. More recently, the use of intraarticular lidocaine has been advocated as a safe and effective analgesic for emergency department usage with few complications.9,1° Whether or not prereduction radiographs were taken, postreduction radiographs should be obtained both to document proper relocation of the humerus in the glenoid fossa, and to reassess for any associated fractures.
PATHOLOGY There is a range of pathology found in anteriorly dislocated shoulders. In some cases of atraumatic dislocations, little or no pathology may be present. Interstitial stretching and tearing of the anterior joint capsule can occur, but more commonly, especially in younger patients, detachment of the capsulolabral (IGHL-labral) complex from the anterior glenoid rim occurs, the classic Bankart lesion. 11 Capsular detachment at the humeral insertion is reported more often in older patients. Rotator cuff tears can occur in older individuals, but are relatively rare in younger patients. There exists some controversy about what the "essential" lesion is that allows anterior dislocation of the humeral head. Recent arthroscopic series implicate the Bankart lesion as being responsible. Matsen and Thomas 12 classified patients with anterior dislocations into 2 groups. Those with traumatic dislocations were represented by the acronym TUBS, standing for Traumatic, Unidirectional (ie, purely anterior), Bankart lesion present, Surgical treatment often necessary.
DENNIS Y. WEN • SHOULDER DISLOCATIONS
The second group was an atraumatic group with the acronym AMBRI, standing for Atraumatic, Multidirectional (ie, instability in some combination of anterior, posterior, or inferior directions), Bilateral (ie, these patients often exhibit generalized ligamentous laxity), Rehabilitative treatment is preferred, Inferior capsular shift as the preferred surgical operation for those few who do need operative treatment. They found that in 63 traumatic dislocations, 97% had the presence of a Bankart lesion. Similarly, Norlin 13 found that 100% of 24 mostly young patients (median age, 22 years) with first-time anterior dislocations had Bankart lesions. Baker et a114 reported their arthroscopic findings in 45 patients under the age of 30 after initial anterior dislocations. Sixty-two percent had complete capsulolabral detachments (ie, Bankart lesions) from the anterior glenoid and all of these shoulders were unstable on examination under anesthesia. Another 24% had partial capsulolabral detachments with varying degrees of instability under anesthesia. The other 13% were found to have capsular injuries without labral detachment; these were all stable under anesthesia. They concluded that arthroscopy may be useful in determining the intraarticular pathology, and therefore predicting chances of recurrence. A more recent arthroscopic series by Taylor and Arciero 15 lends further support that the Bankart lesion may very well be the "essential" lesion. The results were part of a prospective study at the United States Military Academy where subjects with first-time traumatic anterior dislocations were allowed to choose between conservative management with sling immobilization followed by rehabilitation, or arthroscopic Bankart repair. All patients were age 24 years or younger. The results reported were for the 63 subjects in the arthroscopy arm of the study. They found that 97% of these subjects had Bankart lesions without evidence of intracapsular injury. Only one subject had an interstitial capsular tear. No rotator cuff tears were found. They concluded that in a young patient population, the Bankart lesion appeared to be the primary pathological lesion, and that this lesion was likely to be strongly associated with future recurrent dislocations. In contrast to these arthroscopic studies, 2 recent cadaveric studies lead to different conclusions regarding the essential lesion. Bigliani et all6 stretched isolated bone-IGHLbone specimens to failure. They found that the IGHLcapsule complex stretched significantly before failure and that, therefore, significant capsular injury was probably involved with anterior dislocations in addition to capsular detachment. Speer et a117 created Bankart lesions in cadaveric specimens and found that this resulted in only minimalty increased anterior translations of the humeral head. Their conclusion was that the capsulolabral detachment alone was not enough to allow anterior dislocation, and that stretching or elongation of the IGHL-capsular structure must also occur. Reeves 18 reported a cadaveric study that consisted of loading the glenohumeral joint to determine the weakest points. They found that the weakest point in young cadavers was at the glenoid labrat attachment, and the weakest points in older cadavers were the capsule itself and the subscapularis tendon. The pathology found in older patients appears to be quite
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different from that in younger patients. Hawkins et a119noted physical examination findings consistent with rotator cuff tear in 35 of 39 patients over the age of 40 years. Most of these tears were confirmed arthrographically. Similarly, Neviaser et al20 found rotator cuff tears to be a common complication of anterior dislocation in patients over age 40. No Bankart lesions were found, and they postulated that tears of the subscapularis and the anterior capsule from the lesser tuberosity was a frequent cause of recurrent instability in this age group. Although the issue is not totally resolved, most authorities believe that the capsulolabral detachment from the anterior glenoid rim is the primary pathological lesion in young active patients with traumatic dislocations. It is believed that this Bankart lesion is what predisposes to the high redislocation rate in younger patients, perhaps because of its poor spontaneous healing potential. In older individuals there may be a greater component of interstitial capsular tearing and stretching, with capsulolabral detachments occurring rarely. The rotator cuff tears found in older patients, although a potential cause of continued pain and disability, are not necessarily a cause of recurrent instability. The arthroscopic studies reported have been performed predominately on younger patients. In contrast, most cadaveric studies have used older individuals: age range of 56 to 87 years in Bigliani et al, 16 and age range of 56 to 85 years in Speer et al. 17Even in young patients, interstitial capsular injury likely exists, but detecting these injuries arthroscopically may be difficult or impossible.
