Weight reduction may mitigate structural defects in knee osteoarthritis

medwireNews: Reducing BMI is associated with a reduced risk of onset and progression of structural defects in knee osteoarthritis (OA), results from a multi-cohort study show.

Zubeyir Salis (University of New South Wales, Sydney, Australia) and co-authors analyzed radiological data from three cohorts – namely the Osteoarthritis Initiative, the Multicenter Osteoarthritis Study and the Cohort Hip and Cohort Knee Study – and categorized the subjects according to whether or not they had structural defects at baseline.

Among 9683 knees with a Kellgren-Lawrence (KL) score of 0 or 1 at baseline (incidence cohort), 12.6% developed new structural defects during 4-5 years of follow-up, defined as a KL score of at least 2 Points. And among the 6075 knees with a KL score of at least 2 points at baseline (progression cohort), 15.0% increased by at least 1 KL score during follow-up, indicating structural OA progression.

Salis and his team report that about 45% of knees in the incidence and progression cohorts experienced a BMI increase of at least 1 kg/m2 during follow-up, while about 20% experienced a decrease of the same magnitude and about 5% were subjected to a decrease of at least 3 kg/m2.

In an analysis adjusted for factors such as baseline BMI, baseline KL score, comorbidities, and physical activity, each 1 kg/m2 reduction in BMI during follow-up was associated with a reduction in the risk of onset or progression structural defects associated with knee OA by 4.76%.

While the researchers acknowledge that the magnitude of this association “can be considered weak,” they also found that a 5 kg/m2 decrease in BMI — “that’s an amount that may lead to a reduction in the BMI category.” (e.g. from overweight to normal)” – was associated with a 21.65% reduced risk.

Therefore, “BMI reduction could be an intervention to prevent, delay, or slow the structural defects of knee osteoarthritis,” they write in Arthritis & Rheumatology.

Salis et al. note that these associations were observed in both people who were overweight or obese and those with a healthy baseline weight, but warn that “the potential benefits of reducing BMI are considered alongside the potential dangers of weight loss need people with normal BMI.”

The team also assessed the association between changing BMI and individual structural characteristics of the knee. In the incidence cohort, BMI reduction was associated with a significant reduction in joint space narrowing and deterioration of tibial and femoral surfaces on the medial but not the lateral side of the knee.

“This finding is consistent with the literature showing that higher rates of cartilage loss generally occur medial [rather] than the lateral side of the knee in people with knee osteoarthritis, and that the medial side of the knee supports more force from the weight than the lateral side of the knee,” the researchers write.

They observed a similar association for medial joint space narrowing in the progression cohort, but not for deterioration of tibial and femoral surfaces.

medwireNews is an independent medical news service from Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group

Arthritis Rheumatol 2022; doi:10.1002/art.42307

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