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Hamstring Strains
Season Ending Injury
EpidemiologyA. Second Most common injury in NFL, Knee
sprains number 1b. Running backs 22%, Defensive Backs
14%, Wide Receivers 12%C. 12% of all injuries in pro soccer.D. Memphis State University study: HS
Injuries were third most common sports injuries behind Knee and Ankle.
Most affected in SportsSprinting SportsSoccerRugbyAustralian Rules Football.Gymnastics and dancing
Significant Recovery TimeIncreased recovery time and increased
chance of recurrance.
A. Study of 858 Australian rules footballers: 12.6 % recurrence in the first week. 8.1% in second week. 30.6 % recurrence in the course of a 22 week season.
15 out of 30 sprinters recurrence.
Second injury is more severe and results in more time lost than initial injury.
Anatomy
Anatomy ( cont.)
Innervation
Sciatic Nerve Entrapment
Mechanism of InjuryMaximum HS Lengths Occurred during the
late swing phase of sprinting.A. 7.4 % SM, 8.1% ST, 9.5% BFPeak Length did not increase as speed
increasedPeak HS Force did increase as speed
increasedNegative MT activity increased with speed.
Running Gait
Late Swing Phase
Causes ( continued)Data demonstrates that injury occurs as
peak length and peak force meet ( eccentric forces).
Most Common Injury is to the BF.Weakest component is the MT Junction.
( MTJ ).Most injuries occurrat the proximal MTJ.Avulsion Injuries occur mostly in
gymnastics or dancing.A. Hip flexion combined with knee
extension.
Causes ( continued)Trunk, Hip , Pelvic movementVerrdall et al. Using video analysis Showed:A. High speed running with pelvic twisting
to catch a ballB. Contralateral Hip Flexor contractile
forces had the largest influence on increased stretch.
C. Conclusion : sudden perturbations to the trunk and pelvis caused by the sudden action during high speed running creates peak stretch and negative work simultaneously
Causes from a Chiropractic View pointRunning Mechanics as it relates to:SI Joint NutationPelvic RotationSymetric Movement and transition of
motion at the T/L Junction.Lumbar Segmental Function as it relates to
Iliopsoas Function.Pronation: Internal Tibial Rotation.
Pronation in Running
Factors Affecting Recovery TimeA. American Football: 8.3 days.B. Australian Football: 23-27 daysC. High Speed Sports: 22-37 days.D. Competitive Sprinters: 6-50 weeks.
Kicking Injuries: median time 50 weeksStretch related injuries averaged 31 weeks.Askling Et Al: Involvement of the proximal
tendon of the semimembranosis, adductor magnus, quad femoris
Risk of RecurrenceRates of Recurrence:Depending on population groups:Low of 7%, high of 70% average 30%.Sherry and Best: 6-8 reinjuries occur in the
first two weeks.Greatest predictor is a prior injury: 74% in
australian Footballers.
Re injury Healing Time25 days for second injuries vs. 14 days for
first time injuries.
Australian FB: 26 days vs 35 days: 10 of 31 had second HS injuries.
MRI: First injury showed 95 mm damage longitudinally for first injury vs. 115 mm for second injury.
Risk factorsAge: Higher RiskHip Flexor limitations on Contralateral side.
( iliopsoas)Increased Anterior Pelvic Tilt.Decreased Rectus Femoris
Flexibility( Thomas Test)
Decreased HS flexibility has not been related to higher incidence on HS strains
Sprinters have less HS flexibility as a result of previous HS injury.
Efficacy of HS Stretching in injury prevention
Overall, the body of evidence to support HS stretching as a means of preventing HS injuries is weak and needs further evidence before it is accepted into practice
Strength TrainingA. Muscle Imbalances may be an important
component in identifying athletes at risk.B. Quad to HS ratio .45 unilaterally or .85
bilaterally = 95% confidence interval for injury.
C. Biodex evals may not be practical at the High school Level.
Efficacy of strength Training for PreventionThe HS eccentrically de cellerate knee
extension and hip flexion at the end of the swing phase of the running gait. This has been identified as when HS strain occurs.
Studies show that the HS’s tensile strength can be increased doing eccentric strength training.
Askling et al: Eccentric overloading of female soccer players.
A.30 elite players divided into two groups. 10 months of training. Group 1. did basic HS training including stretching. Group 2 did 4 sets of 8 reps 1-2 times per week with focus on eccentric contractions. Results 3/15 vs 10/15
Strength Training ( continued)Brooks et al: Eccentric training had lowest
injury rate vs traditional strength training.A. .39 vs 1.1 per 1000 hrs.
