Changes in knee pain and perceived need for surgery, physical function and quality of life after dietary weight loss in obese women diagnosed with knee ...
Changes in knee pain and perceived need for surgery, physical function and quality of life after dietary weight loss in obese women diagnosed with knee osteoarthritis Kamary Coriolano–Da Silva PhD (candidate), PT1; Alice B. Aiken PhD, PT1; Mark Harrison MD2; Caroline F. Pukall PhD3; Brenda Brower PhD4; Dianne L. Groll5 PhD 1School
of Rehabilitation Therapy, 2Department of Surgery, 3Department of Pyschology, School of Graduate Studies, Department of Psychiatry, Queen’s University, Kingston, ON, Canada
Results
Obesity increases the incidence of many chronic conditions, including osteoarthritis (OA) 1-2. An increased biomechanical load due to excessive body weight intensifies deterioration of the cartilage and causes vary degrees of stiffness, swelling and pain 3-4. Therefore, many obese individuals with knee OA require a total knee replacement (TKR) surgery to improve their quality of life. However, many surgeons refuse to operate on obese patients until they have lost weight due to increased rates of infection, and complications such as deep vein thromboses, or early failure of the prosthetic 5-6. Interestingly, after losing considerable amount of weight these individuals show reduced knee pain and increased functional performance 7-8 which might encourage patients to postpone surgery indefinitely. Yet, the amount of weight that obese people with knee OA needs to lose to significantly reduce pain and improve performance, to a point where a TKR surgery could be prolong or alleviate, remains unknown.
Objectives Investigate whether weight loss is associated with a reduction in perceived need for surgery (PNS) due to decrease in knee pain and improvement in physical function. Identify what percentage of weight loss is associated with a reduction in knee pain to a point where the need for surgery could be prolonged or alleviated.
Hypothesis It was hypothesized that a reduction in perceived need for TKR surgery among obese women diagnosed with knee OA would be associated with a decrease in knee pain and improvement in physical function followed by significant weight loss.
Table 2: significant values at 6 weeks, 3 months and 6 months 6weeks
p value 3months p value 6months
p value
% weight lost
9.5%
.000
16.5%
.000
27%
45
% Knee Pain change % WOMAC total change % 6MWT change % TUG change % SF-36 (PF) % SF-36 (BP)
17.8%
.087
21.1%
37%
.015
18.7%
.129
3.8% 53% 10.6%
1.00 .038 1.00
30% 28.9% 17.6% 62.8% 26.4%
.004 .012 .029 .162 .050 .045
33.5%
.026
40.2%
.003
42%
.006
31.2% 145% 53.2%
.027 .002 .020
Percentage of yes response at each time point - significant difference with p ≤ 0.05 at 6 weeks, 3 months and 6 months
Baselin 6weeks p 3 months p e value value PNS % responding yes 100% 60% .041 44% .227 (yes / number of (26/26) (15/25) (11/25) respondents)
Pain related to body weight
6months p value 29.4% .0001 (5/17)
Subject demographics, WOMAC & SF-36
6MWT & TUG
Patients
with BMI ≥ 35, who indicated severe pain and radiological knee OA, were identified by the surgeons as requiring total knee replacement surgery were included. Participants presenting non-knee OA related mobility restrictions (neurological and musculoskeletal), cardiac disease (unstable angina, peripheral vascular disease, congestive heart failure), uncontrolled hypertension, kidney disease or gallbladder attacks were excluded
Weight Loss Intervention: After baseline testing, subjects were referred for a full medical examination and
TUG * http://on.drbdiet.com/
12.1 ± 4.6
25 20 15 10 5 0 20
40
60
80 mass (kg)
100
120
140
160
Discussion It’s been emphasized that a reduction of more than 5 % of body weight is needed to promote reduction in disability and pain 7-8. Our results indicated that a significant decrease of 9.5% of body weight significantly improved subjective levels of physical function and quality of life. Even though knee pain and PNS decreased after subjects had lost 9.5% of body weight, these measurements did not significantly change until subjects had lost 16.5% of body weight. Therefore, our statistical analysis indicated that a significant loss of 16.5% of body weight for morbidly obese women (BMI ≥ 35 kg/m2) represented a significant reduction of 37% of knee pain followed by a decrease of 56% of PNS (Table 4).
