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Tom Collins
04-09-2008, 02:06 AM
Hello all,

We are having problems with tracking ASIS markers during 3D-kinematic gait analysis of some patients; we wondered if any of you had come across a similar problem and had found any solutions?:

For clinical gait analysis we use a variation of the Helen Hayes marker set (Kadaba et al. 1990, J Orthopaedic Research 8(3):383-392) with 8 Qualisys infra-red cameras, distributed approximately in an oval around the measurement volume, above head height. For some patients seen in the Gait Lab, particularly with hemiplegia, one arm is held relatively immobile beside the body during walking. Depending on the particular position of the arm it sometimes blocks line-of-sight for cameras recording the position of the ASIS marker nearest to the arm, with the result that there are considerable gaps in the trajectory data for this marker.

We have tested using various alternative markers, such as over the iliac crest, or using 2PSIS markers and 1ASIS, but results have notable differences when compared to the standard marker set results, which means we don't have confidence in what is being shown. One possible solution could be to strap the patient's arm in an elevated position but presumably this would alter their gait pattern, and the change would be hard to quantify.

Have you incountered similar problems with some patients?
If so, what solutions have you found?

Thank you very much for any suggestions you can offer. I will post a summary of any replies, as appropriate.

Tom Collins
Gait Laboratory
Douglas Bader Rehabilitation Centre
Queen Mary's Hospital
London, UK
thomas.collins@wpct.nhs.uk

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