Association of Surgical Experience With Risk of Complication in Total Hip Arthroplasty Among Patients With Severe Obesity

Is Preoperative Weight Reduction in Patients Who Have Body Mass Index ≥ 40 Associated With Lower Complication Rates After Primary Total Hip Arthroplasty?

BACKGROUND

Given the heightened risk of postoperative complications associated with obesity, delaying total hip arthroplasty (THA) in patients who have a body mass index (BMI) > 40 to maximize preoperative weight loss has been advocated by professional societies and orthopaedic surgeons. While the benefits of this strategy are not well-understood, previous studies have suggested that a 5% reduction in weight or BMI may be associated with reduced complications after THA.

METHODS

We identified 613 patients who underwent primary THA in a single institution during a 7-year period and who had a BMI >40 recorded from 9 to 12 months prior to surgery. Subjects were stratified into 3 cohorts based on whether their baseline BMI decreased by >5% (147 patients, 24%), was unchanged ( ± 5%) (336 patients, 55%), or increased by >5% (130 patients, 21%) on the day of surgery. The frequency of 90-days Hip Society and Centers for Medicare & Medicaid Services complications was compared between these cohorts. There were significant baseline differences between the cohorts with respect to baseline American Society of Anesthesiologists class (P < .001) and hemoglobin A1C (P = .011), which were accounted for in a multivariate regression analysis.

RESULTS

In univariate analysis, there was a lower incidence of readmission (P = .025) and total complications (P = .005) in the increased BMI cohort. The overall complication rate was 18.4% in the decreased BMI cohort, 17.6% in the unchanged cohort, and 6.2% in the increased cohort. However, multivariable regression analysis controlling for potential confounders did not find that preoperative change in BMI was associated with differences in 90-days complications between cohorts (P > .05).

CONCLUSIONS

Patients who have a BMI >40 and achieved a clinically significant (>5%) BMI reduction prior to THA did not have a lower risk of 90-days complications or readmissions. Thus, delaying THA in these patients to encourage weight loss may result in restricting access to a beneficial surgery without an appreciable safety benefit.

The Association Between Surgeon Volume and Dislocation After Total Hip Arthroplasty: A Nationwide Evaluation of 5,106 Orthopaedic Surgeons

INTRODUCTION

The relationship between surgeon volume and risk of dislocation after total hip arthroplasty (THA) is debated. This study sought to characterize this association and assess patient outcomes using a nationwide patient and surgeon registry.

METHODS

The Premier Healthcare Database was queried for adult primary elective THA patients from January 1, 2016, to December 31, 2019. Annual surgeon volume and 90-day risk of dislocation were modeled using multivariable logistic regression with restricted cubic splines. Bootstrap analysis identified a threshold annual case volume, corresponding to the maximum decrease in dislocation risk. Surgeons with an annual volume greater than the threshold were deemed high volume, and those with an annual volume less than the threshold were low volume. Each surgeon within a given year was treated as a unique entity (surgeon-year unit). 90-day complications of patients treated by high-volume and low-volume surgeons were compared.

RESULTS

From 2016 to 2019, 352,131 THAs were performed by 5,106 surgeons. The restricted cubic spline model demonstrated an inverse relationship between risk of dislocation and surgeon volume (threshold: 109 cases per year). A total of 9,967 (87.8%) low-volume surgeon-year units had individual dislocation rates lower than the average of the entire surgeon cohort. Patients treated by high-volume surgeons had decreased risk of dislocation (adjusted odds ratio [aOR], 0.60; 95% CI, 0.54 to 0.67), periprosthetic fracture (aOR, 0.87; 95% CI, 0.76 to 0.99), periprosthetic joint infection (aOR, 0.63; 95% CI, 0.56 to 0.69), readmission (aOR, 0.70; 95% CI, 0.67 to 0.73), and in-hospital death (aOR, 0.60; 95% CI, 0.46 to 0.80).

CONCLUSION

While most of the low-volume surgeons had dislocation rates lower than the cohort average, increasing annual surgeon case volume was associated with a reduction in risk of dislocation after primary elective THA.

THERAPEUTIC LEVEL OF EVIDENCE

Level IV.

Dealing With Complications as a Young Surgeon

Rewarding and honorable, yet challenging and humbling, this is our chosen profession. No matter how robust of a residency and fellowship training we have had or how impactful our mentors have been, nothing can truly prepare us for dealing with complications as new attendings.