Gabbe et all: 4% of eccentric group has HS injury vs. 13% of control group.
Best results optained using eccentric bilateral biarticular exercises.
Biarticular eccentric exercisesEccentric box dropEccentric backward stepEccentric loaded lunge dropEccentric forward pullSingle leg dead lift.
Loaded Lunge Drop
Eccentric Box Drop
Eccentric Back drop
Forward Pull
Eccentric Resistance
Eccentric Resistance
Neuromuscular Control TrainingNFL Study showed most injuries occurred in
the first two weeks of training camp.A. ConditioningB. Less movement control: study of 28 NFL
players investigated for low limb movement discrimination. 6 subsequenly experienced HS strains. All 6 showed had movement discrimination deficits below the mean.
Core Training: Pelvic stabilization Training.Form running and running mechanics drills
SummaryPreseason evaluation of muscle imbalances
Focus of eccentric resistance training
Focus on neuromuscular control
Injury Character
HS Strain Avulsion Refered pain
Onset sudden sudden Usually gradual
mechanism Sprinting, kicking, self directed stretching
Passive knee extension with hip flexion. Secondary trauma
Unknown
Pain Minimal to severe
sever even with rest
Tightness, cramping. Min to smoderate
Function Difficult walking
Often unable to walk
Reduce symptoms with activity, worse after.
Brusing Mild baseball size
Severe, usually entire thigh
none
palpation Substancial local tenderness
severe Minimal to none
Decrease in length
substancial substancial minimal
Lumbar and Si exam
Occassionally abnormal
Possible acute nerve injury in addition
abnormal
MRI Abnormal signal T2
Abnormal signal T2
normal
DiagnosisHistory of an eventDifficulty walkingPalpation at the site of injuryNormal vs abnormal HS strengthProvocative tests for Low back, SI, Pyriformis
will be positive for refered pain.Provcoative tests for HS Strength at various
angles, HS length and knee extension positive for HS injury
EcchymosisAvulsion and Hematoma
AvulsionCommon in immature athletes
Palp defect may be felt
Athletes 9-16 Should be imaged a/p Pelvis
Positive if greater than 2 cm dispacement
MRIUsed to determine extent and location,
Chronic vs AcuteIn Acute there will be edema and increased
signal intensity on T2 imagingIn Chronic usually scar tissue will be
evidentStudy of 83 HS injuries only had positive
MRI on 68A. Small tears donot image wellB. Symptoms may be refered C. Positive MRI 5/10 pain score v 2/10 on
negative.D. Time lost 24 days positive 16 days
negative
MRI ( continued)Conclusion: Clinical examination was a
better predictor of time lost for minor injuries. MRI for moderate to severe injuries
Transverse tears greater than 50% of the injured area or 60mm had a predictive value of time lost and recurrence.
TreatmentInitial goal is to reduce pain and inflamationProper treatment will reduce the formation
of scar tissue thus reducing the risk of reinjury
Rehabilitation: Restore motion, strength, agility, and trunk stabilization.
ModalitiesHVGInterferentialVersacoolerNASIDSCompressionIceLight Therapy ( Laser/LED)
Kinesiotaping
RehabilitationBegin as symptoms allowTwo Theories:A. Worrell Et Al : Four phase program of strengthening
and stretching. To remodel and align scar tissue.B. A model focusing on the pelvis as the attachment
site of the HS muscle thus neuromuscular control of the lumbopelvic region including A/P pelvic tilt to create optimal function in sprinting and high speed skill movement.
C, Studies show the PATS to be significantly better. Progressive stretching/strengthening 6/13 had recurrence
PATS 0/13 had recurrence
Progressive Agility and Trunk Stabilization
PATSStudies show that the ability to control the
lumbopelvic region during high speed skilled movement prevents HS injuries.
A. Pelvic muscles influence the peak stretch of the HS and lack of control may contribute to HS strains
Conclusion: Neuromuscular control of the hip and pelvis is crucial in promoting function of the HS.
TreatmentRICEModalities Including Cyriax Cross FiberMotor Point TherapySpinal AdjustmentsEccentric Resistance ExercisesNeuromuscular Pelvic StabilizationPATS ( progressive agility and trunk
stabilization)
Return to Play: Manual Resistance in four positions at four angles.