Hamstring Injuries in Athletes: Evidence-Based Treatment

Justin W. Arner, MD; Michael P. McClincy, MD; James P. Bradley, MD

Disclosures

J Am Acad Orthop Surg. 2019;27(23):868-877. 

In This Article

Mechanisms of Injury and Risk Factors

The hamstrings are at increased injury risk because they cross both the hip and knee joints. Injury most commonly occurs during eccentric contraction. The greatest strain occurs at the end of swing phase when the hamstrings eccentrically contract at their maximal elongation before heel strike. Eccentric contraction extends the hip and decreases knee extension from heel strike through stance phase. Intramuscular or musculotendinous injuries most commonly occur during the takeoff phase of running, with the biceps femoris being most commonly injured.[2] In contrast, proximal hamstring avulsions typically occur during eccentric contraction with the hip flexed and knee extended, putting the muscle on maximum tension. The semimembranosus origin is the least likely to rupture, and its intact tissue can help prevent notable tendon retraction.[7]

Common risk factors for injury are listed in Table 1 (Supplemental Digital Content 1, http://links.lww.com/JAAOS/A370) as are factors shown not to affect injury.[2,8,9] Risk factors can be grouped into three categories: inadequate preparation (deconditioning, inadequate warm-up, fatigue, dehydration), muscular dysfunction/imbalance (hamstring-quadricep imbalance, hamstring strength deficits, core weakness, muscular recruitment issues), and anatomic abnormalities (leg length inequality, short fascicle length, previous injury).[10] It is postulated that a previous injury leads to a notable recurrence risk because the reparative scar serves as a stress riser adjacent to normal muscle, lowering the threshold for reinjury in areas adjacent to scaring. The quality of scar formation and remodeling is the single most important determinant of subsequent muscle function and risk of reinjury.[2]

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