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.