Surgeon Decision-Making for Individuals With Obesity When Indicating Total Joint Arthroplasty

Total Knee Arthroplasty With or Without Prior Bariatric Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Studies comparing the outcomes of bariatric surgery followed by total knee arthroplasty (TKA) versus TKA alone in obese patients have disparate results. This systematic review and meta-analysis sought to compare TKA with and without prior bariatric surgery in obese patients.

METHODS

MEDLINE, PubMed, and Embase were searched from inception to April 9, 2023. There were twelve included studies that yielded 2,876,547 patients, of whom 62,818 and 2,813,729 underwent TKA with and without prior bariatric surgery, respectively. Primary outcomes were medical complications (ie, urinary tract infection, pneumonia, renal failure, respiratory failure, venous thromboembolism [VTE], arrhythmia, myocardial infarction, and stroke); surgical complications (ie, wound complications [eg, infection, hematoma, dehiscence, delayed wound healing, and seroma], periprosthetic joint infection, mechanical complications, periprosthetic fracture, knee stiffness, and failed hardware); revision, and mortality. Secondary outcomes were blood transfusion, length of stay (day), and readmission.

RESULTS

The odds ratios (OR) of 90-day VTE (OR = 0.75 [0.66, 0.85], P < .00001), 90-day stroke (OR = 0.58 [0.41, 0.81], P = .002), and 1-year periprosthetic fracture (OR = 0.74 [0.55, 0.99], P = .04) were lower in those who underwent bariatric surgery before TKA. Although the mean difference in hospital stays (-0.19 days [-0.23, -0.15], P < .00001) was statistically less in those who underwent bariatric surgery before TKA, it was not clinically relevant. The other outcomes were similar between the groups.

CONCLUSIONS

Bariatric surgery before TKA is beneficial in terms of a lower risk of VTE, stroke, and periprosthetic fracture. This analysis suggests surgeons consider discussing bariatric surgery before TKA in obese patients, especially those who are at risk of VTE and stroke.

Body Mass Index Improvement Reduces Total Knee Arthroplasty Complications Among Patients Who Have Extreme, But Not Severe, Obesity

BACKGROUND

While morbid obesity has been associated with increased complication risk in primary total knee arthroplasty (TKA), limited evidence is available to attribute decreased surgical complication rates with body mass index (BMI) reduction.

METHODS

We retrospectively assessed 464 unilateral TKAs performed in morbidly obese patients, including 158 extremely obese (BMI > 45) and 306 severely obese patients (BMI 40 to 44.9). A detailed medical record review identified concurrent modifiable risk factors and successful preoperative BMI reduction, reaching either a contemporary risk target (BMI < 40) or an institutionally accepted threshold (BMI < 45). Postoperative blood glucose levels and one-year adverse outcomes (periprosthetic joint infection (PJI), wound dehiscence, knee manipulation, periprosthetic fracture) were compared to 557 contemporary control subjects with expected slightly lower (moderate obesity, BMI 35 to 39.9) or sufficiently lower complication risk (overweight, BMI 25 to 29.9).

RESULTS

PJI and postoperative hyperglycemia were identified more frequently among morbidly obese patients in comparison with a moderately obese control group. Extremely obese patients (BMI > 45) whose BMI improved below 45 had no measurable difference in infection risk from the control group (OR [odds ratio] 0.84, 95% CI [confidence interval] 0.04 to 16.88), while those with a non-improved BMI had a significantly higher risk (OR 7.70, 95% CI 1.89 to 31.41). No significant differences in the risk for infection were observed between severely obese patients (BMI 40 to 44.9) with preoperative BMI improvement (1.5% rate, OR 1.70, 95% CI 0.17 to 16.57) or non-improvement (1.7% rate, OR 1.87, 95% CI 0.41 to 8.43).

CONCLUSIONS

Preoperative medical optimization may decrease postoperative TKA complications. The findings of this study support BMI improvement for extremely obese patients (BMI > 45). The assignment of 40 BMI as a threshold for otherwise healthy patients may exclude patients from potential surgical benefits without realizing risk reduction.

Substantial Weight Loss May Not Improve Early Outcomes of Total Knee Arthroplasty in the Morbidly Obese

BACKGROUND

Body mass index (BMI) cutoffs for morbidly obese patients otherwise indicated for total knee arthroplasty (TKA) have been widely proposed and implemented, though they remain controversial. Previous studies suggested that a 5% reduction in BMI may be associated with fewer postoperative complications. Thus, the purpose of this study was to determine whether a substantial reduction in preoperative BMI in morbidly obese patients improved 90-day outcomes after TKA.

