Ankle and foot complex

description regarding ankle and foot complex.

1. ANKLE AND FOOT COMPLEX BY DR. RAJAL B. SUKHIYAJI (MPT IN SPORTS SCIENCE)

2. Contents Introduction Definitions of motions Ankle joint The Subtalar Joint Transverse Tarsal Joint Tarsometatarsal Joints Metatarsophalangeal Joints Interphalangeal Joints Plantar Arches

3. INTRODUCTION Structurally analogus to the wrist – hand complex of the upper extremity. Primary role to bear weight. Structure of foot allow the foot to sustain large weight-bearing stresses under a variety of surfaces and activities that maximize stability and mobility.

4. Bones & Joints 28 bones that forms 25 component joints : The proximal and distal tibiofibular joint The telocrural or ankle joint The telocalcaneal joint or subtalar joint The telonavicular joint The calcaneocuboid joints ( transeverse tarsal joints) The five tarsometatarsal joints The five metatarsophalangeal joints The nine interphalangeal joints

5. Three functional segments : Hindfoot (Posterior segment) – talus & calcaneus Midfoot (middle segment) – navicular , cuboid & three cuneiform bones Forefoot (anterior segment)) – metatarsals & phalanges

6. Definitions of Motions Three motions : Dorsiflexion / Plantarflexion Inversion / Eversion Abduction / Adduction

7. Dorsiflexion and Plantarflexion that occurs in the sagittal plane around a coronal axis. Dorsiflexion : Decreases the angle between the leg and the dorsum of the foot. Plantarflexion : Increases the angle. At the toes, Extension – Bringing the toes up Flexion – Bringing the toes down or curling them

8. Inversion and eversion occur in the frontal plane around longitudinal axis ( anteroposterior axis). Inversion occurs when the plantar surface of the segment is brought toward the midline. Eversion is the opposite.

9. Abduction and adduction occur in transeverse plane around vertical axis. Abduction is when the distal aspect of a segment moves away from the midline of the body. Adduction is the opposite.

10. Composite motions : Pronation and Supination Pronation - Dorsiflexion , eversion , & abduction Supination – Plantarflexion , inversion & adduction

11. Valgus & Varus Valgus ( calcaneovalgus ) – an increase in the medial angle between the calcaneus and posterior leg. Varus ( calcaneovarus ) – decrease in the medial angle between the calcaneus and posterior leg.

12. Ankle joint Talocrural joint Articulation between the distal tibia and fibula proximally and the body of talus distally. Synovial hinge joint with joint capsule and associated ligaments. Single oblique axis with one degree of freedom around which the motions of dorsiflexion / plantarflexion occur.

13. Ankle joint structure Proximal articular surfaces : Concave surface of the distal tibia and of the tibial and fibular malleoli . These three facets form an almost continuous concave joint surface that extends more distally on the fibular (lateral) side than on the tibial (medial) side and more distally on the posterior margin of the tibia than on the anterior margin.

14. Mortise : The distal most aspect of the fibula is called the lateral malleolus . Together, the malloli , along with their supporting ligaments, stabilize the talus underneath the tibia. The bony arch formed by the tibial plafond and the two malleoli is referred to as the ankle “mortise”.

15. The structure of the distal tibia and the malleoli resembles and is referred to as a mortise. A common example of a mortise is the gripping part of a wrench. Either the wrench can be fixed (fitting a bolt of only one size) or it can be adjustable (permitting use of the wrench on a variety of bolt sizes). The adjustable mortise is more complex than a fixed mortise because it combines mobility and stability functions. The mortise of the ankle is adjustable, relying on the proximal and distal tibiofibular joints to both permit and control the changes in the mortise.

16. Proximal tibiofibular joint Plane synovial joint Articulation of the head of the fibula with the posterolateral aspect of the tibia. Slight convexity of the tibial facet and concavity of the fibular facet. Surrounded by joint capsule that is reinforsed by anterior and posterior tibiofibular ligaments. Motion – superior and inferior sliding of the fibula and as fibular rotation

17. Distal tibiofibular joint Syndesmosis or fibrous union Concave facet of the tibia and the convex facet of the fibula. The distal tibia and fibula do not actually come into contact with each other but are separated by fibroadipose tissue. No joint capsule Ligaments : 1) Maintaining the stable mortise 2) Support distal tibiofibular joint Anterior and posterior tibiofibular ligaments Interosseous membrane

18. Distal articular surface Body of talus Three articular surfaces : Large lateral (fibular) facet Smaller medial ( tibial ) facet Trochlear (superior) facet

19. The large, convex trochlear surface has a central groove that runs at a slight angle to the head and neck of the talus. The body of the talus also appears wider anteriorly than posteriorly , which gives it a wedge shape.

20. CAPSULE AND LIGAMENTS Capsule : thin and weak Ligaments of Proximal and distal tibiofibular joint : Crural tibiofibular interosseous ligament Anterior and posterior tibiofibular ligaments Tibiofibular interosseous membrane Function: Provide stability to mortise and therefore stability of ankle.

21. Major ligaments: Medial collateral ligament Lateral collateral ligament Function : Maintain contact and congruence of the mortise and talus Control medial – lateral joint stability Provide key support for the subtalar joint (or talocalcaneal joint ).

