More than you ever wanted to know about the foot

1
More than you ever wanted to know about the foot

• MAJ Joel L. Shaw
• Sports Medicine
• 24 May 2007

2
Overview

• Describe foot and ankle joints
• Joint actions during running
• Related pathology
• How to prescribe running shoes

3
Foot function

• 1. Accept vertical forces during heel strike
• 2. Absorb and dissipate these forces across a
  flexible mid- and forefoot during pronation
• 3. Provide propulsion as the foot becomes a rigid
  lever with resupination and toe-off

4
Articulations

• Subtalar
• Talocalcaneonavicular
• Calcanealcuboid
• Midtarsal
• Tarsometatarsal
• Metatarsophalangeal
• Interphalangeal

5
Subtalar

• Triplanar
• Supination vs. Pronation
• Bones inferior talus, superior calcaneus
• Alternating concave-convex facets limit mobility
• Ligaments- talocalcaneal, interosseous
  talocalcaneal, cervical

6
Subtalar joint

• Supination
• Inversion by calcaneus
• Abduction by talus.
• Dorsiflexion by talus
• Talar abduction causes external rotation of the
  tibia
• Position of most stability

7
Subtalar joint

• Pronation
• Eversion by calcaneus
• Adduction by talus
• Plantarflexion by talus
• Talar adduction causes internal rotation of the
  tibia
• May increase Q angle
• Increased flexibility and shock absorption

8
Subtalar joint

• Clinical significance
• Mobility
• Shock absorption
• Stability

9
Midtarsal joint

• Functional joint- includes talonavicular and
  calcaneocuboid joint
• Triplanar supination/pronation- primarily DF/PF
  and abd/add
• Navicular- highest point of medial arch

10
Midtarsal joint

• Assist pronation/supination of the subtalar joint
• Maintain normal weight bearing forces on the
  forefoot
• Control/communication between rear foot and
  forefoot

11
Tarsometatarsal joint

• Connection from cuneiforms/cuboid to metatarsals
• Continue function of midtarsal joint
• Positional regulation of metatarsals/ phalanges
  to the weight-bearing surface
• Distributes body weight laterally
• Pronate/supinate to keep forefoot on ground

12
Metatarsophalangeal joint

• Biplanar- mostly dorsiflexion/plantarflexion with
  10 degrees of abduction/adduction
• Dorsiflexion- allows body to pass over foot while
  toes balance body weight during gait
• Plantarflexion- allows toes to press into ground
  for balance during gait

13
Metatarsophalangeal joint

• Metatarsal break
• Oblique axis for flexion/extension passing
  through 2nd to 5th metatarsal heads
• Where foot hinges as the heel raises
• Rigid lever during plantarflexion
• Supination causes rearfoot/midfoot locking
• Shifts body weight from medial to lateral

14
First ray

• Functional joint
• Bones- Navicular, 1st Cuneiform, 1st Metatarsal
• Plantarflexion at late stance to assist 1st MTP
  dorsiflexion
• Peroneus longus and abductor hallicus brevis
  muscles

15
Supporting soft tissues

• Plantar aponeurosis
• Plantar arches
• Ligaments

16
Plantar fascia

• Causes tension along the arch
• Supination facilitated as arch heightened
• Windlass effect

17
Windlass effect

• Websters machine for pulling a rope around a
  drum. Pulley system to lift anchor in a boat.

18
Windlass effect

• Tension in the aponeurosis secondary to toe
  extension elevates the arch by acting as a pulley
  around which the aponeurosis is tightened.

19
Plantar arches

• Longitudinal arch
• Shock absorption
• Continuous medially and laterally
• Bears most weight medially
• Transverse arch
• Mobility
• Extends from anterior tarsals to base of
  metatarsals

20
Ligaments

• Spring ligament
• Tension wire which helps maintain arch
• Helps rigidity during propulsion
• Long plantar ligament
• Plantar aponeurosis
• Short plantar ligament

21
Function of arches

• Stability
• Distribution of weight
• Mobility
• Dampens shock of weight bearing
• Adaptation to changes in support surfaces
• Dampening of superimposed rotations

22
Running gait

• Stance phase
• 40 of gait cycle
• 2 phases
• Absorption
• Propulsion

• Swing phase
• 60 of gait cycle
• 2 phases
• Initial swing (ISW)- 75
• Terminal swing (TSW)- 25

23
Running gait

• Double float
• Stride length
• Step length
• Cadence

• Velocitystride length x cadence

24
Running gait

• Kinematics vs. Kinetics
• Kinematics- motion of joints independent of
  forces that cause the motion to occur
• Kinetics- study of forces that cause movement,
  both internally and externally
• Internal- muscle forces
• External- ground reactive forces

25
Ankle/foot kinematics

• Ankle joint
• Dorsiflexion/plantarflexion
• Foot joints
• Triplanar
• Pronation and supination

26
Running gait- ankle kinematics

• Absorption and midstance
• Rapid dorsiflexion (response to increased hip and
  knee flexion)
• Decreased plantarflexion in running? decreased
  supination?cause of increased running injuries??