METHODS

There were 1,270 patients who underwent primary TKA at a single institution and had a BMI > 40 recorded during the year prior to surgery. Patients were stratified into three cohorts based on whether their BMI within 3 months to 1 year preoperatively had decreased by ≥ 5% (228 patients [18%]); increased by ≥ 5% (310 [24%]); or remained unchanged (within 5%) (732 [58%]) on the day of surgery. There were several baseline differences between the cohorts with respect to medical comorbidities. The rate of 90-day complications and six-week patient-reported outcome measures were compared via univariate and multivariable analyses.

RESULTS

On univariate analysis, individual and total complication rates were similar between the cohorts (P > .05). On multivariable logistic regression, the risk of complications was similar in patients who had decreased versus unchanged BMI (OR [odds ratio] 1.0; P = .898). However, there was a higher risk of complications in the increased BMI cohort compared to those patients who had an unchanged BMI (OR 1.5; P = .039). The six-week patient-reported outcome measures were similar between the cohorts.

CONCLUSIONS

Patients who have a BMI > 40 who achieved a meaningful reduction in BMI prior to TKA did not have a lower rate of 90-day complications than those whose BMI remained unchanged. Furthermore, considering that nearly one in four patients experienced a significant increase in BMI while awaiting surgery, postponing TKA may actually be detrimental.

Obesity Severity Does Not Associate With Rate, Timing, or Invasiveness of Early Reinterventions After Total Knee Arthroplasty

BACKGROUND

The use of body mass index (BMI) cutoff values has been suggested for proceeding with total knee arthroplasty (TKA) in obese patients. However, the relationship between obesity severity and early reoperations after TKA is poorly defined. This study evaluated whether increased World Health Organization (WHO) obesity class was associated with risk, severity, and timing of reintervention within one year after TKA.

METHODS

There were 8,674 patients from our institution who had a BMI ≥ 30 and underwent unilateral TKA for primary osteoarthritis between 2016 and 2021. Patients were grouped by WHO obesity class: 4,456 class I (51.5%), 2,527 class II (29.2%), and 1,677 class III (19.4%). A chart review was performed to determine patient characteristics and identify patients who underwent any closed or open reintervention requiring anesthesia within the first postoperative year. Regression analyses were performed to identify variables associated with increased odds ratios (ORs) for requiring a reintervention, its timing, and invasiveness.

RESULTS

There were 158 patients (1.8%) who required at least one reintervention, and 15 patients (0.2%) required at least 2 reinterventions. Reintervention rates for obesity classes I, II, and III were 1.8% (n = 81), 2.0% (n = 51), and 1.4% (n = 23), respectively. There were 65 closed procedures (41.1%), 47 minor procedures (29.7%), 34 open with or without liner exchange (21.5%), and 12 revisions with component exchange (7.6%). Obesity class was not associated with reintervention rate (P = .3), timing (P = .36), or invasiveness (P = .93). Diabetes (odds ratio [OR] = 2.47; P = .008) was associated with a need for reintervention. Non-Caucasian race (OR = 1.7; P = .01) and Charlson comorbidity index (OR = 2.1; P = .008) were associated with earlier reintervention. No factors were associated with the invasiveness of reintervention.

CONCLUSIONS

The WHO obesity class did not associate with rate, timing, or invasiveness of reintervention after TKA in obese patients. These findings suggest that policies that restrict the indication for elective TKA based only on a BMI limit have limited efficacy in reducing early reintervention after TKA in obese patients.

LEVEL OF EVIDENCE

III.

Consistent Factors Influence Body Mass Index Thresholds for Total Joint Arthroplasty Across Health-Care Systems: A Qualitative Study

BACKGROUND

Body mass index (BMI) thresholds are used as eligibility criteria to reduce complication risk in total joint arthroplasty (TJA). This approach oversimplifies preoperative risk assessment and inadvertently restricts access to effective surgical treatment for osteoarthritis. A prior survey of orthopaedic surgeons in the United States identified complex underlying factors that influence BMI considerations. To understand whether similar factors exist and influence surgeons in a different health-care system setting, we investigated Canadian surgeons' views and use of BMI criterion thresholds for TJA access.

METHODS

A cross-sectional online qualitative survey was conducted with orthopaedic surgeons performing TJA in the Canadian health-care system. Responses were anonymous and questions were open-ended to allow for candid perspectives. Survey data were coded and a systematic process was followed to identify major themes. Findings were compared with U.S. surgeon perspectives.