Is Operative Time Associated With Obesity-related Outcomes in TKA?

BACKGROUND

Obesity-based cutoffs in TKA are premised on higher rates of postoperative complications. However, operative time may be associated with postoperative complications, leading to an unnecessary restriction of TKA in patients with obesity. If operative time is associated with these obesity-related outcomes, it should be accounted for in order to ensure all measurable factors associated with negative outcomes are examined for patients with obesity after TKA.

QUESTIONS/PURPOSES

We asked: (1) Is operative time, controlling for BMI class, associated with readmission, reoperation, and postoperative major and minor complications? (2) Is operative time associated with a difference in the direction or strength of obesity-related adverse outcomes?

METHODS

In this comparative study, we extracted all records on elective, unilateral TKA between January 2014 and December 2020 in the American College of Surgeons National Surgical Quality Improvement Program database, resulting in an initial sample of 394,381 TKAs. Patients with emergency procedures (0.1% [270]) and simultaneous bilateral TKAs (2% [8736]), missing or null data (1% [4834]), and those with operative times less than 25 minutes (0.1% [548]) were excluded, leaving 96% (379,993) of our original sample size. The National Surgical Quality Improvement Program database was selected because of its inclusion of operative time, which is not found in any other national database. BMI was subdivided into underweight (BMI < 18.5 kg/m 2 , < 1% [719]), normal weight (BMI 18.5 to 24.9 kg/m 2 , 9% [34,513]), overweight (BMI 25.0 to 29.9 kg/m 2 , 27% [101,538]), Class I obesity (BMI 30.0 to 34.9 kg/m 2 , 29% [111,712]), Class II obesity (BMI 35.0 to 39.9 kg/m 2 , 20% [76,605]), and Class III obesity (BMI ≥ 40.0 kg/m 2 , 14% [54,906]). The mean operative time was 91 ± 36 minutes, 61% of patients were women (233,062 of 379,993), and the mean age was 67 ± 9 years. Patients with obesity tended to be younger and more likely to have preoperative comorbidities and longer operative times than patients with normal weight. Multivariable logistic regression models examined the main effects of operative time with respect to 30-day readmission, reoperation, and major and minor medical complications, while adjusting for BMI class and other covariates including age, sex, race, smoking status, and number of preoperative comorbidities. We then evaluated the potential interaction effect of BMI class and operative time. This interaction term helps determine whether the association of BMI with postoperative outcomes changes based on the duration of the surgery, and vice versa. If the interaction term is statistically significant, it implies the association of BMI with adverse postoperative outcomes is inconsistent across all patients. Instead, it varies with the operative time. Adjusted odds ratios and 95% confidence intervals were calculated, and interaction effects were plotted.

RESULTS

After controlling for obesity, longer procedure duration was independently associated with higher odds of all outcomes (30-minute estimates; adjusted ORs are per minute), including readmission (9% per half-hour of surgical duration; adjusted OR 1.003 [95% CI 1.003 to 1.004]; p < 0.001), reoperation (15% per half-hour of surgical duration; adjusted OR 1.005 [95% CI 1.004 to 1.005]; p < 0.001), postoperative major complications (9% per half-hour of surgical duration; adjusted OR 1.003 [95% CI 1.003 to 1.004]; p < 0.001), and postoperative minor complications (18% per half-hour of surgical duration; adjusted OR 1.006 [95% CI 1.006 to 1.007]; p < 0.001). The interaction effect indicates that patients with obesity had lower odds of reoperation than patients with normal weight when operative times were shorter, but higher odds of reoperation with a longer operative duration.

CONCLUSION

We found that operative time, a proxy for surgical complexity, had a moderate, differential association with obesity over a 30-minute period. Perioperative modification of surgical complexity such as surgical techniques, training, and team dynamics may make safe TKA possible for certain patients who might have otherwise been denied surgery. Decisions to refuse TKA to patients with obesity should be based on a holistic assessment of a patient's operative complexity, rather than strictly assessing a patient's weight or their ability to lose weight. Future studies should assess patient-specific characteristics that are associated with operative time, which can further push the development of techniques and strategies that reduce surgical complexity and improve TKA outcomes.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The Impact of Obesity on Total Hip Arthroplasty Outcomes When Performed by High-Volume Surgeons-A Propensity Matched Analysis From a High-Volume Urban Center

BACKGROUND

Previous data suggest that obesity does not impact surgical outcomes following total knee arthroplasty performed by high-volume (HV) surgeons. However, this effect has yet to be studied in total hip arthroplasty (THA) patients. This study aimed to evaluate the impact of patient obesity on THA outcomes when surgery is performed by HV surgeons.

