Role of obesity on the risk for total hip or knee arthroplasty

The role of body mass index in survivorship and clinical outcomes in total shoulder arthroplasty

BACKGROUND

Increased body mass index (BMI) is a potential risk factor for poorer outcomes and complications. However, the influence of BMI on the long-term outcomes of anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) remains to be fully elucidated.

METHODS

Institutional records were queried to identify patients who underwent primary total shoulder arthroplasty (TSA) between 2009 and 2020 with a minimum of 2 years of clinical follow-up. Retrospective review was performed to collect demographic characteristics; comorbidity status; and range-of-motion and strength measurements in forward elevation, external rotation, and internal rotation. Patients were contacted by telephone to provide patient-reported outcomes (PROs). Patients were stratified into 3 cohorts by BMI: underweight or normal weight (U/NW, BMI ≤25 kg/m2), overweight (OW, BMI >25 to ≤30 kg/m2), and obese (BMI >30 kg/m2).

RESULTS

Among 466 TSA patients, 245 underwent aTSA whereas 221 underwent rTSA. In the aTSA cohort, 40 patients were classified as U/NW; 72, as OW; and 133, as obese. Comparatively, the rTSA cohort was composed of 33 U/NW, 79 OW, and 209 obese patients. Patients in the aTSA and rTSA cohorts had an average follow-up period of 5.8 ± 3.2 years and 4.5 ± 2.3 years, respectively. No differences in age at surgery were found in the aTSA group (U/NW vs. obese, 65.2 ± 7.9 years vs. 61.9 ± 8.9 years; P = .133); however, in the rTSA cohort, BMI was found to be inversely related to age at surgery (U/NW vs. obese, 72.4 ± 8.8 years vs. 65.7 ± 8.3 years; P < .001). Across all BMI cohorts, patients saw great improvements in range of motion and strength. Postoperative PROs after TSA did not vary by BMI in terms of Single Assessment Numeric Evaluation, Simple Shoulder Test, visual analog scale pain, and American Shoulder and Elbow Surgeons scores. There was no significant difference in survival rates at 10-year follow-up in the aTSA cohort (U/NW vs. obese, 95.8% vs. 93.2%; P = .753) or rTSA cohort (U/NW vs. obese, 94.7% vs. 94.5%; P = .791).

CONCLUSION

With dramatic improvements in range of motion, minimal differences in PROs, and high rates of implant survival, TSA is a safe and effective treatment option for all patients, including overweight and obese patients.

Genetic and Modifiable Risk Factors for Postoperative Complications of Total Joint Arthroplasty: A Genome-Wide Association and Mendelian Randomization Study

Background: Total joint arthroplasty (TJA) is an orthopedic procedure commonly used to treat damaged joints. Despite the efficacy of TJA, postoperative complications, including aseptic prosthesis loosening and infections, are common. Moreover, the effects of individual genetic susceptibility and modifiable risk factors on these complications are unclear. This study analyzed these effects to enhance patient prognosis and postoperative management. Methods: We conducted an extensive genome-wide association study (GWAS) and Mendelian randomization (MR) study using UK Biobank data. The cohort included 2964 patients with mechanical complications post-TJA, 957 with periprosthetic joint infection (PJI), and a control group of 398,708 individuals. Genetic loci associated with postoperative complications were identified by a GWAS analysis, and the causal relationships of 11 modifiable risk factors with complications were assessed using MR. Results: The GWAS analysis identified nine loci associated with post-TJA complications. Two loci near the PPP1R3B and RBM26 genes were significantly linked to mechanical complications and PJI, respectively. The MR analysis demonstrated that body mass index was positively associated with the risk of mechanical complications (odds ratio [OR]: 1.42; p < 0.001). Higher educational attainment was associated with a decreased risk of mechanical complications (OR: 0.55; p < 0.001) and PJI (OR: 0.43; p = 0.001). Type 2 diabetes was suggestively associated with mechanical complications (OR, 1.18, p = 0.02), and hypertension was suggestively associated with PJI (OR, 1.41, p = 0.008). Other lifestyle factors, including smoking and alcohol consumption, were not causally related to postoperative complications. Conclusions: The genetic loci near PPP1R3B and RBM26 influenced the risk of post-TJA mechanical complications and infections, respectively. The effects of genetic and modifiable risk factors, including body mass index and educational attainment, underscore the need to perform personalized preoperative assessments and the postoperative management of surgical patients. These results indicate that integrating genetic screening and lifestyle interventions into patient care can improve the outcomes of TJA and patient quality of life.

Athlete-Specific Considerations of Cartilage Injuries

Cartilage injuries can present in a diverse setting of anatomic locations, with varying severity, and can impact athletes of all ages and competition levels. Moreover, the timing of when an injury presents introduces an additional dimension to treatment decision-making. Frequently, the level of competition, in conjunction with career trajectory and short-term and long-term athlete goals, will dictate whether a temporary or definitive treatment strategy is ideal. Although indicating the correct therapeutic regimen may prove challenging, understanding the athlete-specific considerations can be essential to meeting the goals of the athlete and other stakeholders involved in the athlete's career. The purpose of this review is to comprehensively present the deliberations a treating physician must consider in managing cartilage injuries within a spectrum of athletic levels ranging from youth to professional levels, with a secondary focus on the presentation of temporizing treatment strategies and associated outcomes.

Glucagon-Like Peptide Receptor-1 Agonists Used for Medically-Supervised Weight Loss in Patients With Hip and Knee Osteoarthritis: Critical Considerations for the Arthroplasty Surgeon

Patients with morbid obesity and concomitant hip or knee osteoarthritis represent a challenging patient demographic to treat as these patients often present earlier in life, have more severe symptoms, and have worse surgical outcomes following total hip and total knee arthroplasty. Previously, bariatric and metabolic surgeries represented one of the few weight loss interventions that morbidly obese patients could undergo prior to total joint arthroplasty. However, data regarding the reduction in complications with preoperative bariatric surgery remain mixed. Glucagon-like peptide receptor-1 (GLP-1) agonists have emerged as an effective treatment option for obesity in patients with and without diabetes mellitus. Furthermore, recent data suggest these medications may serve as potential anti-inflammatory and disease-modifying agents for numerous chronic conditions, including osteoarthritis. This review will discuss the GLP-1 agonists and GLP-1/glucose-dependent insulinotropic polypeptide dual agonists currently available, along with GLP-1/glucose-dependent insulinotropic polypeptide/glucagon triple agonists presently being developed to address the obesity epidemic. Furthermore, this review will address the potential problem of GLP-1-related delayed gastric emptying and its impact on the timing of elective total joint arthroplasty. The review aims to provide arthroplasty surgeons with a primer for implementing this class of medication in their current and future practice, including perioperative instructions and perioperative safety considerations when treating patients taking these medications.

The influence of body mass index on patient-reported outcome measures following total hip arthroplasty: a retrospective study of 3,903 Cases

BACKGROUND

The influence of obesity on patient-reported outcome measures (PROMs) following total hip arthroplasty (THA) is currently controversial. This study aimed to compare PROM scores for pain, functional status, and global physical/mental health based on body mass index (BMI) classification.

METHODS

Primary, elective THA procedures at a single institution between 2018 and 2021 were retrospectively reviewed, and patients were stratified into four groups based on BMI: normal weight (18.5-24.99 kg/m2), overweight (25-29.99 kg/m2), obese (30-39.99 kg/m2), and morbidly obese (> 40 kg/m2). Patient-Reported Outcome Measurement Information System (PROMIS) and Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR) scores were collected. Preoperative, postoperative, and pre/post- changes (pre/post-Δ) in scores were compared between groups. Multiple linear regression was used to assess for confounders.

RESULTS

We analyzed 3,404 patients undergoing 3,903 THAs, including 919 (23.5%) normal weight, 1,374 (35.2%) overweight, 1,356 (35.2%) obese, and 254 (6.5%) morbidly obese cases. HOOS, JR scores were worse preoperatively and postoperatively for higher BMI classes, however HOOS, JR pre/post-Δ was comparable between groups. All PROMIS measures were worse preoperatively and postoperatively in higher BMI classes, though pre/post-Δ were comparable for all groups. Clinically significant improvements for all BMI classes were observed in all PROM metrics except PROMIS mental health. Regression analysis demonstrated that obesity, but not morbid obesity, was independently associated with greater improvement in HOOS, JR.

CONCLUSIONS

Obese patients undergoing THA achieve lower absolute scores for pain, function, and self-perceived health, despite achieving comparable relative improvements in pain and function with surgery. Denying THA based on BMI restricts patients from clinically beneficial improvements comparable to those of non-obese patients, though morbidly obese patients may benefit from additional weight loss to achieve maximal functional improvement.

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.