RESULTS

Sixty-nine respondents had a mean age of 49.0 ± 11.4 years (range, 33 to 79 years), with a mean surgical experience duration of 15.7 ± 11.4 years (range, 2 to 50 years). Surgeons reported variable use of BMI thresholds in practice. Twelve interconnected factors that influence BMI considerations were identified: (1) variable evidence interpretation, (2) surgical challenge, (3) surgeon beliefs and biases, (4) hospital differences, (5) access to resources, (6) health system bias, (7) patient health status, (8) patient body fat distribution, (9) patient decisional burden (to lose weight or accept risk), (10) evidence gaps and uncertainties, (11) need for innovation, and (12) societal views. Nine themes matched with findings from U.S. surgeons.

CONCLUSIONS

Parallel to the United States, complex, interconnected factors influence Canadian orthopaedic surgeons' variable use of BMI restrictions for TJA eligibility. Despite different health-care systems and reimbursement models, similar technical and personal factors were identified. With TJA practice guidelines advising against hard BMI criteria, attention regarding access to resources, surgical training, and innovations to address TJA complexity in patients with large bodies are critically needed. Future advancements in this sphere must balance barrier removal with risk reduction to ensure safe and equitable surgical care.

CLINICAL RELEVANCE

This study may influence surgeon behaviors with regard to hard BMI cutoffs for TJA and encourage critical thought about factors that influence decisions about surgical eligibility for patients with high BMI.

The obesity challenge in joint replacement: a multifaceted analysis of self-reported health status and exercise capacity using NHANES data: a population-based study

BACKGROUND

Joint replacement is successful for end-stage oeteoarthritis, with obesity linked to elevated risk. But the impact of obesity on self-reported health and exercise capacity among joint replacement patients remains complex and requires investigation.

METHODS

This study utilizes data from the National Health and Nutrition Examination Survey (NHANES) to examine the relationship between obesity severity, demographic factors, medical comorbidities, and self-reported health status. The relationship between general health status and BMI was analyzed using multivariable regression, and further illustrated using a restricted cubic spline. Additionally, a bibliometric analysis and systematic review was done to frame the research within the broader context of existing knowledge and demographic specifics.

RESULTS

Analysis of NHANES data involving 327 joint replacement patients yielded intriguing insights. The difference in self-reported health between BMI groups did not achieve conventional statistical significance ( P =0.06), and multivariable analysis showed that even severely obese patients did not exhibit significantly elevated risk of poor/fair self-reported health compared to normal weight subjects. Among severely obese individuals (BMI>40), 40.63% still rated their health positively. However, stratified analyses indicated that obesity correlated with negative health reports across sex, age, and education strata. Notably, physical functioning emerged as a robust predictor of self-reported health, with those reporting no walking difficulties having significantly lower odds of poor/fair health (Odds ratio=0.37, P =0.01).

CONCLUSION

The study highlights the need for healthcare providers to consider individual physical abilities and comorbidities alongside obesity severity when discussing treatment options with joint replacement patients. It supports tailored interventions and informed shared decision-making. Future research could explore effective weight management strategies for obese individuals undergoing joint replacement.

Increasing Body Mass Index Not Associated With Worse Patient-Reported Outcomes After Primary THA or TKA

INTRODUCTION

As the US obesity epidemic continues to grow, so too does comorbid hip and knee arthritis. Strict body mass index (BMI) cutoffs for total hip and knee arthroplasty (THA and TKA) in the morbidly obese have been proposed and remain controversial, although current American Academy of Orthopaedic Surgeons guidelines recommend a BMI of less than 40 m/kg2 before surgery. This study sought to compare patient-reported outcomes and 30-day complication, readmission, and revision surgery rates after THA or TKA between morbidly obese patients and nonmorbidly obese control subjects.

METHODS

All patients undergoing primary THA and TKA at our institution from May 2020 to July 2022 were identified. Patient demographics, surgical time, length of stay and 30-day readmission, revision surgery, and complication rates were prospectively collected. Preoperative and postoperative Hip and Knee Society (Hip Osteoarthritis Outcome Score [HOOS] and Knee Osteoarthritis Outcome Score [KOOS]) were collected. Patients were stratified by BMI as ideal weight (20 to 24.9), overweight (25 to 29.9), class I obese (30 to 34.9), class II obese (35 to 39.9), and morbidly obese (>40 m/kg2).

RESULTS

A total of 1,423 patients were included for final analysis. No difference was observed in 30-day unplanned return to emergency department, readmission, or revision surgery in the morbidly obese cohort. Morbidly obese patients undergoing THA had lower preoperative HOOS (49.5 versus 54.5, P = 0.004); however, there was no difference in postoperative HOOS or KOOS at 12 months across all cohorts.

