Presentation on theme: "More than you ever wanted to know about the foot"— Presentation transcript:
1More than you ever wanted to know about the foot MAJ Joel L. ShawSports Medicine24 May 2007
2Overview Describe foot and ankle joints Joint actions during running Related pathologyHow to prescribe running shoes
3Foot function 1. Accept vertical forces during heel strike 2. Absorb and dissipate these forces across a flexible mid- and forefoot during pronation3. Provide propulsion as the foot becomes a rigid lever with resupination and toe-off
5Subtalar Triplanar Bones: inferior talus, superior calcaneus Supination vs. PronationBones: inferior talus, superior calcaneusAlternating concave-convex facets limit mobilityLigaments- talocalcaneal, interosseous talocalcaneal, cervical
6Subtalar joint Supination Inversion by calcaneusAbduction by talus.Dorsiflexion by talusTalar abduction causes external rotation of the tibiaPosition of most stability
7Subtalar joint Pronation Eversion by calcaneusAdduction by talusPlantarflexion by talusTalar adduction causes internal rotation of the tibiaMay increase Q angleIncreased flexibility and shock absorption
9Midtarsal jointFunctional joint- includes talonavicular and calcaneocuboid jointTriplanar supination/pronation- primarily DF/PF and abd/addNavicular- highest point of medial archTalonavicular- 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).
10Midtarsal joint Assist pronation/supination of the subtalar joint Maintain normal weight bearing forces on the forefootControl/communication between rear foot and forefoot
11Tarsometatarsal joint Connection from cuneiforms/cuboid to metatarsalsContinue function of midtarsal jointPositional regulation of metatarsals/ phalanges to the weight-bearing surfaceDistributes body weight laterallyPronate/supinate to keep forefoot on ground
12Metatarsophalangeal joint Biplanar- mostly dorsiflexion/plantarflexion with 10 degrees of abduction/adductionDorsiflexion- allows body to pass over foot while toes balance body weight during gaitPlantarflexion- allows toes to press into ground for balance during gait
13Metatarsophalangeal joint Metatarsal breakOblique axis for flexion/extension passing through 2nd to 5th metatarsal headsWhere foot hinges as the heel raisesRigid lever during plantarflexionSupination causes rearfoot/midfoot lockingShifts body weight from medial to lateral
14First ray Functional joint Bones- Navicular, 1st Cuneiform, 1st MetatarsalPlantarflexion at late stance to assist 1st MTP dorsiflexionPeroneus longus and abductor hallicus brevis muscles
16Plantar fascia Causes tension along the arch Supination facilitated as arch heightenedWindlass effect
17Windlass effectWebster’s: machine for pulling a rope around a drum. Pulley system to lift anchor in a boat.
18Windlass effectTension 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
19Plantar arches Longitudinal arch Transverse arch Shock absorption Continuous medially and laterallyBears most weight mediallyTransverse archMobilityExtends from anterior tarsals to base of metatarsals
20Ligaments Spring ligament Long plantar ligament Plantar aponeurosis Tension wire which helps maintain archHelps rigidity during propulsionLong plantar ligamentPlantar aponeurosisShort plantar ligament
21Function of arches Stability Mobility Distribution of weight Dampens shock of weight bearingAdaptation to changes in support surfacesDampening of superimposed rotations
23Running gait Double float Stride length Step length Cadence Velocity=stride length x cadenceDouble 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 footStep 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.
24Running gait Kinematics vs. Kinetics Kinematics- motion of joints independent of forces that cause the motion to occurKinetics- study of forces that cause movement, both internally and externallyInternal- muscle forcesExternal- ground reactive forces
25Ankle/foot kinematics Ankle jointDorsiflexion/plantarflexionFoot jointsTriplanarPronation and supination
26Running gait- ankle kinematics Absorption and midstanceRapid dorsiflexion (response to increased hip and knee flexion)Decreased plantarflexion in running decreased supinationcause 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.
27Running gait- foot kinematics Subtalar motion determined by muscular activity and ground reactive forcesMidtarsal motion determined by subtalar position
29Axis of transverse tarsal joint Calcaneus in eversionparallel axes (talonavicular and calcaneocuboid).Increased motion in the transverse tarsal joint. Increased flexibility. PronationB. Calcaneus in inversion axes are obliqueDecreased motion in transverse tarsal joint. Increased stability. More rigid. SupinationPage 13O'Connor FG, Wilder RP: Textbook of Running Medicine, McGraw Hill Companies, Page 13.
