Variation in the origin of the plantar aponeurosis and its relationship to the origin of the abductor hallucis muscle

The plantar aponeurosis comprises medial, central, and lateral bands, which arise from the calcaneal tuberosity. Descriptions of the origin of the abductor hallucis vary among different textbooks. The central band and abductor hallucis muscles are related to the windlass mechanism. Given the uncertainties regarding the details of the origins of the central band and the abductor hallucis muscle, we examined those origins in 100 feet of 50 cadavers (25 males and 25 females) by dissection. There were three central band patterns, depending on the attachment sites of the origins of the central and lateral bands: Pattern Ia, the central band covers the lateral band completely; Pattern Ib, the central band covers part of the lateral band; Pattern II, the lateral band covers part of the central band. The origin of the abductor hallucis muscle was confirmed. It showed two types of variation: attachment type, originating from the central band; non-attachment type, not originating from the central band. Central band Patterns Ia, Ib, and II were found in 23 feet (17 males, 6 females), 24 feet (25 males, 28 females), and 24 feet (eight males, 16 females), respectively. Pattern Ia predominated in males and Pattern II in females. The attachment and non-attachment types of abductor hallucis muscle were observed in 28 feet (28%) and 72 feet (72%), respectively. The attachment type with Patterns Ia, Ib, and II was shown in 17 feet, 10 feet, and one foot, respectively. Thus, we revealed variation and sex differences in the central band, which could affect foot morphology and the efficacy of the windlass mechanism.

Calcaneal osteotomy due to insertional calcaneal tendinopathy: preoperative planning

Purpose

Dorsal closing wedge calcaneal osteotomy (DCWCO) is indicated in patients with insertional tendinopathy of the calcaneal (Achilles) tendon. The Chauveaus-Liet’s (CL) angle is represented by the difference between the angle of verticalization (α) and morphological angle (β) of the calcaneus (CL angle = α − β). The purpose of the study was to assess whether the DCWCO affects the Chauveaus-Liet’s angle.

Methods

The study included 12 patients indicated to DCWCO. Three directions of close wedge osteotomy were designed for each patient—horizontal, vertical and in the middle type of osteotomy and a virtual osteotomy was created in each of them in the ABAQUS system in cooperation with Czech Technical University. The most used directions of osteotomy according to the available literature were used. We evaluated α and β angles before and after osteotomy, changes of the length plantar aponeurosis and the elevation of distal insertional point of the calcaneal tendon. The changes of grades, median and standard deviation were observed.

Results

The change of the alfa angle was dependent on the direction of the osteotomy and the change of the beta angle was affected by the size of the osteotomy. The greatest elevation of the distal insertional point of the calcaneal tendon occurred in the horizontal type of the osteotomy.

Conclusion

Our study shows that the more we want to reduce the tension in the calcaneal tendon, the more we have to perform an osteotomy horizontally. This study could serve as a preoperative guide for osteotomy planning.

Foot stiffening during the push-off phase of human walking is linked to active muscle contraction, and not the windlass mechanism

The rigidity of the human foot is often described as a feature of our evolution for upright walking and is bolstered by a thick plantar aponeurosis that connects the heel to the toes. Previous descriptions of human foot function consider stretch of the plantar aponeurosis via toe extension (windlass mechanism) to stiffen the foot as it is levered against the ground for push-off during walking. In this study, we applied controlled loading to human feet in vivo, and studied foot function during the push-off phase of walking, with the aim of carefully testing how the foot is tensioned during contact with the ground. Both experimental paradigms revealed that plantar aponeurosis strain via the 'windlass mechanism' could not explain the tensioning and stiffening of the foot that is observed with increased foot-ground contact forces and push-off effort. Instead, electromyographic recordings suggested that active contractions of ankle plantar flexors provide the source of tension in the plantar aponeurosis. Furthermore, plantar intrinsic foot muscles were also contributing to the developed tension along the plantar aspect of the foot. We conclude that active muscular contraction, not the passive windlass mechanism, is the foot's primary source of rigidity for push-off against the ground during bipedal walking.

Surgical Repair of Complete Plantar Fascia Ruptures in High-Demand Power Athletes: An Alternative Treatment Option

Surgical repair of complete plantar fascia ruptures has not yet been reported in the literature. Operative technique and outcome are described in 2 gymnasts with heavy plyometric demands who received surgical repair compared with 3 athletes treated nonoperatively. Biomechanics and clinical implications are discussed. In the last 8 years, we have seen 5 high-demand athletes with total rupture of the plantar fascia. This is a retrospective clinical evaluation 1.5 to 8 years postinjury of all 5 patients using dynamic ultrasound, Foot Function Index, sports-specific questions, Foot Posture Index, and foot length. The operated gymnasts returned to the same level of performance within 12 months. None of the conservatively treated athletes returned to preinjury plyometric sports levels but reached a foot load capacity of distance running with the injured foot as limiting factor. Ultrasound with simultaneous dorsiflexion of the toes showed a normal fascia in the operated patients, but a slack fascia that tightened up only at terminal toe dorsiflexion in the conservatively treated group. According to the Foot Function Index, the operated patients reported no complaints, whereas the nonoperative group had clinical relevant impairments in activities of daily life. The Foot Posture Index in all nonoperated patients showed a relative shift toward pronation with increased foot length compared with the noninjured foot. The operated patients showed no difference in foot length but minimal shift into supination with a slightly altered arch contour. Surgical repair of plantar fascia ruptures is technically feasible to restore normal foot load capability with return to high-demand plyometric sports within 12 months.