27
Running gait- foot kinematics

• Subtalar motion determined by muscular activity
  and ground reactive forces
• Midtarsal motion determined by subtalar position

28
Running gait- midtarsal joint

• Calcaneus/talus supination
• Increase midtarsal obliquity
• Lock joint
• Rigid lever
• During propulsion and ISW

• Calcaneus/talus pronation
• Parallel midtarsal joints
• Increased ROM
• Mobile adapter
• Mid stance

29
Axis of transverse tarsal joint
30
Running gait- foot kinematics

• Absorption
• Pelvis, femur, tibia internally rotate
• Eversion and unlocking of subtalar joint
• Pronation of midtarsal joints
• Allows mobility and shock absorption.
• Able to adapt to ground surface.
• Plantar fascia- relax medial arch

31
Running gait- foot kinematics

• Propulsion
• Pelvis, femur, tibia externally rotate
• Inversion/locking of subtalar joint
• Supination of forefoot
• Plantar fascia- increase medial arch stability
  and invert heel
• Metatarsal break- promote hindfoot inversion and
  external rotation of leg

32
Running gait- foot kinetics

• External forces- ground reactive forces
• Vertical- 3-4 times body weight
• Fore-aft- 30 of body weight
• Medial-lateral- 10 of body weight
• Newtons third law
• Internal forces- muscle forces

33
External forces

• Foot strike pattern
• Forefoot Midfoot
  Rearfoot

34
Rearfoot striker

• 80 of runners
• Initial contact- posterolateral foot
• Center of Pressure (COP)
• Outer border of rear foot?progresses along
  lateral border?then across forefoot medially?
  toward 1st and 2nd metatarsal head

35
Midfoot strikers

• Most other runners
• Initial contact- midlateral border of foot
• COP
• Lateral midfoot?progresses posteriorly
  (corresponds to heel contact)?rapidly moves to
  the medial forefoot

36
Center of Pressure
37
Evaluation of running injuries

• Training log
• Shoe examination
• Arch appraisal
• Gait analysis
• Running shoe prescription

38
Training log

• Weekly mileage
• Transition point
• Increase in distance or intensity
• Increase in mileage gt10 per week
• Change in terrain or running surface

39
Shoe examination

• Current running shoes
• Age (days and miles)
• Replacement frequency
• New brand or model? (change biomechanics)

40
Shoe examination

• Outsole wear
• Lateral heel vs. inside heel vs. lateral sole
• Midsole wear
• Heel counter tilt
• Midsole wrinkling, tilt, or decomposition

41
Shoe wear

• Based on foot strike pattern, initial contact,
  and center of pressure
• Neutral gait
• Wear on lateral aspect of heel
• Uniform wear under the toes

42
Shoe wear

• Overpronator
• Excessive wear on medial portion of heel and
  forefoot
• Underpronator
• Excessive wear on lateral heel
• Wear on entire lateral portion of the outersole

43
Arch appraisal

• Standing arch contour
• Wet test
• Static evaluationrunning evaluation?

44
Biomechanical function

• Required functions of locomotion
• Adaptation
• Shock absorption
• Torque conversion
• Stability
• Rigidity

45
Biomechanical assessment

• Video gait analysis
• Always base on running gait, not arch height
• Evaluate shoe wear

46
Gait analysis

• Behind- location of heel strike, foot motion
  during single stance, foot engaged at push-off
• Side- gastroc-soleus flexibility, great toe
  dorsiflexion
• Treadmill-based analysis
• Force plate analysis

47
Neutral gait

• Level Heel Throughout Gait Cycle
• 90 Degree Medial Angle Throughout Gait Cycle

48
Intrinsic abnormalities

• Pes cavus- abnormal supination
• Pes Planus- abnormal pronation

49
Supination

• Normal
• Late stance phase
• Provides rigidity, support, propulsion
• Facilitates lower leg external rotation

• Abnormal
• Minimal pronation at subtalar joint
• Little drop of medial longitudinal arch

50
Abnormal supination- signs

• Lateral Leaning Foot Surface Placement
• Inflexible Foot
• Callus- 1st and 5th metatarsal heads
• Clawing of 4th and 5th digits

