It has widely been thought that there must be a relationship between increasing obesity and osteoarthritis (OA). The mechanisms are hypothesised to be related to biomechanics and loading as well as meta-inflammation.

Meta-inflammation with fat producing adipocytokines is thought to be important in early OA, with biomechanics and loading becoming more important as OA advances.

This study aimed to look at the evidence relating obesity using BMI (body mass index), body weight and body composition to knee cartilage changes on MRI scanning.

Here’s what they did

MEDLINE and EMBASE were searched for studies published between 1998 and December 2012 linking obesity and knee cartilage using MRI scanning. All included studies were assessed using a methodological quality score, a scoring system relating to design aspects and statistical methods of individual trials. A study was deemed to be high quality if the methodological quality score was greater than 88%. The results were analysed using best evidence synthesis. Best evidence synthesis is an alternative to meta-analysis and traditional reviews and takes into account the ‘best evidence’ in a specific field looking at well-specified and defended inclusion criteria.

Here’s what they found

They examined 434 references and found 22 trials that satisfied their strict criteria.

• With regards to bodyweight and knee cartilage there was no evidence for weight affecting either cartilage volume nor the prevalence or change in cartilage defects.
•  In the case of BMI there was limited evidence that increased BMI caused reduced cartilage volume and increased cartilage lesions.
• The same could also be said for increased body composition with one high quality trial also showing a link with cartilage defects.

The authors concluded

This systematic review identified a consistent detrimental effect of obesity, particularly related to elevated BMI and fat mass on cartilage defects.

However, the authors also felt the evidence was poor due to the lack of high quality longitudinal studies. They also thought that more studies looking at these mechanisms may give rise to interesting and novel ideas for treatment and prevention of knee OA.

The authors felt the evidence was poor and further research in this area may give rise to interesting and novel ideas.

The Musculoskeletal Elf’s view

These are interesting mechanisms for development of knee OA. We frequently advise obese patients to lose weight in an effort to improve their symptoms and hopefully slow the disease process.However, it appears to be quite difficult to provide specific evidence on which to base this advice.

What do you think?

• Do you feel high quality longitudinal trials may be helpful to prove the cause/effect link between obesity and knee OA?
• Moving forwards, could trials be developed to explore different interventions for the treatment and prevention of OA?

Send us your views on this blog and become part of the ever expanding Musculoskeletal Elf community. Post your comment below, or get in touch via social media (Facebook, Twitter, LinkedIn, Google+).

Links

Mezhov, V., Ciccutini, F.M., Hanna, F.S., Brennan, S.L., Wang, Y.Y. et al. 2014, ‘Does obesity affect knee cartilage? A systematic review of magnetic resonance imaging data, Obesity Reviews, Vol.15, no.2, pp.143-57 [Abstract]

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