Hamstring Strains

Season Ending Injury

Epidemiology A. Second Most common injury in NFL, Knee sprains number 1 b. 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 Sports Sprinting Sports Soccer Rugby Australian Rules Football. Gymnastics and dancing

Significant Recovery Time Increased 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 % 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 Injury Maximum HS Lengths Occurred during the late swing phase of sprinting. A. 7.4 % SM, 8.1% ST, 9.5% BF Peak Length did not increase as speed increased Peak HS Force did increase as speed increased Negative 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 movement Verrdall et al. Using video analysis Showed: A. High speed running with pelvic twisting to catch a ball B. 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 point Running Mechanics as it relates to: SI Joint Nutation Pelvic Rotation Symetric 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 Time A. American Football: 8.3 days. B. Australian Football: days C. High Speed Sports: days. D. Competitive Sprinters: 6-50 weeks. Kicking Injuries: median time 50 weeks Stretch related injuries averaged 31 weeks. Askling Et Al: Involvement of the proximal tendon of the semimembranosis, adductor magnus, quad femoris

Risk of Recurrence Rates 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 Time 25 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 factors Age: Higher Risk Hip 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 Training A. 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 Prevention The 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 exercises Eccentric box drop Eccentric backward step Eccentric loaded lunge drop Eccentric forward pull Single leg dead lift.

Loaded Lunge Drop

Eccentric Box Drop

Eccentric Back drop

Forward Pull

Eccentric Resistance

Neuromuscular Control Training NFL Study showed most injuries occurred in the first two weeks of training camp. A. Conditioning B. 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

Summary Preseason evaluation of muscle imbalances Focus of eccentric resistance training Focus on neuromuscular control

Injury CharacterHS StrainAvulsionRefered pain Onsetsudden Usually gradual mechanismSprinting, kicking, self directed stretching Passive knee extension with hip flexion. Secondary trauma Unknown PainMinimal to severe sever even with restTightness, cramping. Min to smoderate FunctionDifficult walkingOften unable to walkReduce symptoms with activity, worse after. BrusingMild baseball sizeSevere, usually entire thigh none palpationSubstancial local tenderness severeMinimal to none Decrease in lengthsubstancial minimal Lumbar and Si examOccassionally abnormal Possible acute nerve injury in addition abnormal MRIAbnormal signal T2 normal

Diagnosis History of an event Difficulty walking Palpation at the site of injury Normal vs abnormal HS strength Provocative 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 Ecchymosis Avulsion and Hematoma

Avulsion Common in immature athletes Palp defect may be felt Athletes 9-16 Should be imaged a/p Pelvis Positive if greater than 2 cm dispacement

MRI Used to determine extent and location, Chronic vs Acute In Acute there will be edema and increased signal intensity on T2 imaging In Chronic usually scar tissue will be evident Study of 83 HS injuries only had positive MRI on 68 A. Small tears donot image well B. 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.

Treatment Initial goal is to reduce pain and inflamation Proper treatment will reduce the formation of scar tissue thus reducing the risk of reinjury Rehabilitation: Restore motion, strength, agility, and trunk stabilization.

Modalities HVG Interferential Versacooler NASIDS Compression Ice Light Therapy ( Laser/LED)

Kinesiotaping

Rehabilitation Begin as symptoms allow Two 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

PATS Studies 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.

Treatment RICE Modalities Including Cyriax Cross Fiber Motor Point Therapy Spinal Adjustments Eccentric Resistance Exercises Neuromuscular Pelvic Stabilization PATS ( progressive agility and trunk stabilization) Return to Play: Manual Resistance in four positions at four angles.