inadequate impact attenuation€¦ · • 10 degree change in the q‐angle increased peak...

Christopher M. Powers PT, PhD, FACSM, FAPTA

University of Southern California

Proximal Factors Contributing to Running Injuries

Christopher M. Powers PhD, PT, FACSM, FAPTA

Division Biokinesiology & Physical TherapyCo‐Director, Musculoskeletal Biomechanics Research Laboratory



Running is comprised of a series of repetitive single limb impacts

Requirements:

Adequate impact force attenuation Limb/trunk stability


Proximal Factors Contributing to Running Injuries

• Inadequate impact force attenuation (↑ load)– Poor use of hip in the sagittal plane

– Quadriceps dominance

• Poor dynamic hip stability (alters alignment)– Excessive hip adduction & IR

• Poor pelvis and trunk stability (↑ load)


Inadequate Impact Attenuation


Impact Attenuation

Passive Shock AbsorbersB & C tilBone & Cartilage

Active Shock AbsorbersEccentric muscle contraction


Impact Attenuation

Active Passive


University of Southern California University of Southern California


“Stiff” Landing

Increased Knee Extensor Moments

Increased Quadriceps Activation

Decreased Hip Extensor Moments

Increased valgus loading at the knee

Decreased Hip Extensor Moments

Decreased Glut Max EMG

“Knee Strategy”Pollard et al, Clin Biomech, 2010


“Soft” Landing

Decreased Knee Extensor Moments

Decreased Quadriceps Activation

Increased Hip Extensor Moments

Decreased valgus loading at the knee

Increased Glut Max EMG

“Hip Strategy”

Pollard et al, Clin Biomech, 2010


↑ Knee↓ Hip

↑ Frontal ↓ Sagittal

↑ Hip↓ Knee

↑ Sagittal↓ Frontal


Greater Utilization of the Hip Extensors is Associated with Decreased

Knee Valgus Moments & Angles

Pollard et al, Clin Biomech, 2010



Abnormal Distribution of the Abnormal Distribution of the

Sagittal Plane Support Sagittal Plane Support Moment in FemalesMoment in Females

Why?Why?

Hi tHi t k l ti t d ik l ti t d iHip extensor Hip extensor weakness relative to quadricepsweakness relative to quadriceps

Quadriceps overuseQuadriceps overuse

Increased Knee and Patellofemoral loadingIncreased Knee and Patellofemoral loading


Trunk Position Influences Sagittal Plane Biomechanics

Powers, JOSPT, 2010


Characteristics of Quadriceps Dominance

• Knees in front of toes

• Excessive dorsiflexion

• Heels off the ground

• Limited hip flexion


1300 N 1200 N



Clinical Conditions Associated with Quadriceps Dominance

• ACL strain

• Quadriceps tendon overuse

• Patellofemoral joint compression


Poor Dynamic Hip StabilityPoor Dynamic Hip Stability


Medial Collapse


Hip PronationTri‐Planar motion

• Flexion

• Adduction

• Internal rotation


Medial collapse & lower extremity injury

Anterior hip impingement

Lateral hip pain

ITB stress

Patellofemoral stress

ACL loading

Tibialis Posterior stress

ITB stress

MCL strain



Poor Pelvis & Trunk StabilityPoor Pelvis & Trunk Stability



Uncompensated Compensated


Trunk Position Influences Frontal Plane Knee loading

Powers, JOSPT, 2010

Normal Uncompensated Compensated




What is the True “Core”?

Trunk Muscles?

Abd i lAbdominalsObliquesParaspinals


What is the True “Core”?

Hip/Pelvis Muscles

Gl M diGluteus MediusGluteus Maximus


10 most common overuse injuries in runners (n=1579)

Taunton et al., Br. J Sports Med, 2002

1. Patellofemoral pain (21%)2. ITB friction syndrome (11%)3. Plantar facsitis (10%)4. Meniscal injuries (6%)5. Shin splints (6%)6. Patellar tendinitis (6%)7. Achilles tendinitis(6%)8. Gluteus Medius injuries (4%)9. Tibia stress fractures (4%)10. Spine injuries (3%)


Proximal factors that can influence the patellofemoral joint

• Femoral internal rotation

Powers CM. J Orthop Sports Phys Ther, 2003, 2010.

