HIP ISSN 1120-7000
Hip Int 2015; 00 (00): 000-000 DOI: 10.5301/hipint.5000224
ORIGINAL ARTICLE
Does osteonecrosis of the femoral head increase surgical and medical complication rates after total hip arthroplasty? A comprehensive analysis in the United States Scott Yang, Alexander Y. Halim, Brian C. Werner, F. Winston Gwathmey, Quanjun Cui University of Virginia Health System, Charlottesville, Virginia - USA
Abstract Total hip arthroplasty (THA) is a definitive option for end-stage osteonecrosis of the femoral head (ONFH). Historically, higher revision rates were observed in this population compared to THA for osteoarthritis (OA). This study provides a comprehensive evaluation of postoperative medical and surgical complications comparing THA in ONFH and OA at 90 days, 1 year, and 2 years after surgery. The PearlDiver database identified 45,002 OA and 8,429 ONFH patients who underwent THA. Mechanical complications (prosthetic loosening and osteolysis, implant failure), dislocation, renal and respiratory complications were significantly increased in the ONFH group within 2 years after THA. Pulmonary embolism rates where increased in younger ONFH patients within 2 years after THA. This data helps clinicians in the postoperative risk assessment of patients with ONFH. Keywords: Total hip arthroplasty, Osteonecrosis, Complications, Avascular necrosis
Introduction Osteonecrosis of the femoral head (ONFH) is a disabling condition that often leads to collapse of the femoral head after an interruption of blood supply, with subsequent degenerative arthritis of the hip. A variety of etiologies have been proposed including local factors affecting blood supply such as microvascular damage, increased intraosseous pressure, adipogenic differentiation of marrow stem cells and mechanical stresses (1-3). ONFH is often observed in patients with excessive alcohol use, coagulopathies, lupus, and other chronic diseases that require long term corticosteroid use (46). Treatment varies according to the disease stage, and in the presence of collapse of the femoral head the most reliable treatment remains total hip arthroplasty (THA) (7). Earlier studies in the ONFH population demonstrated high failure rates defined as prosthetic loosening or revision in patients who underwent THA for ONFH (8-15). Historically, Accepted: December 17, 2014 Published online: Corresponding Author: Scott Yang Department of Orthopaedic Surgery University of Virginia Health System 400 Ray C Hunt Dr, Suite 330 Charlottesville 22903 Virginia, USA
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increased revision rates have been reported for THA in ONFH, yet newer studies have demonstrated low revision rates for uncemented THA in ONFH comparable to THA for osteoarthritis (OA) (16-19). A recent meta-analysis of 3,277 THAs in 2,593 ONFH patients demonstrated a significantly lower revision rate of 3% in patients who had surgery in 1990 or later as compared to a 17% revision rate in patients with THA before 1990 (17). Despite promising recent results, the literature remains conflicted as large European database studies recently demonstrated higher revision THA rates in ONFH patients compared to OA patients (20, 21). Although a large volume of literature exists reporting increased revision rates in THA for ONFH, a comprehensive comparison of all major postoperative surgical and medical complications in the United States remains lacking. The aim of the present study is to systematically compare all surgical and medical postoperative complications including but not limited to prosthetic hip dislocation, wound issues, postoperative infection, deep vein thrombosis (DVT), pulmonary embolism (PE), and medical complications (cardiac, gastrointestinal (GI), respiratory, renal, urinary tract infection (UTI)) for patients who have had THA for ONFH and THA for OA from a large United States database.
Materials and Methods All data was derived from the PearlDiver Patient Record Database (www.pearldiverinc.com; PearlDiver Inc, Fort Wayne, Indiana) of patient records from years 2007-2011. The database was queried for International Classification of Diseases, ninth revision (ICD-9) codes for hip OA (715.15),
Does osteonecrosis of the femoral head increase complication rates after THA?
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and ONFH (733.42). Current Procedural Terminology (CPT) codes for THA (27130 & 27132) were co-queried for both OA and ONFH to create 2 distinct patient groups. As multivariate analysis cannot be run on the PearlDiver database, we stratified both the ONFH study group and hip OA control group by age less than 65 years old and greater than 65 years old to group more similar patients and potential age related chronic comorbidities separately. For each cohort, ICD-9 and CPT codes for comorbid medical conditions were queried to evaluate baseline group characteristics. ICD-9 and CPT codes for postoperative medical complications and postoperative surgical complications were queried within three time points: 90 days, 1 year, and 2 years. The codes queried including each diagnosis, complication, and comorbidity is referenced in appendix A. Multiple codes were grouped into categories for analysis; for example, the respiratory complications category grouped ICD-9 codes including but not limited to several types of pneumonia, acute respiratory failure, and pulmonary oedema. The PearlDiver database contains records from multiple private payer insurance agencies as well as from Medicare. We gathered data for our younger cohort (65 years old) from a Medicare database within PearlDiver, which contains 128,467,231 individual
patient records from 2007-2011. We calculated the odds ratios of complications between the ONFH and OA groups, and used a chi-square test to determine statistical significance. All of our analyses were set for significance at p
