Sports Medicine Research: In the Lab & In the Field: Clinical Findings Triumph Baseline MRI Findings in Predicting Hamstring Re-injury Just After Return to Play (Sports Med Res)
Thursday, November 6, 2014

Clinical Findings Triumph Baseline MRI Findings in Predicting Hamstring Re-injury Just After Return to Play

Clinical findings just after return to play predict hamstring re-injury, but baseline MRI findings do not

De Vos RJ, Reurink G, Goudswaard GJ, Moen MH, Weir A, Tol JL. Br J Sports Med. ePub 18 July 2014. doi:10.1136/bjsports-2014-093737.

Take Home Message: Key predictors of hamstring re-injury are higher number of previous hamstring injuries, more degrees of active knee extension deficit, isometric knee flexion force deficit at 15°, and the presence of localized discomfort on posterior thigh palpation just after return to play (RTP).

There are no specific guidelines regarding return to play (RTP) after a hamstring injury. Despite using imaging techniques and agility and stabilization exercises for treatment, re-injury rates remain a problem and increase the rehabilitation period. De Vos and colleagues investigated the association between clinical and imaging findings at baseline and clinical tests performed after RTP to identify factors associated with re-injury following initial hamstring injury. Eighty participants (age 18-50 years) were diagnosed with a hamstring injury by one of six sports medicine physicians using both clinical evaluation and magnetic resonance imaging (MRI) performed within 5 days of initial injury. As part of the procedures, all participants completed a rehabilitation program consisting of progressive agility and trunk stabilization exercises. The clinical tests performed during initial diagnosis were also performed just after RTP. These tests included hamstring flexibility, strength testing, and muscle palpation. Participants reported possible hamstring re-injuries to the study team and the lead investigator conducted a phone interview to confirm the presence of a hamstring re-injury. The study team also asked the participants about any possible re-injuries at a 6-month and 12-month follow-up visit. Sixty-four of the eighty participants were included in the final analysis; 17 (27%) reported a hamstring re-injury that occurred at a median 100 days after RTP. Four specific factors were associated with re-injury, including 1) the number of previous hamstring injuries (33% increased risk per number of previous hamstring injury), 2) degrees of active knee extension deficit (13% increased risk per degree), 3) isometric knee flexion force deficit at 15° (4% increased risk per measure of force in Newtons), and 4) the presence of localized discomfort on posterior thigh palpation just after RTP. The MRI findings showed 89% of clinically recovered hamstring injuries had increased intramuscular signal intensity, but the re-injury rate was too small to discriminate the findings as a predictor for re-injury. In conclusion, the weak association of MRI results after RTP emphasizes that clinical and functional tests are better predictors of hamstring re-injury than an MRI just after RTP.

Clinical findings combined with a history of previous hamstring injuries were significant predictors of re-injury of the hamstring within one year after the athlete returned to play. Hamstring strains take time to heal so the rehabilitation process must be carefully observed. Functional testing may be the best way to determine if the hamstring is healed and if there is a chance of reoccurrence. Functional testing may be the better and safer route to predict re-injury of a hamstring strain over MRIs. Key predictors of hamstring re-injury were decreased isometric knee flexion, decreased knee extension, and tenderness with palpation of the hamstring muscles after return to play. The baseline MRIs of the hamstring injury showed no significance in predicting re-injury of the hamstring once the participant returned to play. If the re-injury predictors in this study are implemented to clinical practice, athletes that demonstrate the positive functional or clinical findings once they RTP may be more likely to suffer subsequent injury. The findings of this study can also help to identify rehabilitation and injury prevention strategies for hamstring re-injury, by addressing the deficits reported in this study. Hence, we need to keep sure we monitor the 3 key risk factors that we can modify (active knee extension deficit, isometric knee flexion force deficit, and localized tenderness), incorporate reducing these into our treatment goals, and reassess them prior to RTP.

Questions for Discussion: What are examples of different rehabilitation programs that might focus more on the recovery of the clinical findings that are associated with re-injury? What kind of training programs can be utilized by high-risk athletes to prevent hamstring re-injury?

Written by: Samantha Sisson, Grace Brooks
Reviewed by: Kim Pritchard

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De Vos, R., Reurink, G., Goudswaard, G., Moen, M., Weir, A., & Tol, J. (2014). Clinical findings just after return to play predict hamstring re-injury, but baseline MRI findings do not British Journal of Sports Medicine, 48 (18), 1377-1384 DOI: 10.1136/bjsports-2014-093737

6 comments:

Rose Schmieg said...

Regarding "functional testing may be the better and safer route", what are we proposing as the best functional test(s)? The article I reference below looked at single leg hamstring bridge (SLHB). Thoughts?Br J Sports Med doi:10.1136/bjsports-2013-092356
Original article
The predictive validity of a single leg bridge test for hamstring injuries in Australian Rules Football Players
Grant Freckleton1, Jill Cook2, Tania Pizzari1

Rose Schmieg said...

