J Shoulder Elbow Surg (2015) 24, 593-600

www.elsevier.com/locate/ymse

Obesity is associated with increased postoperative complications after operative management of proximal humerus fractures Brian C. Werner, MD, Justin W. Griffin, MD, Scott Yang, MD, Stephen F. Brockmeier, MD, F. Winston Gwathmey, MD* Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA Background: Obesity has become a significant public health concern in the United States. The goal of this study was to assess the effect of obesity on postoperative complications after operative management of proximal humerus fractures by use of a national database. Methods: Patients who underwent operative management of a proximal humerus fracture were identified in a national database by Current Procedural Terminology codes for procedures in patients with International Classification of Diseases, Ninth Revision (ICD-9) codes for proximal humerus fracture, including (1) open reduction and internal fixation, (2) intramedullary nailing, (3) hemiarthroplasty, and (4) total shoulder arthroplasty. These groups were then divided into obese and nonobese cohorts by use of ICD-9 codes for obesity, morbid obesity, or body mass index >30. Each cohort was then assessed for local and systemic complications within 90 days and mortality within 2 years postoperatively. Odds ratios and 95% confidence intervals were calculated. Results: From 2005 to 2011, 20,319 patients who underwent operative management of proximal humerus fractures were identified, including 14,833 (73.0%) open reduction and internal fixation, 1368 (9.2%) intramedullary nail, 3391 (16.7%) hemiarthroplasty, and 727 (3.6%) shoulder arthroplasty. Overall, 3794 patients (18.7%) were coded as obese, morbidly obese, or body mass index >30. In each operative group, obesity was associated with a substantial increase in local and systemic complications. Conclusions: Obesity and its resultant medical comorbidities are associated with increased rates of postoperative complications after operative management of proximal humerus fractures. Obese patients for whom operative management of proximal humerus fractures is planned should be counseled preoperatively about their increased risk for postoperative complications. Level of evidence: Level III, Retrospective Cohort Design from Large Database, Treatment Study. Ó 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Proximal humerus fracture; obesity; open reduction and internal fixation; humeral intramedullary nail; hemiarthroplasty; reverse total shoulder arthroplasty

This study is exempt from IRB review by the University of Virginia Institutional Review Board for Health Sciences Research.

*Reprint requests: F. Winston Gwathmey, MD, Department of Orthopaedic Surgery, University of Virginia Health System, 400 Ray C Hunt Dr, Suite 330, Charlottesville, VA 22908, USA. E-mail address: [email protected] (F.W. Gwathmey).

1058-2746/$ - see front matter Ó 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. http://dx.doi.org/10.1016/j.jse.2014.08.028

594 Proximal humerus fractures in the elderly population are the third most common fracture type and consequently represent a significant socioeconomic burden.5,17 Treatment of these injuries remains challenging, and the optimal management and expected outcomes of displaced proximal humerus fractures vary on the basis of the characteristics of the fracture and the patient, including but not limited to the number of parts to the fracture, predicted viability of the head fragment, and bone quality of the patient.77 Fortunately, the majority of proximal humerus fractures are nondisplaced or minimally displaced, for which good to excellent outcomes can be expected with nonoperative management.16 Operative management is often chosen for Neer 3or 4-part fractures.76 During the past 15 years, there has been significant literature reporting the outcomes and complications of a variety of surgical treatment options, including osteosynthesis by open reduction and internal fixation (ORIF) with locked plating or intramedullary (IM) nailing, humeral head hemiarthroplasty, and reverse total shoulder arthroplasty (RTSA).7,12,14,19,22,40,45,51,61,63,74,77,91,96,100,114,118 Although significant advances have been made in the operative management of proximal humerus fractures, complications still occur not infrequently. Many complications, both local and systemic, are reported after operative management of proximal humerus fractures. Local complications include deep infection, neurovascular injury, malunion, nonunion, hardware failure, joint stiffness, heterotopic ossification, and avascular necrosis.10,12,45,79,91,118 Systemic complications include deep venous thrombosis (DVT), pulmonary embolism (PE), end-organ failure, and nonsurgical site infection such as urinary tract infection or pneumonia. Obesity has become a significant public health concern in the United States. Obesity has been associated with increased perioperative and postoperative complications after numerous orthopedic procedures, including total hip and knee arthroplasty,1,8,21,25,28,29,37,49,52,53,56,62,65,67,72,75,85,92,93,103,104 ,107 total shoulder arthroplasty,31,33,64 spine sur43,54,66,70,80,84,89,101,102,111 gery, fixation of acetabulum, ankle, and femur fractures,47,59,60,69,83,94,99 knee arthroscopy,23,97,109 shoulder arthroscopy,73,106 and others.26,27,30,34,90 Few published data have examined the association between obesity and postoperative complications after operative management of proximal humerus fractures. The objective of this study was to use a national database to assess the effect of obesity and its associated medical comorbidities on postoperative complications after operative management of proximal humerus fractures, including ORIF, IM nailing, hemiarthroplasty, and RTSA.