The Role of Perioperative Nutritional Status and Supplementation in Orthopaedic Surgery: A Review of Postoperative Outcomes

» Identification of malnourished and at-risk patients should be a standardized part of the preoperative evaluation process for every patient.» Malnourishment is defined as a disorder of energy, protein, and nutrients based on the presence of insufficient energy intake, weight loss, muscle atrophy, loss of subcutaneous fat, localized or generalized fluid accumulation, or diminished functional status.» Malnutrition has been associated with worse outcomes postoperatively across a variety of orthopaedic procedures because malnourished patients do not have a robust metabolic reserve available for recovery after surgery.» Screening assessment and basic laboratory studies may indicate patients' nutritional risk; however, laboratory values are often not specific for malnutrition, necessitating the use of prognostic screening tools.» Nutrition consultation and perioperative supplementation with amino acids and micronutrients are 2 readily available interventions that orthopaedic surgeons can select for malnourished patients.

Short stem hip arthroplasty with the optimys prosthesis is a safe and effective option for obese patients: a mid-term follow-up multicenter study

INTRODUCTION

Short stems are a valuable option in young patients undergoing total hip arthroplasty (THA) because of their bone stock preserving properties facilitating revision hip arthroplasty. Although the effect of obesity on conventional THA is well studied, data about short stem THA in obese patients are lacking. Therefore, this study aimed to investigate the influence of obesity on complications, revisions, and outcome after short stem THA.

MATERIALS AND METHODS

This multicenter, observational cohort study included patients undergoing short stem THA with the optimys prosthesis. Follow-up examinations were performed at specific intervals up to 7 years postoperatively. Operation characteristics, general and specific complications, revisions, VAS rest pain, VAS load pain, VAS patient satisfaction, and Harris Hip Score (HHS) were recorded and statistically compared between obese (BMI ≥ 30 kg/m2) and non-obese (BMI < 30 kg/m2) patients.

RESULTS

Of the 224 patients included with a mean follow-up of 87.2 months (range 81.9-104.0), 69 were assigned to the OB group and 155 to the non-OB group. A minimally invasive approach was significantly less often selected in obese patients (p = 0.049), whereas operating time and length of hospital stay were not significantly different. The rate of general and specific complications did not significantly differ between both groups. Survival of the optimys prosthesis was 99.1% at 7-year follow-up and one patient per group had to undergo revision surgery. VAS rest pain, load pain, and satisfaction improved from preoperatively to postoperatively in both groups without a significant difference between both groups. While the HHS was improved from preoperatively to postoperatively, obese patients showed a significantly lower HHS at the 7-year follow-up (p = 0.01) but still exhibited an excellent scoring above the PASS threshold.

CONCLUSION

Short stem THA with the optimys prosthesis is a safe and effective option also in obese patients with an excellent clinical outcome and a low complication rate.

No Difference in Revision Rates up to 10 years Following Total Hip Arthroplasty in Patients Who Had Prior Bariatric Surgery When Compared to Patients Who Had Class III Obesity: A Propensity Matched Analysis

BACKGROUND

There is no clear research showcasing bariatric surgery's (BS's) impact on long-term surgical complications following total hip arthroplasty (THA). Therefore, this study compared the 10-year cumulative incidence and risk of revision following THA in patients who underwent BS when compared to the general population and class III obesity patients who did not undergo BS.

METHODS

Patients who underwent elective THA from 2010 to 2021 were identified using an all-payer claims database. Patients who underwent BS prior to THA were separately matched to a control of the general population and those who had class III obesity (body mass index ≥40) by age, sex, Charlson Comorbidity Index, and diabetes using a 1:4 ratio. Kaplan-Meier analyses generated 10-year cumulative incidence rates, and a Cox proportional hazard ratio (HR) model generated HRs and 95% confidence intervals (CIs).

RESULTS

When compared to the general control, patients who have a history of BS had an elevated 10-year risk of all-cause revision (HR 1.31, 95% CI: 1.16 to 1.47, P < .001), prosthetic joint infection (HR: 1.62, CI: 1.30 to 2.04; P < .001), mechanical loosening (HR: 1.20, CI: 1.01 to 1.44; P = .040), and dislocation/instability (HR: 1.35, CI: 1.09 to 1.68; P = .007). There was no difference in the 10-year risk of all-cause revision or other indications for revision in the BS cohort compared to the matched class III obesity cohort (P = .142).

CONCLUSIONS

Those who underwent BS before THA had comparable 10-year revision rates when compared to those who had class III obesity and higher rates compared to the general population. This suggests BS may not reduce the 10-year surgical risks associated with obesity when compared to a class III obese surgical population.

Association between periodontal disease and malignant soft tissue sarcomas

OBJECTIVE

Malignant soft tissue sarcoma (MSTS) is a rare disease, but is seen in patients undergoing orthopedic surgery. Although the association of periodontal disease with various cancers occurring in the oral cavity, gastrointestinal tract, lungs, and prostate, has been reported, the association between periodontal disease and MSTS remains unclear. This study investigated the association between periodontal disease and MSTS in patients undergoing orthopedic surgery.

SUBJECTS AND METHODS

One hundred fifteen patients who underwent orthopedic surgery between 2017 and 2021 were retrospectively enrolled (mean age = 66.8 ± 10.7 years). The patient background was adjusted by the propensity score (PS). Subsequently, the association of periodontal disease with MSTS was analyzed using PS inverse probability of treatment weighting (IPTW). Periodontal status was determined by evaluating the periodontal inflamed surface area, which was calculated by measuring the periodontal probing pocket depth and detecting bleeding on probing.

RESULTS

Multivariate logistic regression analysis after adjustment by the PS showed that severe periodontitis was significantly associated with MSTS (odds ratio 2.81, p = 0.04). Furthermore, IPTW showed that severe periodontitis was significantly associated with MSTS (odds ratio 3.21, p = 0.01).

CONCLUSION

The results indicate an association between periodontal inflammation and MSTS.

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.

Is There a Difference in PROMs Between Morbidly Obese Patients and Nonobese Patients Following Primary Total Knee Arthroplasty?

Background

Patient satisfaction and patient-reported outcome measures (PROMs) are important for patients, surgeons, and payers in the current healthcare climate. Morbidly obese patients (body mass index [BMI] >40) have demonstrated higher incidence of complications after total knee arthroplasty (TKA) and can have difficulty obtaining access for their surgical care. The purpose of this study was to evaluate PROMs and patient satisfaction in morbidly obese patients undergoing primary TKA.

Methods

A total of 75 patients with BMI >40 kg/m² undergoing robotic-assisted TKA were retrospectively identified and matched 2:1 to a consecutive cohort of patients with BMI <35. The average BMI of the study cohort was 42.4 kg/m² (39.5-51.3) compared to 28.6 kg/m² (18.5-34.9) in the control group. Clinical outcomes, PROMs, and patient satisfaction were evaluated at a minimum 2-year follow-up.

Results

The patients of the BMI >40 cohort were less likely to be discharged home (P = .0076), had less active flexion at 2 years (P = .0046), and had worse knee scores at 2 years (0.0497). Despite this, the percentage of patients who were satisfied or very satisfied after surgery was similar between the groups (87.5% vs 91.2%, P = .1943).

Conclusions

Morbidly obese patients are less likely to be discharged directly to home and may have functional differences after primary TKA. However, morbidly obese patients have similar PROMs and are as satisfied as nonobese patients at 2 years. Morbidly obese patients with end-stage knee osteoarthritis should also be able to enjoy the benefits of primary TKA following medical and surgical optimization.

Does body mass index influence improvement in patient reported outcomes following total knee arthroplasty? A retrospective analysis of 3918 cases

PURPOSE

The study aimed to determine whether body mass index (BMI) classification for patients undergoing total knee arthroplasty (TKA) is associated with differences in mean patient reported outcome measure (PROM) score improvements across multiple domains-including pain, functional status, mental health, and global physical health. We hypothesized that patients with larger BMIs would have worse preoperative and postoperative PROM scores, though improvements in scores would be comparable between groups.

MATERIALS AND METHODS

Patients undergoing primary TKA from 2018 to 2021 were retrospectively reviewed and stratified into four groups: Normal Weight; 18.5-25 kg/m², Overweight; 25.01-30 kg/m², Obese; 30.01-40 kg/m², and Morbidly Obese > 40 kg/m². Preoperative, postoperative, and pre/post-changes (Δ) in knee injury and osteoarthritis, joint replacement (KOOS, JR) and Patient-Reported Outcome Measurement Information System (PROMIS) measures of pain intensity, pain interference, physical function, mobility, mental health, and physical health were compared. Multivariate linear regression was used to assess for confounding comorbid conditions.

RESULTS

In univariate analysis, patients with larger BMIs had worse scores for KOOS, JR and all PROMIS metrics preoperatively. Postoperatively, scores for KOOS, JR and PROMIS pain interference, mobility, and physical health were statistically worse in higher BMI groups, though differences were not clinically significant. Morbidly obese patients achieved greater pre/post-Δ improvements in KOOS, JR and global physical health scores. Multivariate regression analysis showed high BMI was independently associated with greater pre/post-Δ improvements in KOOS, JR and global health scores.

CONCLUSION

Obese patients report worse preoperative scores for function and health, but greater pre/post-Δ improvements in KOOS, JR and physical health scores following TKA. Quality of life benefits of TKA in obese patients should be a factor when assessing surgical candidacy.

