Yes, this is a real muscle and it may have an important function in joint and capsular protection. There is a rapidly growing evidence base for understanding function and dysfunction of the complex layered muscle synergies around the hip. The development of safe fine wire EMG techniques and reliable dynamic ultrasound imaging around the hip has seen an explosion of research into this fascinating area. We have recent information on deep gluteal and external rotator function, and now for the first time we have fine wire information on normal function of iliocapsularis. Early EMG findings for iliacus and iliocapsularis have been released today in our paper in Gait & Posture1. The landscape in this field is undergoing substantial change and is it important that physiotherapy assessment methods and exercise prescription reflect contemporary understanding in this field.
Iliocapsularis sits beneath the rectus femoris and has a substantial attachment to the anterior hip capsule. This anatomical relationship has led to suggestions from the available literature that this deep muscle may be important in joint stability and preventing capsular impingement during deep flexion tasks. Ongoing work at the University of Queensland will be able to shed more light on this over the next couple of years. Clinically, we find that working on activation of this muscle, together with the deep joint protection portions of iliacus can be very useful in the management of anterior hip pain. While iliacus is able to be palpated with careful hand position and awareness of surface anatomy, iliocapsularis is too deep to reliably palpate due to the overlying rectus femoris and sartorius. Real time ultrasound provides a perfect tool to visualize, assess size and recruitment and retrain iliocapsularis and all the deep joint protectors of the hip.
In my online course, Dynamic Stabilisation of the Hip & Pelvis, we explore in detail the functional anatomy, patterns of dysfunction and implications for therapeutic exercise for the hip flexors, including the iliocapsularis. In the accompanying practical workshop, specific assessment and exercise techniques for the hip flexor group are taught. Real time ultrasound is used as a tool to visualise and retrain the deep hip flexors. This course does not require access to real time ultrasound in your clinical practice but uses ultrasound as an advanced teaching tool – great for your freshening up your anatomy and palpation skills!
I also run ultrasound focused workshops, with one 4-hour workshop focused on ultrasound assessment and muscle retraining around the hip.
Twitter: @alisongrimaldi for further infobytes
- Lawrenson P, Grimaldi A, Crossley K, Hodges P, Vicenzino B, Semciw A. Iliocapsularis: Technical application of fine-wire electromyography, and direction specific action during maximum voluntary isometric contractions. Gait & Posture 2017; 54: 300-303. http://dx.doi.org/10.1016/j.gaitpost.2017.03.027
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