Regarding the statement: "functional testing may be the best and safer route to predict re-injury". what shall wee propose as the best functional test(s)? The authors below looked at single leg hamstring bridge (SLHB). Thoughts?The predictive validity of a single leg bridge test for hamstring injuries in Australian Rules Football Players
Grant Freckleton, Jill Cook and Tania Pizzari
Br J Sports Med 2014 48: 713-717 originally published online August 5, 2013

Jeffrey Driban said...

Hi Rose:
Thanks for the comment. I agree the single leg hamstring bridge has potential as a screening tool. For reinjury I think we also need to assess lingering point tenderness strength deficits, and limited knee extension. I suspect a lot of the emphasis will eventually be placed on hamstring strength and activation. We'll need to see more studies to really highlight the best predictors in various populations and age groups. Then the question is what do we do about this. I wonder if our injury prevention programs are sufficient or if they could be easily modified to help reduce the risk of hamstring injuries.

Samantha Sisson said...

This article suggested a very good rerun to play functional test that has a high potential of determining if the player is healed enough for play. Single leg hamstring bridge assesses the hamstring strength while the hip and knee are in a functional position. During athletic participation the hip is extended through movements while the knee is flexed. Doing single leg hamstring bridge assesses the individual leg or hamstring that is injured; therefore the athlete cannot favor the injured hamstring with the uninjured leg. This functional test showed that hamstrings that were strained during the ongoing season were weaker than uninjured hamstring strings. The single leg hamstring bridge is a test that looks at endurance and strength of an injured hamstring, which can be used to asses if the athlete is ready to return to play.[1] Irregular or poor muscle strength of the injured hamstring is a risk factor for a reoccurrence hamstring strain. Thus, muscle strength of the previously injured hamstring must be assessed during functional movements to determine if there is a strength deficiency. Other functional tests that can be used for rehabilitation and for return to play are progressive agility tests and trunk stabilization.[2] These tests are shown to help prevent re-injury of the hamstring on returned to play. Recently injured tissues are weak and can be reinjured with stresses in the sagittal plane. Therefore agility training in the frontal plane can strengthen without lengthening and overusing the healing tissues.2 If the tissues heal properly then the chance of re-injury is decreased. Performing agility and trunk stabilization is important to maintain range of motion at the hip and pelvis and reduce atrophy. The trunk stabilization and hamstring length can be assessed through windmills, prone bridges, and side planks. Low to moderate intensity sidestepping and grapevine stepping were good functional tests for hamstring return to play.[2] Jogging in place at a fast speed was also used as a functional test to return to play since many acute hamstring stains are sustained during sprinting activities.2 Single leg bridges as well as sprinting combined with side to side agility and core stabilization testing is best to determine if there is full mobility of the hip and knee, full muscle strength and length of the injured hamstring compared to the healthy leg.[1,2]

1. Freckleton G, Cook J, Pizzari T. The predictive validity of the single leg bridge test for hamstring injuries in australian rules football players. British J Sports Med. 2014;48(8):1-5. http://eds.b.ebscohost.com.suproxy.su.edu/ehost/detail/ detail?vid=3&sid=69673831-cb1a-46bb-858c 0c3fbac54af1%40sessionmgr 198&hid=112&bdata=JkF1dGhUeXBlPWlwLHVybCxjb29raWUmc2l0ZT1laG9zdC1saXZl#db=s3h&AN=95315130. Accessed November 10, 2014.

2. Sherry M, Best T. A comparison of 2 rehabilitation programs in the treatment of acute hamstring strains. J Orthopaedic & Sports Physical Therapy. 2004;34(3):116-125. http://eds.b.ebscohost.com.suproxy.su.edu/ehost/detail/detail?vid
=12&sid=69673831-cb1a-46bb-858c-0c3fbac54af1%40sessionmgr198&hid
=112&bdata=JkF1dGhUeXBlPWlwLHVybCxjb29raWUmc2l0ZT1laG9zdC1saXZl#db=s3h&AN=SPHS-937449. Accessed November 10, 2014.

Kyle Hernden said...

This article stuck out to me because with our great advances in technology, it is easy for patients to rely on imaging to assure they are structurally healthy enough to return to play. Although imaging is an important component of returning to play, this study demonstrates the importance of our knowledge as clinicians to treat sports medicine as an "art", and not just as a science. Ultimately, patients need our expertise and experience dealing with certain injuries to give them the best opportunity to successfully return to play. I enjoyed reading this article because it gives all readers a reminder that our evaluation skills and ability to identify even the smallest differences can make a great impact on the success of our patients in the future.

Jeffrey Driban said...

Thanks Kyle! These days it is so easy to get an MRI or ultrasound but I agree that we can never underestimate the value of a comprehensive physical exam.

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