The effect of severe obesity on three-dimensional ground reaction force signals during walking

BACKGROUND

The gait pattern of adults with class I obesity [30 ≤ body mass index < 35kg/m²] was characterized by altered three-dimensional ground reaction force signals compared to lean adults (18.5 ≤ body mass index < 25 kg/m²). However, results might not be generalizable to adults with severe obesity (class II and III; body mass index ≥ 35 kg/m²). Hence, the purpose of the present study was to investigate the differences in relative ground reaction force signals, i.e., normalized by body weight, between adults with severe obesity and lean adults using functional principal component analysis.

METHODS

Thirteen lean and eighteen sedentary adults with severe obesity performed a 5-min walking trial (1.11 m/s) on an instrumented treadmill. The first five functional principal components of the relative force signals (mediolateral, anterior-posterior, and vertical directions) were obtained using functional principal component analysis. Functional principal component scores were compared between groups using an analysis of covariance with age as covariable.

FINDINGS

Functional principal component analysis reported a statistically significant group effect for first functional principal component score for mediolateral (P = 0.004), and second and fifth functional principal component scores for anterior-posterior (P ≤ 0.02) force signals. Adults with severe obesity displayed a greater mediolateral force during most of the stance but similar magnitudes of the anterior-posterior and vertical forces compared to lean adults.

INTERPRETATION

Therefore, increasing the obesity level accentuates differences in mediolateral force but promotes no specific changes in anterior-posterior force likely due to chronic loading adaptation.

Obesity is associated with an increased risk of undergoing hip replacement in Australia

BACKGROUND

Obesity is a known risk factor for the development of hip osteoarthritis. The aim of this study was to investigate whether obesity is associated with the risk of undergoing total hip replacement (THR) in Australia.

METHODS

A cohort study was conducted comparing data from the Australian Bureau of Statistics and the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 2017 to 2018. Body mass index (BMI) data for patients undergoing primary total hip replacement and resurfacing for osteoarthritis were obtained from the AOANJRR. The distribution of THR patients by BMI category was compared to the general population, in age and sex sub-groups.

RESULTS

During the study period, 32 495 primary THR were performed for osteoarthritis in Australia. Compared to the general population, there was a higher prevalence of Class I, II and III obesity in patients undergoing THR in both sexes aged 35-74 years. Class III obese females and males aged 55-64 years were 2.9 and 1.7 times more likely to undergo THR, respectively (P < 0.001). Class III obese females and males underwent THR on average 5.7 and 7.0 years younger than their normal weight counterparts, respectively.

CONCLUSION

Obese Australians are at increased risk of undergoing THR, and at a younger age.

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.

Minimum 2 Year Outcomes of All-Polyethylene Tibial Components in Patients who have Body Mass Index of 35 or Greater

BACKGROUND

Several studies have reported negative results after total knee arthroplasty (TKA) in obese patients. This study aims to analyze the minimum 2 year outcomes in patients who have a body mass index (BMI) ˃35 undergoing cemented TKA using an all-polyethylene tibial component (APTC) at a minimum of two years of follow-up.

METHODS

We retrospectively studied 163 obese patients (192 TKAs) who underwent a primary cemented TKA using an APTC comparing the outcomes of 96 TKA patients who had a BMI ˃35 to 39.9 (group A) with 96 patients who a TKA and a BMI ≥ 40 (group B). Median follow-up of groups A and B was 3.8 years and 3.5 years respectively (P=0.02). Multiple regression analyses were performed to evaluate independent risk factors associated with complications. Kaplan-Meier survival curves were estimated, defining failure as the need for any further femoral or tibial revision surgery with implant removal, irrespective of the reason.

RESULTS

There was no significant difference at the latest follow-up patient reported outcomes between both groups. Survivorship, as defined by revision for any reason, was 99% for group A and 99% for group B (P=1.00). There was one aseptic tibial failure in group A, and one septic failure in group B. Multiple regression analyses showed no significant associations between age (Odds Ratio [OR]= 1.00; P=0.98; 95% Confidence Interval (CI)= 0.93 to 1.08), sex (OR=1.38; P=0.70; 95% CI=0.26 to 7.25), BMI (OR=1.00; P=0.95; 95% CI=0.87 to 1.16), and complication rate.

CONCLUSIONS

At a median 3.7-year follow-up, the use of an APTC provided excellent outcomes and survivorship in patients who had Class 2 and Class 3 obesity.

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.

The Arthroplasty Surgeon Growth Indicator: A Tool for Monitoring Supply and Demand Trends in the Orthopaedic Surgeon Workforce from 2020 to 2050

BACKGROUND

Orthopaedic practices in the U.S. face a growing demand for total joint arthroplasties (TJAs), while the orthopaedic workforce size has been stagnant for decades. This study aimed to estimate annual TJA demand and orthopaedic surgeon workforce supply from 2020 to 2050, and to develop an arthroplasty surgeon growth indicator (ASGI), based on the arthroplasty-to-surgeon ratio (ASR), to gauge nationwide supply and demand trends.

METHODS

National Inpatient Sample and Association of American Medical Colleges data were reviewed for individuals who underwent primary TJA and for active orthopaedic surgeons (2010 to 2020), respectively. The projected annual TJA volume and number of orthopaedic surgeons were modeled using negative binominal and linear regression, respectively. The ASR is the number of actual (or projected) annual total hip (THA) and/or knee (TKA) arthroplasties divided by the number of actual (or projected) orthopaedic surgeons. ASGI values were calculated using the 2017 ASR values as the reference, with the resulting 2017 ASGI defined as 100.

RESULTS

The ASR calculation for 2017 showed an annual caseload per orthopaedic surgeon (n = 19,001) of 24.1 THAs, 41.1 TKAs, and 65.2 TJAs. By 2050, the TJA volume was projected to be 1,219,852 THAs (95% confidence interval [CI]: 464,808 to 3,201,804) and 1,037,474 TKAs (95% CI: 575,589 to 1,870,037). The number of orthopaedic surgeons was projected to decrease by 14% from 2020 to 2050 (18,834 [95% CI: 18,573 to 19,095] to 16,189 [95% CI: 14,724 to 17,655]). This would yield ASRs of 75.4 THAs (95% CI: 31.6 to 181.4), 64.1 TKAs (95% CI: 39.1 to 105.9), and 139.4 TJAs (95% CI: 70.7 to 287.3) by 2050. The TJA ASGI would double from 100 in 2017 to 213.9 (95% CI: 108.4 to 440.7) in 2050.

CONCLUSIONS

Based on historical trends in TJA volumes and active orthopaedic surgeons, the average TJA caseload per orthopaedic surgeon may need to double by 2050 to meet projected U.S. demand. Further studies are needed to determine how the workforce can best meet this demand without compromising the quality of care in a value-driven health-care model. However, increasing the number of trained orthopaedic surgeons by 10% every 5 years may be a potential solution.

A Novel Method for Stratification of 30-Day Major Complication Risk Using Body Mass Index Thresholds for Patients Undergoing Total Knee Arthroplasty: A National Cohort of 443,157 Patients

INTRODUCTION

Many organizations have utilized pre-established body mass index (BMI) cut-offs to guide surgical decision making. As there have been many improvements in patient optimization, surgical technique, and perioperative care over time, it is important to reassess these thresholds as well as contextualize them to total knee arthroplasty (TKA). The purpose of this study was to calculate data-driven BMI thresholds that predict significant differences in risk of 30-day major complications following TKA.

METHODS

Patients who underwent primary TKA from 2010 to 2020 were identified in a national database. Stratum-specific likelihood ratio (SSLR) methodology was utilized to determine data-driven BMI thresholds at which the risk of 30-day major complications increased significantly. These BMI thresholds were tested using multivariable logistic regression analyses. A total of 443,157 patients were included, who had a mean age of 67 (range, 18 to 89), mean BMI of 33 (range 19 to 59), and 11,766 (2.7%) of patients had a 30-day major complication RESULTS: SSLR analysis identified four BMI thresholds that were associated with significant differences in 30-day major complications: 19 to 33, 34 to 38, 39 to 50, and 51+. When compared to those who had a BMI between 19 and 33, the odds of sustaining a major complication sequentially and significantly increased by 1.1, 1.3, and 2.1 times (p<0.05 for all) for the other thresholds.

CONCLUSION

This study identified four data-driven BMI strata utilizing SSLR analysis that were associated with significant differences in the risk of 30-day major complications following TKA. These strata can be utilized to guide shared decision making in patients undergoing TKA.

Bariatric surgery, osteoarthritis and arthroplasty of the hip and knee in Swedish Obese Subjects - up to 31 years follow-up of a controlled intervention study

OBJECTIVE

To study the long-term effect of obesity and bariatric surgery on incidences of osteoarthritis and arthroplasty of hip and knee.

DESIGN

Hazard ratios (HR) and incidence rates (IR) of osteoarthritis and arthroplasty of hip and knee were studied in the prospective, controlled, non-randomized Swedish Obese Subjects (SOS) study (bariatric surgery group, n = 2007; matched controls given usual obesity care, n = 2040) and the SOS reference cohort (n = 1135, general population). Osteoarthritis diagnosis and arthroplasty for osteoarthritis were captured from the National Swedish Patient Register. Median follow-up time was 21.2 (IQR 16.4-24.8), 22.9 (IQR 19.1-25.7), and 20.1 years (IQR 18.7-20.9) for the control group, surgery group and reference cohort, respectively.