POSTREDUCTION MANAGEMENT The traditional treatment of anterior glenohumeral dislocations after successful closed reduction and assuming no major associated injuries or complications, generally consists of some form of immobilization. This immobilization may take the form of a sling, a sling and swathe, or any of several commercially available immobilizers. The recommended duration of immobilization varies widely, but generally falls in the range of 3 to 6 weeks, depending on age of patient, first-time versus recurrence, traumatic versus atraumatic, and associated injuries. Immobilization theoretically allows the pathological lesions to heal, and the injured anterior tissues to "scar" in order to provide some resistance to excessive external rotation, and thereby prevent redislocations. Postimmobilization rehabilitation to restore motion and strength is also often recommended. The major long-term sequela after traumatic anterior shoulder dislocation is recurrent instability, ie, redislocation or subluxation. Other long-term sequelae include persistent pain, weakness, decreased range of motion, and glenohumeral degenerative arthritis. The long-term sequelae, with the exception of recurrence, are generally uncommon and generally not severe. Several factors have been implicated to contribute to the natural history in terms of redislocation, including age at time of first dislocation, level of activity, traumatic versus atraumatic (ie, TUBS versus AMBRI), duration of immobilization, postimmobilization rehabilitation, and presence of a Hills-Sachs lesion. Although the traditional treatment of immobilization with or without postimmobilization rehabilitation may effectively decrease
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the recurrence rate in older individuals, this treatment method does little to alter the high incidence of redislocation in younger patients. In 1950, McLanghlin and Cavallaro 21 reported a case series of 101 patients with shoulder dislocations. The recurrence rates for patients under age 20 was 90%, for ages 20 to 40 it was 60%, and for patients over 40 it was 10%. These results were confirmed in the large case series presented by Rowe and Sakellarides, first in 1956, 22 and then a continuation in 1961.23 Their retrospective analysis of 324 first-time dislocations showed that age at the time of initial dislocation was the most important factor relating to the risk of recurrence. Ninety-four percent of patients under age 20 had recurrences, 79% in ages 21 to 30, 50% in ages 31 to 40, and 14% in patients over 40. They found that immobilization, postreduction exercises, and humeral head defects were not clearly related to the rate of recurrence. Kiviluoto et a124 recommended 1 week of immobilization for patients older than 30 years, due to their low inherent redislocation rate. For patients younger than 30 years, those immobilized for 3 weeks had lower redislocation rates than those immobilized for only 1 week, 22% v 56%. In contrast, Henry and Genung 25 found no effect of immobilization or length of immobilization on recurrence rates in young athletic patients. Simonet and Cofield 26 in 1984 reported a retrospective series of 116 first-time anterior dislocations and found a lower rate of recurrence than the previous reports. After a mean 4.63 years of follow-up, recurrence rates were 66% for under age 20, 40% for ages 20 to 40, and 0% for those over 40. However, 82% of patients with dislocations occurring during athletic activity had recurrences, compared with 30% of patients with dislocations not occurring during athletic activity. In the only large-scale prospective study on first-time anterior dislocations, Hovelius et a127 recently reported on their 10-year follow-up for the cohort. Patients under the age of 40 were randomly assigned to 1 of 2 treatment groups: immobilization for 3 to 4 weeks versus sling until comfortable. The results indicated that immobilization made no significant difference in rate of recurrence, and that age still stood as the primary prognostic factor. The strict immobilization group had recurrence rates of 70% in age 12 to 22, 63% in ages 23 to 29, and 21% in ages 30 to 40. The sling only