20 January 2025: Clinical Research
Five-Year Impact of Weight Loss on Knee Pain and Quality of Life in Obese Patients
Mehmet Cenk Belibağlı

DOI: 10.12659/MSM.946550
Med Sci Monit 2025; 31:e946550
Abstract
BACKGROUND: Studies on patients with obesity who lose a considerable amount of body fat show that the severity of knee pain and movement limitation is decreased. This study aimed to analyze the effects of weight loss on knee pain and quality of life in patients with obesity.
MATERIAL AND METHODS: The study included patients aged 18-65 years with a body mass index (BMI) of 30 kg/m² and above, who expressed knee pain in daily life routines and applied to the Obesity Center of Adana City Training and Research Hospital as of June 2018. The retrospective analysis included age, sex, weight, height, annual radiological imaging follow-up scores (Kellgren-Lawrence), visual analog scale (VAS) scores, EuroQol-5D (EQ-5D) scores, and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores of the patients throughout the 5-year follow-up period.
RESULTS: The mean age of the 89 patients was 50.3±10.5 years, and 82% were women. The initial BMI, EQ-5D, VAS, and WOMAC scores differed significantly from the scores at year 5 (P=0.0001). Receiver operating characteristic analysis showed the probability of reducing the progression of knee joint degeneration was 74% if the BMI reduction was greater than 13.3% over the 5-year follow-up period.
CONCLUSIONS: The overall interpretation of the results was that a 13.3% or greater reduction in BMI in the first year, despite an increase in the following years, triggered improvements in various aspects of pain and functionality scores, improved quality of life, and reduced KOA progression.
Keywords: Obesity, Osteoarthritis, Knee, Pain, Weight Loss
Introduction
The World Health Organization defines obesity as a disease caused by abnormal and excessive fat accumulation, which can deteriorate health. Overweight is described as having a body mass index (BMI) of 25 kg/m2 or higher, with increased adipose tissue mass, while obesity is defined as a BMI of 30 kg/m2 or higher. Obesity is shown to be the second most common cause of preventable deaths after smoking. Currently, more than one-third of the global population is categorized as overweight or obese based on BMI measurements. The rising prevalence indicates that by 2030, approximately 55% of the global population may have a BMI over 25 kg/m2 [1].
The increased body weight associated with obesity induces alterations in posture, gait pattern, biochemistry of the body, and physical activity, resulting in diverse variations. One of the many consequences of excessive weight is knee pain, the most prevalent musculoskeletal ailment, which is mainly attributed to mechanical loading. The management of non-traumatic knee pain is challenging, since, in addition to the biomechanical load, the causes include septic arthritis, gout, pseudogout, and neoplastic factors [2].
Biomechanical changes lead to a rise in the load exerted on the medial compartment of the knee, thereby accelerating the degenerative process in the knee joint [3]. In addition to the mechanical effect of increased body weight, metabolic factors released from adipose tissue contribute to cartilage damage and affect the development and progression of knee osteoarthritis (KOA) by decelerating the repair process [4]. Reports indicate that individuals with a higher BMI, particularly patients with KOA, express poorer mobility, poorer self-reported scores, and more pain than do individuals with a lower BMI [5,6].
Although the effect of body weight on knee symptoms has not been fully elucidated, there is a limited number of studies focused on the long-term outcomes of excess weight on loss of mobility, knee pain status, and quality of life, especially in patients with weight cycling [7].
In terms of conservative and minor surgical treatment procedures, the current clinical guidelines have not yet reached a consensus and suggest various specific treatment modalities for the treatment of KOA, particularly for young patients. However, despite the many alternatives, there seems to be a large gap regarding a definitive treatment solution, since both conservative and minimally invasive surgery were shown to fail in the long-term treatment of KOA for young patients [8].
Total knee arthroplasty might be considered the solution for patients with KOA that do not respond to non-surgical treatments, including analgesics, bracing, activity modification, physiotherapy, and intra-articular injections, but cannot be recommended in all cases [9]. The studies conducted on the risk factors for KOA suggest that obesity is included in the main preventable risk factor group [10].
The study of Messier et al on the effect of weight loss on patients with KOA, involving a follow-up duration of 18 months, showed that although the difference in severity was not great, a statistically significant decrease in pain was observed [11].