RESULTS

The surgery group displayed lower incidence of hip osteoarthritis (IR 5.3, 95% CI 4.7-6.1) compared to controls (IR 6.6, 95% CI 5.9-7.5, adjHR 0.83, 95% CI 0.69-1.00) but similar incidence of hip arthroplasty. Similar incidence of knee osteoarthritis was observed in the surgery group and controls, but knee arthroplasty was more common in the surgery group (IR 7.4, 95% CI 6.6-8.2 and 5.6, 95% CI 4.9-6.4, adjHR 1.45, 95% CI 1.22-1.74). The reference cohort displayed lower incidences of osteoarthritis and arthroplasty of hip and knee compared with the surgery group and controls.

CONCLUSION

Bariatric surgery did not normalize the increased risk of knee and hip osteoarthritis in patients with obesity but was associated with an increased incidence of knee arthroplasty compared to the control group. With the limitations inherent to the present data, additional studies are needed to confirm these results.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01479452.

The Impact of Hospital Size and Teaching Status on Outcomes Following Total Ankle Arthroplasty

The popularity and utilization of total ankle arthroplasty (TAA) as treatment for ankle arthritis has increased exponentially from 1998 to 2012. Overall the outcomes have improved for TAA with the introduction of new-generation implants and this has increased the focus on optimizing other variables affecting outcomes for TAA. The purpose of this study was to examine the effects of hospital characteristics and teaching status on outcomes for TAA. The Nationwide Inpatient Sample database was queried from 2002 to 2012 using the ICD-9 procedure code for TAA. The primary outcomes evaluated included: in-hospital mortality, length of stay, total hospital charges, discharge disposition, perioperative complications, and patient demographics. Analyses were carried out based on hospital size: small, medium, and large; and teaching status: rural nonteaching, urban nonteaching, and urban teaching. A total weighted national estimate of 16,621 discharges for patients undergoing TAA was reported over the 10-year period. There were significant differences in length of stay and total charges between all hospitals when comparing location and teaching status; however, no significant differences were noted for in-hospital mortality. Rural, nonteaching hospitals had higher odds of perioperative complications. There were also significant differences in length of stay and total charges when comparing hospital sizes. Overall, there is no increased risk of mortality after TAA regardless of hospital size or setting. However, rural hospitals had increased rates of perioperative complications compared to urban hospitals. Our analyses demonstrated important factors affecting cost and resource utilization for TAA, clearly additional work is needed to optimize this relationship, especially in the upcoming bundled payment models.

Does Body Mass Index Influence the Outcomes and Survivorship of Modern Cementless Total Knee Arthroplasty?

BACKGROUND

Higher body mass index (BMI) has been associated with higher rates of aseptic loosening following cemented total knee arthroplasty (TKA). However, there is a paucity of evidence on the effect of BMI on the durability of modern cementless TKA. We aimed to assess the association between BMI and clinical outcomes following cementless TKA and to determine if there was a BMI threshold beyond which the risk of revision significantly increased.

METHODS

We identified 1,408 cementless TKAs of a modern design from an institutional registry. Patients were classified into BMI categories: normal (n = 136), overweight (n = 476), obese class I (n = 423), II (n = 258), and III (n = 115). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and 12-item Short Form Health Survey scores were collected preoperatively and 2 years postoperatively. Survivorship was recorded at minimum 2 years (range, 24 to 88 months). BMI was analyzed as a continuous and categorical variable.

RESULTS

The improvement in patient-reported outcomes was similar across the groups. Thirty four knees (2.4%) were revised and 14 (1.0%) were for aseptic failure. Mean time-to-revision was 1.2 ± 1.3 years and did not differ across BMI categories (P = .455). Survivorship free from all-cause and aseptic revision was 97.1% and 99.0% at mean 4 years, respectively. Using Cox regression to control for demographics and bilateral procedures, BMI had no association with all-cause revision (P = .612) or aseptic revision (P = .186). Receiver operating characteristic curve analysis found no relationship between BMI and revision risk (c-statistic = 0.51).

CONCLUSION

BMI did not influence functional outcomes and survivorship of modern cementless TKA, possibly due to improved biological fixation at the bone-implant interface. Longer follow-up is necessary to confirm these findings.

ASSESSMENT OF THE EFFICIENCY OF ANALGETIC ACTION OF ULTRASOUND-GUIDED FICB AS A COMPONENT OF PERIOPERATIVE MULTIMODAL ANALGESIA IN ERAS- STRUCTURE IN OBESE PATIENTS UNDERGOING TOTAL HIP REPLACEMENT

OBJECTIVE

The aim: To compare the efficiency of analgetic action of Ultrasound-guided FICB and prolonged EA as the components of perioperative multimodal analgesia in ERAS-structure in obese patients undergoing THR.

PATIENTS AND METHODS

Materials and methods: The retrospective study included 80 patients with obesity, who underwent elective anterolateral THR under conditions of low-flow inhalation anesthesia with sevoflurane in combination with PEA (n1=38) or with FICB (n2=42). Primary endpoints: VAS pain level during the first postoperative day.

RESULTS

Results: Static and dynamic VAS pain scores were similar in both groups during the first 6 hours. Since the 8th postoperative hour, there was a statistically significant increase in both static and dynamic VAS pain scores in the FICB group. A significant difference in static and dynamic VAS pain scores was obtained with a trend toward an increase in the PEA group within 48 hours (p < 0.05).

CONCLUSION

Conclusions: USG- FICB is an effective, practically feasible, minimally invasive and safe regional method for eleclive anterior-lateral THR and can be an alternative to PEA in obese patients.

Bikini anterior hip replacements in obese patients are not associated with an increased risk of complication

PURPOSE

Direct anterior approach (DAA) arthroplasty has generated great interest because of its minimally invasive and muscle sparing nature. Obese patients are reported to be associated with greater incidence of complications in primary joint replacement. The purpose of this study was to compare patient outcomes and complication rates between obese and non-obese patients undergoing primary total hip arthroplasty (THA) through a Bikini direct anterior incision.

METHODS

This retrospective, single surgeon study compared the outcome of 258 obese patients and 200 non-obese patients undergoing DAA THA using a Bikini incision, over a 5-year period. The average follow-up was 3.2 years (range 1.1-5.6 years).

RESULTS

There was no statistically significant differences in the complication rate between the two groups. The obese group recorded 2 major (venous thromboembolism and peri-prosthetic fracture) and 2 minor complications (superficial wound infection), compared with the non-obese group, which recorded 2 major (deep-wound infection and peri-prosthetic fracture) and 1 minor complication (superficial wound infection). Patient-reported outcomes (WOMAC and Harris Hip Scores) showed significant post-operative improvements (p < 0.001) and did not differ between the two groups.

CONCLUSIONS

Bikini DDA THA does not increase the complication rate in obese patients and offers similar clinical improvements compared to non-obese patients.

A Novel Method for Stratification of Major Complication Risk Using Body Mass Index Thresholds for Patients Undergoing Total Hip Arthroplasty: A National Cohort of 224,413 Patients

INTRODUCTION

Elevated body mass index (BMI) is associated with complications following Total Hip Arthroplasty (THA). Since obese individuals are almost 10 times more likely to require THA compared to non-obese individuals, we need to understand the risk-benefit continuum while considering THA in obese patients. We aimed to determine data-driven thresholds for BMI at which the risk of major complications following THA increases significantly.

METHODS

Patients were identified in a national database who underwent primary THA from 2010 to 2020. BMI thresholds were identified using the stratum-specific likelihood ratio (SSLR) methodology, which is an adaptive technique that allows for identification of BMI cut-offs, at which the risk of major complications is increased significantly . BMI cutoffs identified using SSLR were used to create a logistic regression model.

RESULTS

A total of 224,413 patients were identified with a mean age of 66 ± 10, BMI 32 ± 6.7, and 7,186 (3%) sustained a major complication. BMI thresholds were defined as 19-31, 32-37, 38-49 and 50+. Overall, the absolute risk of major complications increased from 2.9% in the lowest BMI strata to 7.5% in the highest BMI strata. Compared to patients with a BMI between 19-31, the odds of sustaining a major complication sequentially increased by 1.2, 1.6, and 2.5-times for patients in each higher BMI strata (all, P < .05).

CONCLUSIONS

We have identified BMI cutoffs using SSLR that categorizes patients into four categories of risk for major complications in a nationally representative patient sample. These thresholds can be used in the surgical decision-making process between patients and surgeons.