DISCUSSION

No difference was observed in 30-day return to emergency department, readmission, or revision surgery in the morbidly obese cohort. Despite a lower preoperative HOOS, there was no difference in 12-month HOOS or KOOS when stratified by BMI. These findings suggest that such patients may achieve similar benefit from arthroplasty as their ideal weight counterparts.

Optimal timing of hip and knee arthroplasty after bariatric surgery: A systematic review

Background

Obesity is a risk factor for the development of osteoarthritis and contributes to the increasing demand for total joint arthroplasty (TJA). Because a lower preoperative weight decreases the risk of complications after TJA, and because bariatric surgery (BS) can reduce weight and comorbidity burden, orthopedic surgeons often recommend BS prior to TJA in patients with obesity. However, the optimal timing of TJA after BS in terms of complications, revisions and dislocations is unknown.

Methods

PubMed, Embase and Cochrane CENTRAL databases were systematically searched for any type of study reporting rates of complications, revisions and dislocations in patients who had TJA after BS. The included studies' quality was assessed using the Newcastle-Ottawa Scale.

Results

Out of the 16 studies eligible for review, eight registry-based retrospective studies of high to moderate quality compared different time periods between BS and TJA and overall their results suggest little differences in complication rates. The remaining eight retrospective studies evaluated only one time period and had moderate to poor quality. Overall, there were no clear differences in outcomes after TJA for the different time frames between BS and TJA.

Conclusion

The results of this systematic review suggest that there is limited and insufficient high-quality evidence to determine the optimal timing of TJA after BS in terms of the rates of complications, revisions and dislocations. Given this lack of evidence, timing of TJA after BS will have to be decided by weighing the individual patients' risk factors against the expected benefits of TJA.

Osteoarthritis in patients with obesity: The bariatric surgery impacts on its evolution

Obesity is one of the main modifiable risk factors for osteoarthritis (OA). Moreover, obesity is associated with greater pain intensity and functional limitation, but also with a significantly lower responder rate to intra-articular treatments. Consequently, an arthroplasty is indicated earlier and more frequently in patients with obesity. However, pain and functional symptoms improve slightly less after arthroplasty in patients with obesity, who display higher incidence of early and late complications following prosthetic surgery. Bariatric surgery (BS) has increased worldwide and is efficient to induce major and sustainable weight-loss. Importantly, BS significantly reduces pain and functional limitation in patients with symptomatic knee OA. Biomarkers analysis also revealed a decrease in catabolic factors and an increase in anabolic one after BS suggesting a structural protective effect in knee OA. Nevertheless, the impact of BS prior to arthroplasty remains unclear. BS seems to decrease short- and mid-term complications such as infections or thrombosis. However, BS does not appear to modify long-term complications rate, and may even increase it, especially revisions and infections. Although few studies have compared the symptomatic and functional outcomes of joint replacement with or without BS, these are not significantly improved by prior BS. Despite these heterogeneous results, medico-economic studies found that BS prior to arthroplasty was cost-effective. To conclude, BS could significantly reduce the symptoms of OA and potentially slow its progression, but appears more disappointing in preventing long-term complications of arthroplasties and improving their functional results.

A Longitudinal Analysis of Weight Changes before and after Total Knee Arthroplasty: Weight Trends, Patterns, and Predictors

Longitudinal data on patient trends in body mass index (BMI) and the proportion that gains or loses significant weight before and after total knee arthroplasty (TKA) are scarce. This study aimed to observe patients longitudinally for a 2-year period and determine (1) clinically significant BMI changes during the 1 year before and 1 year after TKA and (2) identify factors associated with clinically significant weight changes.A prospective cohort of 5,388 patients who underwent primary TKA at a tertiary health care institution between January 2016 and December 2019 was analyzed. The outcome of interests was clinically significant weight changes, defined as a ≥5% change in BMI, during the 1-year preoperative and postoperative periods, respectively. Patient-specific variables and demographics were assessed as potential predictors of weight change using multinomial logistic regression.Overall, 47% had a stable weight throughout the study period (preoperative: 17% gained, 15% lost weight; postoperative: 19% gained, 16% lost weight). Patients who were older (odds ratio [OR] = 0.95), men (OR = 0.47), overweight (OR = 0.36), and Obese Class III (OR = 0.06) were less likely to gain weight preoperatively. Preoperative weight loss was associated with postoperative weight gain 1 year after TKA (OR = 3.03). Preoperative weight gain was associated with postoperative weight loss 1 year after TKA (OR = 3.16).Most patients maintained a stable weight before and after TKA. Weight changes during the 1 year before TKA were strongly associated with reciprocal rebounds in BMI postoperatively, emphasizing the importance of ongoing weight management during TKA and the recognition of patients at higher risk for weight gain.Level of evidence II (prospective cohort study).

