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 Bones: inferior talus, superior calcaneus
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
Talonavicular- navicular is relatively fixed. Talus moves on fixed navicular. Maintains medial longitudinal arch.
Calcaneocuboid- Rotation in transverse plane. Pulley for peroneus longus and stabilizes 1st ray. Cuboid most common foot subluxation (inferiorly).

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
Webster’s: 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.
Dorsiflexion of toes forces metatarsal head into plantar flexion and brings plantar pad over head of metatarsal

19. Plantar arches Longitudinal arch Transverse 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 Long plantar ligament Plantar aponeurosis
Tension wire which helps maintain arch
Helps rigidity during propulsion
Long plantar ligament
Plantar aponeurosis
Short plantar ligament

21. Function of arches Stability Mobility Distribution of weight
Dampens shock of weight bearing
Adaptation to changes in support surfaces
Dampening of superimposed rotations
                                            

22. Running gait Stance phase Swing 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
Velocity=stride length x cadence
Double float- neither limb is in contact with the floor. Beginning and end of each running swing phase.
Stride length- distance from initial contact of one foot until initial contact of contralateral foot
Step length- distance from IC of one foot until IC of the same foot. One complete gait cycle.
Cadence- number of steps in a given period of time. Average natural cadence- 101 to 122 steps/minute.
Women- average cadence 6 to 9 steps a minute higher than men.

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??
One theory is that the decreased time in supination in running is the cause of increased injuries during running- loss of stable foot position.

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
Calcaneus in eversionparallel axes (talonavicular and calcaneocuboid).
Increased motion in the transverse tarsal joint. Increased flexibility. Pronation
B. Calcaneus in inversion axes are oblique
Decreased motion in transverse tarsal joint. Increased stability. More rigid. Supination
Page 13
O'Connor FG, Wilder RP: Textbook of Running Medicine, McGraw Hill Companies, Page 13.

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
Newton’s third law
Internal forces- muscle forces
Newton’s third law- for every action there is an equal and opposite reaction
Vertical- small force peak in first 20% of stance and gradual larger peak in remainder of stance.
Fore-aft- absorption and propulsion

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
Page 17.
O'Connor FG, WilderRP: Textbook of Running Medicine, McGraw-Hill Companies, Page 17

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 >10% 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 Midsole 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 Underpronator
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 evaluation=running 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
25% or runners

48. Intrinsic abnormalities
Pes cavus- abnormal supination
Pes Planus- abnormal pronation

49. Supination Normal Abnormal 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
5% of runners

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 Abnormal 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
Most runners.

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. Anatomy of the Running Shoe
Uppers
                                                                                                                                       
Midsole
Outersole
Vamp- toe box (wide to prevent blisters), toe cap (protects toes and durability), throat (make sure not too tight)
Quarters- conform to arch and midfoot. Stability with stabilizing bars or arch braces.
Heel counter- withstand torsional force. Rear stability. Reduce speed of pronation and rotation
Midsole

59. Anatomy of the Running Shoe
Heel notch
Lacing system
Toebox
Heel counter
Outersole- traction and protection from surface. Carbon rubber- dense, durable, not flexible. Blown rubber- lighter and more flexible. OR hard rubber- mixture.
Insole- reduce friction. Remove when using orthotics. Neoprene vs. viscoelastic
Tongue

60. Anatomy of the Running Shoe
Flex Grooves
                                                                                                                                       
Split Heel

61. Anatomy of the Running Shoe Last (Curvature) Straight, Semi-curved and Curved
If we looked at arch only, the shoe on the left (straight) would be worn by low-arched runners: the middle (semi-curved) by normal-arched runners; and the right (curved) by high-arches runners. However, the running shoe clinic’s main diagnostic tool is dynamic assessment of your running gait. Arch shape is a secondary factor in the shoe selection process.

62. Anatomy of the Running Shoe
Lasts (Shoe Template)
Board
Slip
Combination
If you cannot remove insole, remove shoe…it is of poor quality

63. Shoe Design Motion Control, Stability, Cushion
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%.
American journal of Sport Medicine runners with knee, foot, ankle, and hip pain. 31% complete relief, 45% great improvement, 15% slight improvement. 90% continued to use orthotic after symptoms resolved. 90% satisfaction.
Journal of American Podiatric Medical Association Studied 43 patients with symptoms due to heel spurs. Treated with customized rigid plastic foot orthosis. 81% with complete symptom relief.
JAPMA Functional foot orthosis for plantar fasciitis. Reduced pain by 80%.

68. Orthotics Motion control Shock absorption
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/Morton’s 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??