title: Iliocapsularis: Technical application of fine-wire electromyography, and direction specific action during maximum voluntary isometric contractions.
abstract: The iliocapsularis muscle of the anterior hip may play an important role in hip function, but no electromyographic (EMG) recordings have been made. This muscle provides the most substantial muscular attachment to the anterior hip capsule and is hypothesised to have a dynamic role to limit capsular impingement and to augment joint stability. Current understanding of the function of iliocapsularis is based on limited cadaveric and radiographic studies. Located deep over the hip joint it would require intramuscular fine-wire EMG to evaluate its activity directly with limited cross-talk from overlying muscles. The primary aim of this study was to describe a new technique for insertion of intramuscular EMG electrodes into iliocapsularis and to report its activation during different directions of hip maximum voluntary isometric contraction (MVIC). Fifteen healthy volunteers (10M, mean age (SD) 22 (2) years) who were free from hip pain were recruited for electrode insertion and to perform MVIC's in six directions at 0° and three directions at 90° of hip flexion. Intramuscular electrodes were successfully inserted into the iliocapsularis muscle with guidance from real-time ultrasound imaging. The greatest muscle activity occurred during resisted hip flexion at 90° (Median (IQR); 100.0 (1.2) % MVIC) and lowest activity during hip extension, 0° (0.5 (0.3) % MVIC). These findings have implications for our understanding of iliocapsularis' functional role. This paper provides the first report of intramuscular electrode insertion into iliocapsularis with guided technical instructions for future EMG investigations in other populations and tasks.
authors.affiliation: The University of Queensland, School of Health & Rehabilitation Sciences, Brisbane, QLD, 4072, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Lawrenson
authors.affiliation: The University of Queensland, School of Health & Rehabilitation Sciences, Brisbane, QLD, 4072, Australia; Physiotec Physiotherapy, 23 Weller Rd, Tarragindi, QLD, 4121, Australia.
authors.forename: Alison
authors.initials: A
authors.lastname: Grimaldi
authors.affiliation: The University of Queensland, School of Health & Rehabilitation Sciences, Brisbane, QLD, 4072, Australia; College of Science, Health and Engineering, School of Allied Health, La Trobe University, Melbourne, Victoria, Australia.
authors.forename: Kay
authors.initials: K
authors.lastname: Crossley
authors.affiliation: The University of Queensland, School of Health & Rehabilitation Sciences, Brisbane, QLD, 4072, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Hodges
authors.affiliation: The University of Queensland, School of Health & Rehabilitation Sciences, Brisbane, QLD, 4072, Australia.
authors.forename: Bill
authors.initials: B
authors.lastname: Vicenzino
authors.affiliation: The University of Queensland, School of Health & Rehabilitation Sciences, Brisbane, QLD, 4072, Australia; College of Science, Health and Engineering, School of Allied Health, La Trobe University, Melbourne, Victoria, Australia. Electronic address: a.semciw@uq.edu.au.
authors.forename: Adam Ivan
authors.initials: AI
authors.lastname: Semciw
mesh_terms: D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D064368:Healthy Volunteers; D006615:Hip / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D055815:Young Adult
keywords: Electromyography; Groin; Hip; Hip capsule; Intramuscular