Plantar fascia anatomy and its relationship with Achilles tendon and paratenon.

The aim of this work was to focus on the macroscopic and microscopic properties of the planta fascia (PF) and study how diseases of the Achilles tendon might affect it. PF was isolated from twelve feet of unembalmed human cadavers, and specimens were tested with various histological and immunohistochemical stains. In a second stage, fifty-two magnetic resonance images (MRI) obtained from patients complaining of aspecific ankle/foot pain were analyzed and divided based on the presence of signs of Achilles tendon pathologies. The dissections showed that PF is more closely connected to the paratenon of the Achilles tendon than to the Achilles tendon, through the periosteum of the heel. Under microscopical analysis, the PF was rich in hyaluronan, probably produced by fibroblastic-like cells described as ‘fasciacytes’ and nerve endings; Pacini and Ruffini corpuscles were present. In the radiological study, 27/52 MRI showed signs of Achilles tendon pathology, and the PF was 3.43±0.48 mm thick, as opposed to 2.09±0.24 mm of the control group, with a statistically significant difference (P<0.001). There was a statistically significant correlation between the thicknesses of the PF and the paratenon. These findings suggest that PF has a role in proprioception and peripheral motor coordination of the foot. Its relationship with the paratenon of the Achilles tendon is consistent with the idea of triceps surae structures being involved in PF pathology, so their rehabilitation can be considered appropriate. Finally, the high concentration of hyaluronan in the PF indicates the feasibility of using hyaluronan injections in the fascia to treat plantar fasciitis.