title: Plantar fascia anatomy and its relationship with Achilles tendon and paratenon.
abstract: Although the plantar fascia (PF) has been studied quite well from a biomechanical viewpoint, its microscopic properties have been overlooked: nothing is known about its content of elastic fibers, the features of the extracellular matrix or the extent of innervation. From a functional and clinical standpoint, the PF is often correlated with the triceps surae muscle, but the anatomical grounds for this link are not clear. The aim of this work was to focus on the PF macroscopic and microscopic properties and study how Achilles tendon diseases might affect it. Twelve feet from unembalmed human cadavers were dissected to isolate the PF. Specimens from each PF were tested with various histological and immunohistochemical stains. In a second stage, 52 magnetic resonance images (MRI) obtained from patients complaining of aspecific ankle or foot pain were analyzed, dividing the cases into two groups based on the presence or absence of signs of degeneration and/or inflammation of the Achilles tendon. The thickness of PF and paratenon was assessed in the two groups and statistical analyses were conducted. The PF is a tissue firmly joined to plantar muscles and skin. Analyzing its possible connections to the sural structures showed that this fascia is more closely connected to the paratenon of Achilles tendon than to the Achilles tendon, through the periosteum of the heel. The PF extended medially and laterally, continuing into the deep fasciae enveloping the abductor hallucis and abductor digiti minimi muscles, respectively. The PF was rich in hyaluronan, probably produced by fibroblastic-like cells described as 'fasciacytes'. Nerve endings and Pacini and Ruffini corpuscles were present, particularly in the medial and lateral portions, and on the surface of the muscles, suggesting a role for the PF in the proprioception of foot. In the radiological study, 27 of the 52 MRI showed signs of Achilles tendon inflammation and/or degeneration, and the PF was 3.43 ± 0.48 mm thick (99%CI and SD = 0.95), as opposed to 2.09 ± 0.24 mm (99%CI, SD = 0.47) in the patients in which the MRI revealed no Achilles tendon diseases; this difference in thickness of 1.29 ± 0.57 mm (99%CI) was statistically significant (P < 0.001). In the group of 27/52 patients with tendinopathies, the PF was more than 4.5 mm thick in 5, i.e. they exceeded the threshold for a diagnosis of plantar fasciitis. None of the other 25/52 paitents had a PF more than 4 mm thick. There was a statistically significant correlation between the thicknesses of the PF and the paratenon. These findings suggest that the plantar fascia has a role not only in supporting the longitudinal arch of the foot, but also in its proprioception and peripheral motor coordination. Its relationship with the paratenon of the Achilles tendon is consistent with the idea of triceps surae structures being involved in the PF pathology, so their rehabilitation can be considered appropriate. Finally, the high concentration of hyaluronan in the PF points to the feasibility of using hyaluronan injections in the fascia to treat plantar fasciitis.
authors.affiliation: Department of Molecular Medicine, University of Padua, Padova, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Stecco
authors.forename: Marco
authors.initials: M
authors.lastname: Corradin
authors.forename: Veronica
authors.initials: V
authors.lastname: Macchi
authors.forename: Aldo
authors.initials: A
authors.lastname: Morra
authors.forename: Andrea
authors.initials: A
authors.lastname: Porzionato
authors.forename: Carlo
authors.initials: C
authors.lastname: Biz
authors.forename: Raffaele
authors.initials: R
authors.lastname: De Caro
mesh_terms: D000125:Achilles Tendon / Q000033:anatomy & histology; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005205:Fascia / Q000033:anatomy & histology*; D005260:Female; D005528:Foot / Q000033:anatomy & histology*; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D052256:Tendinopathy / Q000473:pathology
keywords: Achilles tendon; fasciacyte; hyaluronan; paratenon; plantar aponeurosis; plantar fascia; plantar fasciitis
references.citation: J Anat. 2009 Jan;214(1):1-18
references.pmid: 19166469
references.citation: Foot Ankle Spec. 2010 Dec;3(6):335-7
references.pmid: 20817847
references.citation: BMJ. 2003 Jul 12;327(7406):75
references.pmid: 12855524
references.citation: Foot Ankle Int. 1998 Feb;19(2):91-7
references.pmid: 9498581
references.citation: Rheumatology (Oxford). 2004 Jul;43(7):823-8
references.pmid: 15138330
references.citation: J Foot Ankle Surg. 2011 Jan-Feb;50(1):41-3
references.pmid: 21172640
references.citation: Clin Podiatr Med Surg. 2010 Jul;27(3):369-80
