20/02/2023
Plantar Aponeurosis: Analysis by Physio Meets Science
“The plantar aponeurosis (PA) originates from the medial and anterior aspect of the calcaneus (calcaneal tubercle) and extends to the forefoot.” https://pubmed.ncbi.nlm.nih.gov/24392127/, https://pubmed.ncbi.nlm.nih.gov/24559879/
“The aponeurosis consists of a medial, central and lateral part. The medial and lateral parts attach to the abductor hallucis and the musculus abductor digiti minimi pedis, respectively. These parts are usually categorized as “fascia”. https://pubmed.ncbi.nlm.nih.gov/24392127/
“The central part is thicker (4mm, https://pubmed.ncbi.nlm.nih.gov/24814176/ ) and is considered an “aponeurosis”. https://www.sciencedirect.com/science/article/pii/S0958259299905205.
“The central component is proximally thick and distally thin. As the central aponeurosis extends towards the forefoot, it divides into five separate bundles at the metatarsophalangeal joints.” https://pubmed.ncbi.nlm.nih.gov/24559879/, https://pubmed.ncbi.nlm.nih.gov/12831690/
“These bundles radiate towards and attach through the plantar plates to the proximal phalanges, which in combination with the osseous structures of the arch effectively creates a truss.” https://pubmed.ncbi.nlm.nih.gov/35097359/, https://pubmed.ncbi.nlm.nih.gov/24392127/
“Histologically, the PA is mostly composed of type I collagen fibres forming bundles arranged in a proximal-distal direction, with a few transverse and vertical collagen fibres. These large fibrous bundles are embedded within a matrix of loose connective tissue containing type III collagen and a few elastic fibres.” https://pubmed.ncbi.nlm.nih.gov/24028383/
“PA has a fundamental biomechanical role in supporting the medial longitudinal arch (“arch-spring mechanism”) of the foot” [https://pubmed.ncbi.nlm.nih.gov/16558682/, https://pubmed.ncbi.nlm.nih.gov/15342156/, https://pubmed.ncbi.nlm.nih.gov/3808070/, https://pubmed.ncbi.nlm.nih.gov/26783259/] and is capable of storing strain energy and converting it into propulsive force, behaving as a quasi-elastic tissue [https://pubmed.ncbi.nlm.nih.gov/20175692/, https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2095 ]
“On the other hand, Hicks proposed that the arch's transition from compliant to rigid during late stance is a function of the windlass action of the plantar fascia.” https://pubmed.ncbi.nlm.nih.gov/30111662/
“Hick's windlass mechanism suggests that dorsiflexion of the metatarsophalangeal joint (MTPJ) during late stance produces winding of the plantar fascia around the metatarsal head (or drum of the windlass). This winding of the plantar fascia pulls on the calcaneus, shortens and raises the arch, and inverts the subtalar joint” [https://pubmed.ncbi.nlm.nih.gov/13129168/, https://pubmed.ncbi.nlm.nih.gov/16558682/]
Photo Credit: Frank Netter MD
📙 Illustration: Richie Jr, D.H. (2021). Plantar Heel Pain. In: Pathomechanics of Common Foot Disorders. Springer, Cham. https://doi.org/10.1007/978-3-030-54201-6_8
