Abstract
Background:
Rarely, closed reduction cannot be achieved in patients with acute shoulder dislocation, necessitating open management. A paucity of literature exists regarding these cases.
Purpose:
To perform a systematic review on the mechanism, management, and outcome data of acute irreducible shoulder dislocations.
Study Design:
Systematic review; Level of evidence, 4.
Methods:
A systematic review of the literature was performed using the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE between 2000 and 2020. Inclusion criteria were as follows: human participants, acute irreducible shoulder dislocation requiring open management, English language, and publication within the past 20 years. We excluded basic science articles, technique articles, reviews, editorials, and studies of chronic shoulder dislocations or dislocations with ipsilateral humeral shaft fractures.
Results:
Twelve articles fit the inclusion criteria and were considered for review. All studies were single case reports (level 4 evidence). Ten of the 12 studies were of male patients. The direction of dislocation included 7 anterior/anteroinferior, 2 posterior, 1 inferior, 1 bilateral inferior, and 1 superolateral. Most dislocations were irreducible owing to a mechanical block to reduction. The most common type of block was an incarcerated long head of the biceps tendon, followed by interposition of 1 of the rotator cuff tendons. The axillary and musculocutaneous nerves, displaced fracture fragments, and Hill-Sachs and bony Bankart lesions were other causes of blocks to reduction. Eleven patients were treated with open surgery, while 1 patient was treated arthroscopically. Procedures performed were dependent on concurrent pathology. Final follow-up ranged from 6 weeks to 2 years, with no repeat dislocation episodes reported. Complications after open reduction included 1 case of brachial plexopathy (posterior cord) and 1 case of musculocutaneous nerve palsy.
Conclusion:
There is a paucity of literature on the management of irreducible acute shoulder dislocations. The most common irreducible dislocation found in this systematic review was anterior with a mechanical block attributed to interposition of the long head of the biceps tendon. When patients were treated with an open or arthroscopic procedure, recurrence was low, with none reporting recurrent dislocation in limited follow-up.
The glenohumeral joint of the shoulder is the most commonly dislocated joint, with an overall US incidence of 23.9 dislocations per 100,000 person-years. 31 Shoulder dislocations are more than twice as common in male than female patients and occur most often in the third decade of life. 31 Recent literature has suggested good results with operative treatment of first-time shoulder dislocations. 16,23 However, acute shoulder dislocations are usually treated urgently and initially with closed reduction and physical therapy.
The majority of shoulder dislocations are anterior (95%) and can be reduced by using closed manipulation techniques with local injection or conscious sedation. 17 Similar success rates and outcomes have been reported between local injection and sedation. 19 In the acute setting, several reduction techniques have been described with similar success rates as high as 97.8%. 1,11 The majority of failed initial reductions are subsequently successful when a different technique is used. 11 Repeated attempts at closed reduction rarely fail, requiring closed reduction under general anesthesia or possibly open reduction. Currently, the incidence, risk factors, and causes of acute irreducible dislocations are not well defined. Additionally, no comprehensive overview for the treatment of irreducible shoulder dislocations exists.
The purpose of this study was to review the recent literature for cases of irreducible shoulder dislocations, focusing on associated injuries, blocks to reduction, and operative treatment strategies. The secondary aims were to examine the redislocation rate and patient outcomes after the index procedure.
Methods
Article Selection
This study was conducted in accordance with the 2009 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. 20 A systematic review of the literature regarding diagnosis, risk factors, management, and outcomes of irreducible acute shoulder dislocations was performed using the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE. The queries were performed in April 2020.
The literature search strategy included the following criteria: (“irreducible” [All Fields]) AND (“shoulder” [All Fields] OR “glenohumeral” [All Fields]). Inclusion criteria were as follows: human participants, acute irreducible shoulder dislocations requiring open management, English language, and studies between 2000 and 2020. Exclusion criteria consisted of basic science articles, technique articles, reviews, editorials, studies of chronic shoulder dislocations, studies of dislocations with ipsilateral humeral shaft fractures, and studies published >20 years before the query.
