Purpose: Weight loss in overweight patients with knee osteoarthritis (OA) is recommended because it effectively induces symptomatic relief. However, maintaining weight loss and symptomatic relief is a challenge, and the effects of weight and symptom maintenance programs on cartilage deterioration are unknown. The purpose of this study was to compare cartilage loss in the knee joint over 1-year of dietary consultancy or therapeutic exercise vs. control in obese knee OA patients after a clinically significant weight loss.
Methods: Obese individuals (>50 years) with knee OA (ACR criteria), and motivated for weight loss, were enrolled in a 16-week weight loss program that induced a clinically significant weight loss (>10%). They were then randomized to either 1-year maintenance program with [D] continuous dietary consultations, or [E] knee exercise program supervised by a physical therapist or [C] a control group receiving no support from the study team for 1 year. The primary endpoint was annual change in total knee joint cartilage volume assessed by MRI. Secondary outcomes included changes in the individual regional cartilage volumes assessed by automatic segmentation of MRI and changes in average knee symptoms measured as the mean of 4 out of the 5 KOOS subscales (excluding sports and recreation subscale) over 1 year. The outcomes were analyzed statistically using ANCOVA with a factor for maintenance group, adjusting for the level at baseline.
Results: 192 participants, mean age 63 years (SD 6), mean weight 103.2 kg (15.0), and BMI of 37.3 (4.8) were randomized (1:1:1; 64 patients in each group). The average annual loss in total cartilage volume across groups was 1,150 mm3. There were no statistically significant group differences in changes in cartilage volumes at the 1 year follow-up (Table). The average symptoms deteriorated by 8.4 points (SE 1.1) across groups. There were also no statistically significant group differences for the average symptoms (KOOS) or any of the other secondary outcomes. Ancillary analysis showed that the annual changes in total cartilage volume were not associated with annual changes in average symptoms (r=-0.007, P=0.93).
Conclusion: This study showed no differences in knee joint cartilage loss between obese knee OA patients who after a significant weight loss participated in either dietary maintenance, knee exercise or a control group for 1 year. The cartilage loss was not associated with changes in symptoms.Trial registration: {NCT00655941}
Tabled
1ANCOVA results for changes in weight, BMI and cartilage volumes (mm3) and average symptoms (KOOS)
| Group C | Group D | Group E | ANCOVA | ||||
|---|---|---|---|---|---|---|---|
| Mean | 95% CI | Mean | 95% CI | Mean | 95% CI | P-value | |
| Weight, kg | -9.8 | -11.7 to -7.8 | -12.8 | -14.7 to -11.0 | -8.0 | -9.9 to -6.1 | 0.0018 |
| BMI | -3.5 | -4.2 to -2.8 | -4.6 | -5.3 to -4.0 | -2.9 | -3.6 to -2.2 | 0.0023 |
| Cartilage Volume (mm3) | |||||||
| Total knee | -1219 | -1378 to -1061 | -1119 | -1273 to -965 | -1112 | -1275 to -949 | 0.5770 |
| Lateral Femoral | -251 | -284 to -219 | -227 | -259 to -196 | -236 | -270 to -203 | 0.5755 |
| Medial Femoral | -319 | -363 to -275 | -269 | -311 to -226 | -285 | -330 to -340 | 0.2651 |
| Patellar | -214 | -261 to -167 | -202 | -247 to -156 | -167 | -215 to -119 | 0.3595 |
| Lateral Tibial | -265 | -331 to -199 | -246 | -309 to -182 | -279 | -347 to -211 | 0.7745 |
| Medial Tibial | -172 | -238 to -107 | -173 | -237 to -110 | -146 | -214 to 78 | 0.8099 |
| Average Symptoms (KOOS) | 8.3 | 4.6 to 11.9 | 9.0 | 5.5 to 12.6 | 7.8 | 4.1 to 11.4 | 0.8843 |
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