30Running gait- foot kinematics AbsorptionPelvis, femur, tibia internally rotateEversion and unlocking of subtalar jointPronation of midtarsal jointsAllows mobility and shock absorption.Able to adapt to ground surface.Plantar fascia- relax medial arch
31Running gait- foot kinematics PropulsionPelvis, femur, tibia externally rotateInversion/locking of subtalar jointSupination of forefootPlantar fascia- increase medial arch stability and invert heelMetatarsal break- promote hindfoot inversion and external rotation of leg
32Running gait- foot kinetics External forces- ground reactive forcesVertical- 3-4 times body weightFore-aft- 30% of body weightMedial-lateral- 10% of body weightNewton’s third lawInternal forces- muscle forcesNewton’s third law- for every action there is an equal and opposite reactionVertical- small force peak in first 20% of stance and gradual larger peak in remainder of stance.Fore-aft- absorption and propulsion
34Rearfoot striker 80% of runners Initial contact- posterolateral foot Center of Pressure (COP)Outer border of rear footprogresses along lateral borderthen across forefoot medially toward 1st and 2nd metatarsal head
35Midfoot strikers Most other runners Initial contact- midlateral border of footCOPLateral midfootprogresses posteriorly (corresponds to heel contact)rapidly moves to the medial forefoot
36Center of PressurePage 17.O'Connor FG, WilderRP: Textbook of Running Medicine, McGraw-Hill Companies, Page 17
37Evaluation of running injuries Training logShoe examinationArch appraisalGait analysisRunning shoe prescription
38Training log Weekly mileage Transition point Increase in distance or intensityIncrease in mileage >10% per weekChange in terrain or running surface
39Shoe examination Current running shoes Age (days and miles) Replacement frequencyNew brand or model? (change biomechanics)
40Shoe examination Outsole wear Midsole wear Lateral heel vs. inside heel vs. lateral soleMidsole wearHeel counter tiltMidsole wrinkling, tilt, or decomposition
41Shoe wearBased on foot strike pattern, initial contact, and center of pressureNeutral gaitWear on lateral aspect of heelUniform wear under the toes
42Shoe wear Overpronator Underpronator Excessive wear on medial portion of heel and forefootUnderpronatorExcessive wear on lateral heelWear on entire lateral portion of the outersole
44Biomechanical function Required functions of locomotionAdaptationShock absorptionTorque conversionStabilityRigidity
45Biomechanical assessment Video gait analysisAlways base on running gait, not arch heightEvaluate shoe wear
46Gait analysisBehind- location of heel strike, foot motion during single stance, foot engaged at push-offSide- gastroc-soleus flexibility, great toe dorsiflexionTreadmill-based analysisForce plate analysis
47Neutral gait Level Heel Throughout Gait Cycle 90 Degree Medial Angle Throughout Gait Cycle25% or runners
48Intrinsic abnormalities Pes cavus- abnormal supinationPes Planus- abnormal pronation
49Supination Normal Abnormal Late stance phase Provides rigidity, support, propulsionFacilitates lower leg external rotationAbnormalMinimal pronation at subtalar jointLittle drop of medial longitudinal arch
50Abnormal supination- signs Lateral Leaning Foot Surface PlacementInflexible FootCallus- 1st and 5th metatarsal headsClawing of 4th and 5th digits5% of runners
51Abnormal supinators Stable and rigid foot Lacks flexibility and adaptabilityPoor gastroc-soleus flexibilityAchilles tendonitisPlantar fasciitisPoor shock absorptionTibial and femoral stress fractures
52Pronation Normal Abnormal Early in stance phase Provides flexibility, adaptability and shock absorptionFacilitates lower leg internal rotationAbnormalContinues throughout stance phase
56Arch Height Will Produce Different Levels of Flexibility Normal feet:are flexible as they grip the ground and become stiff at push offFlat feet:are flexible as they grip the ground and remain flexible at push offHigh arched feetare inflexible and do not adjust to terrain well, but provide a good base for push off.
57Running Shoe DesignIn an attempt to minimize injuries, running shoes need to provide:CushioningMotion ControlSupport
58Anatomy of the Running Shoe UppersMidsoleOutersoleVamp- 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 rotationMidsole
59Anatomy of the Running Shoe Heel notchLacing systemToeboxHeel counterOutersole- 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. viscoelasticTongue
60Anatomy of the Running Shoe Flex GroovesSplit Heel
61Anatomy 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.
62Anatomy of the Running Shoe Lasts (Shoe Template)BoardSlipCombinationIf you cannot remove insole, remove shoe…it is of poor quality
63Shoe Design Motion Control, Stability, Cushion Mod-Severe overpronatorStabilitymajority of the population, slight overpronationCushionedNeutral/underpronator runner
64Stabilizing FeaturesSupport is added to the inside or medial portion of the heel to counteract the foot rolling inward (pronation)
65Running Shoe Selection The three basic types of running gait based on ankle biomechanics are: over-pronation, neutral and underpronationShoes should be bought to accommodate your running gait, not your arch height!
66Shoe prescription High arch- curve-lasted, cushion shoe Flat arch- motion control or stability shoes with firm midsoles and straight to semi-curved lastsNeutral arch- cushion or stability shoe
67Orthotics Effectiveness Gross, et al. 90% with symptom improvement Schere. 81% with complete symptoms reliefBlake 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%.
68Orthotics Motion control Shock absorption Control excessive pronationShock absorptionPressure relief in specific areaPlantar heel or great toe metatarsophalangealRedistribution of forces away from areaMetatarsal pad for metatarsalgia/Morton’s neuroma
69Orthotics Adjunct to rehab and training modification Return athlete to full functionPrevent further injuryFunctional orthosesAlter foot functionGuide foot through stance phasePromote biomechanical efficiency
71High arch orthotic Dropped forefoot Plantarflexed first metatarsal and forefoot valgusDecreased subtalar range of motionPlantarflexed first ray, unstable cuboidPeroneal cuboid syndrome
72Pronated foot orthotic Flat medial archUnstable rearfoot and excessive motion of plantar calcaneal fat padWeak plantarflexion of first metatarsal head and weak “windlass” effect
73Common mistakes Only looking at standing gait Failure to evaluate various needs of different runnersNeed of different orthoses for running and everyday activity
74Summary Understand normal foot biomechanics- pronation vs. supination Evaluate with functional arch and shoe wearSigns of abnormal archMatch shoes and orthotics to running alignment- correct shoes and over-the-counter inserts first