METHODS

A retrospective analysis of patients who underwent primary, elective THA between January 2012 and December 2022 with a HV surgeon (top 25% of surgeons by number of annual primary THA) was performed. Patients were stratified by their body mass index (BMI) into 3 cohorts: BMI ≥ 40 (morbidly obese [MO]), 30 ≤ BMI < 40 (obese), and BMI < 30 (nonobese); and 1:1:1 propensity matched based on baseline characteristics. A total of 13,223 patients were evaluated, of which 669 patients were included in the final matched analysis (223 patients per group). The average number of annual THAs performed for HV surgeons was 171 cases.

RESULTS

The MO patients had significantly longer surgical times (P < .001) and hospital lengths of stay (P < .001). Rates of 90-day readmissions (P = .211) and all-cause, septic, and aseptic revisions at the latest follow-up (P = .268, P = .903, and P = .168, respectively) were comparable between groups. In a subanalysis for non-HV surgeons, MO patients had a significantly greater risk of revision (P = .021) and trended toward significantly greater readmissions (P = .056).

CONCLUSIONS

Clinical outcomes and complication rates after THA performed by a HV surgeon are similar regardless of patient obesity status. Patients who have MO may experience improved outcomes and reduced procedural risks if they are referred to HV surgeons.

LEVEL OF EVIDENCE

III.

Does Operative Time Modify Obesity-related Outcomes in THA?

BACKGROUND

Most orthopaedic surgeons refuse to perform arthroplasty on patients with morbid obesity, citing the higher rate of postoperative complications. However, that recommendation does not account for the relationship of operative time (which is often longer in patients with obesity) to obesity-related arthroplasty outcomes, such as readmission, reoperation, and postoperative complications. If operative time is associated with these obesity-related outcomes, it should be accounted for and addressed to properly assess the risk of patients with obesity undergoing THA.

QUESTIONS/PURPOSES

We therefore asked: (1) Is the increased risk seen in overweight and obese patients, compared with patients in a normal BMI class, associated with increased operative time? (2) Is increased operative time independent of BMI class a risk factor for readmission, reoperation, and postoperative medical complications? (3) Does operative time modify the direction or strength of obesity-related adverse outcomes?

METHODS

This retrospective, comparative study examined 247,108 patients who underwent THA between January 2014 and December 2020 in the National Surgical Quality Improvement Project (NSQIP). Of those, emergency cases (1% [2404]), bilateral procedures (1% [1605]), missing and/or null data (1% [3280]), extreme BMI and operative time outliers (1% [2032]), and patients with comorbidities that are not typical of an elective procedure, such as disseminated cancer, open wounds, sepsis, and ventilator dependence (1% [2726]), were excluded, leaving 95% (235,061) of elective, unilateral THA cases for analysis. The NSQIP was selected due to its inclusion of operative time, which is not found in any other national database. BMI was subdivided into underweight, normal weight, overweight, Class I obesity, Class II obesity, and Class III obesity. Of the patients with a normal weight, 69% (30,932 of 44,556) were female and 36% (16,032 of 44,556) had at least one comorbidity, with a mean operative time of 86 ± 32 minutes and a mean age of 68 ± 12 years. Patients with obesity tend to be younger, male, more likely to have preoperative comorbidities, with longer operative times. Multivariable logistic regression models examined the effects of obesity on 30-day readmission, reoperation, and medical complications, while adjusting for age, sex, race, smoking status, and number of preoperative comorbidities. After we repeated this analysis after adjusting for operative time, an interaction model was conducted to test whether operative time changes the direction or strength of the association of BMI class and adverse outcomes. Adjusted odds ratios (AOR) and 95% confidence intervals (CIs) were calculated, and the interaction effects were plotted.