Materials and methods All data were derived from a publicly available database of patients, the PearlDiver Patient Records Database (www.pearldiverinc.com;

B.C. Werner et al. PearlDiver Inc, Warsaw, IN, USA). The database contains procedure volumes, demographics, and average charge information for patients with International Classification of Diseases, Ninth Revision (ICD-9) diagnoses and procedures or Current Procedural Terminology (CPT) codes. Data for this study were derived from the Medicare database within the PearlDiver records, which has more than 100 million individual patient records from 2005 to 2011. Access to the database was granted by PearlDiver Technologies for the purpose of academic research. The database was stored on a password-protected server maintained by PearlDiver. CPT and ICD-9 codes can be searched in isolation or in combination with one another. The search results yield the number of patients with the searched code or combination of codes. For the purposes of this study, the database was queried for a diagnosis of proximal humerus fracture by use of ICD-9 codes 812.00 to 812.03 and 812.09. Four methods of operative management were assessed: ORIF, IM nail, shoulder hemiarthroplasty, and total (assumed to be reverse) shoulder arthroplasty. The associated CPT and ICD-9 codes used to define each operative cohort are listed in Supplementary Table I (available on the journal’s website at www.jshoulderelbow.org). Patients in each operative group were then divided into nonobese and obese cohorts by ICD-9 codes for overweight, obesity, morbid obesity, and body mass index >30 as listed in Supplementary Table I. The obese and nonobese cohorts for each operative management group were queried for basic demographics including gender, age (80 years), and smoking status. Comorbidities for each cohort were assessed, including diabetes mellitus, obstructive sleep apnea, hyperlipidemia, hypertension, peripheral vascular disease, congestive heart failure, coronary artery disease, chronic kidney disease, chronic lung disease, and chronic liver disease, with ICD-9 codes for each disease. The obese and nonobese cohorts for each operative management group were then queried for postoperative complications within 90 days after the surgical procedure by use of ICD-9 and CPT codes. The PearlDiver database cannot report patient groups of fewer than 10 patients to remain Health Insurance Portability and Accountability Act (HIPAA) compliant; thus, complications were pooled to yield usable data. Overall complications were queried as ‘‘local’’ and ‘‘systemic’’ complications. Local complications included postoperative stiffness requiring manipulation under anesthesia or lysis of adhesions, diagnosis of postoperative infection, and need for postoperative irrigation and debridement. Systemic complications included PE, DVT, acute myocardial infarction, respiratory failure, acute postoperative cerebrovascular accident, urinary tract infection, pneumonia, and acute renal failure. Postoperative venous thromboembolism (VTE, including PE and DVT) and postoperative infection (including diagnosis and irrigation and debridement) were also separately queried. Mortality within 6 months, 1 year, and 2 years postoperatively was also queried. The associated ICD-9 and CPT codes for each postoperative complication are provided in Supplementary Table II (available on the journal’s website at www.jshoulderelbow.org). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each comparison between obese and nonobese cohorts. c2 tests were calculated to determine statistical significance, with P < .05 considered significant.

