Ninety-Day Costs, Reoperations, and Readmissions for Primary Total Hip Arthroplasty Patients of Varying Body Mass Index Levels

Effects of elevated body mass index on the success of total knee and total hip arthroplasty: a comprehensive overview

INTRODUCTION

The average body mass index (BMI) in the United States has tripled over the last five decades despite concerted population-based efforts for weight management. Elevated BMI and, in particular, obesity are risk factors for osteoarthritis. This trend has led to increased demands for total knee (TKA) and total hip arthroplasty (THA), necessitating an in-depth understanding of how elevated BMI impacts TKA and THA.

AREAS COVERED

This paper reviews the literature investigating the effects of elevated BMI, primarily obesity, on TKA and THA, focusing on preoperative, intraoperative, and postoperative considerations. It describes the associated risks, economic implications, and ethical considerations of patients with high BMIs undergoing TKA or THA. To ensure all relevant literature was included, Ovid Medline and Google Scholar databases were searched for the following terms, 'body mass index,' 'obesity,' 'knee,' 'hip,' and 'arthroplasty' for articles published from January 2019 through July 2024.

EXPERT OPINION

Despite the challenges of high BMI in TKA and THA, a deeper understanding of obesity as a chronic illness, coupled with advances in surgical techniques, can improve patient outcomes. A multidisciplinary approach and further research will optimize the care of patients with elevated BMIs undergoing total joint arthroplasty (TJA).

Inpatient Hospital Costs, Emergency Department Visits, and Readmissions for Revision Hip and Knee Arthroplasty

BACKGROUND

Revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) tremendously burden hospital resources. This study evaluated factors influencing perioperative costs, including emergency department (ED) visits, readmissions, and total costs-of-care within 90 days following revision surgery.

METHODS

A retrospective analysis of 772 revision TKAs and THAs performed on 630 subjects at a single center between January 2007 and December 2019 was conducted. Cost data were available from January 2015 to December 2019 for 277 patients. Factors examined included comorbidities, demographic information, preoperative Anesthesia Society of Anesthesiologists score, implant selection, and operative indication using mixed-effects linear regression models.

RESULTS

Among 772 revisions (425 THAs and 347 TKAs), 213 patients required an ED visit, and 90 required hospital readmission within 90 days. There were 22.6% of patients who underwent a second procedure after their initial revision. Liver disease was a significant predictor of ED readmission for THA patients (multivariable odds ratio [OR]: 3.473, P = .001), while aseptic loosening, osteolysis, or instability significantly reduced the odds of readmission for TKA patients (OR: 0.368, P = .014). In terms of ED visits, liver disease increased the odds for THA patients (OR: 1.845, P = .100), and aseptic loosening, osteolysis, or instability decreased the odds for TKA patients (OR: 0.223, P < .001). Increased age was associated with increased costs in both THA and TKA patients, with significant cost factors including congestive heart failure for TKA patients (OR: $7,308.17, P = .004) and kidney disease for THA patients. Revision surgeries took longer than primary ones, with TKA averaging 3.0 hours (1.6 times longer) and THA 2.8 hours (1.5 times longer).

CONCLUSIONS

Liver disease increases ED readmission risk in revision THA, while aseptic loosening, osteolysis, or instability decreases it in revision TKA. Increased age and congestive heart failure are associated with increased costs. These findings inform postoperative care and resource allocation in revision arthroplasty.

LEVEL OF EVIDENCE

Economic and Decision Analysis, Level IV.

Patient Characteristics, Length of Stay, Cost of Care, and Complications in Super-Obese Patients Undergoing Total Hip Arthroplasty: A National Database Study

BACKGROUND

The purpose of this study was to compare postoperative complication rates in super-obese (SO) patients with a body mass index (BMI) ≥ 50 kg/m2 undergoing total hip arthroplasty (THA) versus non-super-obese (NSO) patients undergoing THA.

METHODS

In this retrospective study using the National Inpatient Sample (NIS) database, 1,646 cases of THA in SO (BMI ≥ 50 kg/m2) patients were reviewed. We used International Classification of Diseases (ICD)-10 codes to assess postoperative variables including length of stay, cost of care (cost of inpatient hospitalization), and medical and surgical complications among SO patients undergoing THA compared to NSO patients before being discharged.