until comfortable group had recurrence rates of 63%, 53%, and 29%, respectively, for the same age categories. Shoulder rehabilitative exercises are often prescribed after anterior shoulder dislocations, generally after some period of immobilization. As mentioned, Rowe and Sakellarides 23 did not find exercises to be helpful in preventing recurrences. Similarly, Simonet and Cofield's 26 study could document no significant benefit from rehabilitative exercises. More recently, Wheeler et al28 and Arciero et a129 found recurrence rates of 92% and 80% in young active patients despite an exercise program. Contrary to these studies citing no benefit from postreduction rehabilitation, Aronen and Regan 3° showed a recurrence rate of only 25% of 20 young active patients after a strengthening program, with a follow-up period averaging 35.8 months. Yoneda et al, 31 in abstract form, reported a recurrence rate of 17.3% in
104 young patients after a postimmobilization exercise program. In a related study concerning exercises, Burkhead and Rockwood 32 reported on a series of 140 patients with subluxations, but without dislocations, who were treated with a supervised rehabilitative program. They found that only 16% of patients with a traumatic cause of subluxation had satisfactory response to the exercise program, compared with 80% with atraumatic subluxations. They concluded that it was helpful to classify patients as to the etiology of their instability, similar to the TUBS versus AMBRI classification of Thomas and Matsen, 9 to optimize treatment. To summarize the data concerning immobilization with or without postimmobilization rehabilitation, it appears that neither immobilization nor rehabilitation has a significant effect on the high rate of recurrent dislocation in young individuals with traumatic dislocations. Their youth, and probably therefore their higher level of physical activity, athletic and otherwise, makes them prone to redislocation, despite postreduction immobilization and/or rehabilitation. The data for older individuals is less clear. Their redislocation rate is lower at baseline, and it may be that immobilization is helpful. Most authorities advise against prolonged (over 3 to 4 weeks) immobilization in older patients (over age 50) because of the risks of iatrogenic adhesive capsulitis. Rehabilitative exercises do appear to be helpful in patients with atraumatic dislocations who may have multidirectional instability or generalized ligamentous laxity. Based on the available and somewhat conflicting data, immobilization is recommended as long as necessary to treat symptoms, and may be discontinued when symptoms allow. Despite these data suggesting lack of efficacy of immobilization and rehabilitation in young active patients with traumatic anterior dislocations, this very treatment remains the traditional standard of care. One possible reason that this remains the case is that, until recently, no effective alternative with acceptable complications has been shown to be clearly superior. Another reason may be that, although the traditional treatment may not prevent recurrences, it may be effective in treating the pain and other potential complications of shoulder dislocations, such as loss of range of motion or loss of strength, although limited data are available on these issues.
SURGICALTREATMENTS Over 250 operative techniques have been described for the treatment of anterior instability. These can be classified into four basic groups33: (1) procedures that limit external rotation by tightening the anterior structures such as the Magnuson-Stack 34 and Putti-Platt 35 procedures, (2) bony blocks to prevent anterior humeral head translation such as the Bristow procedure, ~6 (3) osteotomies to either the glenoid or the humerus to change the rotational alignment, and (4) anatomic reconstruction of the disrupted anteroinferior capsulolabral complex, such as the Bankart procedures Because of its success in preventing recurrences (generally 95% success rates with less than 5% recurrences 2) the open Bankart repair and its modifications are generally considered the gold standard procedure. The procedure involves repairing the "essential lesion."