12
From a clinical perspective, by knowing the amount of weight obese women need to lose to significantly reduce pain and therefore prolong or alleviate surgery; one could predict need for surgery for those who really need surgery, even after losing a significant percentage of body weight. Moreover health care providers could prevent premature knee replacement surgeries and subsequent early prosthetic revision for those who could primarily benefit from conservative interventions. Even though a weight loss of 16.5% might influence a patients’ choice to undergo TKR surgery, this finding might not be extended to the general morbidly obese population. However, based on our results, we expect that a weight loss of 16.5% might provide a major decrease in knee pain and increase in function. Therefore, even if an initial weight loss of 16.5% or more does not change the actual need for TKR surgery for some participants, the observed reduction in pain and increase in function after losing weight will likely benefit them before surgery.
basline 6wk 3 mo 6mo
10 8 6 4
0 0
20
40
60
80 mass (kg)
WOMAC total score related to body weight
100
120
140
160
r2=.564; p=.019
90 80 70 60 basline 6wk 3 mo 6mo
50 40 30 20 10
The program is based on a low-fat, low calorie and low carbohydrate diet. The patients were monitored and weighed three times a week at the clinic, and saw by a physician every two weeks.
0
STATISTICAL ANALYSES
20
40
60
80 mass kg
6MWT related to body weight
100
120
140
160
r2=.709; p=.000
Directions for future research: Combine diet and exercise and possibly integrate health education programs to enhance the use of physical activity. A larger sample is needed and a strong strategy to improve retention and adherence is critical, particularly if the duration of the diet is to be increased. It is also important to observe physiological measures of physical function such as quadriceps and hamstrings strength as well as oxygen consumption, which are important in determining functional capacity of obese individuals with knee OA.
References
600
1. Luo W, Morrison H, de Groh M, et al: The burden of adult obesity in Canada. Chronic Dis Can.2007;27:135-44.
500 400 6MWT (meters)
Independent T-test: To compare the participants who were enrolled but dropped out prior to commencing the diet with those who remained in the program. Pearson’s correlation analysis: To compare whether body weight was associated with knee pain, WOMAC, SF-36 and objective measures of physical function (6MWT and TUG).. Repeated Measures ANOVA: To observe whether significant changes occurred in body weight, knee pain, WOMAC, SF-36, 6MWT and TUG.
basline 6wk 3 mo 6mo
Clinical & patient Implications:
0
Group Baseline characteristic (n=34) s Age 58.2 ± 5.8 Weight 120.1 ± 12 Height 1.6 ± 0.63 BMI 47.1 ± 4.9 WOMAC56.1 ± 17 total 6MWT 274.4 ± 135.9
30
14
2
enrolment into a weight loss program in a local diet clinic* at no charge.
Table 1: Baseline groups characteristics
35
16 WOMAC Pain Scale (0-20)
Data Collection (Baseline and Follow up sessions)
r2=.511; p=.048
18
WOMAC total score (0-96)
Study Criteria
40
0
Table 3: Perceived need for surgery (PNS) Chi-square
Study design and subjects: A longitudinal study including 34 women between 40 and 65 years old with morbid obesity (BMI ≥ 35 kg/m2) and OA of the knee was conducted in a laboratory setting. Subjects were pre-selected during an orthopedic consult for TKR surgery at Hotel Dieu Hospital.
50
.000
CORRELATIONS
Methods
r2=.633; p=.000
TUG related to body weight
TUG (seconds)
Introduction
300
basline
2. Hunter DJ, Felson DT: Osteoarthritis. BMJ.2006;332:639-42.
6wk
3. Felson DT. Clinical practice. Osteoarthritis of the knee: N Engl J Med.2006;354:841-48.
3 mo
4. Winiarsky R, Barth P, Lotke P: Total knee arthroplasty in morbidly obese patients. J Bone Joint Surg Am.1998;80:1770-74.
6mo
200
5. Pritchett JW, Bortel DT: Knee replacement in morbidly obese women. Surg Gynecol Obstet.1991;173:119-22.
100 0 0
20
40
60
80 mass (kg)
100
120
140
160
6. Mulhall KJ, Ghomrawi HM, Mihalko W, Cui Q, Saleh KJ: Adverse effects of increased body mass index and weight on survivorship of total knee arthroplasty and subsequent outcomes of revision TKA. J Knee Surg.2007;20(3):199-204. 7. Christensen R, Bartels EM, Astrup A, Bliddal H: Effect of weight reduction in obese patients diagnosed with knee osteoarthritis: a systematic review and meta-analysis. Ann Rheum Dis.2007;66:433-39. 8. Messier SP. Diet and exercise for obese adults with knee osteoarthritis: Clin Geriatr Med.2010;26:46177.