22. i ) Medial collateral ligament : Deltoid ligament – fan shaped Superficial and deep fibers Origin : borders of the tibial malleolus Insertion : navicular bone anteriorly and on the talus and calcaneus distally and posteriorly Extremely strong Function : Control medial distraction stresses on the ankle joint Check motion at the extremes of joint range, paricularly with calcaneal eversion .

23. Lateral collateral ligament : 3 separate bands : Anterior and posterior talofibular ligaments –run horizontal position Calcaneofibular ligament – run vertical position (longer) Function : Control varus stresses that result in lateral distraction of the joint. Check extremes of join ROM, particularly calcaneal inversion.

24. Retinacula : Superior and inferior extensor retinacula Superior and inferior peroneal retinacula Function : Stability to ankle and subtalar joint

25. Axis : In neutral position of the ankle joint, the joint axis passes approximately through the fibular malleolus and the body of the talus and through or just below the tibial malleolus .

26. The fibular malleolus and its associated fibular facet on the talus are located more distally and posteriorly than the tibial malleolus and its associated tibial facet. The more posterior position of the fibular malleolus is due to the normal torsion or twist that exists in the distal tibia in relation to the tibia’s proximal plateau. This twisting may be referred to as tibial torsion(or tibiofibular torsion because both the tibia and fibula are involved with the rotation in the transverse plane) and accounts for the toe-out position of the foot in normal standing.

27. Ankle joint function Primary motions : Dorsiflexion : 10 to 20 degree : Motion of the head of the talus dorsally (or upward) while the body of talus moves posteriorly in the mortise. Plantarflexion : 20 to 50 degree : Opposite motion of the head and body of talus. Talar rotation or talar abduction/adduction : 7 degree medial rotation and 10 degree lateral rotation : Talus may rotate slightly within the mortise in the transverse plane around a vertical axis. Talar tilt or talar inversion/ eversion : 5 degree or less : If in the frontal plane around an A-P axis.

28. When the foot is weight-bearing, dorsiflexion occurs by the tibia’s rotating over the talus. The concave tibiofibular segment slides forward on the trochlear surface of the talus. Wider anterior portion of the talus “wedges” into the mortise. Enhancing stability of the ankle joint.

29. The loosepacked position of the ankle joint is in plantarflexion . During plantarflexion , only the relatively narrow posterior body of the talus is in contact with the mortise. The ankle is considered to be less stable. There is a higher incidence of ankle sprains when the ankle is plantarflexed than when dorsiflexed .

30. The lateral (fibular) facet is substantially larger than the medial ( tibial ) facet. Distal fibula moving on the larger lateral facet of the talus must undergo a greater displacement than the tibial malleolus as the tibia and fibular move together during dorsiflexion . Results in superior/inferior motion and medial/lateral rotation of the fibula that requires mobility of the fibula at both the proximal and the distal tibiofibular joints.

31. Ankle dorsiflexion and plantarflexion movements are limited primarily by soft tissue restrictions. Tension in the triceps surae ( gastrocnemius and soleus muscles) is the primary limitation to dorsiflexion . Dorsiflexion is more limited typically with the knee in extension than with the knee in flexion.

32. Tension in the tibialis anterior, extensor hallucis longus , and extensor digitorum longus muscles is the primary limit to plantarflexion . The tibialis posterior, flexor hallucis longus , and flexor digitorum longus muscles help protect the medial aspect of the ankle. The peroneus longus and peroneus brevis muscles protect the lateral aspect.

33. The Subtalar joint Talocalcaneal joint Composite joint formed by the talus superiorly and the calcaneus inferiorly. Provide a triplanar movement around a single joint axis.

34. Subtalar joint structure Articulations : The posterior articulation is formed by a concave facet on the undersurface of the body of the talus and a convex facet on the body of the calcaneus . The smaller anterior and medial talocalcaneal articulations are formed by two convex facets on the inferior body and neck of the talus and two concave facets on the calcaneus .

35. Tarsal canal : Between the posterior articulation and the anterior and medial articulations, there is a bony tunnel formed by a sulcus (concave groove) in the inferior talus and superior calcaneus . This funnel-shaped tunnel, known as the tarsal canal , runs obliquely across the foot. Sinus tarsi : The lateral opening of the tarsal canal.

36. Sustentaculum tali : Its large end (the sinus tarsi) lies just anterior to the fibular malleolus ; its small end lies posteriorly below the tibial malleolus and above a calcaneus called the Sustentaculum tali .

37. Ligaments The calcaneofibular ligament The lateral talocalcaneal ligament The cervical ligament The interosseous talocalcaneal ligament.

38. The cervical ligament : The strongest of the talocalcaneal structures. It lies in the anterior sinus tarsi and joins the neck of the talus to the neck of the calcaneus (hence its name). The interosseous talocalcaneal ligament : It lies more medially within the tarsal canal, is more oblique and has been described as having anterior and posterior bands. The inferior extensor retinaculum : Provides subtalar support superficially and within the tarsal canal.

39. Subtalar joint function Posterior joint : When the talus moves on the posterior facet of the calcaneus , the articular surface of the talus slide in the same direction as the bone moves—a concave surface moving on a stable convex surface. Middle and anterior joints : The talar surfaces should glide in a direction opposite to movement of the bone—a convex surface moving on a stable concave surface.