Three investigators (D.J.L., J.E.G., and E.J.N.) reviewed the abstracts from all identified articles and applied the inclusion and exclusion criteria independently. When an abstract did not provide enough information to determine inclusion, the full-text article was reviewed. Any discrepancies were reconciled via consensus among the 3 reviewers before final article inclusion.
Data Collection
The 3 investigators reviewed the full text of the qualified articles. Each article was assigned a level of evidence according to the classification by Wright et al. 29 Patient data were collected: characteristics, injury characteristics (direction of dislocation, associated fractures), attempts at closed reduction, preoperative imaging, surgical technique, blocks to reduction, follow-up, objective and subjective outcomes, and complications (including redislocations). Data were manually recorded using a custom Microsoft Excel spreadsheet by each of the investigators.
Risk of Bias
Studies classified as having an evidence level of 3, 4, or 5 can be affected by selection and performance bias because of the lack of randomization or prospective comparative control groups. Therefore, the 3 investigators extracted the data individually and then analyzed them for accuracy and consistency. Discrepancies were resolved via consensus and the majority with the help of additional authors (S.S. and K.H.S.) for reconciliation.
Results
Study Selection
The search query identified 58 articles from the PubMed/MEDLINE databases, 0 articles from the Cochrane Central Register of Controlled Trials, and 0 articles from the Cochrane Database of Systematic Reviews. There were no duplicate articles. After screening based on the abstract, 17 articles were reviewed for inclusion. After review, 12 articles fit our inclusion criteria (Figure 1). 5 –10,15,18,22,24,25,30 All studies were single case reports (level 4 evidence).
PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart demonstrating the selection of the studies based on the given search criteria.
Patient Characteristics
All studies were retrospective and included 13 shoulders in 12 patients with an age range of 34 to 87 years. Follow-up ranged from 6 weeks to 2 years. Two studies 6,7 did not report time of follow-up. Six patients had dislocations on the right; 4, on the left; and 1, bilaterally. One study 5 did not indicate the affected side. Seven dislocations were anterior/anteroinferior; 3, inferior; 2, posterior; and 1, superolateral. Mechanisms of injury consisted of 7 falls, 2 motorcycle or motor vehicle collisions, and 2 crush injuries. One mechanism was unknown, and another was not reported.Data are summarized in Table 1.
Patient Descriptive Information of the 12 Included Studies a
a All studies were single-patient case reports (level 4 evidence). NR, not reported.
b The same shoulder had been dislocated 18 months earlier, but the first dislocation was reduced easily with closed reduction.
Injury Characteristics
Five of the 13 shoulders had an associated injury of a Hill-Sachs lesion. Attempted closed reduction was reported in all 12 studies. In 7 studies, 7,8,10,22,24,25,30 attempts at closed reduction were performed with conscious sedation, and 4 studies 8,10,22,24 included attempts with general anesthesia. Nine patients underwent advanced imaging before operative reduction: 4 had magnetic resonance imaging, and 5 had a computed tomography scan. Injuries and associated lesions are listed in Table 2.
Shoulder Dislocation Injury Characteristics and Concomitant Pathology a
a CT, computed tomography; ED, emergency department; GT, greater tuberosity; H-S, Hill-Sachs; infrasp, infraspinatus; LHBT, long head of the biceps tendon; MRI, magnetic resonance imaging; NR, not reported; OR, operating room; RC, rotator cuff; subscap, subscapularis; suprasp, supraspinatus.
Operative Data
Eleven of 12 patients underwent open reduction, and 1 underwent arthroscopic reduction. In 1 study, 5 the patient initially underwent diagnostic arthroscopy that was converted to an open procedure. The most commonly performed approach was deltopectoral (n = 8), and the most commonly performed procedures in addition to open reduction were biceps tenotomy or tenodesis (n = 7), rotator cuff repair (n = 7), and internal fixation of the greater tuberosity (n = 4). The most common block to reduction was an incarcerated biceps tendon (n = 7). Other blocks to reduction included buttonholing of the humeral head through the joint capsule or deltoid, as well as glenoid impaction in the humeral head. Blocks to reduction are summarized in Table 2. Operative management data are summarized in Table 3.
