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Chapter 18 The Foot Chapter 18 Extended Lecture Outline Introduction: o The function of the foot is critical in running, jumping and changing directions o The foot must act as a shock absorber to dissipate ground reaction forces, and must act as a rigid lever to propel the body forward, backward or to the side o Due to its complex nature, recognition and management of the foot presents a challenge to the athletic trainer Foot Anatomy o Bones Foot consists of 26 bones: 14 phalangeal, 5 metatarsal and 7 tarsal, also 2 sesamoid bones beneath the first metatarsal Toes Designed to give wider base for balance and for propelling the body forward First toe has 2 phalanges the remaining toes have 3 Sesamoids under the first metatarsal (in the flexor hallucis tendon) assist with reducing pressure in weight bearing, increase the mechanical advantage of the flexor tendons of the great toe, act as sliding pulleys for tendons Metatarsals Five bones that lie between and articulate with the tarsals and the phalanges Ligamentous arrangement gives elasticity to the foot in weight bearing MTP joints permit hinge action of phalanges First metatarsal functions as the main weight bearing support during walking and running Tarsal Bones Calcaneous o Largest tarsal bone; supports the talus and shapes the heel o Main functions: convey the body weight to the ground and serves as attachment of Achilles Tendon and plantar structures Talus o Situated above the calcaneous; consists of the body, neck and head o Trochlea articulates with the medial and lateral malleoli to form the ankle joint o Dorsiflexion is limited due to talus being narrower posteriorly than anteriorly Navicular o Anterior to the talus on the medial aspect of the foot o Articulates with the three cuneiform bones Cuboid o On the lateral aspect of the foot o Articulates posteriorly with the calcaneous and anteriorly with the fourth and fifth metatarsals Cuneiforms o Three cuneiforms located between the navicular and the base of the three metatarsals on the medial aspect of the foot o Arches of the Foot Arches provide support in weight bearing, absorb shock, and provide space on plantar surface for the blood vessels, nerves, and muscles Anterior Metatarsal Arch Shaped by the distal heads of the metatarsals Transverse Arch Extends across the cuboid, and the internal cuneiform Prentice, Principles of Athletic Training , 15e LO-18 | 1 Chapter 18 The Foot Protects the soft tissue and increases foot mobility Medial Longitudinal Arch Originates on medial border of the calcaneous and extends forward to the distal head of the first metatarsal Main supporting ligament = plantar calcaneonavicular ligament (spring ligament) Tendon of the posterior tibialis muscle helps to support the plantar calcaneonavicular ligament Lateral Longitudinal Arch On outer aspect of the foot, formed by the calcaneous, cuboid and fifth metatarsal bone Plantar Fascia (Plantar Aponeurosis) Thick white band of fibrous tissue originates on the medial tubercle of the calcaneous and ends at the proximal heads of the metatarsals Supports the foot against downward forces Articulations Interphalangeal Joint Designed for flexion and extension Reinforced by collateral ligaments Metatarsophalangeal Joint Condyloid type joints permitting flexion, extension, adduction and abduction Intermetatarsal Joint Sliding joints: include two sets of articulations Tarsometatarsal Joint (Lisfranc’s Joint) Formed by junction of the bases of the metatarsal bones with the cuboid and all three cuneiforms – allows for some gliding Subtalar Joint Articulation between the talus and calcaneous Allows for inversion, eversion, pronation, and supination In weight bearing pronation refers to combined movement of talar plantarflexion and adduction and calcaneal eversion In weight bearing supination refers to combined movement of talar dorsiflexion, abduction and calcaneal inversion Midtarsal Joint (Chopart’s Joint) Consists of the calcaneocuboid and the talonavicular joint Directly related to the subtalar joint – if subtalar joint is pronated, the midtarsal joints become hypermobile, if supinated then the midtarsal joint is hypomobile Stabilizing Ligaments Subtalar ligaments: interosseus talocalcaneal and the anterior, posterior, lateral and medial talocalcaneal ligaments Plantar calcaneonavicular ligament provides shock absorption (spring ligament) Midtarsal ligaments: dorsal talonavicular, bifurcate, and dorsal calcaneocuboid Anterior tarsal joints: cuneonavicular, cuboideonavicular, intercuneiform and