40. Complex twisting or screwlike motion - triplanar motion of the talus around a single oblique joint axis, producing the motion of supination / pronation .

41. The subtalar axis Inclined 42 degree upward and anteriorly from the transverse plane (with a interindividual range of 29 to 47 degree).

42. Inclined medially 16 degree from the sagittal plane (with a interindividual range of 8 to 24 degree).

43. The subtalar axis lies about halfway between being longitudinal and being vertical. Consequently, pronation / supination includes about equal magnitudes of eversion /inversion and abduction/adduction. The subtalar axis is inclined only very slightly toward being a coronal axis (16 degree) and therefore has only a small component of dorsiflexion / plantarflexion .

44. Non–Weight-Bearing Subtalar Joint Motion: In non–weight-bearing supination and pronation , subtalar motion is described by motion of its distal segment (the calcaneus ) on the stationary talus and lower leg. Non– weightbearing supination : The coupled calcaneal motions of adduction, inversion, and plantarflexion Non–weight-bearing pronation : The coupled motions of abduction, eversion , and dorsiflexion Reference point : anteriorly located head of calcaneus

45. Weight-Bearing Subtalar Joint Motion : The calcaneus is on the ground. Free : to move around longitudinal axis (inversion/ eversion ) Limitation : limited in its ability to move around a coronal axis ( plantarflexion / dorsiflexion ) and vertical axis (adduction/abduction) It is because of the superimposed body weight. Coupled motion is not exclusively accomplished.

46. Calcaneus will continue to contribute the inversion/ eversion . The other two coupled components of the subtalar motion (abduction/adduction and dorsiflexion / plantarflexion ) will be accomplished by movement of the talus Reference : the head of the talus

47. In weightbearing subtalar motion, the direction of the component movement contributed by the talus is the opposite of what the calcaneus would contribute, although the same relative motion occurs between the segments.

48. Supinated or cavus foot : During Weight-bearing subtalar supination there is elevation of the medial longitudinal arch and convexity on the dorsal lateral midfoot . A foot that appears fixed in this position often is called a “ supinated ” or cavus foot. Pronated , pes planus , or flat foot : During Weight-bearing subtalar pronation there is lowering of the medial longitudinal arch and bulging or convexity in the plantar medial midfoot . A foot that appears fixed in this position often is called “ pronated ,” pes planus , or flat foot.

49. Weight-Bearing Subtalar Joint Motion and Its Effect on the Leg : Dorsiflexion of the head of the talus requires the body of the talus to slide posteriorly within the mortise Plantarflexion of the head of the talus requires the body of the talus to move anteriorly within the mortise.

50. When the head of the talus abducts in weightbearing subtalar supination , the body of the talus must rotate laterally in the transverse plane. When the head of the talus adducts in weight-bearing subtalar pronation , the body of the talus must rotate medially in the transverse plane.

51. Lateral rotation of leg : When the subtalar joint supinates in a weight-bearing position, the coupled component of talar abduction carries the mortise (the tibia and fibula) laterally, producing lateral rotation of the leg. Medial rotation of leg : Weight-bearing subtalar joint pronation causes talar adduction, with the body of the talus rotating medially and carrying the superimposed tibia and fibula into medial rotation.

52. Range of Subtalar Motion and Subtalar Neutral : The calcaneal inversion/ eversion ( varus / valgus ) component of subtalar motion is relatively easy to measure in both weight-bearing and non–weight-bearing positions. Reference point : Posterior calcaneus and posterior midline of the leg and assuming that neutral position (0) is when the two posterior lines coincide

53. For individuals without impairments, 5 to 10 degree of calcaneal eversion ( valgus ) 20 to 30 degree of calcaneal inversion ( varus ) have been reported for a total range of 25 to 40 degree.

54. Subtalar neutral : The point at which the midlines of the posterior calcaneus and the posterior leg coincide. Medial increase in that angle referred to as valgus and an decrease referred to as varus .

55. Transeverse tarsal joint The midtarsal or Chopart joint Compound joint formed by the Talonavicular and Calcaneocuboid joints The two joints together present an S-shaped joint line that transects the foot horizontally, dividing the hindfoot from the midfoot and forefoot.

56. The navicular and the cuboid bones are considered immobile in the weight-bearing foot. Transverse tarsal joint motion, therefore, is considered to be motion of the talus and of the calcaneus on the relatively fixed naviculocuboid unit.

57. Transverse Tarsal Joint Structure Talonavicular Joint : Articulations : Proximal portion :Formed by the anterior portion of the head of the talus, and the Distal portion :Formed by the concave posterior aspect of the navicular bone.

58. With the talus removed, superior view shows, The concavity (“socket”) formed by the navicular bone anteriorly , The deltoid ligament medially The medial band of the bifurcate ligament laterally The spring (plantar calcaneonavicular ) ligament inferiorly.

59. Ligaments : The spring and bifurcate ligaments. Dorsal talonavicular ligament Receives support from the ligaments of the subtalar joint— including the MCL and LCL, the inferior extensor retinacular structures, and the cervical and interosseous talocalcaneal ligaments. Additional support - From the ligaments that reinforce the adjacent calcaneocuboid joint.

60. The spring (plantar calcaneonavicular ) ligament : It is a triangular sheet of ligamentous connective tissue Origin : From the sustentaculum tali of the calcaneus and Insertion : On the inferior navicular bone. Role : Supports the head of the talus and the talonavicular joint The ligament is critical in providing support for the medial longitudinal arch. The spring ligament has little or no elasticity.