DENNIS Y. WEN • SHOULDER DISLOCATIONS
The traditional indications for surgical procedures have been subject to debate, but generally include recurrent instability, pain, or activity limitation, usually after a trial of nonsurgical treatment. Because of the recognized high incidence of recurrent instability after traumatic anterior dislocation, especially in young patients, some authorities have advocated earlier surgical intervention to prevent these recurrences. However, potential surgical complications, along with potential loss of range-of-motion, especially external rotation, have limited the role of open operative procedures. With the development and advances in arthroscopic surgical techniques for treating shoulder pathology, many arthroscopists now advocate arthroscopic Bankart repairs for treating shoulder instability. Arthroscopic surgery has many potential advantages over comparable open procedures. Arthroscopy is relatively atraumatic, does not involve splitting the subcapularis, and can often be performed as an outpatient procedure. The quicker recovery from surgery allows earlier return to work and other activities. However, higher failure rates compared with open procedures have been noted in arthroscopic series, with redislocation rates between 14.7% and 49% .38-44 In a retrospective comparison of arthroscopic versus open reconstruction of Bankart lesions in patients with at least 3 episodes of dislocation or subluxation, Guanche et a145found recurrent instability in 5 of 15 patients after arthroscopic stabilization, compared with 1 of 12 patients after open procedures. They concluded that open stabilization should remain the procedure of choice. Geiger et a146prospectively offered 34 patients the choice between open versus arthroscopic Bankart repair. All patients had recurrent instability and had failed physical therapy. After an average follow-up of 34 months, the 18 patients in the open repair group had 83% good to excellent results, with no recurrent dislocations. In contrast, in the 16 patients in the arthroscopic repair group, only 50% had good to excellent results, with 3 recurrent dislocations and 4 recurrent subluxations. In contrast to the previously mentioned investigators reporting inferior results of arthroscopic Bankart procedures, Wheeler et a128 reported a series of 9 young patients who had arthroscopy after initial anterior dislocations, with Bankart lesions in all 9. The recurrence rate was only 22% in this group, compared with 92% (35 of 38) in patients treated nonoperatively. This same group of investigators (Arciero et a129) from the United States Military Academy reported the results of a nonrandomized prospective study. Thirty-six young (ages 18 to 24 years), active cadet-athletes who suffered traumatic first-time anterior shoulder dislocations were offered the choice between nonoperative treatment with immobilization for 4 weeks followed by supervised rehabilitation, or arthroscopic Bankart repair followed by identical immobilization and rehabilitation. After an average follow-up period of 23 months, 80% (12 of 15) of those treated nonoperatively developed recurrent instability. In contrast, after an average of 32 months of follow-up in the arthroscopy group, only 14% (3 of 21) developed recurrent instability. All 21 arthroscopic procedures were performed within 10 days of the injury, and all 21 had confirmed Bankart lesions which were repaired. Similarly, Uribe and Hechtman 47 reported 11 of 11 good or excellent results in a prospective study of young athletes
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(average age, 20 years) after first-time traumatic anterior dislocations treated with arthroscopic surgery. All procedures were performed within 36 days of the injury. After an average 24.5 months of follow-up, only 1 patient had a recurrent subluxation episode without dislocation. The success of Arciero et al, 29 and Uribe and Hechtman, 47 with arthroscopic stabilization with minimal postoperative morbidity represents strong evidence that perhaps arthroscopy should be considered early in the treatment of anterior shoulder dislocations in certain populations. In these studies, all were young (less than 26 years), all were active, all had first-time dislocations without previous instability, and all dislocations had resulted from trauma. Additionally, all arthroscopies were performed early after dislocation, and Bankart lesions were clearly evident in all the surgical patients. In previous series of arthroscopically treated patients, 38-44as well as comparisons between open and arthroscopic Bankart repairs, 45,46populations were often mixed in terms of age, activity level, degree of instability (subluxation v dislocation), cause of dislocation/subluxation, number of previous dislocations/subluxations, and time between injury and surgery. Green and Christensen48 reported results from 37 patients with anterior instability treated with arthroscopic repair and correlated these results to the severity of the labral lesion found at arthroscopy. After an average follow-up of 37 months, only 1 failure was noted among 22 patients with simple detachment of the anteroinferior capsulolabral complex from the glenoid rim (ie, Bankart lesion). However, of the 15 patients in the group with significant degeneration of the capsulolabral complex, there were 13 failures. Most of the patients in the study had had several recurrences of anterior instability, and there was a trend toward more severe labral pathology with more recurrences. Technical differences between the various arthroscopic reports deserves brief mention. Stabilization techniques in the earlier reports were generally either by a staple technique or by transglenoid sutures. More recently, bioabsorbable tacks have become more popular. Capsular tensioning to reduce redundancy and laxity is technically difficult arthroscopically, and the degree to which this was performed also varied from study to study. Recent reports specifically studying technical advances by Resch et a149 and by Marcacci et al 5° have demonstrated excellent results with low recurrence rates even among patients with multiple preoperative recurrences. Most of the reports on Bankart repairs, whether open or arthroscopic, either exclude patients with multidirectional instability or have found poor surgical results on these individuals. Capsular shift procedures are more appropriate if multidirectional instability is present despite nonoperative treatment. To summarize the recent literature concerning surgical treatment of anterior shoulder dislocations, open Bankart repairs seem superior compared with arthroscopic procedures overall for reducing recurrent episodes of instability. However, because of the invasiveness and potential morbidy associated with open procedures, these operations are generally reserved for those with recurring instability symptoms after nonoperative treatment. Most of the reports of inferior results for arthroscopic Bankart repairs have included patients with chronic recurring instability. Age ranges have
