The Operative Treatment of Scapula Fractures: An Analysis of 10,097 Patients

Abstract

Background

The indications for operative treatment of scapula fractures have been debated over the past decade. Our purpose was to determine 1) the incidence and trends in the operative treatment of scapula fractures, 2) the incidence of conversion from operative fixation to total or hemi-shoulder arthroplasty (THSA) and 3) rates of associated injuries in scapula fractures. We hypothesized that the operative treatment of scapula fractures is increasing over time and that scapula fractures treated with open reduction and internal fixation (ORIF) would have increased risk for conversion to THSA.

Methods

The Humana Inc. administrative claims database was queried from 2008 to 2015. Patients with any scapular fracture, ORIF of scapula fracture, total or hemi-shoulder arthroplasty, and associated injuries were identified by ICD-9 and CPT codes. Analysis was performed for 1) all patients with a scapula fracture undergoing operative fixation (i.e. ORIF and THSA), 2) all scapular fractures treated with ORIF with subsequent conversion to ipsilateral THSA, and 3) all associated injuries.

Results

There were 10,097 scapula fractures (28.4% glenoid, 48% female). 60% occurred in patients 65 years and older. There were 198 (1.96%) fractures (70% glenoid) treated with ORIF. There were 287 (2.84%) fractures (45% glenoid) treated with THSA (76% total shoulder). The rate of ORIF of scapular fractures did not significantly increase (RR=0.87, p=0.58). There was a significant increase in THSA as primary treatment of scapula fractures in 2015 compared to 2007 (RR=0.43, p=0.0016). Conversion from ORIF to THSA was 12.6% (25/198). Scapula fractures treated with ORIF were at significant risk for conversion to THSA (RR=4.77, p<0.0001). Associated injuries occurred in nearly 50% of scapula fractures—other fractures, lung contusion and pneumothorax/hemothorax ranking the highest, accounting for 37%, 14.5% and 8.3% of all associated injuries, respectively.

Conclusion

The incidence of operative treatment of scapula fractures was 1.96% and 2.84% for ORIF and THSA, respectively. Scapular fractures previously treated with ORIF were at significant risk for conversion to THSA. Although ORIF in scapular fractures did not significantly increase over time, both THSA and overall (ORIF+THSA) operative treatment of scapula fractures increased significantly.

Level of Evidence: IV

Introduction

Scapula fractures are relatively uncommon, accounting for approximately 0.5% of all fractures.^1,2 They typically result from high energy trauma, and as such, are associated with multiple concomitant injuries.² The majority of scapula fractures are extra-articular, with fractures of the body or glenoid neck accounting for 62% to 98% of all cases.² Historically, management of these fractures has been conservative, consisting of benign neglect and motion as tolerated.³

The indications for surgical management of scapula fractures is not well established. There are no clear evidence-based guidelines, and the decision to operate remains largely based on expert opinion.³ It is generally accepted that fractures with glenoid involvement or highly displaced extra-articular fractures may warrant surgical intervention.^2-4 Recent studies report that intraarticular fractures are being treated operatively in up to 80% of cases, while isolated body fractures and glenoid neck fractures are being treated non-operatively in up to 99% and 83% of cases, respectively.⁵

In addition, recent studies have shown predictably good functional outcomes of both intra and extra-articular scapular fractures treated with operative fixation. In 2016, Schroder et al. showed good outcomes and low complication rates in patients treated surgically for extra-articular glenoid neck and scapular body fractures.² Similarly, Anavian et al. showed restoration of function and satisfactory muscular recover in patients treated surgically for complex and displaced intra-articular glenoid fractures.⁴

Due to the growing body of evidence of satisfactory post-operative outcomes in patients who sustain scapula fractures, along with improved technology and a higher number of patients surviving high energy trauma, a continued interest in the incidence and operative trends in management of scapula fracture patients exists.³ The purpose of this study is to 1) determine the incidence of operative fixation of scapula fractures and analyze recent trends in management, 2) determine the incidence of conversion from operative fixation to total or hemi-shoulder arthroplasty following scapula fracture, and 3) determine the rates of associated injuries.

Methods

The Pearldiver Research Program (www.pearldiverinc.com; PearlDiver Inc., West Conshohocken, PA) was utilized to query the Humana Inc. administrative claims database from 2007 to the second quarter of 2015 for patients with scapula fractures. A cutoff at the second quarter of 2015 was chosen because after this time period administrative claims transitioned to International Classification of Disease, 10th Revision coding system. This dataset rep- resents approximately 30 million lives and includes both privately insured patients and those who have purchased their Medicare/Medicaid Advantage plans through Humana Inc. All data within this database are Health Insurance Portability and Accountability Act compliant and this study was deemed exempt from institutional review board approval by our institution’s Human Subjects Office.