51
Abnormal supinators

• Stable and rigid foot
• Lacks flexibility and adaptability

• Poor gastroc-soleus flexibility
• Achilles tendonitis
• Plantar fasciitis
• Poor shock absorption
• Tibial and femoral stress fractures

52
Pronation

• Normal
• Early in stance phase
• Provides flexibility, adaptability and shock
  absorption
• Facilitates lower leg internal rotation

• Abnormal
• Continues throughout stance phase

53
Mild Overpronation- signs

• Slightly Greater than 90 Degree Angle Throughout
  Gait Cycle
• Medial Leaning Foot Surface Placement
• Some Ankle Instability/ unstable position

54
Severe overpronation- signs

• Significant Medial Leaning of Surface Foot
• Great Instability
• Excessive internal tibial rotation
• Increased medial stress

55
Overpronators

• Patellofemoral pain
• Popliteal tendonitis
• Posterior tibial tendonitis
• Achilles tendonitis
• Plantar fasciitis
• Metatarsal stress fracture

56
Arch Height Will Produce Different Levels of
Flexibility

• Normal feet
• are flexible as they grip the ground and become
  stiff at push off
• Flat feet
• are flexible as they grip the ground and remain
  flexible at push off
• High arched feet
• are inflexible and do not adjust to terrain
  well, but provide a good base for push off.

57
Running Shoe Design

• In an attempt to minimize injuries, running shoes
  need to provide
• Cushioning
• Motion Control
• Support

58
Anatomyof the Running Shoe
Uppers
Midsole
Outersole
Midsole
59
Anatomy of the Running Shoe
Heel notch
Lacing system
Toebox
Heel counter
Tongue
60
Anatomy of the Running Shoe
Flex Grooves
Split Heel
61
Anatomy of the Running Shoe Last
(Curvature)Straight, Semi-curved and Curved
62
Anatomy of the Running Shoe

• Lasts (Shoe Template)
• Board
• Slip
• Combination
• If you cannot remove insole, remove shoeit is of
  poor quality

63
Shoe DesignMotion Control, Stability, Cushion

• Motion Control
• Mod-Severe overpronator
• Stability
• majority of the population, slight overpronation
• Cushioned
• Neutral/underpronator runner

64
Stabilizing Features

• Support is added to the inside or medial portion
  of the heel to counteract the foot rolling inward
  (pronation)

65
Running Shoe Selection

• The three basic types of running gait based on
  ankle biomechanics are over-pronation, neutral
  and underpronation
• Shoes should be bought to accommodate your
  running gait, not your arch height!

66
Shoe prescription

• High arch- curve-lasted, cushion shoe
• Flat arch- motion control or stability shoes with
  firm midsoles and straight to semi-curved lasts
• Neutral arch- cushion or stability shoe

67
Orthotics

• Effectiveness
• Gross, et al. 90 with symptom improvement
• Schere. 81 with complete symptoms relief
• Blake and Denton. Reduced pain associated with
  plantar fasciitis by 80.

68
Orthotics

• Motion control
• Control excessive pronation
• Shock absorption
• Pressure relief in specific area
• Plantar heel or great toe metatarsophalangeal
• Redistribution of forces away from area
• Metatarsal pad for metatarsalgia/Mortons neuroma

69
Orthotics

• Adjunct to rehab and training modification
• Return athlete to full function
• Prevent further injury
• Functional orthoses
• Alter foot function
• Guide foot through stance phase
• Promote biomechanical efficiency

70
Orthotics

• Start with soft temporary orthotic
• Over-the counter prefabricated devices
• Most athletes report improvement
• Incomplete improvement?custom orthotic

71
High arch orthotic

• Dropped forefoot
• Plantarflexed first metatarsal and forefoot
  valgus
• Decreased subtalar range of motion
• Plantarflexed first ray, unstable cuboid
• Peroneal cuboid syndrome

72
Pronated foot orthotic

• Flat medial arch
• Unstable rearfoot and excessive motion of plantar
  calcaneal fat pad
• Weak plantarflexion of first metatarsal head and
  weak windlass effect

73
Common mistakes

• Only looking at standing gait
• Failure to evaluate various needs of different
  runners
• Need of different orthoses for running and
  everyday activity

74
Summary

• Understand normal foot biomechanics- pronation
  vs. supination
• Evaluate with functional arch and shoe wear
• Signs of abnormal arch
• Match shoes and orthotics to running alignment-
  correct shoes and over-the-counter inserts first

75
Questions??