61. Calcaneocuboid Joint : Articulations : Proximal portion : The anterior calcaneus Distal portion :The posterior cuboid bone. Articular surfaces : Complex Reciprocally concave/convex both side to side and top to bottom. The reciprocal shape makes available motion more restricted.

62. The calcaneocuboid joint, like the talonavicular is linked in weight-bearing to the subtalar joint. In weightbearing subtalar supination / pronation , the inversion/ eversion of the calcaneus on the talus causes the calcaneus to move simultaneously on the relatively fixed cuboid bone, which results in a twisting motion.

63. Ligaments & capsule : Own capsule - reinforced by several important ligaments. Laterally by the lateral band of the bifurcate ligament (also known as the calcaneocuboid ligament) Dorsally by the dorsal calcaneocuboid ligament Inferiorly by 1) the plantar calcaneocuboid (short plantar) and 2) the long plantar ligaments – Most important ligament Provide transverse tarsal joint stability Give support of the lateral longitudinal arch of the foot.

64. Transversal Tarsal Joint Axes : Longitudinal and oblique axes around which the talus and calcaneus move on the relatively fixed naviculocuboid unit. The longitudinal axis is nearly horizontal, being inclined 15 degree upward from the transverse plane and angled 9 degree medially from the sagittal plane.

65. Motion around axis is triplanar , producing supination / pronation with coupled components similar to subtalar joint but simultaneously including both the talus and calcaneus segments moving on the navicular and cuboid segments. The oblique axis of the transverse tarsal joint is positioned approximately 57 degree medial to the sagittal plane and 52 degree superior to the transverse plane.

66. Transverse Tarsal Joint Function : Any weight-bearing subtalar motion includes talar abduction/adduction and dorsiflexion / plantarflexion that also causes motion at the talonavicular joint. Calcaneal inversion/ eversion that causes motion at the calcaneocuboid joint. Weight-bearing subtalar motion, therefore, must involve the entire transverse tarsal joint.

67. When the subtalar joint is fully supinated and locked (bony surfaces are drawn together), the transverse tarsal joint is also carried into full supination , and its bony surfaces are similarly drawn together into a locked position. When the subtalar joint is pronated and loose-packed, the transverse tarsal joint is also mobile and loose-packed. The transverse tarsal joint is the transitional link between the hindfoot and the forefoot, serving to (1)Add to the supination / pronation range of the subtalar joint and (2) Compensate the forefoot for hindfoot position.

68. Weight-Bearing Hindfoot Pronation and Transverse Tarsal Joint Motion : In the weight-bearing position, medial rotation of the Tibia imposes pronation on the subtalar joint. If the pronation force continued distally through the foot, the lateral border of the foot would tend to lift from the ground, diminishing the stability of the base of support. Resulting in unequal weight-bearing, and imposing stress at multiple joints.

69. This is avoided if the forefoot remains flat on the ground. This can occur if the transverse tarsal joint is mobile and can effectively “absorb” the hindfoot pronation (allowing the hindfoot to move without passing the movement on to the forefoot)

70. When the talus and calcaneus move on fixed naviculocuboid unit, there is a relative supination of the bony segments distal to the transverse tarsal joint. With the result that the forefoot remains relatively flat on the ground.

71. Weight-Bearing Hindfoot Supination and Transverse Tarsal Joint Motion : Lateral rotatory force on the leg will create subtalar supination in the weight-bearing subtalar joint with a relative pronation of the transverse tarsal joint (opposite motion of the forefoot segment) to maintain appropriate weight-bearing on a level surface.

72. As bony and ligamentous structures of the subtalar joint draw the talus and calcaneus closer together (become increasingly close-packed), the navicular and cuboid bones are also drawn toward the talus and calcaneus . Transverse tarsal joint mobility is increasingly limited as the subtalar joint moves toward full supination . With increasing supination of the subtalar joint, the transverse tarsal joint cannot absorb the additional rotation but begins to move toward supination as well.

73. In full subtalar joint supination , such as when the tibia is maximally laterally rotated on the weight-bearing foot, supination locks not only the subtalar joint but also the transverse tarsal joint. The fully supinated subtalar joint and transverse tarsal joint will tend to shift the weight-bearing in the forefoot fully to the lateral border of the foot. The entire medial border of the foot may lift and, unless the muscles on the lateral side of the foot and ankle are active, a supination sprain of the lateral ligaments may occur.

74. Tarsometatarsal Joints (TMT joint) Tarsometatarsal Joint Structure : Plane synovial Formed by the distal row of tarsal bones ( posteriorly ) and the bases of the metatarsals.

75. The first (medial) TMT joint : Composed of the articulation between the base of the first metatarsal and the medial cuneiform bone. Has its own articular capsule. The second TMT joint : Composed of the articulation of the base of the second metatarsal with a mortise formed by the middle cuneiform bone and the sides of the medial and lateral cuneiform bones. This joint is set more posteriorly than the other TMT joints. It is stronger and its motion is more restricted.

76. The third TMT joint : Formed by the third metatarsal and the lateral cuneiform , shares a capsule with the second TMT joint. The fourth and fifth TMT joints : The bases of the fourth and fifth metatarsals, with the distal surface of the cuboid bone. These two joints also share a common joint capsule. Small plane articulations exist between the bases of the metatarsals to permit motion of one metatarsal on the next.

