Association Between Body Mass Index Change and Outcome in the First Year After Total Knee Arthroplasty

doi:10.1016/j.arth.2014.09.003

The Journal of Arthroplasty

Volume 30, Issue 2, February 2015, Pages 206-209

https://doi.org/10.1016/j.arth.2014.09.003 Get rights and content

Abstract

There is an association between obesity, osteoarthritis and total knee arthroplasty (TKA), but little is known about how postoperative weight change influences outcomes. Primary TKA patients were identified from an institutional arthroplasty registry. BMI and patient reported outcome measures (PROMs, specifically WOMAC and SF36) were recorded for 1545 patients preoperatively and up to 3 years postoperatively. Mixed effects modelling showed postoperative BMI change had no impact on postoperative WOMAC scores. However, weight gain over 10% had a negative impact on SF36 pain and functional scores although postoperative weight loss was not associated with improved PROMs. Men showed greater improvement in postoperative SF36 function and pain scores, whilst older patients were slower to improve. Postoperative weight gain has a negative association with SF36 pain and function.

Section snippets

Patients and Methods

The Freeman Joint Registry (FJR) was set up in July 2003 as an on-going institutional audit of patient outcomes following hip or knee arthroplasty. It is registered with and has approval from the institutional research and development board (Project ID number: 3290). Inclusion in the FJR requires informed consent preoperatively for the collection, storage and analysis of data. The study was conducted in accordance with the declaration of Helsinki and the guidelines for good clinical practise.

Results

There were 1902 patients in the original dataset, however, after accounting for missing data on variables of interest (age, sex, BMI, PROMS for pain and functionality) there were records for 1821 individuals. Of these, 276 without follow up data were excluded, leaving a sample size of 1545. There were 865 women and 680 men in this dataset, with a median age of 69.8 years (IQR 62.3–75.8). In addition to preoperative data, data were available for three (not necessarily consecutive) annual

Discussion

This study has found a relationship between postoperative BMI change following TKA and PROMs. Preoperative BMI was negatively associated with the rate of improvement of all PROMs scores considered. Weight gain of > 10% following surgery has an association with lower improvements in SF36 pain and SF36 functional domains. In addition, we identified an inter-relationship between other co-variables (Table 2). Lower preoperative WOMAC pain and function scores were associated with lesser improvement

Acknowledgments

The authors would like to thank all surgeons contributing patients to the Freeman arthroplasty register (Prof A McCaskie, Mr N Brewster, Mr D Weir, Mr J Holland, Mr M Siddique, Mr A Gray, Mr M Hashmi).

References (24)

A.C. Gelber et al.
Body mass index in young men and the risk of subsequent knee and hip osteoarthritis
Am J Med
(1999)
J.R. Foran et al.
Total knee arthroplasty in obese patients: a comparison with a matched control group
J Arthroplasty
(2004)
M.J. Franz et al.
Weight-loss outcome: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up
J Am Diet Assoc
(2007)
R.G. Deshmukh et al.
Does body weight influence outcome after total knee arthroplasty? A 1-year analysis
J Arthroplasty
(2002)
E.B. Haverkort et al.
Self-reporting of height and weight: valid and reliable identification of malnutrition in preoperative patients
Am J Surg
(2012)
D.B. Sarwer et al.
A pilot study investigating the efficacy of postoperative dietary counseling to improve outcomes after bariatric surgery
Surg Obes Relat Dis
(2012)
M.M. Dowsey et al.
Early outcomes and complications following joint arthroplasty in obese patients: a review of the published reports
ANZ J Surg
(2008)
M.E. Berend et al.
Tibial component failure mechanisms in total knee arthroplasty
Clin Orthop
(2004)
M.M. Dowsey et al.
The impact of pre-operative obesity on weight change and outcome in total knee replacement
J Bone Joint Surg (Br)
(2010)
J.E. Ware et al.
The MOS 36-Item Short-Form health survey (SF36): I. conceptual framework and item selection
Med Care
(1992)

G. Hawker et al.

Comparison of a generic (SF36) and a disease specific (WOMAC) instrument in the measurement of outcomes after knee replacement surgery

J Rheumatol

(1995)

N. Bellamy et al.

Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to anti rheumatic drug therapy in patients with osteoarthritis of the hip or knee

J Rheumatol

(1998)

Cited by (30)