Acute effects of long-distance running on mechanical and morphological properties of the human plantar fascia

Long‐distance running (LDR) can induce transient lowering of the foot arch, which may be associated with mechanical fatigue of the plantar fascia (PF). However, this has not been experimentally tested in vivo. The purpose of this study was to test our hypothesis that LDR induces transient and site‐specific changes in PF stiffness and morphology and that those changes are related to the lowering of the foot arch. Ten male recreational long‐distance runners and 10 untrained men were requested to run overground for 10 km. Before and after running, shear wave velocity (SWV: an index of soft tissue stiffness) and thickness of PF at three different sites from its proximal to distal end were measured using supersonic shear imaging and B‐mode ultrasonography. Foot dimensions including the navicular height were measured using a three‐dimensional foot scanner. SWV at the proximal site of PF and navicular height was significantly decreased in both groups after running, with a higher degree in untrained men (−21.9% and −14.1%, respectively) than in runners (−4.0% and −6.3%, respectively). The relative change (%Δ) in SWV was positively correlated with %Δnavicular height in both groups (r = .69 and r = .65, respectively). Multiple regression analysis revealed that %ΔSWV at the proximal site solely explained 72.7% of the total variance in %Δnavicular height. It is concluded that LDR induces transient and site‐specific decreases in PF stiffness. These results suggest that the majority of running‐induced lowering of the foot arch is attributable to the reduction of PF stiffness at the proximal site.

Evolutionary anatomy of the plantar aponeurosis in primates, including humans

The plantar aponeurosis in the human foot has been extensively studied and thoroughly described, in part, because of the incidence of plantar fasciitis in humans. It is commonly assumed that the human plantar aponeurosis is a unique adaptation to bipedalism that evolved in concert with the longitudinal arch. However, the comparative anatomy of the plantar aponeurosis is poorly known in most mammals, even among non‐human primates, hindering efforts to understand its function. Here, we review previous anatomical descriptions of 40 primate species and use phylogenetic comparative methods to reconstruct the evolution of the plantar aponeurosis and its relationship to the plantaris muscle in primates. Ancestral state reconstructions suggest that the overall organization of the human plantar aponeurosis is shared with chimpanzees and that a similar anatomical configuration evolved independently in different primate clades as an adaptation to terrestrial locomotion. The presence of a plantar aponeurosis with clearly developed lateral and central bands in the African apes suggests that this structure is not prohibitive to suspensory locomotion and that these species possess versatile feet adapted for both terrestrial and arboreal locomotion. This plantar aponeurosis configuration would have been advantageous in enhancing foot stiffness for bipedal locomotion in the earliest hominins, prior to the evolution of a longitudinal arch. Hominins may have subsequently evolved thicker and stiffer plantar aponeuroses alongside the arch to enable a windlass mechanism and elastic energy storage for bipedal walking and running, although this idea requires further testing.

Percutaneous Plantar Fascia Release With Needle: Anatomic Evaluation with Cadaveric Specimens

Percutaneous plantar fascia release with needle is a novel procedure for the treatment of plantar fasciitis. The objective of this cadaveric study is to perform an anatomic evaluation of the percutaneous plantar fascia release method using a conventional hypodermic needle. In this study, we used 14 fresh-frozen cadaveric trans-tibial amputation specimens. Percutaneous plantar fasciotomy with a conventional hypodermic needle was performed. After a proper dissection, the width of the plantar fascia, the thickness of the medial border, and the width of the cut segment were measured and recorded. Any muscle damage on the flexor digitorum brevis and damaged area depth were recorded. Any damage on the lateral plantar nerve and the first branch of the lateral plantar nerve, also known as Baxter's nerve, and their distance to fasciotomy were also recorded. Mean width (± standard deviation) of the plantar fascia was measured as 20.34 ± 4.25 mm. The mean thickness of the medial border of the plantar fascia was 3.04 ± 0.54 mm. Partial fasciotomy was performed in all cadavers with 49.47% ± 7.25% relative width of the plantar fascia. No lateral plantar nerve, or its first branch Baxter's nerve, was damaged, and the mean distance from the deepest point of the fasciotomy up to the Baxter's nerve was 8.62 ± 2.62 mm. This cadaveric study demonstrated that partial plantar fasciotomy can be achieved via percutaneous plantar fascia release with a conventional hypodermic needle without any nerve damage.

Plantar fascia anatomy and its relationship with Achilles tendon and paratenon

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.

Abnormal attachments between a plantar aponeurosis and calcaneus

BACKGROUND AND AIMS

The plantar aponeurosis or fascia is a thick fascial seal located on the lower surface of the sole. It consists of three parts central, lateral, and medial. The central portion is the thickest. It is narrow behind and wider in front. The central portion has two strong vertical intermuscular septa which are directed upward into the foot. The lateral and medial portions are thinner. The medial portion is thinnest. The lateral portion is thin in front and thick behind. The main function of the plantar fascia is to support the longitudinal arch of the foot. In May 2013 during a routine dissection in the section hall of the Department of Anatomy and Histology in Medical University - Sofia, Bulgaria we came across a very interesting variation of the plantar aponeurosis.

MATERIALS AND METHODS

For the present morphological study tissues from a human corpse material were used. This unusual anatomical variation was photographed using a Nikon Coolpix 995 camera with a 3.34 Megapixels.

RESULTS

We found some fibrous strands which started from the proximal portion of the plantar aponeurosis on the left foot. The fibrous strands resembled the tentacles of an octopus and started from the proximal portion of the aponeurosis. Two of fibrous strands were directed laterally to adipose tissue and one was directed medially and backward. The first lateral fibrous strand was divided into several fascicles. We found very few data in literature about the varieties of the plantar fascia.

CONCLUSION

It is very important to consider the occurrence of above mentioned variations in the plantar aponeurosis when surgical procedures are performed on the sole.