Anatomy of the long head of biceps femoris: An ultrasound study

Abstract

Hamstring strains, particularly involving the long head of biceps femoris (BFlh) at the proximal musculotendinous junction (MTJ), are commonly experienced by athletes. With the use of diagnostic ultrasound increasing, an in‐depth knowledge of normal ultrasonographic anatomy is fundamental to better understanding hamstring strain. The aim of this study was to describe the architecture of BFlh, using ultrasonography, in young men and cadaver specimens. BFlh morphology was examined in 19 healthy male participants (mean age 21.6 years) using ultrasound. Muscle, tendon and MTJ lengths were recorded and architectural parameters assessed at four standardised points along the muscle. Measurement accuracy was validated by ultrasound and dissection of BFlh in six male cadaver lower limbs (mean age 76 years). Intra‐rater reliability of architectural parameters was examined for repeat scans, image analysis and dissection measurements. Distally the BFlh muscle had significantly (P < 0.05) shorter fascicles and larger pennation angles than proximal sites. Agreement between ultrasound and dissection (cadaver study) was excellent for all architectural parameters, except pennation angle (PA), and MTJ length. All other measures demonstrated good‐excellent repeatability. BFlh is not uniform in architecture when imaged using ultrasound. It is likely that its distal‐most segment is better suited for force production in comparison to the more proximal segments, which show excursive potential, traits which possibly contribute to the high rate of injury at the proximal MTJ. The data presented in this study provide specific knowledge of the normal ultrasonographic anatomy of BFlh, which should be of assistance in analysing BFlh injury via imaging. Clin. Anat. 29:738–745, 2016. © 2016 Wiley Periodicals, Inc.

Ultrasonographic Measurement of the Biceps Femoris Long‐Head Muscle Architecture

“…Such values are in accordance with previous studies using US on other muscles, suggesting that errors from measurements do not depend on the muscles studied as much as other factors (eg, rater assessment procedures). Fascicle length, fascicle angle, and muscle thickness measurement reliability rates were similar to those reported previously . In this study, values of 9.6 ± 18.0 cm, 12.4 ° ± 2.8 °, and 2.0 ± 0.4 cm were obtained in the full‐image width for the fascicle length, fascicle angle, and muscle thickness, respectively, whereas in previous studies, values of 5.9 ± 0.3 to 8.8 ± 1.8 cm, 14.9 ° ± 3.3 ° to 23.9 ± 3.8 °, and 1.3 ± 0.2 to 2.7 ± 0.3 cm were reported.…”

“…To our knowledge, a detailed report of a reliability of assessment of the biceps femoris muscle architecture has not been presented previously . Chleboun et al reported high inter‐rater reliability (ICC = 0.87), whereas Kellis et al compared and characterized cadaveric versus US measurements to provide method validation.…”

“…Also, it was not mentioned whether the measurements were made with respect to the midmuscle aponeurosis or the muscle's deep aponeurosis. Tosovic et al reported an ICC of 0.82 for fascicle length measurement but mentioned that the determination was performed from superficial to deep aponeuroses instead of the midmuscle aponeurosis. In this study, we assessed the midmuscle aponeurosis because it was more (ie, clearly) visible compared to the deep aponeurosis.…”

“…Thus, assessment of the biceps femoris architecture is of both scientific and clinical importance. Although a systematic review indicated that studies assessing the biceps femoris architecture did not report reliability statistics for their measurements, 3 recent studies reported reliability for biceps femoris architectural measurements (moderate‐to‐high reliability; intraclass correlation coefficient [ICC] > 0.78) . However, a full exploration of measurement reliability and description of the procedures used to assess the biceps femoris architecture were not presented.…”

Poor agreement between ultrasound and inbuilt diffusion tensor MRI measures of biceps femoris long head fascicle length

“…These US measures display superior clinical utility, considering the change values in FL detailed above, compared to the 3.5 cm established by the current methods. As US measures of BFlh architecture have also compared favorably with direct cadaveric measurement, US measures of BFlh architecture continue to have superior evidence of robustness compared to the current DTI measures. Furthermore, poor agreement between DTI measures and US measures of FL can be observed in Table and Figure .…”