Weight changes after total knee arthroplasty in Chinese patients: a matched cohort study regarding predictors and outcomes

Do Overall Weight, Body Mass Index, or Clinically Meaningful Weight Changes Occur After Total Joint Arthroplasty? A Meta-Analysis of 60,837 Patients

BACKGROUND

Total joint arthroplasty (TJA) is well-recognized for improving quality of life and functional outcomes of patients with osteoarthritis; however, TJA's impact on body weight remains unclear. Recent trends have demonstrated a shift among TJA patients, such that patients who have higher body mass indices (BMIs) are undergoing this common surgery. Given this trend, it is critical to characterize the impact TJA has on body weight or BMI. This meta-analysis aimed to quantitatively assess whether patients lose, gain, or maintain body weight or BMI after TJA.

METHODS

This study followed the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials databases were queried from inception through July 2022. The included studies: (1) reported on weight or BMI after elective, primary total hip arthroplasty (THA) or total knee arthroplasty (TKA); and (2) weight or BMI change was deemed to be associated with THA or TKA. The excluded studies: (1) included weight or BMI interventions; and (2) reported on unicompartmental, partial, or revision arthroplasty or joint arthroscopy. Meta-analyses for weight change, BMI change, and proportion of patients achieving clinically significant change were performed using random-effects models. Factors associated with clinically significant change were systematically reported. A total of 60,837 patients from 39 studies were included.

RESULTS

No significant differences existed between preoperative and postoperative weights (P = 1.0; P = 0.28) or BMIs (P = 1.0; P = 1.0) after THA or TKA, respectively. Overall, 66% of THA patients (P < 0.01) and 65% of TKA patients (P < 0.01) did not experience clinically significant weight change.

CONCLUSIONS

Among a TJA cohort, two-thirds of the patients maintained their preoperative body weight or BMI after surgery. With these results, orthopaedic surgeons can better manage patient expectations of TJA.

The INDICATE Knee expectations survey detects general patient treatment goals for total knee arthroplasty and the influence of demographic factors on patients expectations

PURPOSE

Post-operative outcome after total knee arthroplasty (TKA) in the treatment of end-stage osteoarthritis correlates strongly with pre-operative impairment-driven patient treatment goals. However, a clinical tool for measuring patient treatment goals in correlation to impairments is still missing, which impedes patient-oriented indication in TKA.

METHODS

Patients scheduled for TKA were recruited in four German hospitals. All patients were handed the INDICATE Knee Score pre-operatively. The score contains 31 treatment goals with respective impairments, subdivided into seven categories. They were asked to rank all treatment goals and impairments on a 3-point scale. Treatment goals and impairments were then checked for frequency of occurrence. Correlation of goal and impairment was tested. Analysis for associations of treatment goals and different cohort characteristics (age, sex, BMI) was conducted.

RESULTS

1.298 patients were included in the study. Seven treatment goals were categorised as "main goal" from more than 90% of all patients ("knee pain", "range of motion", "walking distance", "overall physical function", "climbing stairs", "quality of life", "implant survival"). Comparing age groups, there were significant associations towards higher expectations regarding working, physical and sports related treatment goals in younger patients (< 65y) ("ability to work" (P ≤ .001), "sports activities" (P ≤ .001), "sex life" (P ≤ .001), "dependence on help of others" (P = .015), "preventing secondary impairment" (P = .03), "dependence on walking aids" (P = .005)). Higher BMI resulted in increasing relevance of "weight reduction" (P ≤ .001), "climbing stairs" (P = .039) "global health status" (P = .015) and "long standing" (P = .007) as a "main goal". Analysis for differences in treatment goals regarding sex showed women choosing more treatment goals as "main goals" than men.

CONCLUSION

Seven treatment goals which were expected by > 90% in our collective can be classified as general treatment goals for TKA. Demographic factors (age, sex, BMI) were significantly associated with patients' expectations for TKA. We conclude physicians should clearly assess their patients' demands prior to TKA to maximise post-operative outcome.

LEVEL OF EVIDENCE

Prognostic Level III.

Patients successfully lose body weight after primary total knee arthroplasty but not more than a matched general population

INTRODUCTION

High BMI is associated with increased risk for knee osteoarthritis, ultimately necessitating total knee arthroplasty (TKA). The aim of this retrospective study was to (1) analyse the amount of postoperative long-term weight loss as reflected by BMI change in TKA patients, (2) identify factors associated with increased change in BMI, and to (3) compare changes with BMI trends of a general population.

MATERIALS AND METHODS

Overall, 298 TKA patients [198 females; mean age: 65.1 ± 7.9 years, median follow-up 8.8 (interquartile range: 5.9-10.8 years)] were included in the final evaluation and compared with an age group-matched control group from the general population regarding weight trends between 2006 and 2014. Main variable of interest in both cohorts was body mass index (BMI). Linear regression analyses were performed to assess changes in weight and BMI over time between TKA patients and the general population. Furthermore, mixed linear-effects models were constructed to analyse the potential change in BMI independent from age and gender.

RESULTS

In TKA patients, a significant drop in BMI by 0.8 ± 3.2 points from postoperative to final follow-up was observed (p < 0.001), with reduction being significant independently from age (p = 0.382), gender (p = 0.310), or revision surgery (p = 0.195). In the general population, likewise a significant BMI-decrease by 0.7 ± 6.1 points was observed between 2006 and 2014, with younger people (p = 0.004) and females (p < 0.001) being more likely to reduce BMI. Yet, BMI-decrease between TKA patients and the general population over time was comparable (p = 0.734). Notably, patients with initially higher BMI were significantly more likely to lose weight postoperatively than normal-weight patients (p < 0.001).