77. Ligaments : Dorsal, plantar, and interosseous ligaments reinforce each TMT joint. Deep transverse metatarsal ligament : That spans the heads of the metatarsals on the plantar surface. Give stability of the proximally located TMT joints by preventing excessive motion and splaying of the metatarsal heads.

78. Axes : Unique although not fully independent. Ray : It is defined as a functional unit formed by a metatarsal and its associated cuneiform bone (for the first through third rays). The fourth and fifth rays are formed by the metatarsal alone because these metatarsals share an articulation with the cuboid bone. Most motion at the TMT joints occurs at the first and fifth rays. Each axis is oblique and, therefore, triplanar .

79. The axis of the first ray : Has the largest ROM. Inclined in such as way that dorsiflexion of the first ray also includes inversion and adduction, whereas plantarflexion is accompanied by eversion and abduction. The abduction/adduction components normally are minimal. The axis of the fifth ray : Movement more restricted and occur with the opposite arrangement of components: Dorsiflexion is accompanied by eversion and abduction, and Plantarflexion is accompanied by inversion and adduction.

80. The axis for the third ray : It is nearly coincides with a coronal axis; the predominant motion, therefore, is dorsiflexion / plantarflexion . The axes for the second and fourth rays : Not determined but were considered to be intermediate between the adjacent axes for the first and fifth rays, respectively. The second ray moves around an axis that is inclined toward, but is not as oblique as, the first axis. The fourth ray moves around an axis that is similar to, but not as steep as, the fifth axis. The second ray is considered to be the least mobile of the five.

81. Tarsometatarsal Joint Function : The motions of the TMT joints are interdependent. The TMT joints contribute to hollowing and flattening of the foot. In weightbearing , the TMT joints function primarily to augment the function of the transverse tarsal joint; that is, the TMT joints attempt to regulate position of the metatarsals and phalanges (the forefoot) in relation to the weight-bearing surface.

82. As long as transverse tarsal joint motion is adequate to compensate for the hindfoot position, considerable TMT joint motion is not required. When the hindfoot position is at an end point in its available ROM or the transverse tarsal joint is inadequate to provide full compensation, the TMT joints may rotate to provide further adjustment of forefoot position.

83. Supination Twist : When the hindfoot pronates substantially in weightbearing , the transverse tarsal joint generally will supinate to some degree to counterrotate the forefoot and keep the plantar aspect of the foot in contact with the ground. If the range of transverse tarsal supination is not sufficient to meet the demands of the pronating hindfoot , the medial forefoot will press into the ground, and the lateral forefoot will tend to lift.

84. The first and second ray will be pushed into dorsiflexion by the ground reaction force, and the muscles controlling the fourth and fifth rays will plantarflex the TMT joints in an attempt to maintain contact with the ground. Both dorsiflexion of the first and second rays and plantarflexion of the fourth and fifth rays include the component motion of inversion of the ray. Consequently, the entire forefoot undergoes an inversion rotation around a hypothetical axis at the second ray. This rotation is referred to as supination twist of the TMT joints.

85. Pronation Twist : When both the hindfoot and the transverse tarsal joints are locked in supination , the adjustment of forefoot position must be left entirely to the TMT joints. With hindfoot supination , the forefoot tends to lift off the ground on its medial side and press into the ground on its lateral side.

86. The muscles controlling the first and second rays will cause the rays to plantarflex in order to maintain contact with the ground, whereas the fourth and fifth rays are forced into dorsiflexion by the ground reaction force. Because eversion accompanies both plantarflexion of the first and second rays and dorsiflexion of the fourth and fifth rays, the forefoot as a whole undergoes a pronation twist.

87. Pronation twist and supination twist of the TMT joints occur only when the transverse tarsal joint function is inadequate: that is, when the transverse tarsal joint is unable to counterrotate or when the transverse tarsal joint range is insufficient to fully compensate for hindfoot position.

88. Metatarsophalangeal Joints The five metatarsophalangeal (MTP) joints are condyloid synovial joints with two degrees of freedom: Extension/flexion (or dorsiflexion / plantarflexion ) Abduction/adduction. Flexion and extension are the predominant functional movements at these joints.

89. Metatarsophalangeal Joint Structure : The MTP joints are formed proximally by the convex heads of the metatarsals and distally by the concave bases of the proximal phalanges

90. The first MTP joint has two sesamoid bones that are located on the plantar aspect of the first metatarsal head.

91. Ligaments : Stability of the MTP joints is provided by a joint capsule, plantar plates, Collateral ligaments :Two components: Phalangeal portion : that parallels the metatarsal and phalange, and an Accessory component : that runs obliquely from the metatarsal head to the plantar plate. Deep transverse metatarsal ligament.

92. Metatarsophalangeal Joint Function : The MTP joints have two degrees of freedom. Flexion/extension motion is much greater than abduction/adduction motion, and extension exceeds flexion. Although MTP motions can occur in weight-bearing or non–weight-bearing, the MTP joints serve primarily to allow the weight-bearing foot to rotate over the toes through MTP extension (known as the metatarsal break) when rising on the toes or during walking.

