Thomas P. Vail

The Impact of Glycemic Control and Diabetes Mellitus on Perioperative Outcomes After Total Joint Arthroplasty

BACKGROUND As the prevalence of diabetes mellitus in people over the age of sixty years is expected to increase, the number of diabetic patients who undergo total hip and knee arthroplasty should be expected to increase accordingly. In general, patients with diabetes are at increased risk for adverse events following arthroplasty. The goal of the present study was to determine whether the quality of preoperative glycemic control affected the prevalence of in-hospital peri-operative complications following lower extremity total joint arthroplasty. METHODS From 1988 to 2005, the Nationwide Inpatient Sample recorded over 1 million patients who underwent joint replacement surgery. The present retrospective study compared patients with uncontrolled diabetes mellitus (n = 3973), those with controlled diabetes mellitus (n = 105,485), and those without diabetes mellitus (n = 920,555) with regard to common surgical and systemic complications, mortality, and hospital course alterations. Additional stratification compared the effects of glucose control among patients with Type-I and Type-II diabetes. Glycemic control was determined by physician assessments on the basis of the American Diabetes Association guidelines with use of a combination of patient self-monitoring of blood-glucose levels, the hemoglobin A1c level, and related comorbidities. RESULTS Compared with patients with controlled diabetes mellitus, patients with uncontrolled diabetes mellitus had a significantly increased odds of stroke (adjusted odds ratio = 3.42; 95% confidence interval = 1.87 to 6.25; p < 0.001), urinary tract infection (adjusted odds ratio = 1.97; 95% confidence interval = 1.61 to 2.42; p < 0.001), ileus (adjusted odds ratio = 2.47; 95% confidence interval = 1.67 to 3.64; p < 0.001), postoperative hemorrhage (adjusted odds ratio = 1.99; 95% confidence interval = 1.38 to 2.87; p < 0.001), transfusion (adjusted odds ratio = 1.19; 95% confidence interval = 1.04 to 1.36; p = 0.011), wound infection (adjusted odds ratio = 2.28; 95% confidence interval = 1.36 to 3.81; p = 0.002), and death (adjusted odds ratio = 3.23; 95% confidence interval = 1.87 to 5.57; p < 0.001). Patients with uncontrolled diabetes mellitus had a significantly increased length of stay (almost a full day) as compared with patients with controlled diabetes (p < 0.0001). All patients with diabetes had significantly increased inflation-adjusted postoperative charges when compared with nondiabetic patients (p < 0.0001). CONCLUSIONS Regardless of diabetes type, patients with uncontrolled diabetes mellitus exhibited significantly increased odds of surgical and systemic complications, higher mortality, and increased length of stay during the index hospitalization following lower extremity total joint arthroplasty.

The Epidemiology of Bearing Surface Usage in Total Hip Arthroplasty in the United States

BACKGROUND Hard-on-hard bearings offer the potential to improve the survivorship of total hip arthroplasty implants. However, the specific indications for the use of these advanced technologies remain controversial. The purpose of this study was to characterize the epidemiology of bearing surface utilization in total hip arthroplasty in the United States with respect to patient, hospital, geographic, and payer characteristics. METHODS The Nationwide Inpatient Sample database was used to analyze bearing type and demographic characteristics associated with 112,095 primary total hip arthroplasties performed in the United States between October 1, 2005, and December 31, 2006. The prevalence of each type of total hip arthroplasty bearing was calculated for population subgroups as a function of age, sex, census region, payer class, and hospital type. RESULTS The most commonly reported bearing was metal-on-polyethylene (51%) followed by metal-on-metal (35%) and ceramic-on-ceramic (14%). Metal-on-polyethylene bearings were most commonly reported in female Medicare patients who were sixty-five to seventy-four years old, while metal-on-metal and ceramic-on-ceramic bearings were most commonly reported in privately insured male patients who were less than sixty-five years old. Thirty-three percent of patients over sixty-five years old had a hard-on-hard bearing reported. There was substantial regional variation in bearing usage; the highest prevalence of metal-on-polyethylene bearings was reported in the Northeast and at nonteaching hospitals, and the highest prevalence of metal-on-metal bearings was reported in the South and at teaching hospitals. CONCLUSIONS The usage of total hip arthroplasty bearings varies considerably by patient characteristics, hospital type, and geographic location throughout the United States. Despite uncertain advantages in older patients, hard-on-hard bearings are commonly used in patients over the age of sixty-five years. Further study is necessary to define the appropriate indications for these advanced technologies in total hip arthroplasty.