Operative and Postoperative Management a
a ER, external rotation; IR, internal rotation; LHBT, long head of the biceps tendon; NA, not applicable; NR, not reported; OR, operating room; ORIF, open reduction and internal fixation; PT, physical therapy; ROM, range of motion.
Outcomes
Two studies 22,25 cited validated outcome scores at final follow-up but no preoperative outcome scores. Three studies 8,15,24 reported quantitative range of motion assessments, while 3 studies 9,22,25 reported qualitative assessments. Last, 1 study 10 found limited range of motion in the patient owing to the presence of a humeral head defect. No study reported recurrent instability. Out of the 6 studies 8,9,15,22,24,25 that assessed postoperative range of motion, all reported “full” or gave parameters that fell within functional range of motion.
Complications
Complications occurred in 4 of 12 patients. The most common complication was persistent rotator cuff dysfunction (n = 2). 5,9 Connolly et al 5 reported that although the subscapularis tendon was repaired, the massive rotator cuff tear was irreparable. Similarly, Gudena et al 9 reported a massive rotator cuff tear that could not be repaired. There were 3 nerve palsies at the time of presentation: 1 axillary, 1 radial, and 1 musculocutaneous. 8,9 All resolved spontaneously within 3 to 6 months. Outcome data are summarized in Table 4.
Outcomes and Complications a
a Of note, 10 of 12 studies reported on complications and/or patient-reported outcome data. Abd, abduction; ASES, American Shoulder and Elbow Surgeons; EMG, electromyogram; ER, external rotation; FF, forward flexion; IR, internal rotation; KSS, Korean Shoulder Score; NR, not reported; PROM, patient-reported outcome measure; ROM, range of motion; VAS, visual analog scale.
Discussion
The most important findings of this study are that irreducible shoulder dislocations are infrequently reported and there is little available literature supporting clinical decision making. While relatively uncommon, they carry significant risk to patient recovery if not properly managed. The only available literature dedicated to acute irreducible shoulder dislocations is in the form of individual patient case reports. The paucity of data guiding their management highlights an opportunity to review this condition retrospectively or prospectively in high-volume trauma centers.
Irreducible shoulder dislocations are heterogeneous in presentation and pathology. In the literature, male patients account for approximately 70%, with a fall as the most common mechanism of injury. 27 These findings are reflected in our study, in which 10 of 12 patients were men and the mechanism of injury was a fall in 7 of 12 patients. In our series, high- and low-energy mechanisms of injury were observed. The age range of our patient population was 34-87 years; no reports involving children were found.
The most common direction of shoulder dislocation was anterior (Table 2), which is reflective of all shoulder dislocations. 4,27 The direction of shoulder dislocation, however, was not predictive of the mechanical block to reduction, specifically the long head of the biceps tendon. Multiple anatomic structures may block reduction, including the long head of the biceps, labrum, rotator cuff, and axillary and musculocutaneous nerves, as well as displaced fracture fragments and Hill-Sachs and bony Bankart lesions.In this review, the long head of the biceps was the most common block to reduction, as seen in 7 of the 12 case reports. In addition to soft tissue blocks, mechanical block by the greater tuberosity should be considered. In 2 studies, arthroscopically assisted reduction was attempted. 5,25 If arthroscopically assisted reduction is to be attempted, we recommended careful assessment of the long head of the biceps tendon, greater tuberosity, and anteroinferior joint capsule.
