Heel Pad – Sonographic Evaluation of Heel Pad Thickness in a Student Population in Nigeria
The heel pad is an important factor in determining stresses observed in healthy and pathologic feet. It constitutes part of the weight bearing and pressure cushioning part of the foot. As a result, it is subject to repeated weight bearing and functions as an efficient shock absorber (Hsu et al, 2008).
It is located beneath the calcaneus and acts as a hydraulic shock absorbing layer (Aldridge, 2004). The average heel pad is 18mm thick and contains elastic adipose tissue organized as spiral fibrous septa anchored to each other, to the calcaneus and to the skin. The septae are U-shaped fat filled columns designed to resist compressive loads and are reinforced internally with elastic diagonal and transverse fibres which separate the fat into compartments (Standring et al, 2005).
Some studies have examined its importance in the kinetics and kinematics of gait design and have repeatedly stated that deficit in its function may likely induce a high degree of biomechanical stress on other soft tissues of the foot like the plantar fascia (Stupar and Tibbles, 2008). Due to its constant use, heel pain can result from injuries associated with it and with the surrounding osseous and soft tissue structures. In the United State. The diagnosis and treatment of heel pain and the common plantar fascitis that leads to it results in 1 million patient visits per year (Riddle and Schappert, 2004). In Nigeria, its occurrence has not been practically reported but it is believed that there is lots of undiagnosed Heel pain cases among peasants and middle class individuals because a lifetime prevalence of this condition has been estimated to be 10-15% in runners and in similar proportion in the general population (Aldridge, 2004; DeMaio et al, 1993). Other studies have described structural alterations of the heel pad in some systemic disease like Diabetes Mellitus, Achillodynia,
Familial Hypercholesterolemia, rheumatic if arthritis and HIV where the integral pad design is lost due to morphorlogical transformation or redistribution of Pad fat components (Hsu et al, 2009; Stupar and Tibbles, 2008: Buchbinder, 2004; Falsetti et al, 2004; Thomas et al, 2001; Jorgenson et al, 1985). As such, investigations into the structural disposition of heel pad have aided the diagnosis of some of these ailments like Diabetes Mellitus (Ugwu et al, 2008).
The study of fleshed foot variability and utility of foot uniqueness in personal identification has obvious significance in forensic anthropology and forensic science, respectively (Krishan, 2008). Since the heel pad structural orientation is an integral part of foot uniqueness because it contributes a great deal to the outline of the rear foot in loaded and unloaded situations, the anatomical and mechanical properties should be in contention and should obviously assist in forensic determination of individuals.
Therefore, the importance of the human heel pad as a factor in propulsion cannot be overemphasized and thus, it is absolutely necessary to explore its anatomical inclinations in a relatively young and active student population as a further guide to understanding its functions as it relates to other parts of the foot and the possible factors in the occurrence of heel pain. This could enhance its appreciation and application in maintenance of the kinetics and kinematics of gait and comparative locomotion.
The choice of ultrasonography in the assessment of these soft tissues was guided by the recommendations of previous studies, which stated that high resolution ultrasound should be employed as it is versatile in diagnosing soft tissue pathologies in different body locations (Ophir et al, 2000) and has long been a reliable tool in assessing human heel pad thickness (Gooding et al, 1985).
Statement of Problem
1) Studies in our immediate environment have established values for heel pad but none has med comprehensive correlations with other anthropometric parameter can be used to determine their structural inclination in subjects.
Aims and Objectives
(1) To establish a databank for heel pad thickness in a relatively active student population.
(2) To correlate heel pad thickness of individuals with anthropometric variables like BMI, BSA, Height, Weight, Age and Gender.
(3) To establish which anthropometric parameter that best estimates Heel pad thickness for subsequent use as a diagnostic tool.
This study will provide a comprehensive knowledge of some soft tissues of the foot (Heel pad) which is an important aspect of gait control and detection of strain in pathologic conditions and will go a long way to guide pediatricians in the professional management of foot deformities.
Literature Review
The heel pad establishes a natural transfer of forces from the weight bearing parts of the foot to the ground and as such requires an extensive review of its structural and functional characteristics alongside with other surrounding structural entities that make up the foot.
Brief Musculoskeletal Anatomy of the Foot
In Biomechanics, the foot is no longer viewed as the triangle at the bottom of the leg rather the “foot” suggests that some single functional entity exists, when in fact the 26 bones, hundreds of ligaments and muscles demand that we adopt a far more complex conceptual model of the foot (Nester, 2009), Structurally, the foot is a vital connection between the human body and the ground and plays a highly important role in human locomotion (Gefen et al, 2000), therefore, knowledge of the structural dynamics between its components will definitely be fundamental in understanding their functions and better comprehension of common and uncommon disorders associated with them.