Does Your Patient Need to Lose Weight? Weight Change Before and After Total Hip Arthroplasty Does Not Affect Health Care Utilization and Achievement of the Minimal Clinically Important Difference
2024, Journal of Arthroplasty
Despite the potential negative impact of preoperative obesity on total hip arthroplasty (THA) outcomes, the association between preoperative and postoperative weight change and outcomes is much less understood. Therefore, this study aimed to determine the impact of preoperative and postoperative weight change and preoperative body mass index (BMI) on health care utilization, satisfaction, and achievement of minimal clinically important difference (MCID) for Hip Disability and Osteoarthritis Outcome Score Physical Function Short-Form (HOOS PS) and HOOS Pain.
Patients who underwent primary elective unilateral THA between January 2016 and December 2019 were included (N = 2,868). Multivariable logistic regression assessed the association between BMI and preoperative and postoperative weight change on outcomes while controlling for demographic characteristics.
There was no association between preoperative weight change and prolonged length of stay (> 3 days), 90-day readmission, nonhome discharge, patient dissatisfaction at 1 year, or achievement of HOOS Pain or HOOS PS MCID. Postoperative weight loss was an independent risk factor for patient dissatisfaction at 1 year but was not associated with achievement of either HOOS Pain or HOOS PS MCID at 1-year postoperative. Preoperative obesity classes I to III were independent risk factors for nonhome discharge. Nevertheless, preoperative obesity class I and class II were associated with an increased probability of reaching HOOS Pain MCID. Preoperative BMI was not associated with an increased risk of patient dissatisfaction.
Preoperative weight change does not appear to influence health care utilization, satisfaction, or achievement of MCID in pain and function following THA. Postoperative weight loss may play a role as a risk factor for dissatisfaction following THA. Additionally, patients who had a higher baseline BMI may be more likely to see improvement in pain following THA. Therefore, when counseling obese patients for THA, surgeons must balance the risk of perioperative complications with the expectation of greater improvements in pain.
Effect of Weight Change on Patient-Reported Outcomes Following Total Joint Arthroplasty
2022, Journal of Arthroplasty
Increased body mass index (BMI) has been previously described as a risk factor for complications after total joint arthroplasty (TJA); however, its effect on patient-reported outcomes has not been thoroughly investigated. This study examines the effect of postoperative weight change on the Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF) scores for total knee arthroplasty (TKA) and total hip arthroplasty (THA) patients.
A retrospective review of 988 patients undergoing THA or TKA was performed. PROMIS-PF scores and BMI were recorded throughout the study duration. Patients were classified by a 5% change in BMI. A univariate analysis evaluated differences across groups. Mixed-effect models evaluated predictors of change in functional score over the postoperative follow-up time.
43.1% patients had a THA and 56.9% patients had a TKA. At 0 to 3 months, 92% of patients had no change in BMI, 3 to 6 months 82% had no change, and 6 to 12 months 80% had no change. There were no significant demographic or comorbidity differences across groups for both THA and TKA. Similar improvements in PROMIS-PF scores were observed across weight change groups. In the mixed-effect models, postoperative time was found to be a significant predictor of postoperative PF score. Both THA and TKA patients saw greater improvements in PROMIS-PF scores in patients with lower preoperative BMIs.
These results demonstrate most patients do not experience substantial changes in weight following TJA. However, lower BMIs at the time of surgery were associated with an increased functional improvement. Therefore, efforts to optimize BMI should be focused preoperatively to improve surgical outcomes.
Preoperative Weight Loss and Postoperative Weight Gain Independently Increase Risk for Revision After Primary Total Knee Arthroplasty
2022, Journal of Arthroplasty
Citation Excerpt :
However, regression analysis did not show that preoperative weight change alone was predictive of adverse 90-day outcomes. With respect to postoperative weight change, the literature has demonstrated that postoperative weight gain is associated with lower functional scores and a shorter time to aseptic revision [17–19,30,31]. In this study, significant postoperative weight gain was associated with increased 90-day ED visits and readmissions (P = .022).
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.
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.
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).
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.
Change in Body Mass Index after Simultaneous Bilateral Total Knee Arthroplasty: Risk Factors and Its Influence on Functional Outcomes
2021, Journal of Arthroplasty
Citation Excerpt :
This study found that clinically significant changes in weight after SB-TKA were not associated with a difference in functional outcomes. This was consistent with previous studies that evaluated postoperative BMI changes and outcome scores [38,41,43,52]. Although preoperative obesity may influence postoperative functional outcomes [9–11,13,49,50], preoperative to postoperative weight changes did not appear to do so.
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.
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.
