Abstract
Background
Scapulothoracic dissociation is a rare, limb-, and potentially life-threatening injury in which the scapula and shoulder girdle are violently detached from the thoracic cage. However, the published data on the condition is mainly composed of case reports and single institution samples, which limits the overall generalizability. The aim of the current investigation was consequently to use a multi-institutional data set to characterize the injuries observed in patients with scapulothoracic dissociation along with the treatment strategies selected.
Methods
The 2016-2021 Trauma Quality Improvement Project (TQIP) database was used to identify cases of scapulothoracic dissociation. Patients were grouped based on the presence of neurovascular injury. The statistical significance of differences between the cohorts was determined using the Mann-Whitney U-test, chi-squared test, or Fisher’s exact test, as appropriate.
Results
After applying the inclusion criteria, 74 cases of scapulothoracic dissociation were detected in the TQIP database; of these, 20% (N = 15) also suffered a neurovascular injury. The majority of patients with scapulothoracic dissociation without neurovascular injury could be managed non-operatively, while this was only the case for a minority with neurovascular injury (71.2% vs 26.7%, P = 0.004). Among patients who were ≥60 years old without neurovascular injury (N = 13), 92.3% (N = 12) could be managed non-operatively. Of those with neurovascular injury, 46.7% required internal fixation, 40% underwent vascular surgery, and 20% necessitated upper arm or forequarter amputation.
Conclusion
While scapulothoracic dissociation can be a serious, debilitating injury, most cases don’t result in neurovascular injury and can often be managed non-operatively, particularly among the elderly.
Key Takeaways
• Scapulothoracic dissociation can be a serious, debilitating injury; however, most cases don’t result in neurovascular injury and can often be managed non-operatively, particularly among the elderly. • The presence of neurovascular injury is associated with a significantly increased crude rate of complications in patients with scapulothoracic dissociation.
Introduction
Scapulothoracic dissociation is a rare, limb-, and potentially life-threatening injury, with reported mortality up to 11%, in which the scapula and shoulder girdle are violently detached from the thoracic cage.1-3 In this injury, high-energy traction forces rupture the scapulothoracic musculature and ligaments, allowing the scapula to displace laterally and placing significant tension on the neurovascular bundle.1,2,4 Associated injuries frequently include clavicle fracture, sternoclavicular, or acromioclavicular joint dislocation, with more severe cases resulting in subclavian or axillary artery disruption as well as complete brachial plexus avulsion, yielding an insensate, flail arm, or pulseless extremity.1,2,5 In its most extreme form, scapulothoracic dissociation has been likened to an internal forequarter amputation due to the circumferential detachment of the limb,1,2,4 underscoring the need for prompt recognition and management.
Previous publications on scapulothoracic dissociation consistently report that the majority of injuries result from high-energy mechanisms with clavicle fractures being the most common associated injury.3,6-9 Studies also indicate a high prevalence of neurovascular injuries,3,6-9 with comparable rates of vascular repair, brachial plexus repair, and amputation across most cohorts.6,8,9 However, the published data on the condition is mainly composed of case reports and small case series as well as samples gathered from a single institution,6-8,10 which limits the overall generalizability of the results. The aim of the current investigation was consequently to use the American College of Surgeons Trauma Quality Improvement Program data set to characterize and describe the injuries observed in patients with scapulothoracic dissociation along with the treatment strategies selected.
Methods
All data for this investigation were obtained from the American College of Surgeons Trauma Quality Improvement Program (ACS TQIP) database. Variables retrieved included patient demographics (age, sex, race, and comorbidities); clinical characteristics (injury severity score (ISS), abbreviated injury scale (AIS), injury patterns, and level of intervention); and outcomes (mortality, complications, and and hospital length of stay). Patients could undergo more than one intervention, meaning the management categories are not mutually exclusive. All adult patients (≥18 years old) diagnosed with scapulothoracic dissociation between 2016 and 2021 were included. Scapulothoracic dissociation was defined as scapular dissociation along with ipsilateral acromioclavicular (AC) joint dislocation, clavicle fracture, or sternoclavicular (SC) dislocation. Codes used to define injuries are included in Supplemental Table 1. Exemption from ethical approval was granted by the institutional review board due to the use of anonymized, retrospective data for all analyses. This study was conducted in accordance with the Declaration of Helsinki and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.
