The Effect of Body Mass Index Class on Patient-Reported Health-Related Quality of Life Before and After Total Hip Arthroplasty for Osteoarthritis: Registry-Based Cohort Study of 64,055 Patients

[Influence of obesity on midterm outcome after primary hip and knee arthroplasty in Germany : Analysis from the EPRD]

OBJECTIVES

To determine the influence of obesity on revision rates and mortality after primary elective hip and knee arthroplasty in Germany.

MATERIALS AND METHODS

In the German Arthroplasty Registry (EPRD) there were 403,073 elective total hip arthroplasties (THA), 320,913 bicondylar total knee arthroplasties (TKA) and 48,480 unicondylar knee arthroplasties (UKA) with valid BMI available for analysis. Cumulative revision rates and 1‑year mortality was calculated for BMI groups.

RESULTS

There were increased revision rates with increasing BMI, most distinctive for septic revisions in THA during the first year after surgery (non-obese 0.7%, obesity grade 1 1.3%, grade 2 2.1%, grade 3 4.2%). In TKA and UKA this increase was generally less pronounced. Age- and gender-standardized mortality was lower than expected in most groups, but also increasing with increasing BMI.

CONCLUSION

The risk for revisions in obese patients is more distinctive in hip arthroplasty than in knee arthroplasty and is especially high in morbidly obese patients (BMI ≥ 40 kg/m2). Nonetheless, this risk may be acceptable for affected patients. Therefore, the possible benefits and risks of an arthroplasty should be weighed against each other and individually discussed with the patient.

Does Approach Matter in Robotic-Assisted Total Hip Arthroplasty? A Comparison of Early Reoperations Between Direct Anterior and Postero-Lateral Approach

BACKGROUND

There is no consensus on whether direct anterior approach (DAA) or postero-lateral approach (PLA) total hip arthroplasty (THA) confers a lower risk of postoperative complications. Robotic assistance in THA results in a more consistently accurate component position compared to manual THA. The objective of this study was to compare rates of dislocation, reoperation, revision, and patient-reported outcome measures between patients undergoing DAA and PLA robotic-assisted primary THA.

METHODS

We identified 2,040 consecutive robotic-assisted primary THAs performed for primary osteoarthritis, using DAA (n = 497) or PLA (n = 1,542) between 2017 and 2020. The mean follow-up was 18 months. Kaplan-Meier analysis estimated survivorship free of dislocation, reoperation, and revision. Achievement of patient acceptable symptom state and minimum clinically important difference were used to compare changes in the Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS JR) and Visual Analog Scale.

RESULTS

Dislocation was rare in this series (14 in 2,040, 0.7%), including 1 of 497 (0.2%) in the DAA cohort and 13 of 1,542 (0.8%) in the PLA cohort (P = .210). There was no difference in 2-year reoperation-free survivorship (97.8 versus 98.6%, P = .59) or revision-free survivorship (98.8 versus 99.0%, P = .87) at any time point. After controlling for age, sex, and body mass index, there was no difference in dislocation, reoperation, or revision. At 6-week follow-up, after controlling for age, sex, and body mass index, patients in the DAA cohort had higher odds of achieving HOOS JR minimum clinically important difference (odds ratio = 2.01, P = .012) and HOOS JR patient acceptable symptom state (odds ratio = 1.72, P = .028). There were no differences in patient-reported outcome measures by 3 months.

CONCLUSIONS

For robotic-assisted primary THA, DAA may confer enhanced early (<6 weeks) functional recovery compared to the PLA, but there was no significant difference in postoperative dislocation, reoperation, or revision rates.

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.

Patient satisfaction and patient-reported outcomes do not vary by BMI class in total hip arthroplasty

PURPOSE

Obesity has been identified as a risk factor for postoperative complications in patients undergoing total hip arthroplasty (THA). This study aimed to investigate patient-reported outcomes, pain, and satisfaction as a function of body mass index (BMI) class in patients undergoing THA.

METHODS

1736 patients within a prospective observational study were categorized into BMI classes. Pre- and postoperative Hip disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS JR), satisfaction, and pain scores were compared by BMI class using one-way ANOVA.

RESULTS

Healthy weight patients reported the highest preoperative HOOS JR (56.66 ± 13.35) compared to 45.51 ± 14.45 in Class III subjects. Healthy weight and Class III patients reported the lowest (5.65 ± 2.01) and highest (7.06 ± 1.98, p < 0.0001) preoperative pain, respectively. Changes in HOOS JR scores from baseline suggest larger improvements with increasing BMI class, where Class III patients reported an increase of 33.7 ± 15.6 points at 90 days compared to 26.1 ± 17.1 in healthy weight individuals (p = 0.002). Fewer healthy weight patients achieved the minimal clinically important difference (87.4%) for HOOS JR compared to Class II (96.5%) and III (94.7%) obesity groups at 90 days postoperatively. Changes in satisfaction and pain scores were largest in the Class III patients. Overall, no functional outcomes varied by BMI class postoperatively.

CONCLUSION

Patients of higher BMI class reported greater improvements following THA. While risk/benefit shared decision-making remains a personalized requirement of THA, this study highlights that utilization of BMI cutoff may not be warranted based on pain and functional improvement.