Glucagon-like Peptide-1 Agonists: What the Orthopaedic Surgeon Needs to Know

» Orthopaedic surgeons are increasingly likely to encounter patients with obesity and/or type 2 diabetes taking glucagon-like peptide-1 (GLP-1) agonists for weight loss.» GLP-1 agonists are an effective treatment for weight loss with semaglutide and tirzepatide being the most effective agents. Randomized controlled trials using these agents have reported weight loss up to 21 kg (46 lb).» The use of GLP-1 agonists preoperatively can improve glycemic control, which can potentially reduce the risk of postoperative complications. However, multiple cases of intraoperative aspiration/regurgitation have been reported, potentially related to the effect of GLP-1 agonists on gastric emptying.» While efficacious, GLP-1 agonists may not produce sufficient weight loss to achieve body mass index cutoffs for total joint arthroplasty depending on individual patient factors, including starting bodyweight. Multifactorial approaches to weight loss with focus on lifestyle modification in addition to GLP-1 agonists should be considered in such patients.» Although GLP-1 agonists are efficacious agents for weight loss, they may not be accessible or affordable for all patients. Each patient's unique circumstances should be considered when creating an ideal weight loss plan during optimization efforts.

Medical Weight Optimization for Arthroplasty Patients: A Primer of Emerging Therapies for the Joint Arthroplasty Surgeon

The obesity epidemic in the United States continues to grow with more than 40% of individuals now classified as obese (body mass index >30). Obesity has been readily demonstrated to increase the risk of developing hip and knee osteoarthritis and is known to increase the risk of complications following joint arthroplasty. Weight loss prior to arthroplasty may mitigate this risk of complications; however, the existing evidence remains mixed with no clear consensus on the optimal method of weight loss and timing prior to arthroplasty. Treatment options for weight loss have included nonsurgical lifestyle modifications consisting of structured diet, physical activity, and behavioral modification, as well as bariatric and metabolic surgery (ie, sleeve gastrectomy, Roux-en-Y gastric bypass, and the adjustable gastric band). Recently, glucagon-like peptide-1 receptor agonists have gained notable popularity within the scientific literature and media for their efficacy in weight loss. The aim of this review is to provide a foundational primer for joint arthroplasty surgeons regarding the current and emerging options for weight loss to aid surgeons in shared decision-making with patients prior to arthroplasty.

Are Patients With Morbid Obesity at Increased Risk of Pulmonary Embolism or Proximal Deep Vein Thrombosis After Lower Limb Arthroplasty? A Large-database Study

BACKGROUND

Whether increased BMI is associated with an increased risk of venous thromboembolism (VTE) is controversial. Despite this, BMI > 40 kg/m 2 remains a common cutoff for lower limb arthroplasty eligibility. Current United Kingdom national guidelines list obesity as a risk factor for VTE, but these are based on evidence that has largely failed to differentiate between potentially minor (distal deep vein thrombosis [DVT]), and more harmful (pulmonary embolism [PE] and proximal DVT) diagnoses. Determining the association between BMI and the risk of clinically important VTE is needed to improve the utility of national risk stratification tools.

QUESTIONS/PURPOSES

(1) In patients undergoing lower limb arthroplasty, is BMI 40 kg/m 2 or higher (morbid obesity) associated with an increased risk of PE or proximal DVT within 90 days of surgery, compared with patients with BMI less than 40 kg/m 2 ? (2) What proportion of investigations ordered for PE and proximal DVT were positive in patients with morbid obesity who underwent lower limb arthroplasty compared with those with BMI less than 40 kg/m 2 ?

METHODS

Data were collected retrospectively from the Northern Ireland Electronic Care Record, a national database recording patient demographics, diagnoses, encounters, and clinical correspondence. Between January 2016 and December 2020, 10,217 primary joint arthroplasties were performed. Of those, 21% (2184 joints) were excluded; 2183 were in patients with multiple arthroplasties and one had no recorded BMI. All 8033 remaining joints were eligible for inclusion, 52% of which (4184) were THAs, 44% (3494) were TKAs, and 4% (355) were unicompartmental knee arthroplasties; all patients had 90 days of follow-up. The Wells score was used to guide the investigations. Indications for CT pulmonary angiography for suspected PE included pleuritic chest pain, reduced oxygen saturations, dyspnea, or hemoptysis. Indications for ultrasound scans for suspected proximal DVT included leg swelling, pain, warmth, or erythema. Distal DVTs were recorded as negative scans because we do not treat them with modified anticoagulation. The division of categories was set at BMI 40 kg/m 2 , a common clinical cutoff used in surgical eligibility algorithms. Patients were grouped according to WHO BMI categories to assess for the following confounding variables: sex, age, American Society of Anesthesiologists grade, joint replaced, VTE prophylaxis, grade of operative surgeon, and implant cement status.