The foot is distal to the leg and is made up of seven (7) tarsal bones five (5) metatarsals and fourteen (14) phalanges. The foot and its bones are divided into parts: Hindfoot (Talus and Calcaneus), Midfoot (Navicular, Cuboid and Cuneiforms) and Forefoot (Metatarsals and Phalanges). The part of the foot facing the ground is called the plantar surface (Sole of the foot) while the part facing superiorly is called the dorsal surface (Dorsum of the foot) Moore and Dalley, 1999).
The structural feature of the skin of the foot vary within the foot. Skin at the dorsal surface is thinner than that at the sole where the weight bearing areas of the foot are found. The subcutaneous tissue in the sole is more fibrous than any other part of the foot. The plantar skin is hairless and sweat glands are numerous and the entire soul of the foot is sensitive. (Moore and Dalley, 1999).
Over the lateral and posterior aspects of the foot, the deep fascia is continuous with the plantar fascia, which forms the deep fascia of the sole; its thick central part forms the plantar aponeurosis that functions to hold the parts of the foot together, helps protect the plantar surface of the foot from injury and support the longitudinal arches of the foot (Moore and Dalley, 1999). The plantar aponeurosis also has medical and lateral parts. The plantar aponeurosis is mostly affected by plantar fasciitis, which is straining and inflammation of the apponeurosis resulting from running and high- impact aerobics, especially when inappropriate footwear such as worn out shoes are worn. This cause pain on the medial and plantar aspect of the foot (Moore and Dalley, 1999).
The Joints of the Foot
Inversion and eversion of the foot take place at the talocalcaneal articulations and at the mid-tarsal joints between the calcaneum and the cuboid and between the talus and the navicular. Of these, the talocalcaneal joint is the more important. Test this on yourself – hold calcaneus joint is the more important. Test this on yourself – hold your calcaneus between your finger and thumb; iversion and eversion are prevented. Loss of these rotatory movements of the foot, e.g. after injury or because of arthritis, results in quite severe disability because the foot cannot adapt itself to walking on rough or sloping ground. Inversion is brought about by tibia is anterior and posterior assisted by the long extensor and flexor tendons of the hallux; eversion is the duty of peroneus longus and brevis, (peroneus tertius forms part of the extensor muscles). The other tarsal joints allow slight gliding movement only, and individually, are not if clinical importance. The arrangement of the metacarpophalangeal and interphalangeal joints is on the same basic plan as in the upper limb (Ellis, 2006).
The Arches of the Foot
On standing, the heel and the metatarsal heads are the principal weight bearing point, but a moment’s study of footprints on the wet bathroom floor will show that the lateral margin of the foot and the tips of the phalanges also touch the ground. The bones of the foot are arranged in the form of two longitudinal arches. The medial arch comprises calcaneus talus, navicular, the three cuneiforms and the three medial metatarsals; the apex of this arch is the talus. The lateral arch, which is lower, comprises the calcaneus, cuboid and he lateral two metatarsals. The foot plays a double role; it functions as a rigid support for the weight of the body in the standing position, and as a mobile springboard during walking and running.
When one stands, the arches sink somewhat under the body’s weight the individual bones lock together, the ligaments linking them are at maximum tension and the foot becomes an immobile pedestal. When one walks, the weight is released from the arches, which unlock and become a mobile lever system in the spring- like actions of locomotion.
The arches are maintained by: the shape of the interlocking bones, the ligaments of the foot, muscle action. The ligaments concerned are: the dorsal, plantar and interosseous ligaments between the small bones of the forefoot; the spring ligament, which passes from the sustentaculum tali of the calcaneus forward to the tuberosity of the navicular and which supports the inferior aspect of the head of the talus; the short plantar ligament which stretches from the plantar surface of the calcaneus to the cuboid; the long plantar ligament which arises from the posterior tuberosity on the plantar surface of the calcaneus, covers the short pantar ligament, forms a tunne for peroneus longus tendon with the cuboid, and is inserted into the bases of the 2nd, 3rd and metatarsals.
These ligaments are reinforced in their action by the plantar aponeurosis. The principal muscles concerned in the mechanism of the arches of the foot are peroneus longus, tibialis anterior and porsterior, flexor hallucis longus and the intrinsic muscles of the foot. Peroneus longus tendon passes obliquely across the sole in a groove on the cuboid bone and is inserted into the lateral side of the base of the 1st metatarsal and the medial cuneiform. Into the medial aspect of these two bones is inserted the tendon of tibialis anterior so that arches of the foot. The media arch is further reinforced by flexor hallucis longus, whose tendon passes under the sustentaculum tali of the calcaneus, and by tibialis posterior, two- thirds of whose fibres are inserted into the tuberosity of the navicular and support the spring ligament.
The longitudinally running intrinsic muscles of the foot also act as ties to the longitudinal arches.
Muscles of the Foot
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This article was extracted from a Project Research Work/Material Topic “SONOGRAPHIC EVALUATION OF HEEL PAD THICKNESS IN A STUDENT POPULATION IN NIGERIA: CORRELATION WITH ANTHROPOMETRIC VARIABLES”