93. Metatarsophalangeal Extension and the Metatarsal Break : The metatarsal break derives its name from the hinge or “break” that occurs at the MTP joints as the heel rises and the metatarsal heads and toes remain weightbearing . The metatarsal break occurs as MTP extension around a single oblique axis that lies through the second to fifth metatarsal heads.

94. The inclination of the axis is produced by the diminishing lengths of the metatarsals from the second through the fifth toes. The angle of the axis around which the metatarsal break occurs may range from 54 to 73 degree with respect to the long axis of the foot. The ROM of the first MTP joint also may be influenced by the amount of dorsiflexion / plantarflexion motion at the TMT joints and is thought to be more restricted with increasing age. Limited extension ROM at the first MTP joint will interfere with the metatarsal break and is known as Hallux rigidus .

95. For the heel to rise while weight-bearing, there must be an active contraction of ankle plantarflexor musculature. The plantarflexion musculature normally cannot lift the heel completely unless the joints of the hindfoot and midfoot are supinated and locked so that the foot can become a rigid lever from the calcaneus through the metatarsals. This rigid lever will then rotate (“break”) around the MTP axis.

96. As MTP joint extension occurs, the metatarsal heads glide in a posterior and plantar direction on the plantar plates and the phalanges that are stabilized by the supporting surface. The metatarsal heads and toes becomes the base of support, and the body’s line of gravity ( LoG ) must move within this base to remain stable. The obliquity of the axis for the metatarsal break allows weight to be distributed across the metatarsal heads and toes more evenly than would occur if the axis were truly coronal.

97. If metatarsal break occurred around a coronal MTP axis, an excessive amount of weight would be placed on the first and second metatarsal heads. The obliquity of the axis of the metatarsal break shifts the weight laterally, minimizing the large load on the first two digits.

98. Metatarsophalangeal Flexion, Abduction, and Adduction : Flexion ROM at the MTP joints can occur to a limited degree from neutral position. Most MTP flexion occurs as a return to neutral position from extension. Abduction and adduction of the MTP joint appear to be helpful in absorbing some of the force that would be imposed on the toes by the metatarsals as they move in a pronation or supination twist.

99. The first toe normally is adducted on the first metatarsal about 15 to 19 degree. An increase in this normal valgus angulation of the first MTP joint is referred to as hallux valgus and may be associated with a varus angulation of the first metatarsal at the TMT joint, known as metatarsus varus .

100. Interphalangeal Joints The interphalangeal (IP) joints of the toes are synovial hinge joints with one degree of freedom: flexion/extension. The great toe has only one IP joint connecting two phalanges, whereas the four lesser toes have two IP joints (proximal and distal IP joints) connecting three phalanges. The toes function to smooth the weight shift to the opposite foot in gait and help maintain stability by pressing against the ground in standing.

101. Plantar Arches The foot typically is characterized as having three arches: Medial longitudinal arch Lateral longitudinal arch and a Transverse arch, of which the medial longitudinal arch is the largest. The arches are not present at birth but evolve with the progression of weight-bearing. Longitudinal arches in all children examined between 11 and 14 months of age. By 5 years of age, as children approached gait parameters similar to those of adults, the majority of children had developed an adult like arch.

102. Structure of Arches : The longitudinal arches :- They are anchored posteriorly at the calcaneus and anteriorly at the metatarsal heads. The longitudinal arch is continuous both medially and laterally through the foot, but because the arch is higher medially, the medial side usually is the side of reference. The lateral arch is lower than the medial arch. The talus rests at the top of the foot and is considered to be the “keystone” of the arch. All weight transferred from the body to the heel or the forefoot must pass through the talus.

103. The transverse arch :- It is a continuous structure. It is easiest to visualize in the midfoot at the level of the TMT joints. At the anterior tarsals , the middle cuneiform bone forms the keystone of the arch. The transverse arch can be visualized at the distal metatarsals but with less curvature. The second metatarsal is at the apex of this part of the arch. The transverse arch is completely reduced at the level of the metatarsal heads, with all metatarsal heads parallel to the weight-bearing surface.

104. The shape and arrangement of the bones are partially responsible for stability of the plantar arches. The wedge-shaped midtarsal bones provide stability to the transverse arch. The inclination of the calcaneus and first metatarsal contribute to stability of the medial longitudinal arch, particularly in standing. The arches would collapse without additional support from ligaments and muscles.

105. Arches are one continuous set of interdependent linkages, so support at one point in the system contributes to support throughout the system. The plantar calcaneonavicular (spring) ligament The interosseous talocalcaneal ligament, and The plantar aponeurosis Cervical ligament Long and short plantar ligaments

106. Function of the Arches : The plantar arches serve two contrasting mobility and stability weight-bearing functions. First, the foot must accept weight during early stance phase and adapt to various surface shapes. To accomplish this weight-bearing mobility function, the plantar arches must be flexible enough to allow the foot to, (1) Dampen the impact of weight-bearing forces, (2) Dampen superimposed rotational motions, and (3) Adapt to changes in the supporting surface.

107. To accomplish weight-bearing stability functions, the arches must allow, (1) Distribution of weight through the foot for proper weight-bearing and (2) Conversion of the flexible foot to a rigid lever. The mobility-stability functions of the arches of the weight-bearing foot may be examined by looking at the role of the plantar aponeurosis and by looking at the distribution of weight through the foot in different activities.