Clinical Pathways of Patients Denied Total Knee Arthroplasty Due to an Institutional BMI Cutoff

Out of concern for the increased risk of complications with morbid obesity, institutional body mass index (BMI) cutoffs for total knee arthroplasty (TKA) have become commonplace. We sought to answer the questions: what percentage of morbidly obese patients with knee osteoarthritis who present to an arthroplasty clinic will, within 2 years, undergo TKA at (1) a BMI less than 40 kg/m² or (2) at a BMI greater than 40 kg/m²? Of those who do not undergo surgery, (3) what percentage lose enough weight to become TKA-eligible, and (4) what percentage do not? We performed an observational study of 288 patients, of which 256 had complete follow-up. Institutional electronic medical record review and patient follow-up by telephone were conducted to determine which patients underwent surgery, and at what BMI. For those that did not undergo TKA, BMI was examined to see if the patient ever lost enough weight to become TKA eligible. Twelve of 256 patients (4.7%) underwent TKA at a BMI less than 40 kg/m², 64 patients (25%) underwent TKA at a BMI greater than 40 kg/m², and 7 patients (2.7%) underwent surgery at an outside hospital. The average BMI at the time of surgery was 42.3 kg/m². Thirty-seven of 256 patients (14.4%) lost enough weight to become TKA-eligible within 2 years of the initial visit but did not undergo surgery, while 136 patients (53.1%) neither underwent TKA nor became eligible. Strict enforcement of a BMI cutoff for TKA is variable among surgeons. In the absence of weight loss protocols, 19.1% of morbidly obese patients may be expected to reach the sub-40 kg/m² BMI milestone.

Trends of obesity rates between primary total hip arthroplasty patients and the general population from 2013 to 2020

Background

The prevalence of obesity in total hip arthroplasty (THA) patients has been studied in the past. However, there has not been direct comparison against obesity in the general population. This study compared yearly trends in BMI and obesity rates between patients who had undergone primary THA and those from the general patient population.

Methods

We retrospectively reviewed all patients over the age of 18 who underwent primary, elective THA and those who had an annual routine physical exam between January 2013 and December 2020 at our academic tertiary medical center. Baseline demographics were controlled in our statistical models. Significance of yearly trends was determined through a linear regression analysis. Independent samples t-test and Chi-square test were used to compare means and proportions between the two groups, respectively.

Results

A total of 11,250 primary THA patients and 1,039,918 annual physical exam patients were included. Average BMI for the THA group was significantly higher (P < 0.001) each year compared to the annual physicals group (APG). Higher obesity rates were observed in all obesity subgroups (all classes, and class I–III individually) for THA patients each year compared to the APG. Interestingly, while we found a significantly increasing trend in obesity for the general population (P < 0.001), BMI and obesity rates remained stable in the THA population.

Conclusion

While our general patient population showed significant increase in BMI and obesity over time, THA patients had higher, yet stable, BMI. Further investigation is required to determine the role of risk optimization in these findings.

Level III Evidence

Retrospective Cohort Study.

A Prospective, Longitudinal Study of the Influence of Obesity on Total Knee Arthroplasty Revision Rate: Results from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

The aim of this study was to investigate the relationship of obesity with all-cause revision and revision for infection, loosening, instability, and pain after total knee arthroplasty (TKA) performed in Australia.

METHODS

Data for patients undergoing primary TKA for osteoarthritis from January 1, 2015, to December 31, 2020, were obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The rates of all-cause revision and revision for infection, loosening, instability, and pain were compared for non-obese patients (body mass index [BMI], 18.50 to 29.99 kg/m 2 ), class-I and II obese patients (BMI, 30.00 to 39.99 kg/m 2 ), and class-III obese patients (BMI, ≥40.00 kg/m 2 ). The results were adjusted for age, sex, tibial fixation, prosthesis stability, patellar component usage, and computer navigation usage.

RESULTS

During the study period, 141,673 patients underwent primary TKA for osteoarthritis in Australia; of these patients, 48.0% were class-I or II obese, and 10.6% were class-III obese. The mean age was 68.2 years, and 54.7% of patients were female. The mean follow-up period was 2.8 years. Of the 2,655 revision procedures identified, the reasons for the procedures included infection in 39.7%, loosening in 14.8%, instability in 12.0%, and pain in 6.1%. Class-I and II obese patients had a higher risk of all-cause revision (hazard ratio [HR], 1.12 [95% confidence interval (CI), 1.03 to 1.22]; p = 0.007) and revision for infection (HR, 1.25 [95% CI, 1.10 to 1.43]; p = 0.001) than non-obese patients. Class-III obese patients had a higher risk of all-cause revision after 1 year (HR, 1.30 [95% CI, 1.14 to 1.52]; p < 0.001), revision for infection after 3 months (HR, 1.72 [95% CI, 1.33 to 2.17]; p < 0.001), and revision for loosening (HR, 1.39 [95% CI, 1.00 to 1.89]; p = 0.047) than non-obese patients. The risks of revision for instability and pain were similar among groups.

CONCLUSIONS

Obese patients with knee osteoarthritis should be counseled with regard to the increased risks associated with TKA, so they can make informed decisions about their health care. Health services and policymakers need to address the issue of obesity at a population level.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Feasibility of a preoperative strengthening exercise program on postoperative function in patients undergoing hip or knee arthroplasty: a pilot randomized controlled trial

BACKGROUND

There are conflicting results on the effect of preoperative exercise programs on long-term function and little evidence on short-term function. The aim is to assess the feasibility of a preoperative strengthening exercise program in patients undergoing hip or knee joint arthroplasty in terms of trial design, recruitment, and follow-up rates.

METHODS

A randomized controlled feasibility study with patients undergoing hip or knee joint arthroplasty. Patients were randomized to a preoperative strengthening exercise program or standard of care. Feasibility outcome measures were recruitment rate (≥ 50%) and loss to follow-up (≤ 15%).

RESULTS

Of the 129 eligible participants, 63 participants consented to participate in the study (49%), and 27 were successfully randomized prior to surgery (43%). All 27 participants completed the baseline assessment. Of these, 6 (22%) had surgery during the exercise period. Of the remaining 21 participants, 20 (95%) completed the pre-surgery assessment. The study was terminated before five participants could be eligible for the 6-month assessment. Sixteen (76%) participants completed the 6-week post-surgery assessment. Twelve participants completed the 6-month assessment (75%).

CONCLUSION

Given the recruitment rate, randomization barriers, and study participant loss to follow-up, the study was discontinued since it was not considered feasible in this current form at our clinical site despite modifications made to the protocol. Future investigations into a modified intervention via telerehabilitation should be explored.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03483519 . Retrospectively registered in March 2018.

What Is the Impact of Body Mass Index Cutoffs on Total Hip Arthroplasty Complications?

BACKGROUND

Body mass index (BMI) cutoffs are commonly utilized to decide whether to offer obese patients elective total hip arthroplasty (THA). However, weight loss goals may be unachievable for many, and some patients are thereby denied complication-free surgery. The purpose of this study was to assess the impact of varying BMI cutoffs on the rates of complication-free surgery after THA.

METHODS

Patients undergoing THA between 2015 and 2018 were identified in the American College of Surgeons National Surgical Quality Improvement Program database using Common Procedural Terminology code 27130. BMI and rates of 30-day complications were collected. BMI cutoffs of 30, 35, 40, 45, and 50 kg/m² were applied to model the incidence of complications if THA would have been allowed to proceed based on BMI.

RESULTS

A total of 192,394 patients underwent THA, and 13,970 (7%) of them had a BMI ≥40 kg/m². With a BMI cutoff of 40 kg/m², 178,424 (92.7%) patients would have proceeded with THA. From this set, 170,296 (95.4%) would experience complication-free surgery, and 11.8% of complications would be prevented. THA would proceed for 191,217 (99.3%) patients at a BMI cutoff of 50 kg/m², of which 182,123 (95.2%) would not experience a complication, and 1.3% of complications would be prevented. Using 35 kg/m² as the BMI cutoff would prevent 28.6% of complications and permit 75.9% of complication-free surgeries to proceed.

CONCLUSION

Lower BMI cutoffs for THA can result in fewer complications although they will consequentially limit access to complication-free THA. Consideration of risks of obesity in THA may be best considered as part of a holistic assessment and shared decision-making when deciding on goals for weight reduction.

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.

Cementless Total Knee Arthroplasty Using a Highly Porous Tibial Baseplate in Morbidly Obese Patients: Minimum 5-Year Follow-Up

BACKGROUND

 Morbidly obese patients undergoing cemented primary total knee arthroplasty (TKA) can pose a challenging problem with implant survivorship due to greater stress at the cement-bone interface. With the advent of additive manufacturing (three-dimensional printing), highly porous implants are now readily available. The purpose of this study was to review the results of primary TKA in the morbidly obese (body mass index [BMI] ≥ 40) patient using a highly porous cementless tibial baseplate.

METHODS

 This is a retrospective study of 167 TKAs in patients with morbid obesity undergoing primary cementless TKA with a minimum 5-year follow-up. A total of 6 patients died and 14 were lost to follow-up, leaving 147 TKAs in 136 patients with a mean follow-up of 66 months (range 60-79 months). The average age was 59 years (range 36-84 years) and average BMI was 45 kg/m² (range 39.5-63.9). Clinical results, patient-reported outcome measures, radiographs, and complications were reviewed.

RESULTS

 There were 9 failures requiring revision, including 3 for aseptic tibial loosening (2.0%), 2 for deep infection (1.4%), 2 for patellar resurfacing (1.4%), 1 for patella instability (0.7%), and 1 for extensor mechanism rupture (0.7%). Knee Society Score (KSS) improved from 48 to 90 at 2- and 5-year follow-up. KSS function score improved from 49 to 68 and 79 at 2- and 5-year follow-up, respectively. Survivorship with aseptic loosening as the endpoint was 98.0% at 5 years.

