Evidence-Based Assessment of Hamstring Injuries in Sport

This is part 2 in this month’s clinical theme: Hamstring Injuries in Sport.

Following on from our review of the different mechanisms of hamstring injuries, this article will look at the some of the evidence-based clinical assessments we can do on field and in the clinic.

Subjective Examination

This is the biggest strength of a physiotherapist, in my opinion.

Taking the time to listen to the athlete/patient, and giving them the space to describe their current pain (and past history) is something that we are lucky to have time to do.

Some important pieces of information (but not everything) you should look for:

• A description of the incident (mechanism), in as much detail as possible
• Location of area/s of pain
• Indication of self-reported functional limitation (what are they struggling to do?)
• Thorough description of previous history (in particular hamstring injuries, ACL injuries)
• What do they think they have done, and how long do they think this will take to return to sport?

This is a really good opportunity to get to know the athlete better, if you don’t already.

A good chat can help us understand their goals and ambitions, as well as a glimpse of their own cognitive processes around their current and past injuries.

Objective Examination

The three main areas that will give some good specific information are:

1. palpation
2. range of motion, and
3. pain provocation testing

Palpation

This is the one area of the objective examination that you can really take some time doing.

A few key things to be confident with:

• exact location of the worst area/s of pain
• measure the distance of this pain from the ischial tuberosity
• muscle tone, compared to other areas of the same muscle and surrounding tissues
• potential involvement of tendon (remember the long central tendon) or musculotendinous junction

As mentioned in the previous article, the closer the injury is to the ischial tuberosity, the more likely it is to involve the proximal hamstring tendon¹,². Again, this is associated with a statistically longer recovery period¹,².

A good thing to get in the habit of doing is documenting all of these palpation findings, to compare down the track as the athlete is progressing.

Range of Motion

The 2009 survey of AFL medical staff looking into the management of hamstring injuries revealed heaps of different clinical tests amongst all the clubs⁴.

In terms of muscle length and range of motion, the four following tests are most commonly used¹,³,⁴:

• Active knee extension (in supine, hip at 90 degrees flexion)
• Straight leg raise (+/- cervical flexion – for neural tissue sensitivity)
• Passive knee extension
• Slump test

With any of these tests, it helps to note whether their range is limited by pain only, or if it is a real measure of tissue extensibility¹.

Measuring both limbs for comparison is key¹.

Pain Provocation Testing

Referring back to the 2009 AFL survey, each club tends to use a different combination of pain provocation and muscle strength tests⁴.

Here’s a few to help gather more information:

• Hamstring bridge
• Take-off-shoe test
• Manual muscle testing (isometric contraction at 0, 15, 90 degrees knee flexion)

Hamstring bridge

This can be performed with different positions of hip rotation, to bias medial vs. lateral hamstrings.

We are looking first to see if they can do it, and then whether it provokes their specific pain. This video below is an example, but you could probably do it with less knee flexion to bias the hamstrings more.

Video courtesy of MalvernPhysio

This can also be a useful as a screening test for an uninjured athlete, as a measure of hamstring muscle strength.

If done in the pre-season, this can be used as a benchmark to compare uninjured measures with newly injured states.

Take off shoe test

This test has been shown to have 100% sensitivity and specificity, as well as 100% positive and negative predictive value for biceps femoris injury, as confirmed on ultrasound⁵.

Pretty good stats if you ask me.

It simply involves positioning the heel of the injured leg inside the arch of the unaffected leg, and pretend to take off your shoe. The opposite leg is resisting this hamstring contraction.

A positive test is to reproduce the patient’s exact pain.

Manual muscle testing – isometric contractions

As with all muscle tests, it is looking to measure their ability to contract and resist your movement.

A positive test needs also to reproduce their specific pain.

It’s good to get a comparison of 0, 15, and 90 degrees of knee flexion.

Video courtesy of sportsinjuryclinic.net

Other anatomical considerations

During this initial examination, it’s important to differentiate the athlete’s posterior thigh pain from other possible sources.

