Relationship Between Knee Pain and Infrapatellar Fat Pad Morphology: A Within‐ and Between‐Person Analysis From the Osteoarthritis Initiative

Objective

Inflammation is known to be strongly associated with knee pain in osteoarthritis. The infrapatellar fat pad represents a potential source of proinflammatory cytokines. Yet the relationship between infrapatellar fat pad morphology and osteoarthritis symptoms is unclear.

Methods

Here we investigate quantitative imaging parameters of infrapatellar fat pad morphology between painful versus contralateral pain‐free legs of subjects with unilateral knee pain and patients with chronic knee pain versus those of matched pain‐free control subjects. A total of 46 subjects with strictly unilateral frequent knee pain and bilateral radiographic osteoarthritis (Kellgren/Lawrence grade 2/3) were drawn from the Osteoarthritis Initiative. Further, 43 subjects with chronic knee pain over 4 years and 43 matched pain‐free controls without pain over this period were studied. Infrapatellar fat pad morphology (volume, surface area, and depth) was determined by manual segmentation of sagittal magnetic resonance images.

Results

No significant differences in infrapatellar fat pad morphology were observed between painful versus painless knees of persons with strictly unilateral knee pain (mean difference ?0.7% (95% confidence interval [95% CI] ?0.6, 0.9; P = 0.64) or between chronically painful knees versus matched painless controls (?2.1% [95% CI ?2.2, 1.1]; P = 0.51).

Conclusion

Independent of the ambiguous role of the infrapatellar fat pad in knee osteoarthritis (a potential source of proinflammatory cytokines or a mechanical shock absorber), the size of the infrapatellar fat pad does not appear to be related to knee pain.

     

Self‐Acupressure for Older Adults With Symptomatic Knee Osteoarthritis: A Randomized Controlled Trial

Objective

This double‐blind randomized controlled trial aimed to test the efficacy of self‐administered acupressure for pain and physical function improvement for older adults with knee osteoarthritis (OA).

Methods

Participants were community‐dwelling adults with symptomatic knee OA (n = 150, mean age 73 years), randomized to 1 of 3 groups: verum acupressure, sham acupressure, or usual care. Participants in the verum and sham groups, but not those in the usual care group, were taught to self‐apply acupressure once daily, 5 days/week for 8 weeks. Assessments were collected during center visits at baseline, and at 4 and 8 weeks. In addition, pain level was assessed weekly by phone using a numeric rating scale (NRS). Outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale (primary), and subjective and objective physical function measures and the NRS and physical function measures (secondary). Linear mixed regression analysis was conducted to test between‐group differences in mean changes from baseline for the outcomes at 8 weeks.

Results

Compared with usual care, both verum and sham acupressure participants experienced significant improvements in WOMAC pain (mean difference ?1.27 units [95% confidence interval (95% CI) ?1.95, ?0.58] and ?1.24 units [95% CI ?1.92, ?0.55], respectively), NRS pain (?0.74 units [95% CI ?1.24, ?0.24] and ?0.51 units [95% CI ?1.01, ?0.01], respectively), and WOMAC function (?4.83 units [95% CI ?6.99, ?2.67] and ?4.21 units [95% CI ?6.37, ?2.04], respectively) at 8 weeks. There were no significant differences between the verum and sham acupressure groups on any of the outcomes.

Conclusion

Self‐administered acupressure is superior to usual care in pain and physical function improvement for older adults with knee OA. The reason for the benefits is unclear, and the placebo effect may play a role.