Patients with scapula fractures were identified using International Classification of Disease, 9th Revision (ICD-9) coding system and Current Procedural Terminology (CPT) codes. These patients were sub-grouped by specific anatomic location (glenoid, acromion, coracoid, and/or body). Patients undergoing surgical intervention for scapula fracture, either via open reduction internal fixation (ORIF) or total or hemi shoulder arthroplasty (THSA), were also identified using ICD-9 and CPT codes. The rates of operative intervention for scapula fractures were trended through the years of the dataset. These same search methods were utilized to identify scapula fracture patients with additional injuries at the time of presentation. The rates of associated injuries were calculated to identify those that most commonly occur in the setting of scapula fractures. Subgroup analysis was performed on patients initially receiving ORIF as primary treatment for scapula fracture who then subsequently underwent ipsilateral THSA. This cohort was compared to scapula fracture patients initially treated non-operatively who subsequently underwent THSA.

Data analysis was conducted using relative risk (RR) with corresponding 95% confidence interval (95% CI) to evaluate the annual trends in the operative management of scapula fractures. Chi-squared testing and RR with corresponding 95% CI was conducted for the subgroup analysis comparing THSA rates in scapula fracture patients treated initially with ORIF vs. non-operative management.

Results

10,097 scapula fractures were identified within the time interval assessed. Of those, 1517 (15.0%) involved the acromion, 1985 (19.7%) involved the body, 2869 (28.4%) involved the glenoid, and 676 (6.7%) involved the coracoid process. 4882 (48.4%) of cases occurred in females. 6648 (65.8%) of cases occurred in individuals aged 65 years or older.

198 scapula fractures were treated with ORIF. Incidence of operative fixation following scapula fracture was 1.96%. Of those treated with ORIF, 137 (69.2%) involved the glenoid. In 2007, 12/669 (1.8%) scapula fractures were treated with ORIF; in 2015, 32/1471 (2.2%). The increase in incidence of ORIF for scapula fracture from 2007 to 2015 was not statistically significant (p=0.54, RR=1.06). See Table 1.

Table 1.

Operative Treatment of Scapular Fractures

There were 287 scapula fractures treated with THSA. Incidence of THSA following scapula fracture was 2.84%. 128 (44.6%) scapula fractures treated initially with THSA involved the glenoid. In 2007, 12/669 (1.8%) of scapula fractures were treated with THSA; in 2015, 76/1427 (5.3%) of scapula fractures were treated with THSA. There was a significant increase in incidence of THSA as initial management for scapula fracture from 2007 to 2015 (p=.0001, RR=1.27). In addition, rates of total operative management for scapula fractures (ORIF plus THSA) increased from 2007 to 2015. In 2007, 24/669 (3.6%) of cases were treated operatively, versus 108/1427 (7.6%) of cases in 2015. This was a significant increase in operative trends over the interval (p=0.0001, RR=1.20). See Table 1.

Of the 198 cases initially treated with ORIF, 25 went on to receive subsequent ipsilateral THSA. The conversion rate from ORIF to THSA for scapula fracture patients was 12.6%. This risk of conversion to THSA following ORIF was significantly higher than patients who did not initially receive ORIF as management for scapula fracture (p=0.0001, RR=4.77).

4907 (48.6%) cases presented with an additional associated injury. The most common associated injury was an additional fracture, seen in 3698 (36.6%) cases. 1467 (14.5%) cases of lung injury, including lung contusion, pneumothorax, and hemothorax, occurred. Shoulder dislocation occurred in 1078 (10.7%) cases. See Table 2.

Table 2.

Associated Injuries

Discussion

Scapula fractures make up approximately 0.5% of all presenting fractures, they are associated with high energy mechanisms and as such, many patients have concomitant injuries.^1,2 Although historically the large majority of these fractures are treated non-operatively, evidence supports good functional outcomes following operative fixation.^2,4

This study assessed the recent trends in the operative management of scapula fractures from 2007 to 2015. Overall, surgical management (ORIF plus THSA) and THSA as primary treatment for these fractures has increased significantly in the time interval studied, while ORIF has not shown significant increase. Patients who undergo ORIF as primary treatment for scapula fractures are at a significantly greater risk of future conversion to THSA, likely due to glenoid involvement and post-traumatic osteoarthritis. Unsurprisingly, nearly 50% of patients presented with other injuries.

There are multiple limitations to this study. First, this study is limited by its retrospective nature. Additionally, fracture severity was unable to be assessed through the database search, providing a potential confounding variable for risk of conversion to THSA following ORIF for scapula fractures. There was also limited demographic information, including medical comorbidities, which may have influenced management strategies for the study population.

Conclusion

The incidence of operative treatment of scapula fractures was 1.96% and 2.84% for ORIF and total or hemi-shoulder arthroplasty, respectively. Scapular fractures previously treated with ORIF were at significant risk for conversion to total or hemi-shoulder arthroplasty. Although ORIF in scapular fractures did not significantly increase over time, both THSA and overall (ORIF+THSA) operative treatment of scapula fractures increased significantly as hypothesized—indicating an increase in the operative treatment of scapula fractures in 2015 compared to 2007.