108. Plantar Aponeurosis : The role of the plantar aponeurosis (the plantar fascia) is important in supporting the arch. The plantar aponeurosis is a dense fascia that runs nearly the entire length of the foot. It begins posteriorly on the medial tubercle of the calcaneus and continues anteriorly to attach by the plantar plates and then, via the plates, to the proximal phalanx of each toe.

109. The plantar aponeurosis and its role in arch support are linked to the relationship between the plantar aponeurosis and the MTP joint. When the toes are extended at the MTP joints (regardless of whether the motion is active or passive, weight-bearing or non–weight-bearing), the plantar aponeurosis is pulled increasingly tight as the proximal phalanges glide dorsally in relation to the metatarsals,

110. The metatarsal heads act as pulleys around which the plantar aponeurosis is pulled and tightened. As the plantar aponeurosis is tensed with MTP extension, the heel and MTP joint are drawn toward each other, raising the arch and contributing to supination of the foot. This phenomenon allows the plantar aponeurosis to increase its role in supporting the arches as the heel rises and the foot rotates around the MTP joints in weight-bearing (during the metatarsal break).

111. Function : It increasing the longitudinal arch ( supination of the foot) as the heel rises during the metatarsal break, thus contributing to converting the foot to a rigid lever for effective push-off. The tightened plantar aponeurosis also increases the passive flexor force at the MTP joints, preventing excessive toe extension that might stress the MTP joint. Finally, the passive flexor force of the tensed plantar aponeurosis also assists the active toe flexor musculature in pressing the toes into the ground to support the body weight on its limited base of support.

112. Weight Distribution : The distribution of body weight through the foot depends on many factors, including the shape of the arch and the location of the LoG at any given moment. Distribution of superimposed body weight begins with the talus, because the body of the talus receives all the weight that passes down through the leg.

113. In bilateral stance, each talus receives 50% of the body weight. In unilateral stance, the weight-bearing talus receives 100% of the superimposed body weight. In standing, at least 50% of the weight received by the talus passes through the large posterior subtalar articulation to the calcaneus , and 50% or less passes anteriorly through the talonavicular and calcaneocuboid joints to the forefoot. The heel carried 60%, the midfoot 8%, and the forefoot 28% of the weightbearing load. The toes were minimally involved in bearing weight.

114. Plantar pressures are much greater during walking than during standing, with the highest pressures typically under the metatarsal heads and occurring during the push-off phase of walking , when only the forefoot is in contact with the ground and is pushing to accelerate the body forward. Structural and functional factors such as hammer toe deformity, soft tissue thickness, hallux valgus , foot type, and walking speed have been shown to be important predictors of forefoot plantar pressures during walking.

115. Muscular Contribution to the Arches : Key muscular support is provided to, The medial longitudinal arch during gait by the extrinsic muscles that pass posterior to the medial malleolus and inserting on the plantar foot: namely, the tibialis posterior, the flexor digitorum longus , and the flexor hallucis longus muscles. The peroneus longus muscle provides important lateral stability as its tendon passes behind the lateral malleolus and insert into the base of the first metatarsal.

116. These medial and lateral muscles provide a dynamic sling to support the arches of the foot during the entire stance phase of walking and enhance adaptation to uneven surfaces.

117. Muscles of the Ankle and Foot There are no muscles in the ankle or foot that cross and act on one joint in isolation; all these muscles act on at least two joints or joint complexes. The position of the ankle/foot muscles with respect to the talocrural joint axis and subtalar joint axis is represented in Figure.

118. All muscles that pass anterior to the talocrural (ankle) joint will cause dorsiflexion torques or moments, while those that pass posterior to the axis will cause plantarflexion moments. Muscles that pass medial to the subtalar axis will create supination moments at the subtalar joint, whereas those that pass lateral to the subtalar axis will create pronation moments.

119. Extrinsic ankle/foot muscles are those that arise proximal to the ankle and insert onto the foot. Intrinsic foot muscles arise from within the foot (do not cross the ankle) and insert on the foot. Extrinsic muscles will be divided further into the three compartments of the lower leg: the posterior, lateral, and anterior compartments.

120. Extrinsic Musculature Posterior Compartment Muscles: The posterior compartment muscles all pass posterior to the talocrural joint axis and, therefore, are all plantarflexors . The muscles in the posterior compartment are the gastrocnemius , soleus , tibialis posterior, flexor digitorum longus , and flexor hallucis longus muscles.

121. The gastrocnemius muscle arises from two heads of origin on the condyles of the femur and inserts via the Achilles tendon into the most posterior aspect of the calcaneus . The soleus muscle is deep to the gastrocnemius , originating on the tibia and fibula and inserting with the gastrocnemius into the posterior calcaneus . The two heads of the gastrocnemius and the soleus muscles together are known as the triceps surae and are the strongest plantarflexors of the ankle.

122. Activity of the gastrocnemius and soleus on the weight-bearing foot helps lock the foot into a rigid lever both through direct supination of the subtalar joint and through indirect supination of the transverse tarsal joint. Continued plantarflexion force will raise the heel and cause elevation of the arch. Elevation of the arch by the triceps surae when the heel is lifted off the ground is observable in most people when they actively plantarflex the weight bearing foot.