The majority of closed reduction attempts are successful. Therefore, if a validated reduction attempted by an experienced provider fails, an anatomic block should be suspected. In this case, attempting multiple reductions may not be advisable, as they may propagate or lead to iatrogenic proximal humeral fractures. 13,32
After failed closed reduction, all 12 patients in our study underwent surgical intervention. Eight had preoperative computed tomography, magnetic resonance imaging, or both to identify the possible block to reduction and associated pathology. In several cases, however, the intraoperative findings were often more extensive than indicated by the preoperative imaging, which may challenge the value of advanced imaging in these cases. Currently, there are insufficient data to recommend for or against preoperative advanced imaging in the patient with the dislocated shoulder.
The most common surgical option for managing irreducible shoulder dislocations is open reduction of the joint and repair of structures as needed. Arthroscopy may be a valid option as a stand-alone treatment 10 or a diagnostic procedure. 5 Our findings are consistent with prior studies that reported an overall rate between 7% and 32% for rotator cuff tear associated with an anterior shoulder dislocation. 4,14,26 The rate of rotator cuff tear increases substantially with increasing age, 5,26 and repair should be considered at the time of acute operative reduction.
As this review included only case reports, there was substantial variability with reporting of patient outcomes. Three studies reported range of motion measurements, while 3 additional studies indicate “full” functional shoulder range of motion (Table 3). Additionally, just 2 studies cited functional outcome scores. Short- and long-term shoulder dysfunction was, however, noted in the setting of nerve palsies and irreparable rotator cuff tears, respectively. When patients are counseled on the expected outcome of an operatively treated irreducible shoulder dislocation, the pathology specific to the injury should be considered.
There were no cases of recurrent shoulder dislocation. The reason for this may be multifactorial. Namely, with an age range of 34 to 87 years, the patients in this review were older than the typical young and active population. Additionally, all patients in this study required repair of additional structures (e.g. rotator cuff) rather than simple labral repair. Of note, 11 of 12 patients underwent repair via an open approach, which may have played a factor in reducing the incidence of postoperative instability.
Complications were noted in 4 of the 12 patients in this series. These consisted of nerve palsies, rotator cuff dysfunction, and poor range of motion. Axillary, radial, and musculocutaneous nerve palsies were observed, and all resolved over time. This finding is consistent with prior reports, which indicated an overall prevalence of 15.8% to 48% for nerve injuries associated with shoulder dislocations. 2,12,27,28 The axillary nerve is the most common nerve involved, and the risk of nerve injury increases with age. 12 As noted in a review by Avis and Power, 3 most axillary nerve injuries after dislocation resolve spontaneously.
Limitations
There were several limitations to this study. The primary limitation was the small number of patients included, given the rare incidence of irreducible shoulder dislocation. As previously noted, this study included only single-patient case reports. Another limitation was the heterogeneity of patient characteristics, associated injuries, and surgical interventions performed. Certainly, further studies are warranted with adequate follow-up and outcome data. This study searched and analyzed articles in the English language from the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE in the past 20 years. Additional articles may exist if the language and search within other databases (eg, Embase) were expanded. While older articles may exist, this study aimed to examine current management of the dislocated shoulder. Finally, technique articles were excluded, which may have included clinical data. Among technique articles, 1 was identified that included clinical cases of closed shoulder reduction on 4 patients. 21 However, these cases were successful reductions and therefore did not meet inclusion criteria.
Conclusion
A paucity of literature continues to exist on irreducible shoulder dislocations. While we acknowledge that irreducible shoulder dislocation is rare, there was substantial heterogeneity of patient characteristics, clinical course, and postoperative outcomes. Among the studies, the long head of the biceps tendon appears to be the most common block to reduction. When an irreducible dislocation is encountered, we recommend (1) confirming the presence of a block to reduction (eg, soft tissue or bony structure) and (2) considering operative treatment. Better understanding of potential underlying causes of failed closed reduction can help better prepare surgeons for expectations during open reduction and common complications.
Footnotes
Final revision submitted May 2, 2022; accepted June 9, 2022.
One or more of the authors has declared the following potential conflict of interest or source of funding: K.H.S. has received education payments from Smith & Nephew. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.