Responsiveness of Infrapatellar Fat Pad Volume Change to Body Weight Loss or Gain: Data from the Osteoarthritis Initiative

Abstract

Obesity is a potent risk factor for knee osteoarthritis (OA) that is driven by mechanical and potentially endocrine mechanisms, and it affects women more frequently than men. The infrapatellar fat pat (IPFP) represents a potential link between obesity, intra-articular inflammation and structural pathology. Here we investigate whether the IPFP is responsive to body weight loss/gain in women and how its responsiveness to weight change compares to that of subcutaneous fat (SCF) of the thigh. All female participants of the Osteoarthritis Initiative (OAI) with ≥10% weight loss/gain between baseline and a 2-year follow-up were included. Within-subject changes in IPFP volume and SCF cross-sectional areas (CSA) were determined from 3-T magnetic resonance imaging. Linear regression was used to assess the association between change in weight, IPFP volume, and SCF CSA. In the 38 participants with ≥10% weight loss over 2 years (age 59.3 ± 9.1 years, mean loss = 15.9%), there was a significant reduction in IPFP volume (-2.2%, p = 0.02) as well as in SCF CSA (-22%, p < 0.001). In the 34 participants with ≥10% gain (age 61.5 ± 8.7 years, mean gain = 15.9%), there was a significant increase in SCF CSA (+26%, p < 0.001) but not in IPFP volume (0.2%, p = 0.87). Weight change was significantly associated with SCF CSA change (r = 0.76, p < 0.001) but not with IPFP volume change (r = 0.11, p = 0.37). In this first longitudinal, observational study investigating the responsiveness of IPFP and SCF to weight change, IPFP morphology was found responsive to weight loss but not to weight gain. Overall, the responsiveness of the IPFP was substantially less than that of the SCF.

The effects of weight loss on imaging outcomes in osteoarthritis of the hip or knee in people who are overweight or obese: a systematic review

“…In two large OA RCTs, Messier et al 51 and Nicklas et al 52 have reported that weight loss reduced inflammation by lowering circulating concentrations of IL-6. When assessing the IPFP, both Murillo et al 26 and Steidle-Kloc et al 31 found that weight loss is associated with a significant size reduction. A cross-sectional study by Ballegaard et al 53 examining people with overweight and knee OA using dynamic contrast-enhanced MRI found that severe perfusion/ inflammation in the IPFP was associated with more severe pain in knee OA using the KOOS.…”

“…Using 1.5T MRI, one study 26 found a significant reduction in Infrapatellar fat pad (IPFP) volume in all weight loss intervention groups with a maximum of À5.2% reduction (95% CI À3.5, À7.5%). Assessed with 3T MRI, another study 31 found that >10% weight loss was correlated with a significant reduction in IPFP volume of À2.2% (SRM ¼ 0.38).…”

“…Of the 14 included studies 12 were results from 4 cohorts: ADAPT (RCT) 24,25 , CAROT (non-randomized study (NRS)) 23,27 , IDEA (RCT) 7,20,26 and OAI (NRS) 21,22,28,29,31 (Table I). The IDEA studies (n ¼ 3) included only participants with radiographic OA (Kell-greneLawrence grading (KLG)!2); the rest of the studies (n ¼ 11) are based on participants with and without OA ranging from 19 to 53% with KLG !2.…”

“…The most common risk of bias in the NRS was 'Bias due to confounding' with four studies rated serious 19,23,30,31 and one rated critical 27 . Four studies were rated moderate 21,22,28,29 and one were rated critical 27 in 'Overall bias' (Table III).…”

Anterior cruciate ligament transection alters the n-3/n-6 fatty acid balance in the lapine infrapatellar fat pad

“…The overall pattern of FA modifications observed in the rabbits is not unique to this model, as similar changes have been documented in adipose tissue during food deprivation of rodents [36], supporting the present FA results in the rabbits with a slightly negative energy balance compared to the initial body mass. The IFP has been assumed to be resistant to starvation [4], but recent data have shown that its volume can decrease due to weight loss [38]. The effects of OA on the composition of the IFP have not been studied systematically.…”