Location, location, location is a familiar phrase when purchasing property, but does this also ring true in regards to hamstring strains?  

 

With the AFL season now under way, and local competitions about to kick off, let’s shed some light in the increasingly challenging hamstring injury debate.   

 

Among athletes and active individuals, hamstring injuries are one of the most prevalent musculoskeletal injuries. The hamstring muscle group comprises three muscles situated at the back of the thigh: the semimembranosus, semitendinosus, and biceps femoris. These muscles facilitate knee flexion and hip extension. The severity of the injury and the recovery time can be impacted by the location of the injury, which can also cause discomfort and limit mobility. 

 

Despite progressions in injury prevention, surveillance, and strength & conditioning, hamstring re-injury rates remain consistently high, causing frustration for athletes and medical professionals. The physical demands of football continue to increase, with athletes expected to move faster and further than ever before. 

 

Over the past decade, the focus has shifted from functional diagnosis to more anatomical, with the recognition that not all hamstring strains are identical. Within the hamstring complex, there are three (or four, if the short head is included) distinct muscles, each comprising proximal and distal components. Furthermore, the musculotendinous unit consists of peripheral muscle fibers, muscle attachment to the intramuscular tendon, and the intramuscular tendon itself – a connective tissue, similar to the rachis of a feather. Injury can occur to any part of these structures, with their own timeline for return to play and specific management plan. 

 

The current widely adopted British Athletic Muscle Injury Classification System classifies 3 main sites of hamstring injuries: 
  1. Myofascial (a-classification) 
  2. Musculotendinous junction (b-classification)  
  3. Intramuscular tendon (c-classification) 

 

Implications of these anatomical differences in location of tear are evident with regards to injury severity, time lost due to injury & recurrence/re-injury rates. Recent evidence suggests that the intramuscular tendon (intratendinous) injuries are correlated with a significantly longer rehabilitation period and have a much higher chance of recurrence when compared to ‘a’ and ‘b’ type injuries.  

 

Type A

Our type ‘a’ myofascial injuries are typically less severe but can often present with significant pain. This is due to the rich innervation the fascial tissue receives, however the rehabilitation program for these injuries can usually be stream-lined and running can be performed at an earlier stage due to the injury involving less significant muscle tissue.  

Type B

Musculotendinous Junction ‘b’ type injuries are also known as our ‘typical’ hamstring injuries. These injuries are extremely common with a return to play timeline ranging between 3-6 weeks.  

Type C

Intra-tendinous injuries can occur along any aspect of the hamstring tendon. However, there are emerging trends and research in these injuries that can develop within the central tendon and /or the distal tendon of the hamstring known as the T-Junction. Based on the involvement of tendon injury and the location of which tendon is in fact damaged, will have various implications from a physiotherapy management and rehabilitation standpoint. For example, these injuries typically involve delayed eccentric exercises, delayed running drills and delayed introduction to speed work.  

What now?

Like many soft tissue injuries, exercise rehabilitation is vital to return to sport successfully with minimisation of re-injury. In the case of a hamstring strain, it is important that a program is not only tailored to improve functional components of the hamstring muscles, but also the ability to generate force and power.

The location of tear not only impacts total recovery time, but has a role in the type of exercises that are prescribed at a given stage of the rehabilitation process. For example, Type ‘a’ and ‘b’ classifications, are likely to benefit from similar programs that can ultimately be progressed quite quickly through the rehab process.

Whereas, given significant tendon involvement in ‘c’ classification injuries, the nature of the exercise programming may change. This may or may not include, avoiding certain aspects of hamstring contractions (hip based vs knee based) depending on location of tear. One might also benefit from including an isometric hold to help build tolerance and stress the muscle without changing its length. Therefore, the location and structure involved in the hamstring strain, is a key component to determine the type of exercises that will be provided in the rehabilitation programme, but will also impact the speed at which one will progress through the program, and also how and when someone would commence and progress their running loads.  

The images below show an example of a type ‘b’ injury, that subsequently progressed to a type ‘c’ injury.

Over a 12 week rehabilitation program inclusive of a targeted and gradual running program, the third image depicts a fully healed and nicely scarred tendon.  

 

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Type B injury

Type C injury

Healed Type C injury after 12 weeks

In summary

The nature and location of the hamstring injury is a key aspect to determining an appropriate tailored rehabilitation program to return you back to sport while reducing the risk of re-injury rates. While it is not always necessary, MRI imaging can help determine the details of your hamstring injury which can assist with the overall management plan.

If you have recently experienced a hamstring strain or stuck with a recurring strain that just doesn’t seem to get right, perhaps there is a key element missing in your rehabilitation or diagnosis. Get in touch with our physiotherapy team to put you on a path to return back to your activity of choice.   

About the author

CSSM physiotherapist Peter Stath believes a strong and healthy body maintains a healthy mind, which allows us to perform and work to the best of our ability.

Peter is a strength and conditioning enthusiast with a unique understanding of the demands of high level competition and performance.  Having previously worked within the National Premier League Victoria (soccer) as well as part of the medical team for Futsal Victoria at their National Championships, he has a passion for treating all aspects of musculoskeletal or sporting pain with a particular interest in shoulders, hips, knees and ankles.

He is also a great advocate for the involvement of children and adolescents in sport, helping them develop healthy habits as they grow.

 

References 

Ekstrand J, Walden M, Hagglund M. Hamstring injuries have increased by 4% annually in men’s professional football, since 2001: a 13-year longitudinal analysis of the UEFA Elite Club injury study. Br J Sports Med 2016;50(12):731-7. doi: 10.1136/bjsports-2015-095359. 

van der Made AD, Almusa E, Reurink G, et al. Intramuscular tendon injury is not associated with an increased hamstring reinjury rate within 12 months after return to play. 2018(1473-0480). 

Brukner P, Connell D. ‘Serious thigh muscle strains’: beware the intramuscular tendon. Br J Sports Med 2016;50(4):205-8 LID – 10.1136/bjsports-2015-095136.  

Comin J, Malliaras P, Baquie P, et al. Return to competitive play after hamstring injuries involving disruption of the central tendon. Am J Sports Med 2013;41(1):111-5. doi:0.1177/0363546512463679. 

Pollock N, James SL, Lee JC, et al. British athletics muscle injury classification: a new grading system. Br J Sports Med 2014;48(18):1347-51. doi:10.1136/bjsports-2013-093302. 

Pollock, N., Patel, A., Chakraverty, J., Suokas, A., James, S. L. J., & Chakraverty, R. (2015). Time to return to full training is delayed and recurrence rate is higher in intratendinous (“c”) acute hamstring injury in elite track and field athletes: clinical application of the British Athletics Muscle Injury Classification. British Journal of Sports Medicine, 50(5), 305–310. doi:10.1136/bjsports-2015-094657 

Vermeulen, R., Almusa, E., Buckens, S., Six, W., Whiteley, R., Reurink, G., … Tol, J. L. (2020). Complete resolution of a hamstring intramuscular tendon injury on MRI is not necessary for a clinically successful return to play. British Journal of Sports Medicine, 55(7), 397–402. doi:10.1136/bjsports-2019-101808