More than you ever wanted to know about the foot. MAJ Joel L. Shaw, US Army Sports Medicine

Transcription

1 More than you ever wanted to know about the foot MAJ Joel L. Shaw, US Army Sports Medicine

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 Subtalar Talocalcaneonavicular Calcanealcuboid Midtarsal Tarsometatarsal Metatarsophalangeal Interphalangeal Articulations

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 2 nd to 5 th 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, 1 st Cuneiform, 1 st Metatarsal Plantarflexion at late stance to assist 1 st 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 Tension in the aponeurosis secondary to toe extension elevates the arch by acting as a pulley around which the aponeurosis is tightened. Windlass effect

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 Velocity=stride 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 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 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

32 External forces Foot strike pattern Forefoot Midfoot Rearfoot

33 80% of runners Rearfoot striker Initial contact- posterolateral foot Center of Pressure (COP) Outer border of rear foot progresses along lateral border then across forefoot medially toward 1 st and 2 nd metatarsal head

34 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

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

36 Evaluation of running injuries Training log Shoe examination Arch appraisal Gait analysis Running shoe prescription

37 Training log Weekly mileage Transition point Increase in distance or intensity Increase in mileage >10% per week Change in terrain or running surface

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

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

40 To help protect your privacy, PowerPoint prevented this external picture from being automatically downloaded. To download and display this picture, click Options in the Message Bar, and then click Enable external content. 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

41 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

42 Arch appraisal Standing arch contour Wet test Static evaluation=runni ng evaluation?

43 Biomechanical function Required functions of locomotion Adaptation Shock absorption Torque conversion Stability Rigidity

44 Biomechanical assessment Video gait analysis Always base on running gait, not arch height Evaluate shoe wear

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

46 Neutral gait Level Heel Throughout Gait Cycle 90 Degree Medial Angle Throughout Gait Cycle

47 Intrinsic abnormalities Pes cavus- abnormal supination Pes Planus- abnormal pronation

48 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

49 Abnormal supination- signs Lateral Leaning Foot Surface Placement Inflexible Foot Callus- 1 st and 5 th metatarsal heads Clawing of 4 th and 5 th digits

50 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

51 Pronation Normal Early in stance phase Provides flexibility, adaptability and shock absorption Facilitates lower leg internal rotation Abnormal Continues throughout stance phase

52 Mild Overpronation- signs Slightly Greater than 90 Degree Angle Throughout Gait Cycle Medial Leaning Foot Surface Placement Some Ankle Instability/ unstable position

53 Severe overpronation- signs Significant Medial Leaning of Surface Foot Great Instability Excessive internal tibial rotation Increased medial stress

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

55 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.

56 Running Shoe Design In an attempt to minimize injuries, running shoes need to provide: Cushioning Motion Control Support

57 Anatomy of the Running Shoe Uppers Midsole Outersole Midsole

58 Anatomy of the Running Shoe Heel notch Lacing system Toebox Heel counter Tongue

59 Anatomy of the Running Shoe Flex Grooves Split Heel

60 Anatomy of the Running Shoe Last (Curvature) Straight, Semi-curved and Curved

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

62 Shoe Design Motion Control, Stability, Cushion Motion Control Mod-Severe overpronator Stability majority of the population, slight overpronation Cushioned Neutral/underpronator runner

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

64 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!

65 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

66 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%.

67 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/morton s neuroma

68 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

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

70 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

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

72 Summary Understand normal foot biomechanicspronation vs. supination Evaluate with functional arch and shoe wear Signs of abnormal arch Match shoes and orthotics to running alignment- correct shoes and over-thecounter inserts first

73 Questions??