Function of the Quadratus femoris and Obturator externus

Biomechanical study investigating the function of the Quadratus femoris and Obturator externus

Previous literature has shown that the Quadratus femoris (QF) and Obturator externus (OE) muscles are some of the most frequently injured muscles of the hip, which are often overlooked due to the lack of functional and diagnostic knowledge currently available.

In order to better understand their role in symptoms of the hip, the authors of the present study set out to clearly define the primary maximal strength and stretch positions of QF and OE. Following investigation it was shown that maximal strength of the QF is from a flexed position towards extension, whereas OE is from an extended position towards flexion and adduction.

Rehabilitation programs are often designed around the precise understanding of the stretch and strengthening of specific muscles. Considering the lack of consensus regarding QF and OE the present study will help clarify a knowledge gap regarding their clinical anatomy. The QF was shown to be lengthened maximally in flexion, adduction or abduction and internal rotation. Force was shown to be optimally generated in 60-90 degrees of flexion. The OE showed maximal length in extension, abduction and internal rotation with the largest moment generated with the hips in a neutral position. 

> From: Vaarbakken et al., Clin Biomech 30 (2016-01-04 11:41:36) 231-237 (Epub ahead of print). All rights reserved to Elsevier Ltd.. Click here for the online summary. Translation by Eric Walper

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