Because weight loss is crucial in decreasing the incidence and alleviating the symptoms of knee pain, we aimed to analyze the long-term effects of weight loss on knee-related quality of life in patients with obesity enrolled in a weight-loss program.
Material and Methods
ETHICS APPROVAL:
Ethical approval of the study was given by the Clinical Research Ethics Committee of the Adana City Training and Research Hospital on November 23, 2023, with decision no. 2961. Informed consent was obtained from the participants.
STUDY DESIGN AND DATA COLLECTION:
This retrospective study analyzed the records of patients aged 18 to 65 years with obesity (BMI equal to or over 30 kg/m2) who were enrolled in the weight-loss program of the Obesity Center of Adana City Training and Research Hospital as of June 2018. The study included patients experiencing non-traumatic knee pain in daily life.
In addition to demographic data, including age, sex, weight, and height, annual radiological imaging follow-up scores using Kellgren-Lawrence (KL) grading, visual analog scores (VAS) for pain, EuroQol-5D (EQ-5D) scores, and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were compared over the 5-year follow-up period (June 2018–June 2023). The records of orthopedic consultations, including weight-bearing knee X-ray images, were noted. Patients with a history of knee trauma, knee surgery, malignant and benign soft tissue and bone masses involving knee joints, and missing follow-up data and X-ray images were excluded from the analysis.
WEIGHT-LOSS PROGRAM:
The staff of the obesity center included a physician, dietitian, physical therapist, psychologist, and community outreach worker. The design of the weight-loss program included an initial assessment of the patient (a medical check-up), educational and training activities regarding cognitive and behavioral improvement in nutrition knowledge and nutritional habits, and continuity of the change. Patients requiring consultations for additional medical conditions were referred to the relevant clinics (eg, endocrinology, neurology, orthopedics).
RADIOLOGIC AND CLINICAL EVALUATION:
The KL staging system is a well-known grading classification used to assess osteoarthritis in 5 levels in the radiographs of the joint, beginning from grade zero, the absolute absence of osteoarthritis changes, to the formation of osteophytes, periarticular ossicles, narrowing of joint cartilage, small pseudo cystic areas with subchondral sclerosis, and altered shape of the bone ends [12]. An orthopedist performed the KL staging using images obtained from the patients’ medical records. One image per year was chosen for each assessed patient [13].
The WOMAC is a broadly preferred self-administered questionnaire for assessing KOA. It consists of 24 items divided into 3 subscales and assesses pain, stiffness, physical function, social function, and emotional function [14]. The Turkish version of the WOMAC self-reported scale was used in this study [15].
The EQ-5D, a widely used and reliable tool, is a brief self-reported scale to assess general health across 5 dimensions: mobility, self-care, usual activities, pain or discomfort, and anxiety or depression [16].
The patients’ KL grading and EQ-5D, VAS, and WOMAC scores were recorded annually, beginning from admission and ending at the last visit.
STATISTICAL ANALYSIS:
Statistical analysis was performed using the statistical package SPSS software (version 25.0, IBM Corp, Armonk, NY, USA). The continuous variables are described as the mean and standard deviation for normally distributed data and as median and interquartile range for non-normally distributed data. The Kolmogorov-Smirnov test or Shapiro-Wilk test was used to test the normality of the distribution of the variables. The chi-square test and Fisher exact test were used for categorical measurements. Correlations were tested using the Spearman correlation test. A
Results
DEMOGRAPHIC AND CLINICAL CHARACTERISTICS OF THE STUDY POPULATION:
The mean age of the 89 patients included in the study was 50.3±10.5 years, and 82% were women. The initial BMI value was dramatically higher than that of the following 5 years (
The analysis showed that the baseline EQ-5D value was lower than that of the following 5 years (
The VAS scores were significantly decreased over time for all years (P=0.0001). The same statistical significance was found in changes in WOMAC scores (P=0.0001). The mean values of the key variables are presented in Table 1. The trends in the key variables during the 5 years are shown in Figure 1.
The KL grading score analysis showed that the grade levels increased markedly over the years (
CORRELATION ANALYSIS:
The results of the analysis revealed an inverse correlation between age and EQ-5D and the change in BMI, suggesting that an increase in age was associated with a decrease in BMI change and EQ-5D scores. Also, there was a positive correlation between age and WOMAC scores and between age and VAS scores, indicating that with older age, higher WOMAC and VAS scores were expected (Table 2).