123. The other ankle plantarflexion muscles are the plantaris , the tibialis posterior, the flexor hallucis longus , the flexor digitorum longus , the peroneus longus , and the peroneus brevis muscles. Although each of these muscles passes posterior to the ankle axis, the moment arm for plantarflexion for these muscles is so small that they provide only 5% of the total plantarflexor force at the ankle.

124. The tendon of tibialis posterior muscle passes just behind the medial malleolus , medial to the subtalar joint, to insert into the navicular bone and plantar medial arch. The tibialis posterior muscle is the largest extrinsic foot muscle after the triceps surae and has a relatively large moment arm for both subtalar joint and transverse tarsal joint supination .

125. The tibialis posterior muscle is an important dynamic contributor to arch support and has a significant role in controlling and reversing pronation of the foot that occurs during gait. Because of its insertion along the plantar medial longitudinal arch, tibialis posterior dysfunction is a key problem associated with acquired pes planus , or flat foot.

126. The flexor hallucis longus and the flexor digitorum longus muscles pass posterior to the tibialis posterior muscles and the medial malleolus , spanning the medial longitudinal arch and helping support the arch during gait. These muscles attach to the distal phalanges of each digit and, through their actions, cause the toes to flex.

127. The quadratus plantae muscle is an intrinsic muscle arising from either side of the inferior calcaneus that inserts into the lateral border and plantar surface of the flexor digitorum longus tendon.

128. Flexion of the IP joint of the hallux by the flexor hallucis longus muscles produces a press of the toe against the ground. Flexion of the distal and proximal IP joints of the four lesser toes by the flexor digitorum longus causes clawing (MTP extension with IP flexion) similar to what occurs in the fingers when the proximal phalanx is not stabilized by intrinsic musculature.

129. Activity of the interossei muscles can stabilize the MTP joint and prevent MTP hyperextension. Pathologies (such as peripheral neuropathy) that cause weakness of the interossei muscles can contribute to destabilization of the MTP joint, hammer toe deformity (hyperextension at the MTP joint), and excessive stresses under the metatarsal heads. These excessive stresses can contribute to pain under the metatarsal heads (i.e., metatarsalgia ) or skin breakdown in persons who lack protective sensation (i.e., those with peripheral neuropathy).

130. Lateral Compartment Muscles: The peroneus longus and brevis muscles pass lateral to the subtalar joint and, because of their significant moment arms, are the primary pronators at the subtalar joint. Their tendons pass posterior but close to the ankle axis and thus are weak plantar flexors.

131. The tendon of the peroneus longus muscle passes around the lateral malleolus , under the cuboid bone, and across the transverse arch and inserts into the medial cuneiform bone and base of the first metatarsal.

132. Because of its path across the arches, the peroneus longus tendon is credited with support of the transverse and lateral longitudinal arches.

133. Anterior Compartment Muscles: The muscles of the anterior compartment of the leg are the tibialis anterior, the extensor hallucis longus , the extensor digitorum longus , and the peroneus tertius muscles. All muscles in the anterior compartment of the lower leg pass under the extensor retinaculum and insert well anterior to the talocrural joint axis. These muscles are strong ankle dorsiflexors .

134. Besides being a strong dorsiflexor muscle at the ankle joint, the tibialis anterior muscle passes medial to the subtalar axis and is a key supinator of the subtalar and transverse tarsal joints. The tendons of the extensor digitorum longus and the peroneus tertius muscles pass beneath the extensor retinaculum and insert anterior to the ankle joint axis and lateral to the subtalar joint axis; consequently, these muscles are dorsiflexors of the ankle and pronators of the hindfoot .

135. The extensor digitorum longus muscle also extends the MTP joints of the lesser toes, working with the extensor hallucis longus muscle to hold the toes up when the foot is off the ground.

136. Intrinsic Musculature The most important functions of the intrinsic muscles of the foot are their roles as, Stabilizers of the toes and Dynamic supporters of the transverse and longitudinal arches during gait .

137. The intrinsic muscles of the hallux attach either directly or indirectly to the sesamoid bones and contribute to the stabilization of these weight-bearing bones. The extensor digitorum longus and brevis muscles are MTP extensors. Activity in the lumbrical and the dorsal and plantar interossei muscles stabilizes the MTP joints and maintains or produces IP extension.

138. Deviations from Normal Structure and Function Supinated Foot ( Pes Cavus ): In a cavus foot, (1) The calcaneus is noticeably inverted, (2)The medial longitudinal arch height is noticeably high, and (3) Lateral dorsal bulge is present at the talonavicular joint that is associated with talar abduction and dorsiflexion .

139. The subtalar and transverse tarsal joints are excessively supinated and may be locked into full supination , which prohibits these joints from participating in shock absorption or in adapting to uneven terrain. Hindfoot supination often is associated with a lateral rotation stress on the leg. The inability to absorb additional lower limb rotations at the hindfoot may place a strain on the ankle joint structures, especially the LCLs.

140. Because the transverse tarsal joint is locked along with the subtalar joint, the TMT joints are responsible with attempting to maintain the forefoot on the ground by doing a pronation twist. If the sustained pronation twist results in adaptive tissue changes, the deformity known as a forefoot valgus will develop.

141. The excessive pronation and plantarflexion of the first ray that accompanies a pronation twist may create a valgus stress at the first MTP joint and contribute to the formation of a hallux valgus .

142. Thank you