Proximal hamstring morphology and morphometry in men: an anatomic and MRI investigation

Abstract

The proximal musculo-tendinous junction (MTJ) is a common site of hamstring strain injury but the anatomy of this region is not well defined. A morphometric analysis of the proximal MTJs of biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) was undertaken from dissection of 10 thighs from five male cadavers and magnetic resonance imaging of 20 thighs of 10 active young men. The length, volume, and cross-sectional area of the proximal tendon, MTJ and muscle belly, and muscle-tendon interface area were calculated. In both groups, MTJs were reconstructed three-dimensionally. The proximal tendons and MTJs were expansive, particularly within SM and BFlh. Morphology varied between muscles although length measurements within individual muscles were similar in cadavers and young men. Semimembranosus had the longest proximal tendon (cadavers: mean 33.6 ± 2.0 cm; young men: mean 31.7 ± 1.6 cm) and MTJ (>20 cm in both groups) and the greatest muscle-tendon interface area, followed by BFlh and ST. Mean muscle belly volumes were more than three times greater in young men than elderly male cadavers (P < 0.001). These unique morphometric data contribute to a better understanding of hamstring anatomy, an important factor in the pathogenesis of hamstring strain injury.

Is Biceps Femoris Aponeurosis Size an Independent Risk Factor for Strain Injury?

“…only proximal mechanical pathway for the transmission of force developed from the BF LH to the ischial tuberosity [13]; and this region is the most affected within the hamstring muscles [3]. Thus, one would expect a smaller Apo-BF LH in athletes with previous BF LH injury, since it theoretically favors a higher deformation during the BF LH contraction at the interface between the BF LH and the Apo-BF LH [10], which could trigger injuries in this region.…”

“…This study aimed to verify if thighs of professional footballers with previous BF LH injury in the last three years had a lower Apo-BF LH size compared to their counterparts without previous injury. Based on results from previous studies [7,8,10,12,13], we hypothesized that athletes with previous BF LH injury would present a lower size (i. e. volume, length, and width) and, consequently, and a lower interface area with the BF LH . Additionally, the premise under our hypothesis and reported in previous studies were reexamined [7,8,10,12,13].…”

“…Based on results from previous studies [7,8,10,12,13], we hypothesized that athletes with previous BF LH injury would present a lower size (i. e. volume, length, and width) and, consequently, and a lower interface area with the BF LH . Additionally, the premise under our hypothesis and reported in previous studies were reexamined [7,8,10,12,13]. For these purposes, a semi-automated procedure was developed by members of our research team to quantify the Apo-BF LH size with objective criteria, using magnetic resonance imaging (MRI) data (Supplement 1).…”

Stress between the hamstring muscles

“…Nonetheless, strain may have an additive effect to injury risk separate from the increased passive tension. The volume of the MTJ does not change during lengthening therefore an increase would cause a decrease in MTJ area and a subsequent increase in stress [12]. Although not the principal cause, the greater strain in the BF whilst sprinting may compound its vulnerability to injury here.…”

“…It is well established in Newtonian mechanics that materials fracture under excessive tensile stress [12] . Stress is the measure of the internal force acting in a localised area (Eq.…”