RESULTS

A comparison of demographic variables showed there were more women in both groups and nearly 17.2% of SO patients were diabetic patients, 11.1% of SO patients were tobacco users, and 74.8% of the SO patients were whites (African American, 15.1%; Hispanic, 2.9%). The mean length of stay was 3.43 days in the SO group and 2.32 days in the NSO group, and this difference was statistically significant. The cost of care was $79,784.64 for the SO group, which was significantly higher than $66,821.75 for the NSO group. The SO group also showed higher odds of developing medical complications such as anemia (odds ratio [OR], 1.555; 95% confidence interval [CI], 1.395-1.734; p < 0.001), acute renal failure (OR, 3.375; 95% CI, 2.816-4.045; p < 0.001), pneumonia (OR, 2.319; 95% CI, 1.241-4.331; p = 0.014), and need for blood transfusion (OR, 1.596; 95% CI, 1.289-1.975; p < 0.001). The SO patients also showed a higher risk of several postoperative surgical complications such as periprosthetic fractures, infection, and wound dehiscence.

CONCLUSIONS

Postoperative complication rates in SO patients were higher than those in the NSO group. Length of stay and cost of care were higher, whereas the mean age was lower for the SO group. Therefore, THA in SO patients should be undertaken only after careful consideration and preferably in a tertiary facility capable of handling all medical and surgical in-hospital complications.

Are Body Mass Index Cutoffs Creating Racial, Ethnic, and Gender Disparities in Eligibility for Primary Total Hip and Knee Arthroplasty?

BACKGROUND

Unabated increases in the prevalence of obesity among American adults have disproportionately affected women, Black persons, and Hispanic persons. The purpose of this study was to evaluate for disparity in rates of patient eligibility for primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) based on race and ethnicity and gender by applying commonly used body mass index (BMI) eligibility criteria to two large national databases.

METHODS

We retrospectively reviewed data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database for the years 2015-2019 for primary THA and TKA and the National Health and Nutrition Examination Survey (NHANES) from 2011-2018. Designations of race and ethnicity were standardized between cohorts. BMI cutoffs of <50 kg/m², <45 kg/m², <40 kg/m², and <35 kg/m² were then applied. Rates of eligibility for surgery were examined for each respective BMI cutoff and stratified by age, race and ethnicity, and gender.

RESULTS

143,973 NSQIP THA patients, 242,518 NSQIP TKA patients, and 13,255 NHANES participants were analyzed. Female patients were more likely to be ineligible for surgery across all cohorts for all modeled BMI cutoffs (P < .001 for all). Black patients had relatively lower rates of eligibility across all cohorts for all modeled BMI cutoffs (P < .0001 for all). Hispanic patients had disproportionately lower rates of eligibility only at a BMI cutoff of <35 kg/m².

CONCLUSION

Using BMI cutoffs alone to determine the eligibility for primary THA and TKA may disproportionally exclude women, Black persons, and Hispanic persons. These data raise concerns regarding further disparity and restriction of arthroplasty care to vulnerable populations that are already marginalized.

LEVEL OF EVIDENCE

Retrospective Cohort Study, Level III.

Projected Prevalence of Obesity in Primary Total Hip Arthroplasty: How Big Will the Problem Get?

BACKGROUND

Obesity is associated with higher rates of adverse outcomes following primary total hip arthroplasty (THA). The purpose of this study is to utilize 3 national databases to develop projections of obesity within the general population and primary THA patients in the United States through 2029.

METHODS

Data from the National Surgical Quality Improvement Program (NSQIP), the Behavior Risk Factor Surveillance System (BRFSS), and the National Health and Nutrition Examination Survey were queried for years 1999-2019. Current Procedural Terminology code 27130 was used to identify primary THA patients in NSQIP. Individuals were categorized according to body mass index (kg/m²) by year: normal weight (≤24.9); overweight (25.0-29.9); obese (30.0-39.9); and morbidly obese (≥40). Multinomial logistic regression was used to project categorical body mass index data for years 2020-2029.