[Postoperative Sleep Disturbance in Patients Undergoing Arthroplasty: Risk Prediction Modeling Based on Logistic Regression]

Objective

To construct a risk predictive model for postoperative sleep disturbance (PSD) in patients undergoing arthroplasty by using logistic regression.

Methods

We retrospectively collected the data of 4286 patients who underwent joint replacement surgeries at a tertiary-care hospital in Chengdu, China between January 1, 2017 and September 30, 2021. With 3001 cases in the training set and 1285 cases in the test set, we constructed the model by using a logistic regression algorithm to screen for predictors in Matlab, displaying the predicted risks of postoperative sleep disturbance with nomographs. The performance of the model was assessed by the area under the curve ( AUC) of the receiver operating characteristic curve, accuracy, precision, recall, F1 value, and calibration curve.

Results

A total of 9 predictors, including post-admission preoperative sleep disturbance, ward type, body mass index, smoking status, range of diseases, joint mobility (flexion), joint mobility (extension), preoperative last hemoglobin, and type of surgery, were eventually included in the study for predictive modeling . The performance assessment findings of the predictive model were as follows, AUC value, 0.708 (95% confidence interval: 0.677-0.740), accuracy, 75.20%, precision, 65.80%, recall, 43.70%, and F1 value, 0.525. The calibration curve showed good agreement between the predicted probabilities and the actual data.

Conclusion

The model constructed in the study has good predictive efficacy and the nomographs are simple and easy to use. With this model, health workers can make preoperative prediction of the risk of PSD in arthroplasty patients based on the predictors, which facilitates early prevention and reduces the risk of postoperative sleep disturbance in patients.

Underweight Patients are at Increased Risk for Complications following Total Hip Arthroplasty

BACKGROUND

Given the prevalence of obesity in the United States, much of the adult reconstruction literature focuses on the effects of obesity and morbid obesity. However, there is little published data on the effect of being underweight on postoperative outcomes. This study aimed to examine the risk of low body mass index (BMI) on complications after total hip arthroplasty (THA).

METHODS

A large national database was queried between 2010 and 2020 to identify patients who had THAs. Using International Classification of Disease codes, patients were grouped into the following BMI categories: morbid obesity (BMI>40), obesity (BMI 30 to 40), normal BMI (BMI 20 to 30), and underweight (BMI<20). There were 58,151 patients identified, including 2,484 (4.27%) underweight patients, 34,710 (59.69%) obese patients, and 20,957 (36.04%) morbidly obese patients. Control groups were created for each study group, matching for age, sex, and a comorbidity index. Complications that occurred within 1 year postoperatively were isolated. Subanalyses were performed to compare complications between underweight and obese patients. Statistical analyses were performed using Pearson Chi-squares.

RESULTS

Compared to their matched control group, underweight patients showed increased odds of THA revision (Odds Ratio (OR) = 1.32, P = .04), sepsis (OR = 1.51, P = .01), and periprosthetic fractures (OR = 1.63, P = .01). When directly comparing underweight and obese patients (BMI 30 and above), underweight patients had higher odds of aseptic loosening (OR = 1.62, P = .03), sepsis (OR = 1.34, P = .03), dislocation (OR = 1.84, P < .001), and periprosthetic fracture (OR = 1.46, P = .01).

CONCLUSION

Morbidly obese patients experience the highest odds of complications, although underweight patients also had elevated odds for several complications. Underweight patients are an under-recognized and understudied high risk arthroplasty cohort and further research is needed.

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.

Are Morbidly Obese Patients Equally Benefitting From Care Improvements in Total Hip Arthroplasty?

BACKGROUND

Morbidly obese patients have increased rates of complications following primary total hip arthroplasty (THA) and it is not clear whether improvements in THA care pathways are equally benefitting these patients. The purpose of this study is to assess if reductions in complications have similarly improved for both morbidly obese and non-morbidly obese patients after THA.

METHODS

Patients undergoing primary THA between 2011 and 2019 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Patients were stratified by body mass index (BMI) <40 and ≥40 kg/m². Thirty-day rates of infectious complications, readmissions, reoperation, and any complication were assessed. Trends in complications were compared utilizing odds ratios and multivariate analyses.

RESULTS

In total, 234,334 patients underwent THA and 16,979 (7.8%) had BMI ≥40 kg/m². Patients with BMI ≥40 kg/m² were at significantly higher odds for readmission, reoperation, and infectious complications. Odds for any complication were lower for morbidly obese patients in 2011, not different from 2012 to 2014, and higher from 2015 to 2019 compared to lower BMI patients. Odds for any non-transfusion complication were higher for morbidly obese patients and there was no improvement for either group over the study period. There were improvements in rates of readmission and reoperation for patients with BMI <40 kg/m² and readmission for BMI >40 kg/m².

CONCLUSION

Odds for readmission and reoperation for non-morbidly obese patients and readmission for morbidly obese patients improved from 2011 to 2019. Reductions in transfusions are largely responsible for improvements in overall complication rates. Although morbidly obese patients remain at higher risk for complications, there does not appear to be a growing disparity in outcomes between morbidly obese and non-morbidly obese patients.