RESULTS

A comparison of patients with Class III obesity to patients with normal weight showed that the odds of readmission went from 45% (AOR 1.45 [95% CI 1.32 to 1.59]; p < 0.001) to 27% after adjusting for operative time (AOR 1.27 [95% CI 1.01 to 1.62]; p = 0.04), the odds of reoperation went from 93% (AOR 1.93 [95% CI 1.72 to 2.17]; p < 0.001) to 81% after adjusting for operative time (AOR 1.81 [95% CI 1.61 to 2.04]; p < 0.001), and the odds of a postoperative complication went from 96% (AOR 1.96 [95% CI 1.58 to 2.43]; p < 0.001) to 84% after adjusting for operative time (AOR 1.84 [95% CI 1.48 to 2.28]; p < 0.001). Each 15-minute increase in operative time was associated with a 7% increase in the odds of a readmission (AOR 1.07 [95% CI 1.06 to 1.08]; p < 0.001), a 10% increase in the odds of a reoperation (AOR 1.10 [95% CI 1.09 to 1.12]; p < 0.001), and 10% increase in the odds of a postoperative complication (AOR 1.10 [95% CI 1.08 to 1.13]; p < 0.001). There was a positive interaction effect of operative time and BMI for readmission and reoperation, which suggests that longer operations accentuate the risk that patients with obesity have for readmission and reoperation.

CONCLUSION

Operative time is likely a proxy for surgical complexity and contributes modestly to the adverse outcomes previously attributed to obesity alone. Hence, focusing on modulating the accentuated risk associated with lengthened operative times rather than obesity is imperative to increasing the accessibility and safety of THA. Surgeons may do this with specific surgical techniques, training, and practice. Future studies looking at THA outcomes related to obesity should consider the association with operative time to focus on independent associations with obesity to facilitate more equitable access.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Are Patient Outcomes Affected by Surgeon Experience With Total Hip Arthroplasty in Morbidly Obese Patients?

Background

Surgeons with high volume (HV) of total hip arthroplasty (THA) have seen better outcomes than low volume (LV) surgeons. However, literature regarding surgeon volume and outcomes in morbidly obese THA patients is scarce. This study examines the association between surgeon volume with THA in morbidly obese patients (body mass index ≥40) and their clinical outcomes.

Methods

We retrospectively reviewed all morbidly obese patients who underwent primary THA at our institution between March 2012 and July 2020 with 2 years of follow-up. Clinical outcomes were compared between the HV (HVa, top quartile of surgeons with the highest overall yearly THA volume) and LV (LVa) surgeons. Similar analysis was run comparing HV of morbidly obese THA (HVo, top quartile of surgeons with the highest yearly morbidly obese THA volume) and LV of morbidly obese THA (LVo) surgeons.

Results

Six hundred and forty-three patients and 33 surgeons were included. HVa surgeons had significantly shorter length of stay and increased home discharge. HVa and HVo surgeons had significantly shorter operative times. There were no significant differences in overall 90-day major and minor complications or clinical differences in patient-reported outcomes. Revision rates and freedom from revisions did not differ between groups at 2-year follow-up.

Conclusions

HVa surgeons had significantly lower length of stay and operative times and increased discharge to home. There was no significant decrease in complications or revisions in either comparison model. Complications, revision rates, and patient satisfaction in morbidly obese patients who undergo THA may be independent of surgeon volume.

1.5-Stage Versus 2-Stage Exchange Total Hip Arthroplasty for Chronic Periprosthetic Joint Infections: A Comparison of Survivorships, Reinfections, and Patient-Reported Outcomes

BACKGROUND

Management of periprosthetic joint infection after total hip arthroplasty (THA) has traditionally consisted of a 2-stage approach. However, 1.5-stage exchange has garnered recent interest. We compared 1.5-stage to 2-stage exchange recipients. Specifically, we assessed (1) infection-free survivorship and risk factors for reinfection; (2) 2-year surgical/medical outcomes (eg, reoperations, readmissions); (3) Hip Disability and Osteoarthritis Outcome Scores for Joint Replacement (HOOS-JR); and (4) radiographic outcomes (ie, progressive radiolucent lines, subsidences, and failures).

METHODS

We reviewed a consecutive series of 1.5-stage or planned 2-stage THAs. A total of 123 hips were included (1.5-stage: n = 54; 2-stage: n = 69) with mean clinical follow-up of 2.5 years (up to 8 years). Bivariate analyses assessed incidences of medical and surgical outcomes. Additionally, HOOS-JR scores and radiographs were evaluated.

