Hamstring strain injuries: recommendations for diagnosis, rehabilitation, and injury prevention

Abstract

Hamstring strain injuries remain a challenge for both athletes and clinicians, given their high incidence rate, slow healing, and persistent symptoms. Moreover, nearly one third of these injuries recur within the first year following a return to sport, with subsequent injuries often being more severe than the original. This high reinjury rate suggests that commonly utilized rehabilitation programs may be inadequate at resolving possible muscular weakness, reduced tissue extensibility, and/or altered movement patterns associated with the injury. Further, the traditional criteria used to determine the readiness of the athlete to return to sport may be insensitive to these persistent deficits, resulting in a premature return. There is mounting evidence that the risk of reinjury can be minimized by utilizing rehabilitation strategies that incorporate neuromuscular control exercises and eccentric strength training, combined with objective measures to assess musculotendon recovery and readiness to return to sport. In this paper, we first describe the diagnostic examination of an acute hamstring strain injury, including discussion of the value of determining injury location in estimating the duration of the convalescent period. Based on the current available evidence, we then propose a clinical guide for the rehabilitation of acute hamstring injuries, including specific criteria for treatment progression and return to sport. Finally, we describe directions for future research, including injury-specific rehabilitation programs, objective measures to assess reinjury risk, and strategies to prevent injury occurrence.

Level of evidence: Diagnosis/therapy/prevention, level 5.

FIGURE 1

a) The hamstring muscle group consists of the semimembranosus, semitendinosus, and biceps femoris muscles, with the biceps femoris long head being injured most often in high-speed running. b) During the swing phase of high-speed running, the hamstrings are active, stretched (ΔL, change in length relative to upright stance) and absorbing energy from the swing limb, creating the potential circumstances for a lengthening contraction injury. Reproduction of a) is with permission of Springer Science+Business Media, © 2008.

FIGURE 2

T2-weighted coronal images at a) 10 days and b) 30 days following injury to the right biceps femoris long head sustained during high-speed running. Considerable edema and hemorrhage (high-intensity signal) are evident at the site of injury (arrow) on day 10 with persistent fluid remaining at day 30. In addition, a substantial amount of scar tissue (low-intensity signal) is present by day 30. Of note, this individual was cleared to return to sport 23 days after the injury.

FIGURE 3

Supine bent knee bridge walk out: starting in a) supine bridge position, b and c) progressively move feet away from hips while maintaining bridge position.

FIGURE 4

Supine single limb chair-bridge: a) Starting with 1 leg on stationary object, b) raise hips and pelvis off ground.

FIGURE 5

Single limb balance windmill touches with dumbbells: Begin in a) single limb stance position with dumbbells overhead and b) perform windmill motion under control with end position of c) touching dumbbell to floor.

FIGURE 6

Persistent scar tissue, depicted by low-intensity signal (arrow), is evident adjacent to the site of prior injury along the proximal musculotendon junction of the biceps femoris long head in the a) T2-weighted fast spin echo axial and b) recombined in-phase image acquired with 3D-IDEAL-SPGR* coronal views. Such scarring has been observed to persist on a long-term basis (5-23 months post-injury). Reproduced with permission of Springer Science+Business Media, © 2008. *Coronal images were obtained using a 3D T1-weighted spoiled gradient-echo (SPGR) chemical shift based water-fat separation technique known as IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation). Images shown are recombined water+fat (in-phase) images acquired and reconstructed with IDEAL.