Is There a Gender Difference in Fat Distribution around the Hamstring Tendon Insertion? A Prospective MRI Evaluation of 40 Cases

Introduction. Knee ligament reconstructions are commonly performed using hamstring tendon grafts. We observed anecdotally that there was a difference in the fat distribution superficial to the pes anserinus between men and women and proposed that this effect was independent of BMI, being significantly greater in women. Methods. We performed a prospective study to evaluate 40 MRI scans performed in 20 women and 20 men. The scans allowed visualisation of the insertion of the hamstring tendons at the pes anserinus. Results. The mean BMI of the male patients was 25.6 (19.8–37.2) and of the female patients was 24.7 (17.9–34.5). The mean fat distribution superficial to the pes anserinus in men was 16.2？mm (4.1–29.4) and in women was 29.7？mm (19.6–47.5). There was a significant increase in fat superficial to the hamstring tendons in women compared with men ( ), despite no significant difference in BMI ( ). Conclusions. Our evaluation of a prospective series of MRI scans has shown that there is significantly more fat superficial to the insertion of the hamstring tendons in women than in men. This effect is independent of BMI and may influence exposure during hamstring tendon graft harvesting. 1. Introduction Knee ligament reconstructions are commonly performed using hamstring tendon grafts. Whilst performing hamstring tendon graft harvesting for knee ligament reconstructions, we observed that there was a difference in the fat distribution superficial to the pes anserinus between men and women. We felt that this effect was independent of body mass index (BMI), being significantly greater in women. Women and men of similar BMI differ in the percentage of body weight as fat [1], but it has not been determined if this is related specifically to lower limb anatomy. There have been studies demonstrating gender differences of various aspects of knee anatomy and function such as medial femoral condylar height [2] and rotational kinematics and trochlear groove orientation [3]. To our knowledge there have been no studies investigating gender differences regarding the anatomy of the region around the hamstring tendons. We therefore designed a prospective study to evaluate a series of magnetic resonance imaging (MRI) scans to determine if there was a difference in the fat superficial to the pes anserinus. 2. Patients and Methods The study used a total of 40？MRI scans, 20 scans performed in men and 20 scans performed in women. Patients under 16 years of age were excluded from the study. We used a consecutive series of scans that were performed for assessment of patellar