We won’t go into detail with these possible factors, but it’s a good idea to be going through a screening process to see if any of the following are the actual source of posterior thigh pain:

• Lumbar spine
• Pelvic girdle, including sacroiliac joint
• Gluteal muscle length and tone

In all of these cases, specific testing of these structures would reproduce the athlete’s posterior thigh pain, if they are the underlying cause.

The above mentioned hamstring tests would also likely be clear in these cases.

The role of imaging?

The literature is pretty mixed when it comes to the role of imaging (MRI and ultrasound) in assessing hamstring injuries.

Different authors have looked into improving the specificity of diagnosis, by visualising the depth and cross-sectional area of muscle strains.

Attempts have also been made to decipher whether imaging can be predictive of time to return to play.

The previously mentioned study in the Netherlands by Moen et al (2014) didn’t find any statistically significant predictive value from MRI findings⁶, however other studies have taken a different stance.

In the context of an elite sporting club, resources (especially money) are not so much of an issue.

When it comes to athletes on massive contracts, the cost of an MRI is negligible, and so it’s likely that MRI’s will be more commonly used to as part of a broader clinical assessment.

For the everyday clinic, though, it probably doesn’t make much sense to organise an expensive scan, if it’s not going to add a great deal to your clinical reasoning and subsequent management.

The scenarios where imaging could possibly be more helpful to compliment your clinical assessment, would be:

• suspicion of tendon rupture or avulsion (proximal), and possible tendon retraction
• bony avulsion

The results of imaging in these cases may help guide whether surgery is needed.

Other aspects of a physical examination

There are many other aspects to consider, and they will depend on the sports-specific requirements of the athlete.

In my opinion, although not supported a great deal in the literature, would be to screen any relevant functional movement.

This is only if pain allows, and probably better suited in the sub-acute phase, or in the screening of an uninjured athlete.

The purpose of a functional movement analysis is to assess for any motor control deficits.

These deficits can also be addressed in the retraining of efficient and effective functional movement.

Summary

• Subjective examination is underrated. Take your time to have a chat.
• Important information from an objective assessment should include:
  • Palpation
  • Range of motion
  • Pain provocation testing
• Imaging is only really useful if you are suspicious of significant injury (tendon rupture, avulsion, and bony injury).
• Be mindful of other anatomical considerations, as well as an overview of the athlete’s functional movement status.

Extra resources

• Podcast: Physio Edge interview with Dr. Keiran O’Sullivan
• Open access article: ‘Hamstring Strain Injuries: Recommendations for Diagnosis, Rehabilitation and Injury Prevention’, by Heiderscheit et al (2010)
• Open access article: ‘Hamstring injuries: prevention and treatment— an update’, by Peter Brukner.

Feel free to share your experience, and especially share this with any recent grads that might find this helpful.

The next article in this month’s theme will look at potential exercise rehabilitation for hamstring injuries in sport.

References

1. Heiderscheit B et al 2010, ‘Hamstring Strain Injuries: Recommendations for Diagnosis, Rehabilitation and Injury Prevention’, Journal of Orthopaedic Sports Physical Therapy, vo. 40, no. 2, pp. 67–81.
2. Askling C et al 2007, ‘Acute first-time hamstring strains during high-speed running: a longitudinal study including clinical and magnetic resonance imaging findings’, American Journal of Sports Medicine, vol. 35, pp. 197–206.
3. Schneider-Kolsky M et al 2006, ‘A comparison between clinical assessment and magnetic resonance imaging of acute hamstring injuries’, American Journal of Sports Medicine, vol. 34, pp. 1008–1015.
4. Hamstring article review of AFL management
5. Zeren B et al 2006, ‘A new self-diagnostic test for biceps femoris muscle strains’, Clinical Journal of Sports Medicine, vol. 16, no. 2, pp. 166-169.
6. Moen et al 2014, ‘Predicting return to play after hamstring injuries’, British Journal of Sports Medicine, vol. 48, no. 18, pp. 1358-1363.

Special thanks to Greg Mullings (Sports Physiotherapist, Fremantle Football Club), for his hamstring rehabilitation presentation in Perth, November 2014.

Creative Commons image courtesy of Steven Pisano.