Green - Clinical anatomy: function and rehabilitation of stabilizing muscles
Muscles play a key role in stabilizing multiaxial joints such as the hip and the shoulder. The function of these muscles, particularly deeper muscles and those that have multi-directional fibre orientation is poorly understood. As a consequence, rehabilitation programs for these muscles also have limited success. Our electromyography laboratories at Bendigo and Bundoora have pioneered techniques to insert intramuscular electrodes into muscles at both the hip and shoulder to understand the role of these muscles in the human body.
Structure and function of the hip abductors in hip osteoarthritis (OA)
World-first techniques have been developed in our laboratory for the examination of the hip abductors (gluteus medius (Gmed) and gluteus minimus (Gmin)) using intramuscular electromyography (EMG). These muscles are well known to be the key hip stabilizers during gait but we have shown them to be composed of multiple segments with unique functional characteristics.
Hip OA is frequently characterized by atrophy of these muscles and this results in significant functional deficits that are not improved by current rehabilitation programs. An improved understanding of the function of these unique muscle segments in hip OA patients will assist in developing more effective rehabilitation programs. Our work has seen the development of close links with allied health staff at Bendigo Health for the recruitment of participants. Our study has confirmed atrophy and increased levels of fatty infiltration in these muscles compared to a matched control group using magnetic resonance imaging (MRI). The EMG data on individual segments is currently being analyzed and will provide world-first data in an OA population. A second study looking at the function of these muscle segments before and after hip replacement surgery is now underway.
Confirmation of the stabilizing role of the rotator cuff muscles
The shoulder is a notoriously unstable joint that is susceptible to a variety of pathological conditions in both athletic and elderly populations. We have examined the clinical anatomy of a number of shoulder conditions using a combination of electromyographic (EMG) and cadaveric studies over several years.
This project examines more directly the postulated stabilizing role of the rotator cuff group of muscles (supraspinatus, infraspinatus, subscapularis and teres minor) that account for >80% of shoulder pathology cases. We have explored the concept of muscular stability and particularly the rotator cuff muscles in two published reviews and have published a paper establishing the basis for ultrasound guided insertion of EMG electrodes into the teres minor (a notoriously difficult task). Our group recently completed a study establishing the reliability of a new technique for measuring shoulder translation (a measure of instability) using ultrasound. This study was conducted in collaboration with the chief sonographer from Bendigo Health. Data collection, incorporating EMG to look at the postulated stabilizing activity of the rotator cuff muscles, is well underway. Future research will seek to establish 'proof of concept' in a population with rotator cuff pathology in collaboration with shoulder surgeons and local physiotherapy practices.
Gluteal exercise for Hip Osteoarthritis patients – the GHOst trial
Rod is leading a project that has been funded by Arthritis Australia, Arthritis New Zealand and the La Trobe Sports, Exercise and Rehabilitation RFA to conduct a multi-site randomized controlled trial to determine the efficacy of a high intensity exercise program in improving structure and function of the hip muscles in hip osteoarthritis (OA) patients. This project is the culmination of several years of work establishing the electromyography techniques to determine the function of these muscles in healthy young adults and more recently a hip OA population. The program is running at Bendigo, Melbourne (being run by Dr Tania Pizzari) and Dunedin (New Zealand, being run by Dr Stephanie Woodley) sites. The program is particularly targeted at anterior segment of the gluteus minimus muscle that is not routinely targeted by existing programs but is an important anterior hip stabilizer that has shown significant atrophy in our MRI studies. Recruitment is currently underway at all sites.
Meet the team
Lachlan van Schaik