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

1. Introduction

2. Literature review

3. Methods

4. Results and Discussion

5. Conclusions

6. Questions??

Clinical Scenario

e.g.. Posterior thigh pain 7 days before World Cup Final

Can he play??

1. Introduction

Objective

1. To describe the MRI findings of a series of acute hamstring muscle strains (i.e. “posterior thigh pain”)

2. Do these MRI findings help

1. Predict the PROGNOSIS

2. 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

40 professional 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

2. Literature Review

Anatomy

Hamstrings, an “at-risk muscle”

Acts eccentrically

Crosses two joints

High % fast twitch fibres

Function

Main Function during sprintingAnd 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

3. Methods

Methods

Inclusion criteria

1. History

acute onset of posterior thigh pain/ache or tightness while training or playing

2. Examination : tenderness over the posterior thigh: other signs elicited but not the subject of this study

Methods

Exclusion criteria

1. History of trauma to posterior thigh (Contusion)

2. Delayed onset of posterior thigh pain (DOMS)

3. 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 T2 with fat suppression most useful images)

Methods

Muscle strain injury= high signal on T2 weighted images

Methods

MRI diagnosis

Location (MRI category)

1. Which Hamstring muscle (s) injured

2. Location of injury with respect to known musculotendinous junctions

Methods

MRI diagnosis

Size

1. Cross sectional area % (CSA)

2. Length (cm)

Methods

CSA% estimation (“dot” method)

Estimation of Length

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.)

1. Primary muscle injured= greatest CSA%

2. 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)

2. Results and Discussion

Results of acute MRI images

31 acute clinical HAMSTRING strains were imaged

Authors were not blinded to these MRI’s

Clinical Hamstring strains“Posterior thigh pain”

N=31

MRI positiveN=1755%

MRI negativeN=1445%

Single muscleN=12

Double musclen=5

All involving BF as primary injury

Biceps femorisN=8

ST and SMN=2 each

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

02468

101214161820

MRI Diagnosis

MRIpositive(mean=20,range 12-33 days )MRI negative (mean6.6, range 2-12)

RI

(days)

MRIPositive

MRINegative

MRI Positive

n=17

Mean RI=20.2 days

significantly longer RI (p=0.001)

Results: Statistical analysis

0

5

10

15

20

25

30

MRI Diagnosis

Length > 12cmLength 7-12 cmLength < 7cm

RI

(days)

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

0

5

10

15

20

25

0 10 20 30 40

Rehab Interval (days)

leng

th (c

m)

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

Other causes of posterior thigh pain

Neuromeningeal tethering

Nerve root ( “radiculopathy”)

Piriformis syndrome Hamstring syndrome Within HS muscles

Other causes of posterior thigh pain

Intrinsic Muscle causes

Tender points Trigger points Adhesions/fibrosis/

scarring Tendinopathy/bursitis

Other causes of posterior thigh pain

“Not to be missed”

Avulsion Fractures Complete rupture proximal

HS Stress Fractures Compartment syndromes Tumours (benign and

malignant) Infections (bone/soft

tissue) Rheumatologic

CONCLUSIONS

Conclusions

MRI defines muscle strain injury objectively:

“probe beneath the surface of the skin”

Conclusions

Posterior Thigh Pain

MRI Positive“Hamstring strain injury

MRI NegativeNumerous other DDx’s

Somatic referredNeuromeningeal

Etc.

Conclusions

All 17 MRI positive cases of muscle strain injury occurred about known muscle-tendon junctions

(This concurs with basic science studies)

Conclusions

The Biceps femoris was the most commonly injured muscle (8 single, 5 “double” injuries)

Conclusions

Tenderness over the posterior thigh does not always = muscle strain injury

Concept of “MRI NEGATIVE” diagnosis

Conclusions

02468

101214161820

MRI Diagnosis

MRIpositive(mean=20,range 12-33 days )MRI negative (mean6.6, range 2-12)

RI

(days)

MRIPositive

MRINegative

Conclusions

Size ( LENGTH and CSA%) of muscle strain injury is also predictive of RI

0

5

10

15

20

25

30

MRI Diagnosis

Length > 12cmLength 7-12 cmLength < 7cm

Conclusions

Indications for MRI

Acute MRI for elite athletes

Soccer World Cup 2002

e.g. Posterior thigh pain 7 days before Final

Can he play??

