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HAMSTRING INJURY. The accuracy of MRI in predicting recovery and recurrence of hamstring muscle strains. Dr N Gibbs Dr T Cross Mr M Cameron Dr M Houang J Sci Med Sport. 2004 Jun . Introduction Literature review Methods Results and Discussion Conclusions Questions??.
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The accuracy of MRI in predicting recovery and recurrence of hamstring muscle strains • Dr N Gibbs • Dr T Cross • Mr M Cameron • Dr M Houang J Sci Med Sport. 2004 Jun
Introduction • Literature review • Methods • Results and Discussion • Conclusions • Questions??
Clinical Scenarioe.g.. Posterior thigh pain 7 days before World Cup FinalCan he play??
Objective • To describe the MRI findings of a series of acute hamstring muscle strains (i.e. “posterior thigh pain”) • Do these MRI findings help • Predict the PROGNOSIS • Predict The RECURRENCE RATE
Setting • Sydney Swans Football Club • 1 of 16 clubs in the National competition
Design Prospective study over 5 years (1999-2003): Both in-season and pre-season periods
Patients 40professional footballers Consent from Club and individual players
Australian Rules Football “Athletes at risk” • Repetitive sprinting efforts • Repetitive kicking • Repetitive jumping & landing • Game time approximately 100 minutes
Australian Rules Football Ideal sport ( “outdoor laboratory”) to study muscle strain injury
Australian Rules Football Hamstring strain is the most significant injury in ARF (Quadriceps strain in top 10)
Motivation for research • To better understand/diagnose Hamstring muscle strains • To better manage/rehabilitate Hamstring muscle strains
Motivation for research • To make an EARLY ACCURATE PROGNOSIS (i.e. we were unable to clinically differentiate benign from serious Hamstring strains)
Motivation for research • To better understand which “hamstring” injuries recur
Anatomy Hamstrings, an “at-risk muscle” • Acts eccentrically • Crosses two joints • High % fast twitch fibres
Function Main Function during sprinting And kicking is to deceleration of knee extension and hip flexion
AFL injury database • Cause 20% of all missed AFL games • Recurrence rate 34%
Literature review Pomeranz (1993) • Retrospective study of Hamstring strains • n=14 • Prognosis associated with size (cross-sectional area%) of muscle strain injury on MRI scan
Methods Inclusion criteria • History acute onset of posterior thigh pain/ache or tightness while training or playing • Examination : tenderness over the posterior thigh : other signs elicited but not the subject of this study
Methods Exclusion criteria • History of trauma to posterior thigh (Contusion) • Delayed onset of posterior thigh pain (DOMS) • Recurrence of posterior thigh pain in ipsilateral thigh in same season
Methods MRI within 24-72 hours • T1,T2 with fat suppression, STIR • Axial, coronal planes (both thighs imaged) (Axial T2with fat suppressionmost useful images)
Methods Muscle strain injury= high signal on T2 weighted images
Methods MRI diagnosis Location (MRI category) • Which Hamstring muscle (s) injured • Location of injury with respect to known musculotendinous junctions
Methods MRI diagnosis Size • Cross sectional area % (CSA) • Length (cm)
Methods • CSA% estimation (“dot” method)
Methods MRI diagnosis: miscellaneous features… • T2 hyper intensity • muscle fibre disruption • Perifascial fluid • Scarring/fibrosis
Methods What if more than one muscle injured? (i.e. double injury etc.) • Primary muscle injured= greatest CSA% • Secondary muscle injury= smaller CSA%
Methods (rehabilitation phase) • No universally accepted rehabilitation regimen exists for muscle strain injuries
Methods (rehabilitation phase) Rehabilitation was standardised Phase 1 : Acute management • RICE/crutches first 48 hours • Intensive Physiotherapy • soft tissue therapy • flexibility • strengthening
Methods (rehabilitation phase) Phase 2: Remodeling phase • Eligible to start running program when, • Full pain free ROM • Complete 3 x 10 repetitions of single leg hops pain free • 4 Stage running/kicking program (sport specific to ARF) was designed at beginning of study
Methods (rehabilitation phase) 4 stage running/kicking program • Run alternate days • Physiotherapist/Sports Scientist supervision • Combined with intensive physiotherapy • 5 minute jog warm up/cool down • Stage 1 : jog 10 mins x 2 • Stage 2 : 80m intervals ( 40-60 %) 3x 5 repetitions • Stage 3: 80m intervals (90-100%) 3 x 5 repetitions (staged kicking program commenced) • Stage 4: 80m intervals (sport specific drills at 90-100%) 3 x 5 repetitions • Integrate into team training
Methods (rehabilitation phase) 4 stage running/kicking programs • Some advanced rapidly • Others delayed by symptoms of high grade posterior thigh pain, weakness and dysfunction Decision to return to Full Training : Collaborative
Rehabilitation interval (RI) RI= time from the injury to the return to full training (measured in days)
Results of acute MRI images • 31 acute clinical HAMSTRING strains were imaged • Authors were not blinded to these MRI’s
Recurrent hamstring injury • Of the 17 MRI positive cases (“hamstring muscle strains”) • N= 6 recurred within same season!! • 35% recurrence rate • Size of muscle strain injury (length &/or CSA%) did NOT predict risk of recurrence
Recurrent hamstring injury • Of the 14 MRI negative cases • None recurred within same season!! • 0 % recurrence rate
Statistical analysis Statistician analyzed data • t-tests independent samples (dependent vs. independent variables) • Two-way analysis of variance
Results: Statistical analysis (days) RI MRI Positive MRI Negative
MRI Positive • n=17 • Mean RI=20.2 days • significantly longer RI (p=0.001)
Results: Statistical analysis (days) RI
MRI & Prognosis • Length of intra-muscular signal correlates best with RI r=0.84, p<0.001 • CSA% & RI r=0.78 • Size really does matter
MRI negative cases • n=14 • Mean RI= 6.6 days (benign injury)
MRI negative cases Hypotheses • MRI done too early • Strain injury too small to resolve • Other causes of “Posterior thigh pain”
Other causes of posterior thigh pain • Somatic Referred pain • Lumbosacral spine • Pelvis