cuneocuboid ; each of these joints have dorsal and planter ligaments Muscles and Movement Dorsiflexion: tibialis anterior, extensor digitorum longus, extensor hallucis longus and peroneus tertius Plantarflexion: Gastrocnemius, soleus, plantaris, peroneus longus, peroneus brevis, tibialis posterior, flexor hallucis longus and flexor digitorum longus Inversion, Adduction and Supination: Tibialis posterior, flexor digitorum longus, flexor hallucis longus, tibialis anterior and extensor hallucis longus Eversion, Abduction and Pronation: Peroneus longus, peroneus brevis, peroneus tertius and extensor digitorum longus Movements of Phalanges o o o o Prentice, Principles of Athletic Training , 15e LO-18 | 2 Chapter 18 The Foot Flexion of second, third, fourth and fifth distal phalanges: flexor digitorum longus and quadratus plantar Flexion of middle phalanges: flexor digitorum brevis Flexion of proximal phalanges: lumbricales and the interossei Flexion of great toe: flexor hallucis longus Extension of middle phalange: abductor hallucis and abductor digiti quanti, lumbricales and interossei Extension of distal phalanges: Extensor digitorum longus, extensor hallucis longus and extensor digitorum brevis o Nerve Supply and Blood Supply Nerve Supply Medial and lateral plantar nerves (branches of the tibial nerve) supply all intrinsic muscles on the plantar surface of the foot. Deep peroneal nerve supplies the extensor digitorum brevis on the dorsal surface of the foot Blood Supply Primary blood supply of the foot comes from the anterior tibial artery and posterior tibial arteries. Dorsum of foot supplied by the dorsal pedal artery and dorsal metatarsal arteries (branch from anterior tibial artery) Plantar surface of the foot supplied by the lateral plantar artery, medial plantar artery and the plantar arterial arch (branch from posterior tibial artery) Venous drainage from plantar surface: medial and lateral plantar veins into the posterior tibial vein Venous drainage from dorsum of foot: dorsal venous arch and dorsal pedal vein into anterior tibial vein Functional Anatomy and Foot Biomechanics o Normal Gait Stance Phase o Starts with initial heel strike on the ground and ends with toe-off o Accounts for 60% of the total gait cycle o Five Periods: initial contact, loading response, mid stance, terminal stance and pre swing Normal Gait Swing Phase o Time between toe-off and subsequent initial contact – period of nonweight bearing o Swing phase divided into three periods: initial swing, mid swing and terminal swing Running Gait o Period after toe-off when neither foot is in contact with the ground o Running stance phase accounts for only one-third of the gait cycle o Foots function during running stance phase: acts as a shock absorber on impact and adapts to uneven surfaces, at toe-off foot becomes a rigid lever for push off o 80% of distance runners heel strike on the lateral aspect of the calcaneous with subtalar joint in supination, sprinters tend to be forefoot strikers and joggers midfoot strikers o At initial contact the subtalar joint is supinated, obligatory external rotation of the tibia, as foot is loaded – subtalar joint moves into pronation until forefoot is in contact with the surface. As pronation occurs at subtalar joint – obligatory internal rotation of tibia. o Subtalar joint remains in a pronated position through 55-85% of stance phase o Foot will resupinate and will approach neutral subtalar position at 7090% of the stance phase – allows the foot to become rigid for toe-off Structural Deformities Prentice, Principles of Athletic Training , 15e LO-18 | 3 Chapter 18 The Foot Structural forefoot varus, and rearfoot varus deformities associated with excessive pronation Structural forefoot valgus causes excessive supination Compensation occurring at weight bearing rather than the deformity usually causes overuse injuries Excessive Pronation Prolonged pronation one of major causes of stress injuries In pronated foot cuboid loses its mechanical advantage as a pulley and the peroneus longus tendon no longer stabilizes the first ray effectively Prolonged pronation does not allow the subtalar joint to resupinate, thus there is less power for push-off Injuries occurring from excessive pronation include: stress fractures of the second metatarsal, plantar fasciitis, posterior tibial tendonitis, achilles tendonitis, tibial stress syndrome and medial knee pain Excessive Supination Excessive supination at heel strike does not allow subtalar joint to unlock – foot remains rigid Cuboid becomes hypomobile – increasing tension on the