RESULTS

We found no increase in the odds of PE or proximal DVT in any WHO BMI category. When comparing patients with BMI less than 40 kg/m 2 with those with a BMI of 40 kg/m 2 or higher, there was no difference in the odds of PE (0.8% [58 of 7506] versus 0.8% [four of 527]; OR 1.0 [95% CI 0.4 to 2.8]; p > 0.99) or proximal DVT (0.4% [33 of 7506] versus 0.2% [one of 527]; OR 2.3 [95% CI 0.3 to 17.0]; p = 0.72). Of those who received diagnostic imaging, 21% (59 of 276) of CT pulmonary angiograms and 4% (34 of 718) of ultrasounds were positive for patients with BMI less than 40 kg/m 2 compared with 14% (four of 29; OR 1.6 [95% CI 0.6 to 4.5]; p = 0.47) and 2% (one of 57; OR 2.7 [95% CI 0.4 to 18.6]; p = 0.51) for patients with BMI 40 kg/m 2 or higher. There was no difference in the percentage of CT pulmonary angiograms ordered (4% [276 of 7506] versus 5% [29 of 527]; OR 0.7 [95% CI 0.5 to 1.0]; p = 0.07) or ultrasounds ordered (10% [718 of 7506] versus 11% [57 of 527]; OR 0.9 [95% CI 0.7 to 1.2]; p = 0.49) for BMI less than 40 kg/m 2 and BMI 40 kg/m 2 or higher.

CONCLUSION

Increased BMI should not preclude individuals from lower limb arthroplasty based on suspected risk of clinically important VTE. National VTE risk stratification tools should be based on evidence assessing clinically relevant VTE (specifically, proximal DVT, PE, or death of thromboembolism) only.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Go Big or Go Home: Obesity and Total Joint Arthroplasty

Obesity is highly prevalent, and it is expected to grow considerably in the United States. The association between obesity and an increased risk of complications following total joint arthroplasty (TJA) is widely accepted. Many believe that patients with body mass index (BMI) >40 have complications rates that may outweigh the benefits of surgery and should consider delaying it. However, the current literature on obesity and outcomes following TJA is observational, very heterogeneous, and full of confounding variables. BMI in isolation has several flaws and recent literature suggests shifting from an exclusively BMI <40 cutoff to considering 5 to 10% preoperative weight loss. BMI cutoffs to TJA may also restrict access to care to our most vulnerable, marginalized populations. Moreover, only roughly 20% of patients instructed to lose weight for surgery are successful and the practice of demanding mandatory weight loss needs to be reconsidered until convincing evidence exists that supports risk reduction as a result of preoperative weight loss. Obese patients can benefit greatly from this life-changing procedure. When addressing the potential difficulties and by optimizing preoperative assessment and intraoperative management, the surgery can be conducted safely. A multidisciplinary patient-centered approach with patient engagement, shared decision-making, and informed consent is recommended.

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.

The Impact of Metabolic Syndrome and Obesity on Perioperative Total Joint Arthroplasty Outcomes: The Obesity Paradox and Risk Assessment in Total Joint Arthroplasty

Background

The relationship between elevated body mass index (BMI) and adverse outcomes in joint arthroplasty is well established in the literature. This paper aims to challenge the conventional thought of excluding patients from a total knee or hip replacement based on BMI alone. Instead, we propose using the metabolic syndrome (MetS) and its defining components to better identify patients at high risk for intraoperative and postoperative complications.

Methods

Patients who underwent primary, elective total knee and total hip arthroplasty were identified in the 2015-2020 American College of Surgeons National Surgical Quality Improvement Program database. Several defining components of MetS, such as hypertension, diabetes, and obesity, were compared to a metabolically healthy cohort. Postoperative outcomes assessed included mortality, length of hospital stay, 30-day surgical and medical complications, and discharge.

Results

The outcomes of 529,737 patients from the American College of Surgeons National Surgical Quality Improvement Program who underwent total knee and total hip arthroplasty were assessed. MetS is associated with increased complications and increased mortality. Both hypertension and diabetes are associated with increased complications but have no impact on mortality. Interestingly, while obesity was associated with increased complications, there was a significant decrease in mortality.