Patient-related risk factors for periprosthetic joint infection and postoperative mortality following total hip arthroplasty in Medicare patients.

BACKGROUND The patient-related risk factors for periprosthetic joint infection and postoperative mortality in elderly patients undergoing total hip arthroplasty are poorly understood. The purpose of this study was to identify the specific patient comorbidities that are associated with an increased risk of periprosthetic joint infection and of ninety-day postoperative mortality in U.S. Medicare patients undergoing total hip arthroplasty. METHODS The Medicare 5% sample claims database was used to calculate the relative risk of periprosthetic joint infection and of ninety-day postoperative mortality as a function of preexisting comorbidities in 40,919 patients who underwent primary total hip arthroplasty between 1998 and 2007. The impact of twenty-nine comorbid conditions on periprosthetic joint infection and on postoperative mortality was examined with use of Cox regression, controlling for age, sex, census region, public assistance, and all other baseline comorbidities. The adjusted hazard ratios for all comorbid conditions were evaluated, and the Wald chi-square statistic was used to rank the degree of association of each condition with periprosthetic joint infection and with postoperative mortality. The Bonferroni-Holm method was used to adjust for the multiple comparisons resulting from the number of comorbid conditions analyzed. RESULTS Comorbid conditions associated with an increased adjusted risk of periprosthetic joint infection (in decreasing order of significance, p < 0.05 for all comparisons) were rheumatologic disease (hazard ratio [HR] = 1.71), obesity (HR = 1.73), coagulopathy (HR = 1.58), and preoperative anemia (HR = 1.36). Comorbid conditions associated with an increased adjusted risk of ninety-day postoperative mortality (in decreasing order of significance, p < 0.05 for all comparisons) were congestive heart failure (HR = 2.11), metastatic cancer (HR = 3.14), psychosis (HR = 1.85), renal disease (HR = 1.98), dementia (HR = 2.04), hemiplegia or paraplegia (HR = 2.62), cerebrovascular disease (HR = 1.40), and chronic pulmonary disease (HR = 1.32). CONCLUSIONS We identified specific patient comorbidities that were independently associated with an increased risk of periprosthetic joint infection and of ninety-day postoperative mortality in Medicare patients who had undergone total hip arthroplasty. This information is important when counseling elderly patients regarding the risks of periprosthetic joint infection and mortality following total hip arthroplasty, as well as for risk adjustment of publicly reported total hip arthroplasty outcomes.

Trends in Hip Arthroscopy Utilization in the United States

INTRODUCTION The purpose of this study was to evaluate the changing incidence of hip arthroscopy procedures among newly trained surgeons in the United States, the indications for hip arthroscopy, and the reported rate of post-operative complications. METHODS The ABOS database was used to evaluate the annual incidence of hip arthroscopy procedures between 2006-2010. Procedures were categorized by indication and type of procedure. The rate of surgical complications was calculated and compared between the published literature and hip arthroscopy procedures performed for femoroacetabular impingement (FAI)/osteoarthritis (OA) and for labral tears among the newly trained surgeon cohort taking the ABOS Part II Board exam. RESULTS The overall incidence of hip arthroscopy procedures performed by ABOS Part II examinees increased by over 600% during the 5-year period under study from approximately 83 in 2006 to 636 in 2010. The incidence of hip arthroscopy for FAI/OA increased steadily over the time period under study, while the incidence of hip arthroscopy for labral tears was variable over time. The rate of surgical complications was 5.9% for hip arthroscopy procedures for a diagnosis of FAI/OA vs. 4.4% for a diagnosis of labral tear (P=0.36). CONCLUSIONS The incidence of hip arthroscopy has increased dramatically over the past 5 years, particularly for the indication of FAI/OA. Reported surgical complication rates are relatively low, but appear higher than those rates reported in previously published series. Appropriate indications for hip arthroscopy remain unclear.