CONCLUSION

 Cementless TKA using a highly porous tibial baseplate in morbidly obese patients demonstrated excellent clinical results with 98% survivorship at 5 years and appears to offer durable long-term biologic fixation as an alternative to mechanical cement fixation in this challenging group of patients.

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.

Discriminating features of ground reaction forces in overweight old and young adults during walking using functional principal component analysis

BACKGROUND

Limited attention has been paid to age- or body size-related changes in the ground reaction forces (GRF) during walking despite their strong associations with lower limb injuries and pathology.

RESEARCH QUESTION

Do the features of GRF during walking associate with age or body size?

METHODS

Fifty-four participants were subdivided into four groups according to their age and body size: overweight old (n = 12), non-overweight old (n = 13), overweight young (n = 13), and non-overweight young (n = 16). Participants were asked to walk at their self-selected speeds on level ground with force plates embedded in the center of walkway. Functional principal component analysis (FPCA) was performed to extract major modes of variation and functional principal component scores (FPCs) in three-dimensional GRFs. Analysis of variance models were employed to investigate the effect of age, body size, or their interactions on the FPCs of each component of the GRF, with the adjustment to gait speed.

RESULTS

Significant age and body size effects were observed in FPC1 across all three-dimensional GRF. Both overweight and older groups showed greater braking force after heel-strike and greater propulsive forces during pre-swing when compared to the non-overweight and younger groups, respectively. The overweight old group displayed greater medial forces during mid-stance and the overweight young group showed prominently larger medial forces during pre-swing, while non-overweight old showed a tendency of flatter medial-lateral GRF waveforms during the entire stance phase. FPC2 revealed that only body size had an effect on three-dimensional GRF with the highest FPC2 scores in the overweight old group.

SIGNIFICANCE

Three-dimensional GRF during walking could be altered by the body size and age, which were more pronounced in the overweight and older group. The more dynamic GRF pattern with greater and/or lower peaks could be contributing factors to the increased joint load and injury rates observed in overweight aged individuals.

Obesity is associated with an increased risk of undergoing knee replacement in Australia

Background

Obesity is associated with the development of knee osteoarthritis (OA). The aim of this study was to examine the incidence of obesity in patients undergoing knee replacement (KR) for OA in Australia compared to the incidence of obesity in the general population.

Methods

A cohort study was conducted, comparing data from the Australian Bureau of Statistics (ABS) 2017–2018 National Health Survey with data from the National Joint Replacement Registry. The distribution of patients who underwent KR from July 2017 to June 2018 by BMI category was compared to the distribution of the general population, in age and gender sub‐groups.

Results

During the study period, 35.6% of Australian adults were overweight and 31.3% were obese. Of the 56 217 patients who underwent primary KR for OA, 31.9% were overweight and 57.7% were obese. The relative risk of undergoing KR for OA increased with increasing BMI category. Class 1, 2 and 3 obese females aged 55–64 years were 4.7, 8.4 and 17.3 times more likely to undergo KR than their normal weight counterparts, respectively. Males in the same age and BMI categories were 3.4, 4.5 and 5.8 times more likely to undergo KR, respectively. Class 3 obese patients underwent KR 7 years younger, on average, than normal weight individuals.

Conclusion

Obesity is associated with an increased risk of undergoing KR, and at a younger age, particularly for females. There is an urgent need for a societal level approach to address the prevalence of obesity, to reduce the burden of obesity related KR.

Effect of Bariatric Surgery on Risk of Complications After Total Knee Arthroplasty: A Randomized Clinical Trial

IMPORTANCE

People with severe obesity who undergo a total knee arthroplasty (TKA) for osteoarthritis (OA) are at higher risk of short-term and long-term complications compared with people with reference (<30) body mass index (BMI; weight in kilograms divided by height in meters squared). It is not known whether weight loss before TKA modifies this risk.

OBJECTIVE

To determine whether outcomes are improved by undergoing bariatric surgery before TKA in people with BMI greater than or equal to 35 and end-stage OA.

DESIGN, SETTING, AND PARTICIPANTS

This parallel-group, assessor-blinded, randomized clinical trial was conducted between May 2012 and June 2020 with a minimum follow-up of 12 months after TKA. TKA was performed at a tertiary referral university-affiliated public hospital, and bariatric surgery was performed at a private hospital facility and a university-affiliated private practice. Data analysis was performed from February to July 2021.

INTERVENTIONS

Bariatric surgery compared with usual weight management advice (treatment as usual [TAU]) in people scheduled for TKA.

MAIN OUTCOMES AND MEASURES

The primary outcome was complications of TKA measured by a composite of death from any cause, perioperative or postoperative complications resulting in a discharge delay, unplanned procedure, or readmission for at least 12 months after TKA. Secondary outcomes included hospital bed day utilization, anthropomorphic measures, and patient-reported outcomes.

RESULTS

Eighty-two patients waiting for TKA were randomized to undergo bariatric surgery (41 patients) or TAU (41 patients). Of the 82 participants, 66 (80.5%) were women, the mean (SD) age was 57.8 (4.9) years, and the mean (SD) BMI was 43.8 (5.5). Thirty-nine participants (95.1%) in the intervention group underwent laparoscopic adjustable gastric banding, and 29 (70.7%) subsequently underwent TKA. Thirty-nine patients (95.1%) in the TAU group underwent TKA. Six patients (14.6%) in the intervention group incurred the primary outcome (median follow-up, 24 months), compared with 15 (36.6%) in the TAU group (median follow-up, 27 months) (difference, 22.0%; 95% CI, 3.7% to 40.3%; P = .02). The between-group difference in BMI at 12 months was -6.32 (95% CI, -7.90 to -4.50; P < .001) in favor of the intervention group. TKA was declined by 12 participants (29.3%) in the intervention group because of symptom improvement, whereas 2 participants (4.9%) in the TAU group declined TKA (difference, 24.4%; 95% CI, 9.0% to 39.8%; P = .003).

CONCLUSIONS AND RELEVANCE

Weight loss following bariatric surgery reduced the risk of complications of TKA in people with BMI greater than or equal to 35. Significantly fewer participants required TKA following weight loss, contributing to this finding.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry Number: ACTRN12611001178932.

Trends of Obesity Rates Between Patients Undergoing Primary Total Knee Arthroplasty and the General Population from 2013 to 2020

BACKGROUND

Obesity is a recognized risk factor for severe knee osteoarthritis. However, it remains unclear how obesity prevalence trends in the current population undergoing total knee arthroplasty (TKA) compare with those seen in individuals not undergoing this procedure. In this study, we assessed the yearly trends in body mass index (BMI) and obesity rates between patients who have undergone primary TKA and those in the general population.

METHODS

We retrospectively reviewed all patients ≥18 years of age from January 2013 through December 2020 who underwent primary, elective TKA and those who had an annual routine physical examination at our institution within the same period. Baseline demographic characteristics were collected. The independent samples t test was used to compare means and the chi-square test was used to compare proportions between the 2 cohorts, and a linear regression was used to determine the significance of the yearly trends.

RESULTS

A total of 11,333 patients who underwent primary TKA and 1,158,168 patients who underwent an annual physical examination were included in this study. After adjusting for age, we found the mean BMI for the TKA group to be significantly greater (p < 0.001) every year compared with the annual physicals group. The proportion of patients who were categorized into any obesity class (BMI, ≥30 kg/m2), Class-I obesity (BMI, 30 to 34.9 kg/m2), Class-II obesity (BMI, 35 to 39.9 kg/m2), and Class-III obesity (BMI, ≥40 kg/m2) was significantly higher for the TKA group each year compared with the annual physicals group. An analysis of trends over time showed a significantly increasing trend (p < 0.001) in BMI and obesity rates for the annual physicals group, but a stable trend for patients undergoing TKA.

CONCLUSIONS

Patients who underwent TKA continued to have higher BMI than the general population, which showed a steady increase over time. Physicians need to continue in their efforts to educate patients on weight management and healthy lifestyles to potentially delay the need for a surgical procedure.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Obesity, preoperative weight loss, and telemedicine before total joint arthroplasty: a review

The preoperative period prior to elective total joint arthroplasty (TJA) is a critical time for lifestyle interventions since a scheduled surgery may help motivate patients to lose weight. Weight loss may reduce complications associated with obesity following TJA and enable patients with severe obesity (body mass index [BMI] > 40 kg/m²) to become eligible for TJA, as many institutions use a 40 kg/m² cut-off for offering surgery. A comprehensive review was conducted to (1) provide background on complications associated with obesity following TJA, (2) synthesize prior research on the success rate of patients losing weight after being denied TJA for severe obesity, (3) discuss bariatric surgery before TJA, and (4) propose mobile health telemedicine weight loss interventions as potential weight loss methods for patients preoperatively. It is well established that obesity increases complications associated with TJA. In total knee arthroplasty (TKA), obesity increases operative time, length of stay, and hospitalization costs as well as the risk of deep infection, revision, and component malpositioning. Obesity may have an even larger impact on complications associated with total hip arthroplasty (THA), including wound complications and deep infection. Obesity also increases the risk of hip dislocation, aseptic loosening, and venous thromboembolism after THA. Synthesis of the only two studies (n = 417), to our knowledge, that followed patients denied TJA for severe obesity demonstrated that only 7% successfully reduced their BMI below 40 kg/m² via lifestyle modifications and ultimately underwent TJA. Unfortunately, bariatric surgery may only increase certain post-TKA complications including death, pneumonia, and implant failure, and there is limited research on preoperative weight loss via lifestyle modification. A review of short-term mobile health weight loss interventions that combined personalized counseling with self-monitoring via a smartphone app found about 5 kg of weight loss over 3-6 months. Patients with severe obesity have more weight to lose and may have additional motivation to do so before TJA, so weight loss results may differ by patient population. Research is needed to determine whether preoperative mobile health interventions can help patients become eligible for TJA and produce clinically significant weight loss sufficient to improve postoperative outcomes.

