Research Article Is There a Gender Difference in Fat Distribution around the Hamstring Tendon Insertion? A Prospective MRI Evaluation of 40 Cases Nathanael Ahearn, Nick R. Howells, and James L. Williams Department of Trauma and Orthopaedic Surgery, Musgrove Park Hospital, Parkfield Drive, Taunton, Somerset TA1 5DA, UK Correspondence should be addressed to Nathanael Ahearn; nahearn@nhs.net Received 4 June 2014; Revised 27 July 2014; Accepted 29 July 2014; Published 11 August 2014 Academic Editor: Federico Canavese Copyright © 2014 Nathanael Ahearn et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction. Knee ligament reconstructions are commonly performed using hamstring tendon grats. We observed anecdotally that there was a diference in the fat distribution supericial to the pes anserinus between men and women and proposed that this efect was independent of BMI, being signiicantly greater in women. Methods. We performed a prospective study to evaluate 40 MRI scans performed in 20 women and 20 men. he scans allowed visualisation of the insertion of the hamstring tendons at the pes anserinus. Results. he 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). he mean fat distribution supericial to the pes anserinus in men was 16.2mm (4.1–29.4) and in women was 29.7mm (19.6–47.5). here was a signiicant increase in fat supericial to the hamstring tendons in women compared with men ( < 0.001), despite no signiicant diference in BMI ( = 0.5). Conclusions. Our evaluation of a prospective series of MRI scans has shown that there is signiicantly more fat supericial to the insertion of the hamstring tendons in women than in men. his efect is independent of BMI and may inluence exposure during hamstring tendon grat harvesting. 1. Introduction Knee ligament reconstructions are commonly performed using hamstring tendon grats. Whilst performing hamstring tendon grat harvesting for knee ligament reconstructions, we observed that there was a diference in the fat distribution supericial to the pes anserinus between men and women. We felt that this efect was independent of body mass index (BMI), being signiicantly greater in women. Women and men of similar BMI difer in the percentage of body weight as fat [1], but it has not been determined if this is related speciically to lower limb anatomy. here have been studies demonstrating gender diferences 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 diferences 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 diference in the fat supericial to the pes anserinus. 2. Patients and Methods he 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 assess- ment of patellar instability. hese scans allowed us to identify the insertion of the pes anserinus on the T1-weighted axial images. We used the Picture Archiving and Communications System (PACS) Centricity Web sotware (GE Healthcare, Chalfont St Giles, UK) to measure the perpendicular distance from the pes anserinus to the skin. he patient’s height and weight information used to calculate BMI were recorded on a Hindawi Publishing Corporation Advances in Orthopedic Surgery Volume 2014, Article ID 606527, 3 pages http://dx.doi.org/10.1155/2014/606527