The inside word on biomechanics at Melbourne Sports & Allied Health Clinic - Q&A with Dr Oren Tirosh
Q: Your journey as a distinguished biomechanist is impressive. Can you tell us about your background, including highlights in academic, research and clinical practices?
A: My interest in how people coordinate their movements followed me since childhood. Being a sporty person with the ability to run very fast (4x200m Canadian intervarsity bronze medal) I was always curious with the mechanical aspects of movement. Following my degree in Physical Education and Sport Science, I completed my Master of Science in Rehabilitation Therapy in Canada. Later in Australia I completed my PhD studies investigating gait biomechanics and postural control at Deakin University, Melbourne.
Following my studies, I joined world leaders in gait analysis at the Royal Children's Hospital (Melbourne) gait laboratory, working there for 10 years developing better ways to utilize 3 dimensional (3D) clinical gait analysis techniques to assist orthopaedic surgeons in their diagnosis, planning, and decision making. Whilst working in the RCH gait lab, I also conducted gait research at Victoria University, investigating gait tripping probability and biofeedback gait training in older adults and stroke patients. I was also involved in a 2 year research project with the Australian Ballet School, investigating the relationship between postural stability and injury prevention.
The lack of high precision biomechanical assessments in the private sector convinced me in 2010 to establish biomechanical services for general public access, with the mission of providing scientific and high quality but affordable movement analysis services, which have historically only been availability in major sports, university and hospital-based institutions. These days, our scope of clientele is wide and varied, and include professional and amateur athletes; patients with orthopaedic or neurological disorders; commercial research/validation projects; job task analysis across many industries. A highlight in 2014 includes the successful collaboration with Australian high jumper Eleanor Patterson and her coach; winning gold at the 2014 Commonwealth Games.
Q: Biomechanics (high precision anatomical movement analysis) is highly relevant in medicine, sport & exercise performance, research, industry and education. Can you explain the circumstances that would typically bring someone to the clinic to engage biomechanical services?
A: For any diagnosis and intervention, the assessment must be precise and reliable in order to correctly diagnose the problem and later establish the effects of intervention. Precision means measuring with minimal true error and reliability means obtaining similar measurements at separate occasions when no intervention is applied. In clinical application, biomechanics is the diagnosis and treatment of patient’s postural control and movement such as gait. In running, for example, precision and reliability are important to assess the degree of hip rotation to reduce measurement error to correctly diagnose the cause of injury and later the effect of treatment. Similarly in sport, performance is assessed to explore inefficient movement patterns and later the effect of training on those patterns.
In the work place, it is important to understand the postural and movement patterns of workers to reduce work related injuries. Unsafe manual handling, for example, may cause a variety of injuries, and risk assessing can determine which manual handling tasks are hazardous. The postural demand assessment in manual handling during working hours, for example, aims to measure repetitions, sustainability, duration, range of movement, and movement velocity of the trunk (back), where a general guideline describes bending the back forwards or sideways more than 20°, twisting the back more than 20°, and backward bending of the back more than 5°, is a risk to inducing back related problems.
Biomechanics research can be applied on new devices developed for sport or medicine. The effect of the device on movement patterns can be reliably explored with high precision.
Q: Perhaps the most requested biomechanical service in the clinic is for the gold standard 3-dimensional running gait analysis. Can you explain the principle behind 3D gait analysis, and the benefits acquired by recipients? Also, can you briefly elaborate accuracy/reliability problems associated with other methods, such as 2D (single video camera) analysis?
A: 3D motion capture system using several infra-red cameras with reflective markers attached to the body segments are considered to be the gold standard in measuring human movement. The precision of these systems is sub millimetre, with maximum 0.5 mm error. 3D camera system allows assessment of multiplanar motion, and the high frequency cameras offer greater precision for tracking motion than 2D camera systems.
Based on research studies, 3D approach to gait analysis is superior to 2D. In 2D analysis, joint rotation is impossible to measure. Precise measurement of hip rotation for example is important to understand knee injuries such as Patellofemoral Pain Syndrome (very common running injury) where the increased hip internal rotation angle was shown to be associated with the injury. For highly skilled practitioners, the 3D dimensional model is preferred when studying motion between foot and lower leg during running. Researchers tend to err on the side of caution when attempting to assess gait patterns via 2D. Indeed, Cormack & colleagues (2011) verified previous observations and demonstrated a consistent overestimation of hip and knee measurements using 2D approach.
Q: Applying biomechanics across all industries is evolving rapidly. Can you give some examples of how biomechanics is used to quantify specific job tasks, and enabling of high precision “fit for work” and “injury prevention” programs?
A: Measuring the technique that workers use to complete job tasks successfully is important to define the physical demand and injury risk. Lifting-related musculoskeletal disorders affect all sectors of the working population. For example, 75% of bricklayers report low back pain symptoms. It is important to precisely assess what the workers are doing during their work, as there is no evidence that one lifting technique is best. Additionally, instruction in lifting techniques is generally limited to single lift scenarios, and these techniques are usually not applicable to more complex work tasks, such as lifting heavier items or lifting in teams. Knowing (by precise measurement) the task demand, “fit to work” assessments can be utilised. Specific injury prevention programs can be better planned and later their effect can be quantified.
Q: Can you share with us some of the more unusual biomechanical projects that you have been involved with?
A: In 2011 I was approached by John Waters to help with improving the skill of fishing rod casting. A sport event that I had never heard of before and I had no experience or knowledge with. John was ranked 36 in the world, regularly competing in the annual world championship. Initially I had to learn & interpret the biomechanical demands of requisite skills. Using my knowledge in athletic field events, I decided to explore a new movement pattern to improve his mechanical efficiency. Following the subsequent changes and his hard work and determination, John achieved third place in the recent world championship. Now eyeing the top step!
Q: There are very few private practices around the globe that can provide such a high level of biomechanics service and expertise. And even fewer that proactively integrate with physiology and rehabilitation specialists. Can you provide some insight into the typical steps proceeding biomechanical evaluation?
A: The first step in biomechanical evaluation is to understand the mechanical movement demands using the knowledge of mechanical principles and past research performed on the movement. This is to identify key mechanical features (variables) that are important for maximal performance and with minimal risk to injury. Then it’s a matter of choosing the best system that will precisely and reliably measure those key variables. Equally, it is important to choose the best data processing and analysis methods that are sensitive enough to identify any problems. Following assessment and data processing, the interpretation of the data is crucial. Understanding what the data means and how it is related to the performance and/or injury is crucial in the diagnosis and decision making for intervention.
In running for example, 3D motion capture is used to maximise precision and reliability. 3D gait analysis involves 1 hour data capturing where 42 reflective markers are attached to body segments and running is recorded using high speed cameras. Once the data is processed, analysed, and interpreted, we work closely with exercise physiologists to integrate the most appropriate prehab or rehab programs.
In measuring activity and trunk movement in the workplace, 3D accelerometer and gyroscope devices are used. The devices are attached to the back (spine) and record the body acceleration and trunk speed of rotation for several hours during work. Following data acquisition, the signals are processed and analysed to identify when and how much the person was active with additional information on the frequency of high risk events for back injury. Furthermore, data is integrated into practice by exercise physiologists for high precision fit for work programs and ongoing physical/physiological monitoring.