Does obesity affect acetabular cup position, spinopelvic function and sagittal spinal alignment? A prospective investigation with standing and sitting assessment of primary hip arthroplasty patients

Background

Total hip arthroplasty (THA) instability is influenced by acetabular component positioning, spinopelvic function and sagittal spinal alignment. Obesity is considered as a risk factor of THA instability, but the causal relationship remains unknown. This study aimed to investigate the influence of BMI on (1) spinopelvic function (lumbar flexibility, pelvic mobility and hip motion), (2) sagittal spinal alignment pre- and postoperatively and (3) acetabular cup position postoperatively in primary THA patients in a prospective setting.

Methods

One hundred ninety patients receiving primary total hip arthroplasty were enrolled in a prospective cohort study and retrospectively analysed. All patients received stereoradiography (EOS) in standing and relaxed sitting position pre-and postoperatively. C7-sagittal vertical axis (C7-SVA), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), anterior plane pelvic tilt (APPT), and pelvic femoral angle (PFA) were assessed. Key parameters of the spinopelvic function were defined as lumbar flexibility (∆ LL = LL_standing − LL_sitting), pelvic mobility (∆ PT = PT_standing − PT_sitting) and hip motion (∆ PFA = PFA_standing − PFA_sitting). Pelvic mobility was further defined based on ∆ PT as stiff, normal and hypermobile (∆ PT < 10°; 10°–30°; > 30°). The patients were stratified to BMI according to WHO definition: normal BMI ≥ 18.5–24.9 kg/m² (n = 68), overweight ≥ 25.0–29.9 kg/m² (n = 81) and obese ≥ 30–39.9 kg/m² (n = 41). Post-hoc analysis according to Hochberg's GT2 was applied to determine differences between BMI groups.

Results

Standing cup inclination was significant higher in the obese group compared to the normal BMI group (45.3° vs. 40.1°; p = 0.015) whereas standing cup anteversion was significantly decreased (22.0° vs. 25.3°; p = 0.011). There were no significant differences for spinopelvic function key parameter lumbar flexibility (∆ LL), pelvic mobility (∆ PT) and hip motion (∆ PFA) in relation to BMI stratified groups. The obese group demonstrated significant enhanced pelvic retroversion compared to the normal BMI group (APPT − 1.8° vs. 2.4°; p = 0.028). The preoperative proportion of stiff pelvic mobility was decreased in the obese group (12.2%) compared to normal (25.0%) and overweight (27.2%) groups. Spinal sagittal alignment in C7-SVA and PI-LL mismatch demonstrated significantly greater imbalance in the obese group compared to the normal BMI group (68.6 mm vs. 42.6 mm, p = 0.002 and 7.7° vs. 1.2°, p = 0.032, respectively) The proportion of patients with imbalanced C7-SVA was higher in the obese (58.5%) than in the normal BMI group (44.1%).

Conclusions

The significantly increased spinal sagittal imbalance with altered pelvic mechanics is a potential cause for the reported increased risk of THA dislocations in obese patients. Consequently, the increased spinal sagittal imbalance in combination with normal pelvic mobility need to be taken into account when performing THA in obese patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02716-8.

Trends of Obese and Morbidly Obese Patients in Same-Day Bilateral Total Knee Arthroplasty from 2009 to 2016

As obesity in the United States increases, the proportion of obese and morbidly obese patients undergoing same-day bilateral total knee arthroplasty (sd-BTKA) remains unknown. Therefore, this study analyzed: (1) incidence, (2) patient demographics, (3) patient course, and (4) patient outcomes in obese and morbidly obese patients undergoing sd-BTKA in the United States from 2009 to 2016. The National Inpatient Sample was queried for all sd-BTKA patients from 2009 to 2016, yielding 39,901 obese and 20,394 morbidly obese patients. Analyzed variables included overall incidence, age, length of stay (LOS), sex, race, payer, Charlson comorbidity index (CCI) status, disposition, complications, location/teaching status, region of hospital, costs, and charges. Categorical variables were evaluated with chi-square analysis, while continuous variables were analyzed by Student's t-tests. Overall, the number of sd-BTKAs decreased over the study period, although the proportion of both obese and morbidly obese patients increased (p < 0.001 for all). The most common CCI status, 3 + , decreased in proportion for both groups (p < 0.001 for all). Hospital costs decreased and charges increased for both groups (p < 0.001 for all). Mean LOS decreased and patients were most commonly discharged to skilled nursing facilities, although these proportions decreased (p < 0.001 for all). Respiratory failures (p < 0.001 for all) increased for both groups, while proportion of deep vein thromboses and hematomas/seromas (p < 0.001 for all) increased for obese patients and proportion of pulmonary emboli (p < 0.001) increased for morbidly obese patients. The results of this study appear to portray improving optimization and patient selection of higher body mass index (BMI) individuals undergoing this procedure. More information is needed comparing the safety of the sd-BTKA across patients of all BMI groups.

The Fate of Morbidly Obese Patients With Joint Pain: A Retrospective Study of Patient Outcomes

BACKGROUND

The number of obese patients seeking a total joint arthroplasty (TJA) continues to increase. Weight loss is often recommended to treat joint pain and reduce risks associated with TJA. We sought to determine the effectiveness of an orthopedic surgeon's recommendation to lose weight.

METHODS

We identified morbidly obese (body mass index (BMI) 40-49.9 kg/m²) and super obese (BMI ≥50 kg/m²) patients with hip or knee osteoarthritis. Patients with less than 3-month follow-up were excluded. Patient characteristics (age, gender, BMI, comorbidities), disease characteristics (joint affected, radiographic osteoarthritis grading), and treatments were recorded. Clinically meaningful weight loss was defined as weight loss greater than 5%.

RESULTS

Two hundred thirty morbid and 50 super obese patients were identified. Super obese patients were more likely to be referred to weight management (52.0% vs 21.7%, P < .001) and were less likely to receive TJA (20.0% vs 41.7%, P = .004). Each 1 kg/m² increase in BMI decreased the odds of TJA by 10.9% (odds ratio = 0.891, 95% confidence interval: 0.833-0.953, P = .001). Forty (23.0%) of the nonoperatively treated patients achieved clinically meaningful weight loss, and 19 (17.9%) patients who underwent TJA lost weight before surgery. After surgery, the number of patients who achieved a clinically meaningful weight loss grew to 32 (30.2%).

CONCLUSION

In morbid and super obese patients, increasing BMI reduces the likelihood that a patient will receive TJA, and when counseled by their orthopedic surgeon, few patients participate in weight-loss programs or are otherwise able to lose weight. Weight loss is an inconsistently modifiable risk factor for joint replacement surgery.

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

BACKGROUND

Obesity is a risk factor for complications after total joint arthroplasty (TJA). This study analyzed the impact of individual surgeon demographics, financial concerns, and other factors in determining patient candidacy for TJA based on body mass index (BMI).

METHODS

A 21-question survey was approved by the American Association of Hip and Knee Surgeons Research Committee for distribution to its membership. Objective questions asked about surgeon or hospital BMI thresholds for offering TJA. Subjective questions asked about physician comfort discussing topics including obesity, bariatric surgery, and weight loss before TJA, as well as insurance and age considerations.

RESULTS

For TJA procedures, 49.9% of surgeons had a BMI cutoff at 40, 24.5% at 45, and 8.3% at 50. At a BMI cutoff of 40, 23.8% of surgeons felt their patient volume would be adversely affected, whereas at a BMI cutoff of 35, 50% of surgeons felt their patient volume would be adversely affected. Surgeons were more likely to not perform total hip arthroplasty on patients with morbid obesity than total knee arthroplasty (P = .037). Significantly more academic surgeons did not have cutoffs for total hip arthroplasty (P = .003) or total knee arthroplasty (P < .001) compared with all other practice settings.

CONCLUSION

There are myriad factors that affect surgeon BMI thresholds for offering elective TJA including poor outcomes, hospital thresholds, financial considerations, and the well being of the patient. Further work should be performed to minimize the risks associated with TJA while providing the best possible care to patients with morbid obesity.