Obesity and proximal humerus fractures

Results From 2005 to 2011, 20,319 unique patients who underwent operative management of a proximal humerus fracture were identified, including 14,833 (73.0%) ORIF, 1368 (9.2%) IM nail, 3391 (16.7%) hemiarthroplasty, and 727 (3.6%) total shoulder arthroplasty. Overall, 3794 patients (18.7%) were coded as obese or morbidly obese. The nonobese and obese cohorts for each operative management group were significantly different in terms of most medical comorbidities (Supplementary Table III; available on the journal’s website at www.jshoulderelbow.org). Within the ORIF group, 2457 patients (16.6%) were coded as obese. The obese ORIF patients had a significantly increased risk of 90-day local (OR, 4.4; 95% CI [3.3-5.8]; P < .0001) and systemic complications (OR, 4.0; 95% CI [3.5-4.6]; P < .0001) (Supplementary Table IV; available on the journal’s website at www.jshoulderelbow.org). The rates of postoperative VTE and infection in the obese ORIF cohort (2.3% and 2.8%, respectively) were significantly higher than the rates in nonobese patients (0.7% and 0.5%, respectively; P < .0001) (Supplementary Table V; available on the journal’s website at www.jshoulderelbow.org). This yielded an OR of 3.2 (95% CI, 2.3-4.4) for VTE and 5.7 (95% CI, 4.1-8.1) for infection in obese patients undergoing ORIF. There were no significant differences in 6-month, 1year, and 2-year mortality rates (Supplementary Table VI; available on the journal’s website at www.jshoulderelbow. org). Within the IM nail group, 260 patients (19.0%) were coded as obese. The obese IM nail patients had a significantly increased risk of 90-day local (OR, 2.8; 95% CI [1.36.1]; P ¼ .012) and systemic complications (OR, 3.7; 95% CI [2.7-5.0]; P < .0001) (Supplementary Table IV). The rates of postoperative VTE and infection in the obese IM nail cohort (6.5% and 3.8%, respectively) were significantly higher than the rates in nonobese patients (1.7% and 1.2%, respectively; P < .0001, P ¼ .006) (Supplementary Table V). This yielded an OR of 4.0 (95% CI, 2.1-7.8) for VTE and 3.4 (95% CI, 1.4-7.8) for infection in obese patients undergoing IM nailing. There were no significant differences in 6-month, 1-year, and 2-year mortality rates (Supplementary Table VI). Within the hemiarthroplasty group, 821 patients (24.2%) were coded as obese. The obese hemiarthroplasty cohort also had a significantly increased risk of 90-day local (OR, 2.8; 95% CI [1.8-4.3]; P < .0001) and systemic complications (OR, 3.2; 95% CI [2.7-3.9]; P < .0001) (Supplementary Table IV). The rates of postoperative VTE and infection in the obese hemiarthroplasty cohort (5.0% and 4.1%, respectively) were significantly higher than the rates in nonobese patients (1.2% and 1.1%, respectively; P < .0001) (Supplementary Table V). This yielded an OR of 4.5 (95% CI, 2.8-7.2) for VTE and 4.0 (95% CI, 2.4-6.5) for infection in obese patients undergoing hemiarthroplasty.

595 There were no significant differences in 6-month, 1-year, and 2-year mortality rates (Supplementary Table VI). Finally, 256 patients (35.2%) in the total shoulder arthroplasty group were coded as obese. The obese total shoulder arthroplasty cohort also had a significantly increased risk of 90-day local (OR, 2.1; 95% CI [1.1-4.1]; P ¼ .033) and systemic complications (OR, 1.9; 95% CI [1.4-2.6]; P < .0001) (Supplementary Table IV). The rate of postoperative VTE was not significantly different between obese and nonobese patients undergoing total shoulder arthroplasty for proximal humerus fracture (P ¼ .194). The rate of postoperative infection after total shoulder arthroplasty for proximal humerus fracture was significantly increased in obese patients (5.9%) compared with nonobese patients (2.5%), yielding an OR of 2.4 (95% CI [1.1-5.2]; P ¼ .04) (Supplementary Table V). There were no significant differences in 6-month, 1-year, and 2-year mortality rates (Supplementary Table VI).

Discussion The number of obese and morbidly obese patients who sustain proximal humerus fractures is a growing concern, given the potential for postoperative complications demonstrated in shoulder surgery in this population.6,31,33 In this study, 18.7% of patients were coded as obese, which highlights the significance of the present national obesity epidemic. Whereas most proximal humerus fractures occur in elderly osteoporotic patients and can be managed nonoperatively, a subset of patients require surgery for optimal functional outcomes. Published studies have not always agreed on the reported influence of obesity on complications, such as infection, PE, and cardiac disease, among others, after orthopedic surgical procedures.10,12,14,18,40,45 In addition to increasing the difficulty in surgical exposure because of greater volume of soft tissue and depth of wounds, obesity is associated with numerous medical comorbidities that further complicate patient management.32,36,50,68,81 Most notably, obesity has been associated with increased rates of diabetes mellitus,13,15,24,32,35,36,38,42,50,55,68,81 ,95,105,108,117 cardiovascular disease,4,9,32,36,41,46,48,50,68,78,81, 86,87,95,105,110 hypertension,24,32,36,39,42 hyperlipidemia,11,24 ,32,35,36,42,50,81 obstructive sleep apnea,32,36 cerebrovascular 32,42,44,50,57,58,68,88,95 disease, and gallbladder disease,3,11,32 among others. The obese groups in our study demonstrated increased rates of nearly all of these associated medical comorbidities over the nonobese groups, indicating a representative population of obese patients. In this study using a large publicly available database, obesity and its associated medical comorbidities appear to have a significant association with a variety of complications after surgical management of proximal humerus fractures. This study demonstrates that obese patients have

