Richard Baker PhD CEng CSci
Director Gait CCRE/Gait Analysis Service manager
Murdoch Childrens Research Institute
Royal Childrens Hospital
Parkville 3052, Victoria, Australia
Tel (+613) 9345 5354,
Fax (+613) 9345 5447
Email: richard.baker@rch.org.au
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Clinical gait analysts have recently been focusing their attention on marker placement error – a problem which can arise when the reflective markers are not placed in exactly the same position on every occasion. This has been a key focus for Dr. Baker. “Over the past 20 years many of us have
been concerned that this might be a potential source of inconsistencies both within and between different centres. So for example, three clinics performing the same test on the same person may have varying results because the placement of the markers doesn’t match at each clinic.
Over the last five years however several studies have been published suggesting that the problem, in those centres studied, is far bigger than any of us would ever have imagined.” One of the problems is that almost all clinical laboratories are using software developed 20 years ago and designed
for the camera technology that was available then. Dr. Baker’s work has highlighted ways to overcome this by using more markers and placing them
in different positions. He is also using a new generation of software incorporating optimisation techniques to determine where the bones are in relation to the markers. These rely much less on the precise placement of the markers. The most recent results suggest that the repeatability of measurements from the new techniques is at least as repeatable as that of the most experienced staff using the old techniques.
Welcome to the Gaitabase
One of the reason the problem has remained undetected for so long is that clinical labs very rarely share data and make comparisons. To try and solve this issue, Dr Baker and colleague Dr Oren Tirsoh have devised the Gaitabase http://gaitabase.rch.org.au. The Gaitabase is a pool of gait analysis related information contributed by clinics and research centres around the world. The information is accessible to anyone for analysis and
comparison with other research on the site. Information is searchable under categories such as symptoms, research contributor, patient age, left/right foot results, anatomical criteria and many other categories. Early analysis of the data on the Gaitabase has confirmed visually that variability of measurements can vary considerably between laboratories and between different staff in those laboratories.
Another colleague Dr Jenny McGinley has been working on methods to quantify just how much variability there is in data and has developed the concept of Gait Reliability Profiles to tell staff and laboratories just how well they are performing. This uses state of the art statistical techniques to produce measures which are simple and easy to interpret.
Gait reliability profiles showing differences in performance between a very experienced and less experienced assessor.
The most recent step in this work has been to incorporate the Gait Reliability Profile software into Gaitabase so that anyone with access to the internet can upload their own data and receive a full analysis of how well they are performing at a simple mouse click. It is possible that this might lead to a scheme for certifying gait analysts. It certainly has the potential to allow doctors to assess which clinics they can trust and which
they would like to disregard. In practice, this will prove invaluable to patients who suffer with physical impairments. There are a wide range of medical
conditions that might cause someone to require gait analysis, but physiotherapists working with this technology most often find themselves working with children with Cerebral Palsy. This is a neurological disorder that greatly affects the movement of an increasing number of children each
year. There are currently over 17,000,000* people worldwide affected by CP. Dr.Baker explains: “As with most physical impairments each case is different, making the treatment potentially costly and time consuming. It is essential that we can rely on the data we capture from whichever laboratory it is being captured in. The main symptom of cerebral palsy is a difficulty with movement. Simple things that most people take for granted,
like climbing stairs, can be a daily struggle for some sufferers. There is no known cure, and patients are relying on gait analysis-based treatment
diagnoses to help alleviate some of their impaired movement.”
Although 17,000,000 sounds a huge number across the world, any one centre only sees a small proportion of this and some centres see very few. Gaitabase makes it possible for different centres to share data and thus to allow results from a much greater number of patients to be compared. It is hoped that this will greatly increase our capacity to learn more about this disease and how to treat it.
Dr. Baker and Vicon are thus making it possible for surgeons and other medical professionals to make more informed decisions when it comes to their patients, thanks to the data available in the Gaitabase. That can only be good news for all those people with cerebral palsy.