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BACKGROUND & OBJECTIVES:
Hamstring muscle strains are one of the most common injuries seen amongst field athletes who routinely sprint at near maximal speeds. The injury most frequently occurs at the musculotendinous junction. The high rate of hamstring injury and reinjury along with the ambiguity of return to play (RTP) criteria represent a significant challenge in the sporting world.
Recent advancements in MRI diagnostics have shed light on the high frequency of intramuscular tendon hamstring injuries. Currently, there is no consensus as to an ideal course of treatment for this subtype of hamstring injury. In the past, intramuscular hamstring tendon injury was oftentimes repaired surgically with underwhelming and inconsistent outcomes.
In the quest to constantly improve sports medicine treatment and explore the least invasive measure first, this case study examines the rehabilitation of an English Premier League footballer who suffered a proximal hamstring intramuscular tendon injury during competition.
METHODS (WHAT THEY DID):
The conceptual goal of this rehabilitation was to mechanically load the injury site and improve tensile strength, elastic stiffness, and cross-sectional area of the injured tissue. There was a clear progression from isometrics at shortened positions to dynamic exercises at increasing muscle lengths and load. As with many lower extremity rehabilitation protocols, exercise progression typically goes from unloaded to loaded, and bilateral to single leg. The goal is to increase stress on the injured area over time.
Isometric exercises were performed as maximal voluntary contractions in cluster sets of 3-5 sets at 3-5 second holds. The theoretical basis is to provide cyclical high strain magnitudes to increase tendon stiffness, reduce strain, and enhance force development. A force plate was used to determine load progression. For example, at week 7 the criterion for phase progression was peak force asymmetry being less than 10% in the 90/90 isometric supine heel drive (hip flexed to 90, knee flexed to 90, contralateral hip and knee extended – see video).
Exercise selection was thoughtful and specific. Gluteal bridges were one of the mainstay movements in this rehabilitation progress. They were progressed in three ways: increasing lever arm, increasing load, and elevating the feet. The Romanian deadlift was the primary hip dominant weight bearing exercise. It was progressed from bilateral to single leg, with the goal of improving hip symmetry and increased recruitment of the injured muscle group. The reverse lunge was the primary knee dominant movement selected, with progressions in range of motion and load. The reverse lunge was noted as an exercise that has a strong dynamic correspondence to high speed running gait.
The most unique factor of this rehabilitation protocol was the extended time period focused on high speed movement. Re-acclimatization to plyometrics, including high speed running and jumping began at week 10. Prior to week 10, the speed of eccentric contraction was progressively increased to mimic the fast stretch-shortening cycle the hamstring is under during high speed running.
Force plate testing was used to measure hamstring contractile speed. Peak force development was measured at a quick impulse: only 100ms of time. This measurement is thought to be a strong indicator of rate of force development, thus an objective measure for positive musculotendinous adaptations and the contraction speed necessary for high speed running.
RESULTS/WHAT THEY FOUND:
The player returned to competition in 120 days (4 months) and remained injury free 13 months later. The process of increasing running exposure began at week 10 and continued all the way through week 17. This player actually achieved a personal best sprint speed during his RTP rehab phase.
LIMITATIONS (THINGS TO KEEP IN MIND):
The results of this case study were ideal, however the extended timeline and access to expensive equipment (force plates) are not realistic expectations in most competitive sports and rehabilitation environments. This case study was performed in an ideal setting under nearly perfect conditions with state of the art equipment.
The timelines and framework of this case study cannot be applied to other cases. Protocols are not typically helpful clinical guidelines for soft issue rehabilitation. Soft tissue rehabilitation requires a great deal of clinical judgement and decision making, as there is an extremely large range in injury presentation. Tolerance and progression is different for every patient and every injury. While this case study serves as a great example of how RTP rehab should be done, it cannot be used as concrete clinical guideline.
Furthermore, there was much discussion of unproven mechanistic elements in this paper. Thankfully it was recognized that these elements were not researched or measured. Future research is warranted to increase our understanding of the mechanical adaptations to exercise seen in contractile tissue, including stiffness, elasticity, and reactivity.
CLINICAL IMPLICATIONS (HOW THIS IMPACTS CLINICAL PRACTICE):
This was a fantastic case study with extremely helpful video demonstrations. The implications here are limited, as with all case studies. One important takeaway here was the amount of time the rehabilitation process took. This athlete was given 17 weeks to return from a hamstring tear. Oftentimes in soft tissue rehab, an athlete is immediately back on the field once they start to hit near maximal speed. This paper demonstrates that with increased patience and an extended RTP phase, there may be improved long-term outcomes. Reductions in re-injury rates and avoidance of the injury-re-injury cycle potentially represent decreased total time lost due to injury.
Study reference: Taberner M and Cohen D (2018) Physical preparation of the football player with an intramuscular hamstring tendon tear: clinical perspective with video demonstrations. British Journal of Sports Medicine, bjsports-2017-098817.
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