596 a significantly increased rate of local complications including stiffness requiring manipulation under anesthesia or lysis of adhesions and postoperative infection after ORIF, IM nailing, hemiarthroplasty, and total shoulder arthroplasty. In addition, systemic complications including PE, DVT, myocardial infarction, respiratory failure, cerebrovascular accident, renal failure, and urinary tract infection are also significantly more prevalent in obese patients after ORIF, hemiarthroplasty, IM nailing, and total shoulder arthroplasty (Supplementary Tables IV and V). No significant differences in mortality were noted between the obese and nonobese cohorts. Whereas no randomized controlled trials have compared obese and nonobese patients undergoing surgical management of proximal humerus fractures with one another, several previous studies have evaluated outcomes in this regard related to total shoulder arthroplasty and RTSA.6,33 In deciding on operative treatment, the least invasive procedure providing adequate reduction and stability should be executed. The definitive treatment should be based on patient factors as well as fracture characteristics. Increased complications after reverse arthroplasty and hemiarthroplasty may be due to worsening fracture patterns addressed in these patients. Zhu et al118 reported screw penetration of the articular surface as the most common complication leading to revision surgery. In their systematic review, Sproul et al98 demonstrated an overall complication rate of 48% after locked plating osteosynthesis and a revision rate of 13% with an infection rate of 3.5%. Theoretically, obese patients present unique challenges that may lead to the increased rate of complications seen in our study, such as problems with the soft tissue envelope as a result of overall decreased health compared with their nonobese counterparts and increased challenges with obtaining satisfactory intraoperative radiographic views. As noted in Supplementary Table IV, our study found a decreased rate of complications in patients managed with ORIF overall compared with previous reports.40,100 This is likely due to our focus on the 90-day postoperative period, as complications such as avascular necrosis, collapse, and nonunion are unlikely to be captured. There is considerable controversy in the literature surrounding indications for proximal humerus fracture management.40,77,82 The time line for this study is from 2005 to 2011. The rising use of RTSA during this period may influence overall outcomes in this subset, and we are unable to analyze changes in the rates of complications during this time, which may be attributable to improved techniques and learning curve. Significant concern remains for the high complication rate after RTSA. Instability, loosening, and scapular notching provide caution to the improved functional outcomes after RTSA. Chalmers et al,14 in a recent study, demonstrated a low complication rate after RTSA, hemiarthroplasty, and ORIF, with 2 patients developing arthrofibrosis. Beck et al6 recently

B.C. Werner et al. reported their retrospective results after 76 RTSAs and noted a 35% complication rate in obese patients compared with 4% in nonobese counterparts. Similarly, we found a higher incidence of systemic complications after total shoulder arthroplasty for proximal humerus fractures, with 48% of obese patients having a systemic complication compared with 33% of nonobese patients undergoing total shoulder arthroplasty (Supplementary Table IV). Gupta et al33 demonstrated an increased complication rate with increased body mass index in patients undergoing RTSA. Our study did not demonstrate a significant increase in the rate of infection or VTE after total shoulder arthroplasty, although there was a trend observed in this regard (Supplementary Table V). This study has several limitations. Many of the limitations of our study are inherent to the nature of using a large administrative database such as PearlDiver.2,20,71,112,113,115,116 The power of this analysis is dependent on the quality of the available data, which includes accuracy in billing codes, miscoding, and noncoding by physicians as potential sources of error.113 Whereas we attempted to accurately represent a large population of interest by using this database, we cannot ensure that the database represents a true cross section of the United States. In addition, the PearlDiver database currently indexes only a 7-year increment of data for the populations of interest. Although the study period was large enough to find significant trends, some data may not be accurately captured in a 7-year period. Furthermore, the findings in our study represent 90-day outcomes to increase the likelihood that the complications were related to the surgical management of the proximal humerus fracture and not another condition or medical or surgical issue that arose. In addition, certain important complications, such as implant failure or prominence and intraoperative neurovascular injuries, are not captured within this study because of nonspecific ICD-9 codes for these issues. Late complications including nonunion, rotator cuff dysfunction, and glenoid erosion or arthrosis are likewise not captured in our study. Finally, a specific CPT code for RTSA does not exist; the patients in the total shoulder arthroplasty group are assumed to be largely RTSAs as this is the typical procedure performed for this indication.

Conclusions To our knowledge, there are few studies examining the association between obesity and postoperative complications after operative management of proximal humerus fractures. Obesity and its associated medical comorbidities are associated with substantially higher risks for local and systemic complications after operative management of proximal humerus fractures. This

Obesity and proximal humerus fractures information is valuable for counseling of patients in attempting to decide between operative and nonoperative management. In certain equivocal cases, the data from this study can allow better understanding of the risks of undergoing surgical treatment in obese patients. Further prospective studies with long-term outcome data should identify exactly when benefits of operative intervention outweigh risks in obese patients.

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Disclaimer The authors, their immediate families, and any research foundation with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

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Supplementary data 16.

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jse.2014.08.028 17.

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