McMillan et al.88 report: “The histological features of plantar fasciitis are poorly understood, although studies report a predominance of degenerative changes at the plantar fascia enthesis … The presence of biochemical markers of inflammation such as cytokines and prostaglandins have not been well investigated, although, several studies report non-specific evidence of local inflammatory change.”
Interestingly, specific, direct evidence of inflammation has rarely been detected histologically in chronic plantar fasciitis.89 Lemont et al. argue it is a degenerative condition without inflammation.20 While many researchers and clinicians allude to the presence of inflammation they do not provide definitive histological evidence.
Lemont et al. point out that “when photomicrographs are provided, they are often mislabelled as showing inflammation … they provided only photomicrographs of dense fibrous tissue.” Grasel et al.’s study using magnetic resonance imaging indicated the changes were non-inflammatory due to the low prevalence of signal intensity within the fascia and what they did find was likely oedema due to fascial tears and occult marrow abnormalities.90
20. Lemont H, Ammirati KM, Usen N. Plantar fasciitis: A degenerative process (Fasciosis) without inflammation. J Am Podiatr Med Assoc. 2003;93(1-6):234-237.
88. McMillan AM, Landorf KB, Gilheany MF, Bird AR, Morrow AD, Menz HB. Ultrasound guided corticosteroid injection
for plantar fasciitis: randomised controlled trial. BMJ. 2012;344(21):e3260.
89. Wearing SC, Smeathers JE, Urry SR, Hennig EM, Hills AP. The pathomechanics of plantar fasciitis. Sport Med. 2006;36(7):585-611.
90. Grasel RP, Schweitzer ME, Kovalovich AM, et al. Original report. MR imaging of plantar fasciitis: Edema, tears, and occult marrow abnormalities correlated with outcome. Am J Roentgenol. 1999;173(3):699-701.