ROC analysis showed that the probability of reducing the progression of knee joint degeneration was 74%, with a sensitivity of 81.3% and specificity of 67.9% (95% CI 0.66–0.89), if the patient’s BMI reduction was greater than 13.3% over the 5-year follow-up period.
Discussion
The findings showed that there were statistically significant differences between the initial and the final assessment scores of BMI, KL, WOMAC, and EQ-5D.
The study results showed that a decrease in BMI was strongly associated with pain scores, physical functions, overall health, and radiological findings of patients with KOA. In addition, although older patients were less prone to lose body weight, the level of change in quality of life scores with the reduction in BMI was more significant with increasing age. Also, older age was related to worsened pain and physical function scores. A significant relationship between age and functionality scores was also reported by Nikolic et al, who stated that aged patients were classified in higher KL grades (3–4) and had remarkably increased BMI values [17].
In the present study, the initial VAS scores of the study population were significantly elevated and correlated with the BMI; this finding agreed with the results of Garver et al, which highlight that pain scores of patients with class III obesity were considerably higher than those with class II and I [5]. The mean VAS scores in our study decreased in parallel to the BMI in the first year, but the VAS scores continued to decline despite a slight increase, followed by stabilized BMI values. Teichtahl et al suggested that weight loss was linked to decreased medial cartilage volume depletion and decreased knee symptoms [18].
The strong link between BMI and physical functions revealed in our study was also observed in other reports. Lawford et al claimed that a 10% decrease in weight represented improved results of approximately 1 unit in pain in the numerical rating scale and around 5 units in physical function assessed using the WOMAC [19].
In terms of radiographic knee findings, Joseph et al found that a decrease in body weight was related to considerably lower odds of impairment in KL grading, and the increase was linked to higher odds of medial knee joint space narrowing [20]. Similarly, the results of the present study showed that if a BMI is reduced by more than 13.3%, there is a 74% chance of preventing poor progression of the knee degeneration process.
In terms of response to the treatments, Couldrick et al, by contrast, reported that age, sex, BMI, and OA severity were not associated with the response to first-line interventions for KOA. Nevertheless, the authors recommend interventions, including exercise therapy and weight loss, for patients with KOA, regardless of additional factors. However, as expected, increased age was linked to decreased odds of improvement to first-line interventions in patients with KOA [21]. Moreover, Mayfield et al suggest that excessive weight was not only shown to alter the risk of developing KOA but also of complications following knee arthroplasty, and weight loss might decrease both risks for the obese population [22]. In patients in which total knee arthroplasty was required, the reports indicate that following the surgery, patients lost relatively more weight than the general population when adequate levels of joint functions and pain relief were acquired [23].
Regarding overall health, Covinsky et al reported that untreated KOA symptoms in older age worsen functional capacity and increase the level of dependence on daily routines, raising the risk for depression and additional psychological factors, which are strongly related to morbidity and mortality risks [24]. Therefore, the diagnosis and management of KOA should be performed in a multidisciplinary manner, since the primary factors, such as weight loss, level of exercise, and quality of life, are less inclined to change with older age, highlighting the fact that increased age allows for fewer instruments for treatment.
In our study, there was a lower number of patients with higher KL grades in the first 3 years, which was followed by a remarkable rise in KL grades in the last 2 years, with the number of patients classified with KL grades 2 and 3 in the last 2 years being dramatically higher. The mean BMI of the study group decreased, although not linearly; however, the correlation with age should be interpreted carefully, since the link between age and BMI might be a key factor in the management of first-line interventions in patients with KOA.
In the literature, there are many studies focused on elderly KOA patients with severe symptoms. However, the younger population with milder severity KOA for whom arthroplasty may not be recommended might benefit much more from early and adequate intervention methods targeting the deceleration of the progression of structural degradation and deformities, diminishing pain and refining function. London et al stated that treating younger KOA patients with milder symptoms, especially those expressing pain and limited function, was clinically difficult, and the authors identified a treatment gap zone [25]. In addition, Khan et al specifically considered this group and suggested that the first step of a conservative treatment program for young patients with KOA should be weight loss [9]. The biomechanical studies showing that 1 kg (approximately 2 pounds) of weight loss is associated with a 4-fold decrease in the forces acting on the knee indicate that more focus should be placed on weight loss [26].