Femoral internal rotation– Contributes to maltracking

• Hip adduction– Contributes to dynamic Q‐angle

• Quadriceps dominance– Contributes to PFJ compression


Femoral Internal Rotation

Contributes to Patellofemoral Joint Maltracking in Weightbearing


Interventional MRI system

Powers et al. JOSPT, 2003



Non‐weightbearing

Powers et al. JOSPT, 2003

Souza & Powers, JOSPT, 2009

Weightbearing


Hip Internal RotationPFP vs. Control

p < 0.001

Drop Jump Running Step Down

Souza & Powers , JOSPT , 2009


Excessive Hip Internal and PFP

•Boling et al., 2009‐Increased Hip Internal was found to be a risk factor for the development of PFP

•Wirtz et al, 2011‐Increased hip internal rotation in females with PFP while running

•Noehren et al., 2011‐Increased hip internal in female runners with PFP


• Lee, et al., Clin Orthop, 1994

Femur Internal Rotation & Lateral Facet Pressure

• Yang et al., Proc Am Soc Biomech, 2011

Neutral 5⁰ IR 10⁰ IR


Hip Adduction

Contributes to Increased Laterally Directed Patellofemoral Joint

Forces


Lower limb alignment & lateral forces on the patella

Q‐angle: 15°

Lateral vector



Dynamic Q‐AnglePowers, JOSPT, 2003


How much of a change in the Q‐angle is relevant?Huberti & Hayes., JBJS, 1984

• 10 degree change in the Q‐angle increased peak pressures by 45%.

• A decrease in the Q‐angle decreased stress on the lateral facet and median ridge


With Hip Strapping


Quad Dominance & PFJ Compression


Tri‐Planar Loading of the PFJ


Proximal factors that can contribute to Iliotibial Band Syndrome

• Excessive hip adduction*

• Excessive femur internal rotation (knee rotation)

• Knee varus moment/position*Predictor of ITBS in a prospective study (Noehren et al., Clin Biomech ,2007)



Hip Adduction & ITB Stress


Femur Rotation & ITB Stress


Knee Rotation & ITB Stress


Contralateral Pelvic Drop can Influence the Varus Moment at the Knee

Powers, JOSPT, 2010

Normal Uncompensated Compensated


Treatment Implications


General Principles

• Improve dynamic hip stability

• Improve pelvis & trunk stability• Improve pelvis & trunk stability

• Improve dynamic shock absorption

• Reversal of quadriceps dominance

–Promote hip strategy



Dynamic Hip Stability:

Control of femoral rotation & adduction


Gluteus Maximus:

“The Tri‐planar Muscle”

• Extensor

• Abductor

• External Rotator



Improve Pelvis and Trunk St bilitStability



Gluteus Medius




Improve Dynamic Shock p yAbsorption


GRF:1600 N

GRF:1000 N



1300 N 1200 N


Force Feedback Training


Use of a Forward Trunk Lean to Decrease Quadriceps DominanceDecrease Quadriceps Dominance

and Improve Hip Strategy


Forward trunk lean reduces use of quadriceps & patellofemoral stress

Self‐selected trunk (SELF) Forward flexed trunk (FLEX)Self selected Flexed

25.0

Low‐Flex High‐Flex

Teng & Powers (unpublished data)

19.0 14.4

0.0

5.0

10.0

15.0

20.0

PFJ stress

MPa



Trunk Lean & Running Downhill


What about Orthotics?


Can Orthotics Change Lower Extremity Kinematics?

• Medial wedging changed frontal & transverse plane knee kinematics 1‐2°transverse plane knee kinematics 1 2– Nester et al., Gait & Posture, 2003

– Eng & Pierrynowski, Phys Ther, 1994

• Over‐the‐counter orthotic caused a 2°decrease in hip internal rotation– Jenkins et al., J Appl Biomech, 2009


Take Home Messages

• Hip function should be considered when evaluating any lower extremity condition

• Evaluation must be performed during the activity that causes symptoms!!!

• Dominant patterns may exist, but you need to treat each patient as an individual


Questions??

MBRL 2011

inadequate impact attenuation€¦ · • 10 degree change in the q‐angle increased peak...

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