Statistical Analysis
Patients were grouped based on the presence of neurovascular injury. Neurovascular injury was defined as injury to the brachial plexus, subclavian artery, or axillary artery. Continuous variables were characterized using medians and interquartile ranges (IQRs) with the statistical significance of differences being evaluated using the Mann-Whitney U-test. Categorical variables were reported as frequencies and percentages, with statistical significance assessed via the chi-squared test or Fisher’s exact test, as appropriate. 95% confidence intervals (CIs) were calculated for a subset of the proportions reported in the text. Outcomes included in-hospital mortality, complications, failure-to-rescue, non-home discharge, hospital length of stay, ICU admission, and mechanical ventilation. Statistical significance was defined as a two-sided P-value less than 0.05. Analyses were performed using the statistical software R 4.2.2 (R Foundation for Statistical Computing, Vienna, Austria) using the tidyverse, cowplot, and viridis packages.
Results
After applying the inclusion criteria, 74 cases of scapulothoracic dissociation were detected in the TQIP database (Figure 1); of these, 20% (N = 15) also suffered a neurovascular injury. Of those with neurovascular injury, 40% (N = 6) were type 2A, 7% (N = 1) were type 2B, and 40% (N = 6) were type 3 or higher, according to the Zelle classification (Table 1).
6
2 patients lacked vascular injury as well as suffered an unknown degree of brachial plexus injury, which made it impossible to classify these patients. Patients with scapulothoracic dissociation and concomitant neurovascular injury tended to be younger than those without neurovascular injury (33 vs 44 years old, P = 0.029) (Figure 2), with the majority being male and Non-Hispanic White in both cohorts. Owing to the generally younger age of this population, most comorbidities were rare. Nevertheless, 22% (95% CI: 13-33%) had hypertension, 24% (95% CI: 15-36%) were smokers, 18% (95% CI: 10-28%) had diabetes mellitus, and 16% (95% CI: 9-27%) had a major psychiatric illness (Table 2). Patient flow chart Zelle Classification of Scapulothoracic Dissociation Age distribution of scapulothoracic dissociation Demographics of Patients With Scapulothoracic Dissociation

Reflecting the high energy required to cause scapulothoracic dissociation, the majority of patients were severely injured (ISS >15: 66.2%, 95% CI: 54-77%, N = 49) and polytraumatized (AIS ≥2 in ≥2 regions: 94.6%, 95% CI: 87-99%, N = 70). Those with concomitant neurovascular injury had more severe injuries to the thorax (Thorax AIS ≥3: 80.0% vs 61.1%, P = 0.001) as well as more severe spine injuries (Spine AIS ≥3: 33.3% vs 6.8%, P = 0.014). Motorcycle accidents were a significantly more frequent mechanism of injury in those with neurovascular involvement than in those without (46.7% vs 16.9%, P = 0.034) (Figure 3, Table 3). Mechanism of injury in scapulothoracic dissociation Clinical Characteristics of Patients With Scapulothoracic Dissociation AIS, abbreviated injury scale; GCS, Glasgow Coma Scale.
The majority of scapulothoracic dissociations occurred on the left side (62.1%, 95% CI: 50-73%, N = 46), with clavicle fracture being the most common osseous injury (81.0%, 95% CI: 70-89%, N = 60), of which most of were displaced (75%, 95% CI: 62-85%, N = 45). Scapula fractures were more common among patients with neurovascular injury (60.0% vs 27.1%, P = 0.036), compared to those without neurovascular injury. Among patients with neurovascular involvement, the axillary artery was injured in 33% (95% CI: 12-62%), the subclavian artery in 53% (95% CI: 27-79%), and the brachial plexus in 60% (95% CI: 32-84%) of cases; 13.3% (95% CI: 2-40%) also sustained a cervical root avulsion. The majority of patients with scapulothoracic dissociation without neurovascular injury could be managed non-operatively, while this was only the case for a minority with neurovascular injury (71.2% vs 26.7%, P = 0.004). Among patients who were ≥60 years old without neurovascular injury (N = 13), 92.3% (95% CI: 64-100%, N = 12) could be managed non-operatively. Of those with neurovascular injury, 46.7% (95% CI: 21-73%) required internal fixation, 40% (95% CI: 16-68%) underwent vascular surgery, and 20% (95% CI: 4-48%) necessitated an upper arm or forequarter amputation (Figure 4, Table 4). Management of scapulothoracic dissociation Injury Pattern and Management of Patients With Scapulothoracic Dissociation
Crude Outcomes in Patients With Scapulothoracic Dissociation
DVT, deep vein thrombosis; ARDS, acute respiratory distress syndrome.
Discussion
Scapulothoracic dissociation was generally a result of high-energy trauma and was consequently often one of several injuries identified in the included patients. A fifth of patients suffered neurovascular injury, of which half later developed a complication during the hospital stay, likely due to the overall more severe injury panorama. While most of these patients required some degree of operative intervention, the majority of patients without neurovascular compromise could instead be managed non-operatively. Regardless, a large proportion of both cohorts were not able to return home immediately upon discharge.