We believe that this study, although it had major limitations, can contribute to the literature.. In particular, the identification of a cut-off point in weight change and its association with the symptoms and the progression of KOA through further analysis of obesity, a risk factor for KOA already defined in previous studies, may be of critical importance in preventing or slowing KOA progression. The critical limitations were the sample size, design, and single-center setting. Also, the lack of a control group lowered the value of the interpretation. In addition, radiographs and the patients’ weight and height measurements, which provide a basis for the BMI results, were performed at different times, which prevented a reliable comparative analysis; therefore, the study results could only be compared as before and after results of the follow-up duration. Also, the radiologic assessment of the patients was based on X-ray images, which are limited in quality in terms of presenting articular surfaces. Finally, most patients were women, which limits the generalization and interpretation of significant findings.
Conclusions
The overall interpretation of the study was that a 13.3% or greater reduction in BMI in the first year, despite an increase in the following years, triggered improvements in various aspects of pain and functionality scores, improved quality of life, and reduced KOA progression.
Patients with KOA who are not focusing on weight management, are keeping their current weight, or are gaining more weight bear the increased risk of poor KOA progress.
The dose-response relationship revealed in this study is noteworthy and might be beneficial for patients’ clinical management and for the awareness and motivation patients need to proceed with the treatment provided by the physicians.
Future prospective and controlled studies that include larger patient samples, with a more even distribution in terms of sex, and evaluation by magnetic resonance imaging can provide further evidence.
References
1. , Obesity: Preventing and managing the global epidemic. Report of a WHO consultation: World Health Organ Tech Rep Ser, 2000; 894; i-xii
2. Bamania P, Osmani HT, Robinson P, The patient with a painful knee: Br J Hosp Med (Lond), 2024; 85(2); 1-10
3. Kolukisa S, Atlig RS, Icagasioglu A, Demirhan E, Searching parameters that effects on knee and hip osteoarthritis and comparing with quality of life: Göztepe Tıp Dergisi, 2010; 25(2); 58-66
4. Christensen P, Bartels EM, Riecke BF, Improved nutritional status and bone health after diet-induced weight loss in sedentary osteoarthritis patients: A prospective cohort study: Eur J Clin Nutr, 2012; 66(4); 504-9
5. Garver MJ, Focht BC, Dials J, Weight status and differences in mobility performance, pain symptoms, and physical activity in older, knee osteoarthritis patients: Arthritis, 2014; 2014; 375909
6. Rogers MW, Wilder FV, The association of BMI and knee pain among persons with radiographic knee osteoarthritis: A cross-sectional study: BMC Musculoskelet Disord, 2008; 9; 163
7. Riddle DL, Stratford PW, Body weight changes and corresponding changes in pain and function in persons with symptomatic knee osteoarthritis: A cohort study: Arthritis Care Res (Hoboken), 2013; 65(1); 15-22
8. Witjes S, van Geenen RCI, Koenraadt KLM, Expectations of younger patients concerning activities after knee arthroplasty: Are we asking the right questions?: Qual Life Res, 2017; 26(2); 403-17
9. Khan M, Adili A, Winemaker M, Bhandari M, Management of osteoarthritis of the knee in younger patients: CMAJ, 2018; 190(3); E72-E79
10. Powell A, Teichtahl AJ, Wluka AE, Cicuttini FM, Obesity: A preventable risk factor for large joint osteoarthritis which may act through biomechanical factors: Br J Sports Med, 2005; 39(1); 4-5
11. Messier SP, Beavers DP, Queen K, Effect of diet and exercise on knee pain in patients with osteoarthritis and overweight or obesity: A randomized clinical trial: JAMA, 2022; 328(22); 2242
12. Kellgren JH, Lawrence JS, Radiological assessment of osteo-arthrosis: Ann Rheum Dis, 1957; 16(4); 494-502