The Potential Effects of Imposing a Body Mass Index Threshold on Patient-Reported Outcomes After Total Knee Arthroplasty

BACKGROUND

Operative eligibility thresholds based on body mass index (BMI) alone may risk restricting access to improved pain control, function, and quality of life. This study evaluated the use of BMI-cutoffs to offering TKA in avoiding: 1) 90-day readmission, 2) one-year mortality, and 3) failure to achieve clinically important one-year PROMS improvement (MCID).

METHODS

A total of 4126 primary elective unilateral TKA patients from 2015 to 2018 were prospectively collected. For specific BMI(kg/m²) cutoffs: 30, 35, 40, 45, and 50, the positive predictive value (PPV) for 90-day readmission, one-year mortality, and failure to achieve one-year MCID were calculated. The number of patients denied complication-free postoperative courses per averted adverse outcome/failed improvement was estimated.

RESULTS

Rates of 90-day readmission and one-year mortality were similar across BMI categories (P > .05, each). PPVs for preventing 90-day readmission and one-year mortality were low across all models of BMI cutoffs. The highest PPV for 90-day readmission and one-year mortality was detected at cutoffs of 45 (6.4%) and 40 (0.87%), respectively. BMI cutoff of 40 would deny 18 patients 90-day readmission-free, and 194 patients one-year mortality-free postoperative courses for each averted 90-day readmission/one-year mortality. Such cutoff would also deny 11 patients an MCID per avoided failure. Implementing BMI thresholds alone did not influence the rate of improvements in KOOS-PS, KRQOL, or VR-12.

CONCLUSION

Utilizing BMI cutoffs as the sole determinants of TKA ineligibility may deny patients complication-free postoperative courses and clinically important improvements. Shared decision-making supported by predictive tools may aid in balancing the potential benefit TKA offers to obese patients with the potentially increased complication risk and cost of care provision.

Preoperative risk stratification minimizes 90-day complications in morbidly obese patients undergoing primary total knee arthroplasty

AIMS

It has been shown that the preoperative modification of risk factors associated with obesity may reduce complications after total knee arthroplasty (TKA). However, the optimal method of doing so remains unclear. The aim of this study was to investigate whether a preoperative Risk Stratification Tool (RST) devised in our institution could reduce unexpected intensive care unit (ICU) transfers and 90-day emergency department (ED) visits, readmissions, and reoperations after TKA in obese patients.

METHODS

We retrospectively reviewed 1,614 consecutive patients undergoing primary unilateral TKA. Their mean age was 65.1 years (17.9 to 87.7) and the mean BMI was 34.2 kg/m² (SD 7.7). All patients underwent perioperative optimization and monitoring using the RST, which is a validated calculation tool that provides a recommendation for postoperative ICU care or increased nursing support. Patients were divided into three groups: non-obese (BMI < 30 kg/m², n = 512); obese (BMI 30 kg/m² to 39.9 kg/m², n = 748); and morbidly obese (BMI > 40 kg/m², n = 354). Logistic regression analysis was used to evaluate the outcomes among the groups adjusted for age, sex, smoking, and diabetes.

RESULTS

Obese patients had a significantly increased rate of discharge to a rehabilitation facility compared with non-obese patients (38.7% (426/1,102) vs 26.0% (133/512), respectively; p < 0.001). When stratified by BMI, discharge to a rehabilitation facility remained significantly higher compared with non-obese (26.0% (133)) in both obese (34.2% (256), odds ratio (OR) 1.6) and morbidly obese (48.0% (170), OR 3.1) patients (p < 0.001). However, there was no significant difference in unexpected ICU transfer (0.4% (two) non-obese vs 0.9% (seven) obese (OR 2.5) vs 1.7% (six) morbidly obese (OR 5.4); p = 0.054), visits to the ED (8.6% (44) vs 10.3% (77) (OR 1.3) vs 10.5% (37) (OR 1.2); p = 0.379), readmissions (4.5% (23) vs 4.0% (30) (OR 1.0) vs 5.1% (18) (OR 1.4); p = 0.322), or reoperations (2.5% (13) vs 3.3% (25) (OR 1.2) vs 3.1% (11) (OR 0.9); p = 0.939).

CONCLUSION

With the use of a preoperative RST, morbidly obese patients had similar rates of short-term postoperative adverse outcomes after primary TKA as non-obese patients. This supports the assertion that morbidly obese patients can safely undergo TKA with appropriate perioperative optimization and monitoring. Cite this article: Bone Joint J 2021;103-B(6 Supple A):45-50.

Change in Body Mass Index after Simultaneous Bilateral Total Knee Arthroplasty: Risk Factors and Its Influence on Functional Outcomes

BACKGROUND

Previous studies evaluating weight changes following total knee arthroplasty (TKA) were performed on heterogenous cohorts. However, no study has evaluated weight changes in a cohort of simultaneous-bilateral TKA (SB-TKA) patients. This study aimed to evaluate the prevalence of patients who lost or gained weight, determine if postoperative weight change influences functional outcome, and identify predictors of weight change after SB-TKA.

METHODS

Prospectively collected registry data of 560 patients who underwent SB-TKA were reviewed. Patients were assessed preoperatively, at 6 months, and 2 years using the Knee Society Score, Oxford Knee Score, Short-Form 36, and range of motion. Change in body mass index (BMI) >5% was used to categorize patients into 3 groups: lost, maintained, or gained weight. Analysis of variance, Kruskal-Wallis test, and chi-squared test were used to compare functional outcomes between groups. Multivariable logistic regression evaluated predictors for postoperative weight changes.

RESULTS

At 2 years, 59% of patients maintained weight, 28% of patients gained weight, and 13% of patients lost weight. All groups experienced similar improvements in functional outcomes, rates of minimal clinically important difference attainment, and patient satisfaction (P > .05). Older patients were more likely to gain weight (P < .05). Patients with higher preoperative BMI were more likely to gain weight (P < .05) and less likely to lose weight (P < .05). Patients with greater preoperative comorbidities were less likely to lose weight (P < .05).

CONCLUSION

Up to 41% of patients experience significant weight changes after SB-TKA. Older patients with higher preoperative BMI were more likely to gain weight, while higher preoperative BMI with more comorbidities were less likely to lose weight following SB-TKA; however, postoperative weight changes do not appear to affect functional outcomes.

LEVEL OF EVIDENCE

III, therapeutic study.

Does surgical approach affect early outcomes following primary total hip replacement in obese patients?

AIM

The aim of this study was to assess whether obese patients undergoing primary total hip replacement (THR) via a posterior approach had superior revision rates and Oxford Hip Scores (OHS) compared to those via a lateral approach.

PATIENTS AND METHODS

This is a retrospective cohort study using prospective data from the New Zealand Joint Registry applying STROBE and RECORD guidelines. Patients undergoing THR since 2010 were stratified by body mass index (BMI) into obese (BMI 30-39 kg/m²), and morbidly obese (BMI ⩾40 kg/m²) groups. All-cause revision rates, and 6-month OHS post-surgery were compared between groups. Multivariate analysis was performed.

RESULTS

12,109 unilateral THRs in obese patients were identified. The mean follow-up was 2.8 years (range 0.01-6.95 years). Univariate analysis in the BMI ⩾ 40 group showed the posterior approach had a significantly lower all-cause revision rate (0.99/100 observed component years (ocys); 95% CI, 0.65-1.44/100 ocys) than the lateral approach (1.71/100 ocys (95% CI, 0.98-2.77/100 ocys), p < 0.05). There was no significant difference in dislocation rates between the surgical approaches. OHS was statistically higher in the posterior approach group in BMI 30-39 patients (p < 0.001) but not clinically significant. Multivariate analysis showed femoral head size significantly influenced all-cause revision rates and mitigated against the increased risk associated with the surgical approach.

CONCLUSION

The choice of surgical approach in obese patients conveys no advantage in overall revision rates in the short-term. Choosing an appropriate size of femoral head may be of greater importance than choice of surgical approach for obese patients in primary THR.

Identifying Patients with Osteoarthritis at Risk of Sarcopenia using the SARC-F

Background

Sarcopenia is an important modifiable risk factor in patients being considered for elective knee or hip replacement as it may be associated with a higher risk of post-operative joint replacement complications. Our objectives are to determine the prevalence of patients with osteoarthritis at risk of sarcopenia by using the SARC-F tool, and whether risk of sarcopenia is associated with referral to an orthopaedic surgeon.

Methods

We conducted a retrospective review of patients who were 60 years or older assessed at four Canadian musculoskeletal assessment centres. Patients completed the SARC-F as part of their assessment. Multivariable logistic regression analyses were conducted to determine association between risk of sarcopenia and the odds of referral to an orthopedic surgeon for surgical consultation.

Results

3,697 patients were included and 67.8% (2,508/3,697) were at risk of sarcopenia. Prevalence was highest in those assessed for hip replacement at 72.3% (635/878). Patients at risk of sarcopenia were more likely to be referred to an orthopaedic surgeon (OR 1.299; SD 1.074–1.571).

Conclusions

Patients with osteoarthritis assessed for joint replacement are at high risk of sarcopenia, particularly individuals undergoing potential hip replacement. Patients at risk of sarcopenia are more likely to be referred to orthopaedic surgery for surgical consultation.