RESULTS

A total of 8,222,013 individuals were included (7,986,414 BRFSS, 235,599 NSQIP THA). From 2011 to 2019, the prevalence of normal weight and overweight individuals declined in the general population (BRFSS) and in primary THA. Prevalence of obese/morbidly obese individuals increased in the general population from 31% to 36% and in primary THA from 42% to 49%. Projection models estimate that by 2029, 46% of the general population will be obese/morbidly obese and 55% of primary THA will be obese/morbidly obese.

CONCLUSION

By 2029, we estimate ≥55% of primary THA to be obese/morbidly obese. Increased resources dedicated to care pathways and research focused on improving outcomes in obese arthroplasty patients will be necessary as this population continues to grow.

LEVEL OF EVIDENCE

Level III, Retrospective Cohort Study.

The economic impact of periprosthetic infection in total knee arthroplasty

Background

Currently, the gold standard treatment for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is 2-stage revision, but few studies have looked at the economic impact of PJI on the health care system. The objective of this study was to obtain an accurate estimate of the institutional cost associated with the management of PJI in TKA and to assess the economic impact of PJI after TKA compared to uncomplicated primary TKA.

Methods

We identified consecutive patients in our institutional database who had undergone 2-stage revision TKA for PJI between 2010 and 2014 and matched them on age and body mass index with patients who had undergone uncomplicated primary TKA over the same period. We calculated all costs associated with the 2 procedures and compared mean costs, length of stay, clinical visits and readmission rates between the 2 groups.

Results

There were 73 patients (mean age 68.8 [range 48–91] yr) in the revision TKA cohort and 73 patients (mean age 65.9 [range 50–86] yr) in the primary TKA cohort. Two-stage revision surgery was associated with a significantly longer hospital stay (mean 22.7 d v. 3.84 d, p < 0.001), more outpatient clinic visits (mean 8 v. 3, p < 0.001), more readmissions (29 v. 0, p < 0.001) and higher overall cost (mean $35 429.97 v. $6809.94, p < 0.001) than primary TKA.

Conclusion

Treatment for PJI after TKA has an enormous economic impact on the health care system. Our data suggest a fivefold increase in expenditure in the management of this complication compared to uncomplicated primary TKA.

A critical review of weight loss recommendations before total knee arthroplasty

OBJECTIVE

Increased infection risk after total knee arthroplasty (TKA) in patients with a higher body mass index (BMI), particularly a BMI ≥40kg/m², suggests that BMI reduction (through weight loss) prior to TKA may be important. However, the impact of weight loss on TKA risk reduction is unclear. Furthermore, weight loss could have detrimental consequences with respect to muscle loss and development of sarcopenic obesity, whereby a potential weight loss paradox in adults with advanced knee OA and obesity may be present. Using a critical review approach, we examined the current evidence supporting weight loss in adults with obesity and advanced knee osteoarthritis (OA). We focused on three key areas: (1) TKA complication risk with severe obesity compared to obesity (BMI ≥40kg/m² versus 30.0-39.9kg/m²); (2) weight loss recommendations for individuals with advanced knee OA; and (3) TKA outcomes after pre-surgical weight loss.

METHODS

Medline and CINAHL databases were examined from Jan 2010 to May 2020 to identify high-level and/or clinically-influential evidence (systematic reviews, meta-analyses and clinical practice guidelines).

RESULTS

The literature does not show a clear relationship between weight loss and reduction in TKA complications, and no indication that a patients' individual risk is lowered by reducing their BMI from a threshold of ≥40kg/m² to ≤39.9kg/m². Studies that have found a benefit of weight loss for knee OA have not included patients with higher BMIs (≥40kg/m²) or more advanced knee OA. Furthermore, there is unclear evidence of a benefit of pre-surgical weight loss on TKA outcomes. These are important evidence gaps, suggesting that recommendations for BMI reduction prior to TKA should be tempered by the current uncertainty in the literature.

CONCLUSION

Evidence to support a benefit of weight loss prior to TKA is lacking. Until knowledge gaps are clarified, it is recommended that practitioners consider individual patient needs and risk before recommending weight loss (and therefore BMI reduction).