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).
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.
III, therapeutic study.
Elevated Body Mass Index Is a Risk Factor for Failure to Achieve the Knee Disability and Osteoarthritis Outcome Score-Physical Function Short Form Minimal Clinically Important Difference Following Total Knee Arthroplasty
2021, Journal of Arthroplasty
The aims of this study are (1) to assess the association between body mass index (BMI) and failure to achieve the 1-year Knee Disability and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS) minimal clinically important difference (MCID) for total knee arthroplasty (TKA) patients and (2) to determine if there is a BMI threshold beyond which the risk of failing to achieve the MCID is significantly increased.
A regional arthroplasty registry was queried for TKA patients from 2016 to 2019 with completion of preoperative and 1-year postoperative KOOS-PS. The MCID threshold was derived using a distribution-based approach. Demographic and patient-reported outcome measure variables were collected. BMI was analyzed continuously and categorically using cutoffs defined by the Centers for Disease Control and Prevention. The association between failure to achieve 1-year MCID and BMI was analyzed using multiple logistic regression. A BMI threshold was determined using the Youden index and receiver operating characteristic curve.
In total, 1059 TKAs were analyzed. BMI assessed continuously was significantly associated with failure to achieve the KOOS-PS MCID (odds ratio 1.03, 95% confidence interval 1.00-1.05, P = .025). Analysis of BMI categorically revealed that “overweight” (25-30 kg/m²), “obese class I” (30-35 kg/m²), “obese class II” (35-40 kg/m²), and “obese class III” (>40 kg/m²) patients faced 77%, 76%, 83%, and 106% greater risk, respectively, of failing to achieve the KOOS-PS MCID compared to “normal BMI” (<25 kg/m²) patients.
Elevated BMI was associated with an increased risk of failure to achieve the 1-year KOOS-PS MCID following TKA.
Patterns of Weight Change and Their Effects on Clinical Outcomes Following Total Knee Arthroplasty in an Asian Population
2020, Journal of Arthroplasty
Citation Excerpt :
The MCID of PCS for our patients has been established to be 10 points. Definitions of obesity have varied widely, and no standard definition exists [2]. We used the BMI classification as defined by the World Health Organization: underweight (<18.5 kg/m2), normal (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obesity class 1 (30-34.9 kg/m2), class 2 (35-39.9 kg/m2), and class 3 (≥40 kg/m2).
This prospective cohort study was designed to evaluate weight change patterns and their effects on clinical outcomes following total knee arthroplasty (TKA) in the Asian population. We hypothesized that Asian patients will have a different pattern of weight change following TKA compared to Western patients and that weight loss following TKA will be associated with better clinical outcomes.
A cohort of consecutive patients who underwent TKA from 2004 to 2015 was included. All patients received a conventional posterior-stabilized TKA implant and underwent a standard perioperative care pathway. Assessments were done preoperatively, at 6 months, and 2 years after surgery. The range of motion, Knee Society Score, Oxford Knee Score, and the Short-Form 36 questionnaire were used to assess outcomes. Height and weight of patients were recorded for body mass index (BMI) calculation. Patterns of weight loss following TKA in this cohort were charted. Clinical outcomes were then analyzed against the change in BMI.
A total of 602 patients (602 knees) were reviewed. Mean age was 66.39 ± 7.27 years. Mean BMI was 27.75 ± 4.51 kg/m². Overall, 63.12% of all our patients gained weight following TKA. Moreover, weight loss did not influence patients’ odds for better clinical outcomes. Furthermore, patients who were in the preoperative BMI category of obese class I were more likely to gain weight as compared to those in the normal category (odds ratio 0.35, 95% confidence interval 0.2-0.61, P < .001). Moreover, older people were more likely to gain more weight compared to younger people. We also showed that the mean 2-year Knee Society Knee Score was significantly higher in the patients who gained weight while the patients who lost weight had the highest mean 2-year Oxford Knee Score and the lowest mean 2-year Knee Society Function Score.
Asians tend to gain weight following TKA. However, this weight change following TKA does not affect clinical outcomes, which remain good across all BMI groups.
Therapeutic Level III.

View all citing articles on Scopus

: The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2014.09.003.

View full text

Association Between Body Mass Index Change and Outcome in the First Year After Total Knee Arthroplasty

Abstract

Section snippets

Patients and Methods

Results

Discussion

Acknowledgments

Am J Med

J Arthroplasty

J Am Diet Assoc

J Arthroplasty

Am J Surg

Surg Obes Relat Dis

Early outcomes and complications following joint arthroplasty in obese patients: a review of the published reports

ANZ J Surg

Tibial component failure mechanisms in total knee arthroplasty

Clin Orthop

The impact of pre-operative obesity on weight change and outcome in total knee replacement

J Bone Joint Surg (Br)

The MOS 36-Item Short-Form health survey (SF36): I. conceptual framework and item selection

Med Care

Comparison of a generic (SF36) and a disease specific (WOMAC) instrument in the measurement of outcomes after knee replacement surgery

J Rheumatol

Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to anti rheumatic drug therapy in patients with osteoarthritis of the hip or knee

J Rheumatol