Although numerous case reports on scapulothoracic dissociation have been published in the literature, studies involving larger cohorts remain relatively scarce. The most extensive retrospective cohort study to date was published by Zelle et al 6 in 2004, which analyzed 25 patients treated at a single institution over a 24-year span. In terms of pooled data, Kumar et al’s meta-analysis of case reports offers the broadest patient population, encompassing 81 individuals treated from 1980 to 2019. 7 Additional smaller cohorts include those published by Sen et al (8 patients treated at 1 center between 1997 and 2003), 8 Sampson et al (11 patients treated at 2 centers between 1978 and 1990), 9 and Ebraheim et al 3 (15 patients treated at 4 centers between 1979 and 1985). Across these investigations, patient age distributions align closely with those observed in the present study.3,6-9 Furthermore, motor vehicle collisions and motorcycle accidents remained the predominant mechanisms of injury in all publications.3,6-9 Clavicle fractures represented the most frequent osseous injury,6-8 with comparable rates of internal fixation being reported.3,6,7 For cases involving neurovascular compromise, rates of vascular repair, brachial plexus reconstruction, and amputation were generally consistent across the majority of studies.6,8,9 A notable outlier, however, is the earliest report by Ebraheim et al, 3 which documented elevated rates of vascular repair alongside reduced incidences of brachial plexus intervention and amputation, compared to later publications. On the other hand, rates of neurovascular injury were considerably higher across all studies.3,6-9 This more severe pattern of injury may explain the overall higher mortality observed.3,6,7
The current study identified a significantly greater proportion of patients without neurovascular injury (Zelle type 1) compared to previous publications. This discrepancy may reflect evolving trends in trauma evaluation and management. Most patients in prior studies were treated before 2000,3,6-9 a period when advanced imaging such as computerized tomography (CT) was not as routinely utilized in trauma settings.11-17 In modern practice, CT has become a standard component of trauma assessment,13-17 enabling the detection of injuries, such as type 1 scapulothoracic dissociation, that might have been previously overlooked due to a lack of neurovascular injury. Moreover, the existing literature is largely composed of case reports and small case series,7,8,10 which tend to emphasize more severe or complex cases,18-20 potentially biasing the perceived distribution of injury patterns. Conversely, the current study’s findings, demonstrating similar rates of clavicle, vascular, and brachial plexus repairs in patients with neurovascular injury compared to previous investigations, and the absence of such interventions in patients without neurovascular injury, suggest that the differences observed are unlikely to stem from misclassification or registry error, but rather due to the inclusion of milder cases that were historically underdiagnosed.
This study constitutes the largest retrospective cohort study to date on scapulothoracic dissociation by leveraging the ACS TQIP database. Utilizing a national data set enhances the generalizability of the results, offering a broad view of current clinical practice. Nonetheless, the study has limitations, including its retrospective design, which may introduce selection bias. Additionally, the absence of data pertaining to long-term functional outcomes limits the scope of outcomes that can be evaluated using the current data set. Furthermore, as this is a descriptive analysis, all comparisons are unadjusted, and no confounder adjustments were performed. The sample size, despite being the largest to date, may also still limit the generalizability of the results. Observed associations should therefore be interpreted with caution and no claims can be made regarding causality. Finally, the TQIP data set lacks certain clinical details, such as detailed radiology findings and reasoning behind management decisions, which could provide additional clarity regarding optimal treatment of this rare injury pattern.
Conclusion
While scapulothoracic dissociation can be a serious, debilitating injury, most cases don’t result in neurovascular injury and can often be managed non-operatively, particularly among the elderly. The presence of neurovascular injury is associated with a significantly increased crude rate of complications.
Supplemental Material
Supplemental material - Scapulothoracic Dissociation in Contemporary Practice: Revisiting Clinical Reality Through the Trauma Quality Improvement Program
Supplemental material for Scapulothoracic Dissociation in Contemporary Practice: Revisiting Clinical Reality Through the Trauma Quality Improvement Program by Maximilian P Forssten MD, Ahmad W Ismail MD, PhD, Babak Sarani MD and Shahin Mohseni MD, PhD in The American Surgeon™
Footnotes
Ethical Considerations
Exemption was granted by the George Washington University Institutional Review Board.
Author Contributions
Conception and study design: MF, AI, BS, and SM. Literature review: MF and AI. Data acquisition: BS and SM. Data analysis and interpretation: MF. Drafting of the manuscript: MF and SM. Critical revision: AI, BS, and SM.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data Availability Statement
Data is available upon reasonable request.
Supplemental Material
Supplemental material for this article is available online.
References
Supplementary Material
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