Weight Loss Intervention Before Total Knee Replacement

Study Overview
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Brief Summary
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The purpose of this study is to compare the efficacy in a group of patients who must follow the current procedure for treatment of artificial knee, compared with a group of patients who must undergo an 8-week weight loss program before surgery. 1 year after surgery the investigators will examine whether there are differences between the two groups' quality of life and functional capacity.

Detailed Description
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Background In Denmark the numbers of primary total knee arthroplasty (TKA) operations annually increase. In the year 2000 was performed approximately 2,500 operations and in 2008 was performed more than 7,500 total knee arthroplasty operations, and there appears in all countries to be similar tendency. Meanwhile, the prevalence of overweight and obesity has increased markedly over the last 50 years. Approximately 13% of the Danish population is obese. For several years the association between obesity and knee osteoarthritis (OA) has been recognized, and osteoarthritis is the most frequent indication for total knee arthroplasty(80%). The purpose of this study is to investigate whether weight loss interventions before primary total knee arthroplasty will improve quality of life and functional level, reduce pain and risk of early and late postoperative complications. Sample size Significance level is set to 5% by using a 2-sided analysis and the power is set at 80%. Based on an expectation of a difference in patient-reported outcome scores in between the groups at 8%, as measured by SF-36 12 months postoperatively, standard deviation (SD) 13 must be include 41 participants in each group. To allow a drop-out rate of 20% the group size increases to 51 participants in each group. In total 102 participants. Statistical analysis, The two groups scores at 12 months postoperatively, and the two groups' change in the primary outcome measurer, from 1 week before surgery to 12 months postoperatively, compared with t-test or Mann-Whitney test rang sum depending on data distribution.

Official Title
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Weight Loss Intervention Before Total Knee Replacement, a Randomized Controlled Trial

Conditions
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Osteoarthritis, Knee, Obesity

Intervention / Treatment
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* Behavioral: 8 weeks weight loss program, Cambridge.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients recommended for primary total knee replacement. Body mass index > 30. Must be motivated for weight loss. Must be able to read and understand Danish. Exclusion Criteria: Rheumatoid arthritis. Patients who are operated on both knees during the project period can only participate once. Planned obesity surgery.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: control group<br>Standard procedure for knee arthroplasty | |
| Active Comparator: Weight loss program<br>The intervention program consists of 8 weeks of low-diet, using formula foods, and dietary counseling before surgery. When using formula foods the patients can achieve a quicker weight reduction and a greater reduction in fat mass than using conventional dietetic hypo caloric diet. | Behavioral: 8 weeks weight loss program, Cambridge.<br>* Fast weight losses improve the prognosis for the sustained weight loss. During the first week a dietitian will tutor the participants in formula food diet (The Cambridge Health and Weight plan UK.), followed by seven weeks with control guidance and instruction in healthy eating habits once a week. The guidance by the dietitian will be carried out both on an individual basis and in groups. The goal of the intervention is to achieve a preoperative weight loss of at least 5 to 10% of the patient's body weight, thus improving patient's health before surgery.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| SF-36 | A patient reported outcome (PRO). The questionnaire is a tool for measuring health status. The form is used to measure the patient's view of his own health by scoring standardized responses to standardized questions. The schedule consists of 36 questions representing eight health concepts. | Measured 12 months postoperatively. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 6 minutes walk test (6MW). | Used to target the operating level of the patient's daily activities. | Measured 1 week before surgery. | 
| Body composition | Dual energy X-ray absorptiometry (DEXA) can measure total body bone mineral density and obtain accurate measurements of body tissue composition (muscle mass and fat mass). By measuring the body's muscle mass, fat mass and bone mineral density, one can estimate total body fat percentage. | Measured 1 week before surgery. | 
| Bone mineral density (BMD). | Measured by DEXA scan. | Measured 12 months postoperatively. | 
| KOOS | Knee - specific patient-reported outcome that measures the patient's own assessment of knee problems and related problems. The schedule consists of 42 questions representing 5 strands. | Measured 1 week before surgery. | 
| Pain | Visual Analogue Scale (VAS pain score) | Measured 1 week before surgery. | 
| Serum leptin. | Leptin is a hormone produced in fat tissue. | Measured 1 week before surgery. | 
| Heart rate | Cardiovascular complications. | Measured 1 week before surgery. | 
| Blood pressure | Cardiovascular complications. | Measured 1 week before surgery. | 
| 6 minutes walk test (6MW). | Used to target the operating level of the patient's daily activities. | Measured 8 week postoperatively. | 
| 6 minutes walk test (6MW). | Used to target the operating level of the patient's daily activities. | Measured 12 months postoperatively | 
| Body composition | Dual energy X-ray absorptiometry (DEXA) can measure total body bone mineral density and obtain accurate measurements of body tissue composition (muscle mass and fat mass). By measuring the body's muscle mass, fat mass and bone mineral density, one can estimate total body fat percentage. | Measured 8 week postoperatively | 
| Body composition | Dual energy X-ray absorptiometry (DEXA) can measure total body bone mineral density and obtain accurate measurements of body tissue composition (muscle mass and fat mass). By measuring the body's muscle mass, fat mass and bone mineral density, one can estimate total body fat percentage. | Measured 12 months postoperatively | 
| KOOS | Knee - specific patient-reported outcome that measures the patient's own assessment of knee problems and related problems. The schedule consists of 42 questions representing 5 strands. | Measured 8 week postoperatively | 
| KOOS | Knee - specific patient-reported outcome that measures the patient's own assessment of knee problems and related problems. The schedule consists of 42 questions representing 5 strands. | Measured 12 months postoperatively | 
| Pain | Visual Analogue Scale (VAS pain score) | Measured 8 week postoperatively | 
| Pain | Visual Analogue Scale (VAS pain score) | Measured 12 months postoperatively | 
| Serum leptin. | Leptin is a hormone produced in fat tissue. | Measured 8 week postoperatively | 
| Serum leptin. | Leptin is a hormone produced in fat tissue. | Measured 12 months postoperatively | 
| Heart rate | Cardiovascular complications. | Measured 8 week postoperatively | 
| Heart rate | Cardiovascular complications. | Measured 12 months postoperatively | 
| Blood pressure | Cardiovascular complications. | Measured 8 week postoperatively | 
| Blood pressure | Cardiovascular complications. | Measured 12 months postoperatively | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Osteoarthritis, knee, Obesity, Weight Loss, Arthroplasty