peroneus longus tendon Foot cannot absorb ground reaction forces efficiently Injuries seen include: inversion ankle sprains, tibial stress syndrome, peroneal tendonitis, IT band friction syndrome and trochanteric bursitis Prevention of Foot Injuries o Selecting Appropriate Footwear Pronators need stability and firmness to reduce excess motion (need board lasted, straight lasted shoe, with good rearfoot control) Supinators need cushioning and flexibility as foot is too rigid (need slip lasted or combination lasted, curve lasted shoe) o Shoe Orthotics o Foot Hygiene Foot Assessment o History o Observation Look for structural Deformities (bunions, check for forefoot varus/valgus deformities, check for rearfoot varus/valgus deformities, flexibility of first ray) Look at shoe wear patterns Pronators wear out the front of the shoe under the second metatarsal; supinators wear out the outside of the shoe. All have excessive wear on the lateral heel due to heel strike o Palpation Bony Palpation Medial aspects Lateral aspects Dorsal aspects Plantar aspects Soft Tissue Palpation Medial and Plantar aspect Lateral and Dorsal aspect Pulses (posterior tibial and dorsalis pedis arteries) o Special Tests Movement Assessment Morton’s Test: Transverse pressure on metatarsal heads causing sharp pain in forefoot, may indicate presence of neuroma or metatarsalgia Neurological Assessment Prentice, Principles of Athletic Training , 15e LO-18 | 4 Chapter 18 The Foot Check reflexes (achilles = S1) and cutaneous distribution Tinel’s sign: tap over the posterior tibial nerve – numbness, tingling and paresthesia may indicate tarsal tunnel syndrome Recognition and Management of Specific Injuries o Injuries to the Tarsal Region Fractures of the Talus Fractures of the Calcaneous Calcaneal Stress Fracture Apophysitis of the Calcaneous (Sever’s Disease) Retrocalcaneal Bursitis Heel Contusion Cuboid Subluxation Tarsal Tunnel Syndrome Tarsometatarsal Fracture/Dislocation (Lisfranc Injury) o Injuries to the Metatarsal Region Pes Planus Foot (Flatfoot) Pes Cavus Foot (High Arch Foot) Second Metatarsal Stress Fracture (Morton’s Toe) Longitudinal Arch Strain Plantar Fasciitis Jones Fracture Metatarsal Stress Fractures Bunion (Hallux Valgus Deformity) and Bunionettes (Tailor’s Bunions) Sesamoiditis Metatarsalgia Metatarsal Arch Strain Morton’s Neuroma o Injuries to the Toes Sprained Toes Great Toe Hyperextension (Turf Toe) Fractures and Dislocations of Phalanges Morton’s Toe Hallux Rigidus Hammertoe, Mallet Toe or Claw Toe Overlapping Toes Blood under toenail (Subungual Hematoma) Foot Rehabilitation o General Body Conditioning Run in a pool or working on upper body ergometer if not allowed to weight bear or conditioning Continue to strengthen and stretch as allowed by constraints of injury o Weight Bearing If unable to walk without a limp, then have athlete use crutches Progress to full weight bearing as soon as possible o Joint Mobilizations o Flexibility- restore normal ROM in foot and ankle o Muscular Strength Writing the alphabet Picking up objects Ankle Circumduction Gripping and spreading of the toes Towel Gathering Towel Scoop o Neuromuscular Control The foots ability to adjust and adapt to changing surfaces while creating a stable base of support is perhaps the single most important function of the foot in weight bearing Prentice, Principles of Athletic Training , 15e LO-18 | 5 Chapter 18 The Foot o o Athlete’s should perform exercises on variety of surfaces (foam, BAPS board, Wobble boards, Exercise Sandals – excellent for increasing muscle activation in the foot and lower leg Foot Orthotics and Taping Taping techniques explained in Chapter 8 Orthotics help to prevent compensatory problems Soft Orthotics: Pads and flexible felt supports Semirigid Orthotics: Flexible thermoplastics, rubber or leather. Molded from a neutral cast Rigid Orthotics: Made of hard plastic, also require neutral casting to make. Allow control for most overuse symptoms To correct structural forefoot varus deformity (foot excessively pronates) – orthotic should be rigid and should have medial wedge under the head of first metatarsal, and also under the medial calcaneous to make orthotic comfortable To correct structural forefoot valgus deformity (foot excessively supinates) – orthotic should be semirigid and have a lateral wedge under the base of the 5 th metatarsal, and a small wedge under the lateral calcaneous to make orthotic comfortable Functional Progressions (See Focus box 18-2 for functional progression for the foot) Prentice, Principles of Athletic Training , 15e LO-18 | 6