CONCLUSIONS

Our results point against the notion that TKA patients lose a considerable amount of weight in comparison to the general population as soon as improved joint function and pain relief have been achieved. Thus, individualized patient education programmes should be reinforced, promoting a healthy lifestyle.

Preoperative Weight Loss and Postoperative Weight Gain Independently Increase Risk for Revision After Primary Total Knee Arthroplasty

BACKGROUND

The current American Association of Hip and Knee Surgeons (AAHKS) guidelines recommend preoperative weight loss before total knee arthroplasty (TKA) in patients with body mass index (BMI) ≥40 kg/m². However, there is a paucity of evidence on TKA outcomes after preoperative weight loss. This study therefore evaluated predictors of preoperative and postoperative BMI changes and their impact on outcomes after TKA.

METHODS

This is a retrospective review of 3058 primary TKAs at an academic institution from 2015 to 2019. BMI was collected on the day of surgery. Preoperative and postoperative BMI at 6 months and 1 year were also obtained. BMI change of ≥5% was considered clinically significant. Mean follow-up was 3.2 years. Patient demographics, acute postoperative outcomes, and all-cause revisions were compared between patients who gained, lost, or maintained weight using univariate and multivariable analyses.

RESULTS

Preoperative weight loss was predictive of postoperative weight gain (P < .001), and preoperative weight gain was predictive of postoperative weight loss (P < .001). Cox regression analysis revealed that ≥5% BMI loss preoperatively increased risk for all-cause revisions (P = .030), while ≥5% BMI gain postoperatively increased risk for prosthetic joint infections (P = .016). Patients who lost significant weight both before and after surgery had the highest risk for all-cause revisions (P = .022).

CONCLUSION

Weight gain postoperatively was associated with inferior outcomes. Significant weight loss before surgery led to a "rebound" in weight gain, and independently increased risk for all-cause revision. Therefore, current recommendations for weight loss before TKA in morbidly obese patients should be re-evaluated.

Restoration of Continence after Prostatectomy is Associated With Weight Loss: A Pilot Study

OBJECTIVES

To examine association between post-prostatectomy incontinence (PPI) severity and weight changes before and after restoration of continence via artificial urinary sphincter (AUS).

METHODS

Single surgeon, retrospective review of urologic prosthetic surgery (UPS) after radical prostatectomy (RP). A cohort of post-RP inflatable penile prosthesis (IPP) patients served as a surgical control. Body Mass Index (BMI) and total body weight were assessed pre and post-UPS. Multivariable linear regression was utilized to assess BMI changes post-UPS.

RESULTS

187 AUS and 63 IPP patients met selection criteria. Greater PPI severity was associated with faster BMI gain after RP (coeff. 0.14 kg/m2, P = 0.03, per pad used) and magnitude of incontinence improvement (mean reduction in daily pad use) after AUS insertion was associated with greater BMI reduction at 12 months post-UPS (coeff. - 0.13 kg/m2, P = 0.04). On multivariable regression, AUS insertion was associated with a decrease in BMI by - 2.83 kg/m2 12 months post-UPS (P = 0.02). Twelve months post-UPS, men with AUS exhibited a mean BMI reduction of -1.0 kg/m² compared to a mean BMI increase in the IPP cohort of 0.4 kg/m² (P < 0.01). Compared to IPP, AUS patients experienced absolute body weight reduction by 6 kg [Median(IQR): 90.4 (80.3-100.1) vs 96.4 (87.1-108.8) kg, P = 0.03], with nearly one-third having clinically significant weight loss (>5% body weight) at 12 months post-UPS (31.8% vs 8.3%, P < 0.01).

CONCLUSION

Severe PPI appears to be associated with weight gain and correction of PPI via AUS insertion with weight loss.

The relationship between obesity and primary Total Knee Replacement: A scoping review of the literature

BACKGROUND

Primary Total Knee Replacement (TKR) is one of the most commonly performed elective orthopaedic procedures globally. Many patients undergoing this type of surgery are overweight or obese. In the UK, clinical commissioning groups have imposed arbitrary Body Mass Index (BMI) thresholds for TKR surgery. Many obese patients undergoing TKR believe they will lose weight following the procedure because of increased mobility.

AIM

This paper aims to present the findings of a scoping literature review about the relationship between obesity and primary TKR and to make recommendations for clinical practice, education and policy.

METHODS

A scoping literature review investigated the impact of BMI/body weight on the need for TKR, the impact of body weight and or BMI on patient outcomes following TKR, weight loss/gain following TKR and the implications of obesity on cost of TKR.

FINDINGS

Seventy-one papers were included in the review. Seven studies reported statistically significant associations between increased BMI/obesity with the need for TKR. Thirty of the studies reported worse outcomes for obese patients compared to non-obese comparisons. Forty of the studies reported no difference between obese and non-obese participants, including some where outcomes of obese patients were better than non-obese comparisons. Eight studies reported on changes to weight before and after TKR, three of the studies reporting a higher percentage losing weight than gaining weight and four studies reporting that obese patients gained weight. The 8th study reported that morbidly obese patients largely returned to their baseline BMI postoperatively.

CONCLUSION

The findings of the review challenge the legitimacy of setting BMI thresholds to control access to TKR surgery. There is an urgent need to develop evidence based approaches to support weight loss and weight management for this group of patients. Obese patients undergoing TKR should receive specific information regarding potential additional risks of complications and poorer outcomes. There is a need for health promotion regarding the association of being overweight/obese in young adulthood and developing osteoarthritis of the knee joints requiring TKR in middle and older age.

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.