13. Kohn MD, Sassoon AA, Fernando ND, Classifications in brief: Kellgren-Lawrence Classification of osteoarthritis: Clin Orthop Relat Res, 2016; 474(8); 1886-93
14. McConnell S, Kolopack P, Davis AM, The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC): A review of its utility and measurement properties: Arthritis Rheum, 2001; 45(5); 453-61
15. Tüzün EH, Eker L, Aytar A, Acceptability, reliability, validity and responsiveness of the Turkish version of WOMAC osteoarthritis index: Osteoarthritis Cartilage, 2005; 13(1); 28-33
16. Rabin R, Charro FD, EQ-SD: A measure of health status from the EuroQol Group: Ann Med, 2001; 33(5); 337-43
17. Nikolic G, Nedeljkovic B, Trajkovic G, Pain, physical function, radiographic features, and quality of life in knee osteoarthritis agricultural workers living in rural population: Pain Res Manag, 2019; 2019; 7684762
18. Teichtahl AJ, Wluka AE, Tanamas SK, Weight change and change in tibial cartilage volume and symptoms in obese adults: Ann Rheum Dis, 2015; 74(6); 1024-29
19. Lawford BJ, Hinman RS, McManus F, How does exercise, with and without diet, improve pain and function in knee osteoarthritis? A secondary analysis of a randomized controlled trial exploring potential mediators of effects: Arthritis Care Res (Hoboken), 2023; 75(11); 2316-27
20. Joseph GB, McCulloch CE, Nevitt MC, Effects of weight change on knee and hip radiographic measurements and pain over four years: Data from the osteoarthritis initiative: Arthritis Care Res (Hoboken), 2023; 75(4); 860-68
21. Couldrick JM, Woodward AP, Silva MDC, Evidence for key individual characteristics associated with outcomes following combined first-line interventions for knee osteoarthritis: A systematic review: PLoS One, 2023; 18(4); e0284249
22. Mayfield CK, Mont MA, Lieberman JR, Heckmann ND, Medical weight optimization for arthroplasty patients: A primer of emerging therapies for the joint arthroplasty surgeon: J Arthroplasty, 2024; 39(1); 38-43
23. Smolle MA, Musser E, Hauer G, Patients successfully lose body weight after primary total knee arthroplasty but not more than a matched general population: Arch Orthop Trauma Surg, 2023; 143(6); 3327-34
24. Covinsky KE, Lindquist K, Dunlop DD, Effect of arthritis in middle age on older-age functioning: J Am Geriatr Soc, 2008; 56(1); 23-28
25. London NJ, Miller LE, Block JE, Clinical and economic consequences of the treatment gap in knee osteoarthritis management: Med Hypotheses, 2011; 76(6); 887-92
26. Messier SP, Gutekunst DJ, Davis C, DeVita P, Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis: Arthritis Rheum, 2005; 52(7); 2026-32
In Press
Clinical Research
Immune Dysregulation in Acute Herpes Zoster: Predictive Factors for Postherpetic NeuralgiaMed Sci Monit In Press; DOI: 10.12659/MSM.944688
Clinical Research
Inflammatory Biomarkers from Blood Counts as Prognostic Tools in Metastatic Esophageal CancerMed Sci Monit In Press; DOI: 10.12659/MSM.947202
Laboratory Research
Comparison of Color Stability Between Single-Shade and Conventional Composite Resins Following Immersion in...Med Sci Monit In Press; DOI: 10.12659/MSM.946784
Clinical Research
Evaluation of Knowledge, Attitudes, and Practices Toward Thyroid Nodules in 456 Patients with Thyroid NodulesMed Sci Monit In Press; DOI: 10.12659/MSM.945732
Most Viewed Current Articles
17 Jan 2024 : Review article 6,966,841
Vaccination Guidelines for Pregnant Women: Addressing COVID-19 and the Omicron VariantDOI :10.12659/MSM.942799
Med Sci Monit 2024; 30:e942799
16 May 2023 : Clinical Research 701,694
Electrophysiological Testing for an Auditory Processing Disorder and Reading Performance in 54 School Stude...DOI :10.12659/MSM.940387
Med Sci Monit 2023; 29:e940387
01 Mar 2024 : Editorial 25,087
Editorial: First Regulatory Approvals for CRISPR-Cas9 Therapeutic Gene Editing for Sickle Cell Disease and ...DOI :10.12659/MSM.944204
Med Sci Monit 2024; 30:e944204
28 Jan 2024 : Review article 19,746
A Review of IgA Vasculitis (Henoch-Schönlein Purpura) Past, Present, and FutureDOI :10.12659/MSM.943912
Med Sci Monit 2024; 30:e943912