Conclusions

Our results show that the impact of MetS is more than the sum of its constitutive parts. Additionally, obese patients experience a protective effect, with lower mortality than their nonobese counterparts. This study supports moving away from strict BMI cutoffs alone for someone to be eligible for an arthroplasty surgery and offers more granular data for risk stratification and patient selection.

"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.

Total Hip and Knee Arthroplasty Surgery in the Morbidly Obese Patient: A Critical Analysis Review

»

Obesity, defined as body mass index (BMI) ≥30, is a serious public health concern associated with an increased incidence of stroke, diabetes, mental illness, and cardiovascular disease resulting in numerous preventable deaths yearly.

»

From 1999 through 2018, the age-adjusted prevalence of morbid obesity (BMI ≥40) in US adults aged 20 years and older has risen steadily from 4.7% to 9.2%, with other estimates showing that most of the patients undergoing hip and knee replacement by 2029 will be obese (BMI ≥30) or morbidly obese (BMI ≥40).

»

In patients undergoing total joint arthroplasty (TJA), morbid obesity (BMI ≥40) is associated with an increased risk of perioperative complications, including prosthetic joint infection and mechanical failure necessitating aseptic revision.

»

The current literature on the role that bariatric weight loss surgery before TJA has on improving surgical outcomes is split and referral to a bariatric surgeon should be a shared-decision between patient and surgeon on a case-by-case basis.

»

Despite the increased risk profile of TJA in the morbidly obese cohort, these patients consistently show improvement in pain and physical function postoperatively that should be considered when deciding for or against surgery.

Self-Reported Health of Severely Obese US Adults With Osteoarthritis

BACKGROUND

Severe obesity is associated with complications following arthroplasty, leading surgeons to increasingly counsel patients regarding weight loss. For patients seeking arthroplasty, learning that severe obesity may be a relative contraindication to surgery can create a challenging clinical interaction. We sought to describe the self-reported health of United States (US) adults who had severe obesity and osteoarthritis (OA) to better understand patient perspectives.

METHODS

The National Health and Nutrition Examination Survey, a nationally representative sample of the US population, was used to identify adult participants who had a body mass index (BMI) over 35 and an OA diagnosis. In total, 889 participants representing a US population of 9,604,722 were included. Self-reported health was dichotomized as poor to fair versus good to excellent. Analyses were weighted to produce national estimates. Associations between obesity severity and patient characteristics with self-reported health were assessed.

RESULTS

Of US adults with a BMI over 35 and OA diagnosis, 64% rated their health as good or better. For adults who had a BMI over 45, 55% still reported their health as good or better. The strongest predictors of self-reported health were measures of physical functioning. Only 37% of participants who had much difficulty walking a quarter mile rated their health as good or better compared to 86% without difficulty (P < .001).

CONCLUSION

Approximately two-thirds of patients who have severe obesity and OA do not perceive their health as compromised and consider decreased physical function as the primary driver of decreased health. This suggests that counseling about the association between obesity and overall health may improve shared decision making and that patient satisfaction metrics may be difficult to interpret in these clinical situations.

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

BACKGROUND

Obesity is a well-established risk factor for complications following primary total knee arthroplasty (TKA). The purpose of this study is to utilize 3 national databases to develop projections of obesity within the general population and primary TKA 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 27447 was used to identify primary TKA 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 8,372,221 individuals were included (7,986,414 BRFSS, 385,807 NSQIP TKA). From 2011 to 2019, the prevalence of normal weight and overweight individuals declined in the general population (BRFSS) and in primary TKA. Prevalence of obese/morbidly obese individuals increased in the general population from 31% to 36% and in primary TKA from 60% to 64%. Projection models estimate that by 2029, 46% of the general population will be obese/morbidly obese and 69% of primary TKA will be obese/morbidly obese.

CONCLUSION

By 2029, we estimate ≥69% of primary TKA 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.

Does Bariatric Surgery Prior to Primary Total Knee Arthroplasty Improve Outcomes?

BACKGROUND

Recent advancements in bariatric surgical techniques have increased its utilization for the management of morbid obesity prior to total knee arthroplasty (TKA). We hypothesized that bariatric surgery prior to primary TKA would mitigate postoperative complications and improve implant survivorship.

METHODS

A retrospective review from 1992-2020 identified 205 bariatric surgery patients with subsequent primary TKA. This cohort was matched 1:1:1 to patients without bariatric surgery and with BMI <40 kg/m² and BMI ≥40 kg/m². Revisions, reoperations, and 90-day complications were evaluated. Subgroup analysis evaluated bariatric patients with BMI >40 kg/m² at TKA, the time between surgeries, and compared historical to contemporary bariatric techniques.