Provider volume of total knee arthroplasties and patient outcomes in the HCUP-Nationwide Inpatient Sample

BACKGROUND The relationship between volume and outcome of total knee arthroplasties has never been evaluated in a nationally representative sample, to our knowledge. We hypothesized that surgeons and hospitals with higher patient volumes would have better outcomes, as defined by lower mortality rates, shorter hospital stays, and lower postoperative complication rates. METHODS The 1997 Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample, Release 6, provided discharge abstracts of patients undergoing total knee arthroplasty from a national stratified probability sample. Logistic and multiple regression models were used to estimate the adjusted association of surgeon or hospital volume with rates of in-hospital mortality, pulmonary thromboembolism, deep venous thrombosis in the lower extremity, and postoperative wound infection as well as length of hospital stay. Estimates were calculated for a target population of 277,550 patients. Models were adjusted for comorbidity, age, gender, race, household income, and procedure (primary or revision arthroplasty). RESULTS The patients were mostly white (70.2%) and female (62.7%), with a mean age of 68.9 years. The overall in-hospital mortality rate for the target population was 0.2%, and the average length of stay was 4.6 days for the primary total knee arthroplasties and 4.9 days for the revision procedures. Surgeon volumes of at least fifteen procedures per year and hospital volumes of at least eighty-five per year were significantly and linearly associated with lower mortality rates (odds ratio = 0.56 [0.24 to 1.31] for surgeon volume of > or = 60). No other association demonstrated a significant and directionally consistent linear trend for improved outcomes. CONCLUSION Patients treated by providers with lower caseload volumes had higher rates of mortality following total knee arthroplasty in 1997. Proposing volume standards could decrease patient mortality following this procedure.

The Influence of Procedure Volumes and Standardization of Care on Quality and Efficiency in Total Joint Replacement Surgery

BACKGROUND The relationship between surgeon and hospital procedure volumes and clinical outcomes in total joint arthroplasty has long fueled a debate over regionalization of care. At the same time, numerous policy initiatives are focusing on improving quality by incentivizing surgeons to adhere to evidence-based processes of care. The purpose of this study was to evaluate the independent contributions of surgeon procedure volume, hospital procedure volume, and standardization of care on short-term postoperative outcomes and resource utilization in lower-extremity total joint arthroplasty. METHODS An analysis of 182,146 consecutive patients who underwent primary total joint arthroplasty was performed with use of data entered into the Perspective database by 3421 physicians from 312 hospitals over a two-year period. Adherence to evidence-based processes of care was defined by administration of appropriate perioperative antibiotic prophylaxis, beta-blockade, and venous thromboembolism prophylaxis. Patient outcomes included mortality, length of hospital stay, discharge disposition, surgical complications, readmissions, and reoperations within the first thirty days after discharge. Hierarchical models were used to estimate the effects of hospital and surgeon procedure volume and process standardization on individual and combined surgical outcomes and length of stay. RESULTS After adjustment in multivariate models, higher surgeon volume was associated with lower risk of complications, lower rates of readmission and reoperation, shorter length of hospital stay, and higher likelihood of being discharged home. Higher hospital volume was associated with lower risk of mortality, lower risk of readmission, and higher likelihood of being discharged home. The impact of process standardization was substantial; maximizing adherence to evidence-based processes of care resulted in improved clinical outcomes and shorter length of hospital stay, independent of hospital or surgeon procedure volume. CONCLUSIONS Although surgeon and hospital procedure volumes are unquestionably correlated with patient outcomes in total joint arthroplasty, process standardization is also strongly associated with improved quality and efficiency of care. The exact relationship between individual processes of care and patient outcomes has not been established; however, our findings suggest that process standardization could help providers optimize quality and efficiency in total joint arthroplasty, independent of hospital or surgeon volume.

Metal-on-metal hip resurfacing compares favorably with THA at 2 years followup.