references.pmid: 20691370
references.citation: Foot Ankle Int. 2013 Jun;34(6):841-5
references.pmid: 23386754
references.citation: Foot Ankle Int. 2000 Jan;21(1):18-25
references.pmid: 10710257
references.citation: Sports Med. 1990 Nov;10(5):338-45
references.pmid: 1979886
references.citation: Int J Ther Massage Bodywork. 2009 Jun 29;2(2):1-6
references.pmid: 21589727
references.citation: Surg Radiol Anat. 2011 Dec;33(10):905-11
references.pmid: 21947015
references.citation: BMJ. 2012 May 22;344:e3260
references.pmid: 22619193
references.citation: Handchir Mikrochir Plast Chir. 1990 May;22(3):163-6
references.pmid: 2198202
references.citation: J Foot Ankle Res. 2009 Nov 13;2:32
references.pmid: 19912628
references.citation: Knee Surg Sports Traumatol Arthrosc. 2011 Aug;19(8):1367-75
references.pmid: 21567177
references.citation: J Am Podiatr Med Assoc. 2003 May-Jun;93(3):234-7
references.pmid: 12756315
references.citation: Foot Ankle Int. 2013 Jan;34(1):42-8
references.pmid: 23386760
references.citation: Curr Opin Cell Biol. 2000 Oct;12(5):581-6
references.pmid: 10978893
references.citation: J Foot Ankle Surg. 2010 Sep-Oct;49(5):417-20
references.pmid: 20579910
references.citation: Clin Orthop Relat Res. 1997 Jun;(339):227-31
references.pmid: 9186224
references.citation: Matrix Biol. 2002 Jan;21(1):25-9
references.pmid: 11827789
references.citation: J Bone Joint Surg Am. 2005 Jan;87(1):187-202
references.pmid: 15634833
references.citation: Int J Ther Massage Bodywork. 2009 Dec 07;2(4):3-8
references.pmid: 21589739
references.citation: Neuroscience. 2011 Oct 27;194:302-8
references.pmid: 21839150
references.citation: AJR Am J Roentgenol. 1999 Aug;173(2):323-8
references.pmid: 10430128
references.citation: J Orthop Sports Phys Ther. 1999 Dec;29(12):756-60
references.pmid: 10612073
references.citation: J Athl Train. 2004 Jan;39(1):77-82
references.pmid: 16558682
references.citation: Foot Ankle Int. 2012 Jun;33(6):507-12
references.pmid: 22735325
references.citation: Birth Defects Res C Embryo Today. 2004 Mar;72(1):89-108
references.pmid: 15054906
references.citation: Am J Phys Med Rehabil. 2010 Nov;89(11):941-4
references.pmid: 20962604
references.citation: J Anat. 2008 Dec;213(6):718-24
references.pmid: 19094187
references.citation: J Bodyw Mov Ther. 2008 Jul;12(3):274-80
references.pmid: 19083682
references.citation: Semin Musculoskelet Radiol. 2010 Sep;14(3):334-43
references.pmid: 20539958
references.citation: Int Orthop. 2013 Apr;37(4):715-21
references.pmid: 23254856
references.citation: Anat Sci Educ. 2012 Sep-Oct;5(5):264-72
references.pmid: 22573575
references.citation: Surg Radiol Anat. 2011 Dec;33(10):891-6
references.pmid: 21964857
references.citation: Morphologie. 2007 Mar;91(292):38-43
references.pmid: 17574469
references.citation: Pathology. 1987 Jan;19(1):1-11
references.pmid: 3588019
references.citation: Lancet. 2010 Nov 20;376(9754):1751-67
references.pmid: 20970844
references.citation: J Pharm Pharm Sci. 2011;14(3):425-37
references.pmid: 22202225
references.citation: Foot Ankle Int. 2008 Jan;29(1):87-90
references.pmid: 18275744
references.citation: J Hand Surg Am. 2004 May;29(3):494-9
references.pmid: 15140495
references.citation: Foot Ankle Surg. 2012 Mar;18(1):39-41
references.pmid: 22326003
references.citation: Connect Tissue Res. 2010 Oct;51(5):337-46
references.pmid: 20175692
references.citation: Clin Orthop Relat Res. 1997 Nov;(344):307-12
references.pmid: 9372782
references.citation: Retina. 2011 Feb;31(2):222-8
references.pmid: 21240043
references.citation: Sports Med. 1993 May;15(5):344-52
references.pmid: 8100639
references.citation: Foot (Edinb). 2009 Jun;19(2):75-9
references.pmid: 20307454
references.citation: Rheumatology (Oxford). 2012 Jun;51(6):1134-6
references.pmid: 22332120
references.citation: Foot Ankle Int. 1995 Jul;16(7):418-21
references.pmid: 7550955
references.citation: J Clin Ultrasound. 2012 Jan;40(1):14-9
references.pmid: 22109854
references.citation: Foot Ankle Int. 2004 May;25(5):303-10
references.pmid: 15134610
references.citation: J Neurosurg Spine. 2006 Sep;5(3):234-42
references.pmid: 16961085
references.citation: J Anat. 1954 Jan;88(1):25-30
references.pmid: 13129168
references.citation: Osteoarthritis Cartilage. 2009 Jun;17(6):798-804
references.pmid: 19103502
references.citation: Arch Putti Chir Organi Mov. 1991;39(2):335-9
references.pmid: 1843082
references.citation: Immunol Rev. 2010 Jan;233(1):256-66
references.pmid: 20193004
references.citation: Acta Radiol. 2010 May;51(4):438-54
references.pmid: 20380605
references.citation: Radiology. 2013 Apr;267(1):195-200
references.pmid: 23297327
references.citation: Arthritis Rheum. 2000 Mar;43(3):576-83
references.pmid: 10728751