RESULTS

Bariatric patients demonstrated higher revision rates than low (HR 4, P < .01) and high BMI (HR 9, P < .01) controls, and increased reoperations when compared to the low (HR 2, P < .01) and high BMI (HR 6, P < .01) groups. Reoperation for instability was more common in bariatric patients than low (HR 15, P = .01) and high BMI (HR 17, P < .01) groups. Reoperation for infection was higher in bariatric patients relative to the high BMI (HR 6, P = .03), but not the low BMI cohort (HR 3, P = .06). There was no difference in 90-day complications (P = .33). Bariatric patients with high BMI and contemporary bariatric procedures did not significantly impact complications or survivorship, but bariatric surgery >2 years before TKA was associated with higher revision rates (P = .01).

CONCLUSION

This study found that bariatric surgery patients who undergo primary TKA have worse implant survivorship, mostly related to infection and instability. Further investigation into perioperative optimization is warranted.

LEVEL OF EVIDENCE

Prognostic Level IV.

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.

Patterns and Predictors of Weight Change Before and After Total Hip Arthroplasty in Class 2 and 3 Obese Patients

BACKGROUND

This study aimed to better understand body mass index (BMI) change patterns and factors associated with BMI change before and after total hip arthroplasty (THA) in Class 2 and 3 obese patients, and assess if preoperative or postoperative BMI change affects postoperative clinical outcomes.

METHODS

We retrospectively reviewed World Health Organization Class 2 and 3 obese patients (BMI > 35.0 at surgery) who underwent THA at a tertiary medical center from 2010 to 2020. BMI was recorded at 1 year preoperatively (mean 11.6 months), and at most recent postoperative visit (mean 29.0 months). Baseline demographics and postoperative clinical outcomes were recorded.

RESULTS

We reviewed 436 THAs with a mean age of 59.9 (11.5) years. Leading up to surgery 55.5% had unchanged BMI, and postoperatively 48.2% had unchanged BMI. Multivariate logistic regression revealed that those who lost BMI preoperatively were more likely to gain BMI postoperatively (odds ratio [OR] 3.28, confidence interval [CI] 1.83-5.97, P = .005), but those who gained >5% BMI preoperatively had no association with BMI change postoperatively. Those in a higher BMI class preoperatively were less likely to gain BMI preoperatively (Class 3 obese patients: OR 0.001, CI 0.0002-0.004, P < .001). African American patients were more likely to gain BMI preoperatively (OR 2.32, CI 1.16-4.66, P = .017). We did not detect an association between BMI change and postoperative clinical outcomes.

CONCLUSION

In World Health Organization Class 2 or 3 obese patients, most maintained BMI between their first preoperative and final postoperative visit. Preoperatively, Class 3 obese patients were less likely to gain weight than Class 2 obese patients. The primary predictor of postoperative weight gain was preoperative weight loss. Weight change preoperatively and postoperatively were not associated with worse clinical outcomes.

Relative Contribution of Outpatient Arthroplasty Risk Assessment Score Medical Comorbidities to Same-Day Discharge After Primary Total Joint Arthroplasty

BACKGROUND

Selection of patients who can safely undergo outpatient total joint arthroplasty (TJA) is an increasing priority given the growth of ambulatory TJA. This study quantified the relative contribution and weight of 52 medical comorbidities comprising the Outpatient Arthroplasty Risk Assessment (OARA) score as predictors of safe same-day discharge (SDD).

METHODS

The medical records of 2748 primary TJAs consecutively performed between 2014 and 2020 were reviewed to record the presence or absence of medical comorbidities in the OARA score. After controlling for patients not offered SDD due to OARA scores and patients who were offered but declined SDD, the final analysis sample consisted of 631 cases, 92.1% of whom achieved SDD and 7.9% of whom did not achieve SDD. Odds ratios were calculated to quantify the extent to which each comorbidity is associated with achieving SDD.

RESULTS

Demographic characteristics of analysis cases were consistent with a high-volume TJA practice in a US metropolitan area. Among testable OARA comorbidities, 53% significantly decreased the likelihood of SDD by 2.3 (body mass index [BMI] ≥40 kg/m²) to 12 (history of post-operative confusion and pacemaker dependence) times. BMI between 30 and 39 kg/m² did not affect the likelihood of SDD (P = .960), and BMI ≥40 kg/m² had the smallest odds ratio in our study (2.28, 95% confidence interval 1.11-4.67, P = .025).

CONCLUSION

Study findings contribute to the refinement of the OARA score as a successful predictor of safe SDD following primary TJA while maintaining low 90-day readmission rates.