RESULTS

The 1.5-stage exchange had 11% greater infection-free survivorship at final follow-up compared to 2 stages (94% versus 83%, P = .048). Morbid obesity was the only independent risk factor demonstrating increased reinfection among both cohorts. No differences in surgical/medical outcomes were observed between groups (P = .730). HOOS-JR scores improved markedly for both cohorts (1.5-stage difference = 44.3, 2-stage difference = 32.5; P < .001). A total of 82% of 1.5-stage patients did not demonstrate progressive femoral or acetabular radiolucencies, while 94% of 2-stage recipients did not have femoral radiolucencies and 90% did not have acetabular radiolucencies.

CONCLUSION

The 1.5-stage exchange appeared to be an acceptable treatment alternative for periprosthetic joint infections after THAs with noninferior infection eradication. Therefore, this procedure should be considered by joint surgeons for treatment of periprosthetic hip infections.

Total Hip Arthroplasty in Patients Aged 40 to 60 years old: A Population-Based Study

INTRODUCTION

Contemporary total hip arthroplasty (THA) has resolved many implant longevity concerns in younger patients. Patients in their fourth and fifth decades of life are projected to be the fastest growing demographic of THA patients. We aimed to assess this demographic to evaluate the: 1) rate of THA over time; 2) cumulative incidence of revision; and 3) identify risk factors for revision.

METHODS

A retrospective population-based study of patients between 40 and 60 years old undergoing primary THA was conducted using administrative data from a large clinical data repository. A total of 28,414 patients were included for analysis with a mean age of 53 years (range, 40-60 years) and median follow up of 9 years (range, 0-17 years). Linear regressions were used to assess annual rates of THA in this cohort over time. Kaplan-Meier analysis was used to determine cumulative incidence of revision. Multivariate cox proportional hazards models were used to determine association of variables with revision risk.

RESULTS

The annual rate of THA in our population increased by 60.7% over the study period (P <0.0001). Cumulative incidence of revision was 2.9% at 5-years and 4.8% at 10-years. Younger age, women, non-osteoarthritis diagnosis, medical complications, and annual surgeon volume < 60 THA were associated with increased revision risk.

CONCLUSION

Demand for THA continues to dramatically increase in this cohort. Risk of revision was low but multiple risk factors were identified. Future studies will help delineate the effect of these variables on revision risk and assess implant survivorship beyond 10 years.

"I Often Feel Conflicted in Denying Surgery": Perspectives of Orthopaedic Surgeons on Body Mass Index Thresholds for Total Joint Arthroplasty: A Qualitative Study

BACKGROUND

Use of a patient body mass index (BMI) eligibility threshold for total joint arthroplasty (TJA) is controversial. A strict BMI criterion may reduce surgical complication rates, but over-restrict access to effective osteoarthritis (OA) treatment. Factors that influence orthopaedic surgeons' use of BMI thresholds are unknown. We aimed to identify and explore orthopaedic surgeons' perspectives regarding patient BMI eligibility thresholds for TJA.

METHODS

A cross-sectional, online qualitative survey was distributed to orthopaedic surgeons who conduct hip and/or knee TJA in the United States. Survey questions were open-ended, and responses were collected anonymously. Survey data were coded and analyzed in an iterative, systematic process to identify predominant themes.

RESULTS

Forty-five surveys were completed. Respondents were 54.3 ± 12.4 years old (range, 34 to 75 years), practiced in 22 states, and had 21.2 ± 13.3 years (range, 2 to 44 years) of surgical experience. Twelve factors influencing BMI threshold use by orthopaedic surgeons were identified: (1) evidence interpretation, (2) personal experiences, (3) difficulty of surgery, (4) professional ramifications, (5) ethics and biases, (6) health-system policies and performance metrics, (7) surgical capacity and resources, (8) patient body fat distribution, (9) patient self-advocacy, (10) control of decision-making in the clinical encounter, (11) expectations for demonstrated weight loss, and (12) research and innovation gaps.

CONCLUSIONS

Multilevel, complex factors underlie BMI threshold use for TJA eligibility. Addressing identified factors at the patient, surgeon, and health-system levels should be considered to optimally balance complication avoidance with improving access to life-enhancing surgery.

CLINICAL RELEVANCE

This study may influence how orthopaedic surgeons think about their own practices and how they approach patients and consider surgical eligibility.

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.