Proximal Hamstring Origin Architecture: Defining the Vector Angle

Purpose: The posterior compartment of the thigh is composed of three major muscles collectively referred to as the hamstring muscles. These consist of the biceps femoris short and long head, semimembranosus and semitendinosus. Excluding the short head of the biceps femoris, the hamstrings contribute to the movement of the hip and the knee joints as they span across both joints. Our aim was to assess the implications of the angle of origin of the hamstring tendons on the force generated during contraction and the implications of the risks of tears.

Methods and Materials: A total of 100 pelvic magnetic resonance images (MRIs) in patients < 40 years of age were reviewed by a musculoskeletal radiology fellow and a consultant musculoskeletal radiologist with > 10 years of experience in the field.

Results : The p value using an unpaired t test was < 0.05, confirming that the difference in the vector angle of the various hamstring components was statistically significant. Applying the concept of Newton’s second law to the angles calculated, we demonstrated an increase of 9% force was applied to the conjoint tendon origin when compared with the semimembranosus tendon.

Conclusion: In our study we postulated that because the angle of origin of the conjoint tendon and the semimembranosus tendon is different, this may subsequently affect the force exerted on the tendon during muscle contraction, possibly one of the reasons for the difference in the incidence and pattern of injuries of various muscles of the hamstrings.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
17 December 2020