The comparison of normative reference data from different gait analysis services

Abstract

Comparison of normative data between gait analysis services offers the potential to harmonise data collection protocols. This paper presents a method for such a comparison based on an assumption that the root mean square difference from the inter-service mean is a reflection of systematic differences in protocols and that the average standard deviation includes a component attributable to within-centre measurement variability.Substantial normative datasets from two highly respected clinical services were compared. The RMS difference for the difference from the inter-centre mean was less than 1.7° for all kinematic variables apart from hip rotation (2.9°) and foot progression (2.1°), less than 0.1Nm/kg for all joint moments and than 0.21W/kg for all joint powers. The two centres showed very similar normative standard deviations.The data demonstrates a high degree of consistency between data from two highly regarded gait analysis services and establishes a baseline against which other services can assess their performance. An electronic appendix includes data to facilitate this comparison. THE COMPARISON OF NORMATIVE REFERENCE DATA FROM DIFFERENT GAIT ANALYSIS SERVICES ABSTRACTComparison of normative data between gait analysis services offers the potential to harmonise data collection protocols. This paper presents a method for such a comparison based on an assumption that the root mean square difference from the inter-service mean is a reflection of systematic differences in protocols and that the average standard deviation includes a component attributable to within-centre measurement variability.Substantial normative datasets from two highly respected clinical services were compared.The RMS difference for the difference from the inter-centre mean was less than 1.7° for all kinematic variables apart from hip rotation (2.9°) and foot progression (2.1°), less than 0.1Nm/kg for all joint moments and than 0.21W/kg for all joint powers. The two centres showed very similar normative standard deviations.The data demonstrates a high degree of consistency between data from two highly regarded gait analysis services and establishes a baseline against which other services can assess theirperformance. An electronic appendix includes data to facilitate this comparison.

The impact of standard combined anteversion definitions on gait and clinical outcome within one year after total hip arthroplasty

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