YES : if MRI negative

NO: if MRI positive

Conclusions

If no MRI available? Suspect MRI positive if troubled by high grade posterior thigh pain in rehabilitation

Indications for MRI

Thank-you

Questions?

MRI findings determine type & pace of rehab

Positive vs Negative Entirely different

management Length

Predict return to play Set stages of rehab

Other markers Tendon involvement Fluid around sciatic

n.

REHABILITATION Promote healing

Regeneration > Scarring Restore flexibility of injured region

Prevent shortening Common finding in retrospective studies

Restore strength of hamstring group Retraining of hip extension & knee flexion Prevent shortening of angle of peak torque Brockett et al 2002

More prone to damage with eccentric ex Due to injury or rehab or inherent

Running Re-Training Correct contributing factors if possible

RUNNING RETRAINING

Formalised by G. Reid – Hockey background Allows return to competitive sport prior to complete healing of

injury site Involves:

Running early – when stair walking pain-free Running is progressed in stages of speed increments Jog then Fartlek Running 90m intervals EZ

5 stages till sprinting Controlled sport specific drills prior to returning to training

Possible mechanism

Retraining of muscles responsible for the hip extensor & knee flexor torque during running

BF-S & L, ST, SM, Glut, AM, Gastroc Change in relative contribution of each muscle Any change in recruitment yet to be determined Sufficient slack in the system

Inhibit the injured muscle Facilitate remaining muscles

Observations1. Large single hamstring strains exhibit obvious inhibition

Lower resting tone on palpation Poor recruitment during isometric contraction

2. Double hamstring muscle strains 14 BF & ST injuries – 9 recurred within rehab or within

12/12 64% recurrence rate – double the norm May reflect an inability of the system to adequately

compensate for the injured muscle

Role of dual channel biofeedback Early or later stages of rehab

Similar effect as suggested by Sherry & Best

Sherry & Best 2004 JOSPT

RCT of 2 programmes 24 grade 1-2 hamstring injuries Stretch & Strength (11)

Stat bike, static & C-R stretches, isometric to conc to ecc strength X’s with cuff wts, T/B & BW

Progressive Agility & Trunk Stabilisation (13) Sidestepping, grapevines, fwd & bwd steps while

sidestepping, balance exercises, jogging on spot, trunk stabilisation X’s

Progressive intensity

Both programmes involved sport practice when pain- free

Sherry & Best 2004 JOSPT

STST - mean RTS 37.4 days (10-95, sd 27.6)

PATS - mean RTS 22.2 days (10-35, sd 8.3)

p=0.2455

Recurrence rates STST 54.5% at 2 wks, 70% at 1yr PATS 0% at 2 wks, 7.7% at 1 yr p=0.003

Allows regeneration > scar Better prevention of atrophy Better trunk stability, co-ordination or motor control

Contributing Factors

Strength L/R balance, H/Q balanceBurkett 1970, Yamamoto 1993, Orchard et

al 1997, Cameron et al 2003 Inadequate strength for function required

Eg. Running & bending or jumping Determine mechanism

Specific Flexibility Bennell et al 2003 Ankle Dorsiflexion < 10cm p=0.036 Hip Flexors – MTT > 0degs p=0.051

Contributing Factors Other injuries and Gluteal Function

Previous calf injury Orchard 2001 Previous knee injury or osteitis pubis Verrall et al 2001

Altered biomechanical factors - inherent or due to injury Ankle sprain ↓ glut function Bullock-Saxton et al 1994

Poor lower limb motor control Cameron et al 2003

Summary – Hammy Rehab

Diagnosis Muscle strain or posterior thigh pain (PTP)

MRI & clinical testing Extent of strain injury - MRI

Re-training Programme

Pre-disposing factors