Metal-on-metal total hip resurfacing is a bone-conserving reconstructive option for patients with advanced articular damage. While intended to address several problems with conventional THA, the safety and efficacy is not well established. We therefore retrospectively compared the outcomes of 52 patients (57 hips) with resurfacing arthroplasty to 84 patients (93 hips) with cementless primary THAs. The patients had a minimum 2-year followup (mean 3 years). The patients with resurfacing arthroplasty had a mean age of 47 years (range, 22-64) while those with cementless primary THA had a mean age of 57 years (range, 17-92). After controlling for age, gender, and preoperative differences, the total Harris Hip Scores (HHS), function scores, and pain scores were similar between the two groups. However, the resurfacing group had higher activity scores (14 versus 13, p < 0.001) and range of motion (ROM) scores (5.0 versus 4.8, p < 0.001). The complication rates (5.3% for resurfacing versus 14.0% for THA) and reoperation rates (3.5% for resurfacing versus 4.3% for THA) were similar. The total hip arthroplasty and metal-on-metal resurfacing groups both showed improvement in HHS, pain, activity, and ROM and had similar early complication and reoperation rates.Level of Evidence: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The Impact of Diabetes on Perioperative Patient Outcomes After Total Hip and Total Knee Arthroplasty in the United States

The purpose of this study was to determine whether patients with diabetes mellitus (DM) have a higher likelihood of immediate, inpatient complications following primary and revision total hip (THA) and total knee arthroplasty (TKA) than patients without DM. From 1988 to 2003, the Nationwide Inpatient Sample identified 751340 primary or revision THA or TKA patients. 64262 (8.55%) had DM. Comparisons of specific outcome measures between diabetic and nondiabetic cohorts were performed using bivariate and multivariate analyses with logistic regression modeling. Diabetic patients had fewer routine discharges and higher inflation-adjusted hospital charges for all procedures. Although complications were not uniformly increased, diabetic patients had significantly increased odds of pneumonia, stroke, and transfusion (P < .001) after primary arthroplasty. This analysis of a large patient database indicates clinically relevant information for patients and surgeons, suggesting that patients undergoing THA and TKA demonstrate more complications and utilize more resources if they have the comorbidity of DM level II evidence.

Effect of changing indications and techniques on total hip resurfacing.

Recently, improved metal-on-metal bearing technology has led to the reemergence of resurfacing as a reasonable option for total hip arthroplasty. During the course of a prospective multicenter FDA-IDE evaluation of metal-on-metal total hip resurfacings, we modified our indications and emphasized surgical technique where the femoral surface area was small due to femoral cysts and small component size. We assessed the influence of these changes on complication rates in the first cohort of 292 patients and the second of 724, and then compared these outcomes in the second cohort with historical reports of resurfacing. We had a minimum followup of 24 months (mean, 33 months; range, 24-60 months). After changes were made in the indications and technique, the overall complication rate decreased from 13.4% to 2.1% with the femoral neck fracture rate reduced from 7.2% to 0.8%. The outcomes of the second cohort compare with modern-day resurfacing devices and appear superior to historical results. The data suggest patients should be carefully selected and technique optimized to reduce complications. Long-term followup is required to see if these promising results will be maintained.Level of Evidence: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Biomechanical factors in tissue engineered meniscal repair.

Damage to the meniscus after trauma or injury is associated with detrimental changes in joint function that can lead to pain, disability, and degenerative joint changes. Recently, tissue engineering strategies for meniscal repair have been suggested including using biocompatible grafts as a substrate for regeneration, and cellular supplementation to promote remodeling and healing. Little is known, however, about the contributions of these novel repair strategies to restoration of normal meniscal function. Biomechanical factors play a role in the design and synthesis of tissue engineered biomaterials and bioreactors, and also are important for evaluating the efficacy of these new strategies for restoring normal meniscal function. In this report, an overview is presented of biomechanical factors that are critical to meniscal function followed by a review of biomechanical considerations for the design and evaluation of tissue engineered strategies for meniscal repair. Recommendations for future study of biomechanical factors in tissue engineered meniscal repair also are provided.