AMERICAN JOURNAL OF EMERGENCY MEDICINE • Volume 17, Number 4 • July 1999
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also been variable. In contrast, studies by Arciero et a129 as well as other investigators on populations with young, acute first-time dislocators have had favorable results with early arthroscopic repair. Appropriate patient selection appears to be the critical factor. As discussed earlier, the pathology involved in anterior glenohumeral dislocation may differ between different age groups. Younger individuals with traumatic anterior dislocations for the most part have anteroinferior capsulolabral (IGHL-labral) avulsions from the glenoid rim, ie, Bankart lesions. Although controversial, these patients usually seem to have minimal or no interstitial capsular injury. In contrast, older patients may have more intracapsular stretching and tearing. Capsulolabral detachments may not spontaneously heal, or may heal very poorly. This, along with the generally overall higher level of activity in younger populations, may explain their high redislocation rates. Based on the likely pathology present, the young patient with a pure Bankart lesion and no intracapsular tearing or stretching would appear to be the ideal candidate for an arthroscopic Bankart repair. Patients who have chronic recurring instability episodes, even though young, are more likely to have concommitant intracapsular laxity with attenuation and degeneration of the IGHL-labral complex in addition to the Bankart lesion, possibly explaining the inferior arthroscopic results in treatment of recurrent instability. Time between injury and surgery may also be an important factor, although this has not been well studied. It may well be that the acutely dislocated shoulder with a fresh hemarthrosis and associated inflammatory mediators provides the optimal environment for wound healing following a Bankart repair.
SUMMARYAND RECOMMENDATIONS (1) Shoulder dislocations occur commonly because of the inherent instability of the glenohumeral joint. The majority occur anteriorly and are traumatic in origin. (2) Diagnosis is generally straightforward, but radiographs at orthogonal angles should be obtained to document the direction of dislocation and to diagnose associated injuries. (3) Physical examination should also determine if multidirectional instability may be present. (4) Multiple techniques of reduction exist and most have documented high success rates. The method chosen, as well as the decision to use analgesia/ anesthesia, may need to be individualized. (5) The traditional postreduction treatment involves some sort of immobilization for a period of 3 to 6 weeks, possibly followed by physical therapy. Older patients (over age 50 years) should generally be immobilized toward the shorter duration range to prevent the occurrance of adhesive capsulitis. (6) Young age at the time of initial dislocation is the most important factor predicting future recurrences. In these patients, especially active ones,
the traditional method of treatment is ineffective for preventing redislocations, and immobilizations is recommended mainly for treatment of symptoms. (7) Surgical treatments are generally reserved for patients who have failed the nonsurgical treatments of immobilization and/or physical therapy, and have had recurrent episodes of instability. The open Bankart repair remains the gold standard procedure and is currently believed to be superior to arthroscopic Bankart repair in this population of patients. (8) Although controversial and considered by some to be experimental, there is a growing body of literature supporting earlier arthroscopic Bankart repairs in certain well-defined populations. The ideal candidate appears to be a young, active, a first-time dislocator with a traumatic etiology of dislocation, anterior in direction with no evidence of multidirectional instability, and acute in duration before recurrences have occurred. These individuals should be referred promptly to an arthroscopist for consideration of an early arthroscopic Bankart repair. This procedure in the properly selected patient greatly reduces the redislocation rate with minimal surgical morbidity. (9) Patients who have had previous dislocations, as well as those with multidirectional instability, should be treated with traditional methods. Many will need future surgery for recurrences, but should initially be treated with nonoperative means. (10) As technical advances are further developed and experience is gained among arthroscopists, indications and patient populations for early arthroscopic stabilization will likely expand in the near future, possibly to include older patients and those with recurrences.
CONCLUSION Newer advances in the treatment of anterior shoulder dislocations have received increasing attention recently. It has long been apparent that recurrence rates are exceedingly high among young, athletic individuals, despite optimal nonoperative treatment. With the more widespread use of the arthroscope, increasing evidence exists implicating anteroinferior capsulolabral avulsions (Bankart lesions) as the "essential lesion" in young patients, predisposing to recurrent instability. Recent studies have shown that early arthroscopic Bankart repairs in these young individuals can markedly decrease recurrence rates with minimal surgical morbidity. Referral for consideration of early arthroscopic repair should be made in a timely manner for appropriate candidates. If recurrent dislocation is allowed before referral, the opportunity to successfully repair the lesion arthroscopically may be lost.
DENNIS Y. WEN • SHOULDER DISLOCATIONS
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