home | uw health | madison, wi - jenny kempf, mpt · 2010-07-01 · video analysis of frontal and...
TRANSCRIPT
Jenny Kempf, MPT
Review epidemiology of knee pain
Discuss etiology and the biomechanics of knee pain utilizing current literature/evidence
Review commonly seen knee injuries
Discuss treatment strategies
Approximately 85% of all recreational cyclist sustain an injury60% of cycling injuries occur in the knee
Anterior knee painPatellar tendonitis
Overuse injuries most common, traumatic event second
Improper trainingImproper bike fit
Cycling is a repetitive activity1 hour = 5400 pedal revolutionsCan result in microtrauma or overuse injuriesKnee most common location or overuse injury
Training errorBike fitPedaling mechanics/TechniqueMuscular imbalances
NOVICE ELITE
Greater variability b/npedal strokesGreater variability b/nridersGreater amplitude of muscle activityGreater amplitude and duration of muscle activity↓ coordination of sagittal plane motion
Consistent patterned movements at hip and kneeGreater ankle ROM throughout pedal cycleLess motion in frontal and transverse plane at knee
Chapman et al. J Sci Med Sport 2009
Too muchToo soonSo wrong
Why is knee pain so prevalent in cyclists?
Low level repetitive loading Bike fit
Bike anatomyRider anatomy
Driving moments – muscle forces
Non driving moments – varus/valgus, internal/external axial
CommercializedStandardizedDynamic?Individualized?
Patellofemoral painCompression forceShear force
Patellar tendon pain
Iliotibial band syndrome
24 cyclist (14 no injury hx/10 injury hx)Video analysis of frontal and sagittal planesMeasured shank (tibia compared to ankle) angleComparison of groups
Bailey et al. J Sports Sci. 2003
NO INJURY GROUP INJURY GROUP
Mean shank angle neutralSpeed of frontal plane mvmt same Greatest shank abduction - 83º
Mean shank angle in abductionGreatest shank abduction - 88ºIncreased DF angle throughout pedal cycle
Bailey et al. J Sports Sci. 2003
24 cyclist (14 no injury/10 injury)Video analysis of frontal and sagittal planesMeasured knee flexion anglesComparison of groups
Found no differences in knee flexion anglesDoes not support low saddle height increases risk of knee injury!
Bailey et al. J Sports Sci. 2003
8 cadaver legsTested at 60º and 90º knee flexion3 loads placed
Internal moment (femur)Varus moment (tibia)Combined
Measured patellofemoral jointContact areaContact pressure
Wolchok, Howell. J Biomech
1998
ResultsInternal knee moments and combined moments significantly increased mean contact area and force to patellaContact area appeared more sensitive to the internal than varus momentNo effect on mean contact pressure
Wolchok, Howell. J Biomech
1998
11 healthy subjects3 different riding positions
NaturalDorsiflexedPlantarflexed
Measured muscle activity and efficiency
Cannon et al. Eur J Appl Physiol. 2007
Found DF riding position increased gastroc activity and increased energy expenditurePF riding position increased biceps femoris activity
DF riding position places eccentric load to gastroc which may absorb energy produced at kneeEliminating DF during power phase may reduce muscle fatigue and maximize load placed through the pedal
Cannon et al. Eur J Appl Physiol. 2007
15 subjects with varying foot angle positions on pedal
10º inverted5º invertedNeutral10º everted5º everted
Measured varus/valgus and internal/external knee moments
Gregersen
et al. J Biomech
Eng. 2006
ResultsPeak varus and average varus/valgus knee moments are related to foot angleFoot eversion decreased both varus moment during power stroke
Gregersen
et al. J Biomech
Eng. 2006
Based on research - Control the frontal planeReduce medial knee positioning (shank abduction)
FitRiding TechniqueStrength
Pedal widthFoot position
FloatCant
Seat height
Optimal cadence = 88-95+ rpmSpinners – low gear, high cadence
Gear Mashers – high gear, low cadence… increased risk of knee injury in this group
Use entire pedal cycle
Toe down
Clock Analogy1-10 – rolling barrel with bottom of foot. Push pedal forward over top of apex10-7 – push down, easiest and most natural position7- 5 – scraping mud off bottom of shoe5-1 – “de-weight” the pedal
Cadence WorkEasiest way to smooth out pedal inefficiencies is to increase cadence = neuromuscular re -educationKeep toe down, NO bouncing in the saddle“Spin ups”
Lower resistance pedal until you just start to bounce in saddle. Back off rpm slightly or control buttocks
ProgressionsChange in rpm without change in resistance
Isolated Leg Drills
Resistance is key – should be easy to keep high cadence, hard so pelvis isn’t bouncing
Right leg over barrelLeft leg over barrelRight leg scrap mudLeft leg scrap mud