Sensitivity and Specificity of a Weight Distribution Platform for the Detection of Objective Lameness and Orthopaedic Disease

Abstract

Introduction Weight distribution and off-loading at the stance are commonly used subjective assessments during the orthopaedic examination. The clinical relevance, sensitivity and specificity of limb off-loading have not yet been established. The aim of the study was to assess off-loading on a weight distribution platform (WDP) and determine the sensitivity and specificity at various cut-off points for the detection of objective lameness (OL) and orthopaedic disease (OD).

Materials and Methods The total pressure index was used to determine OL on a pressure-sensitive walkway (PSW). Normal weight distribution on both the PSW and WDP was considered 30/30/20/20. A total pressure index standard deviation of 2 was used. The sensitivity and specificity of the WDP for the identification of OL and OD was determined at cut-off points 1 to 6 below normal weight distribution values.

Results All patients in the study (n = 50) had confirmed OD. The PSW identified 36/50 (74%) patients as OL; these were deemed to be OL for sensitivity and specificity analysis of WDP data. At cut-off point 1, the WDP had the highest sensitivity for OD (84%) and OL (97%). At cut-off point 6, the WDP had the highest specificity for OD (98%) and OL (98%). The highest combination of sensitivity and specificity for both OD (1.65) and OL (1.80) was at cut-off point 2.

Discussion/Conclusion The WDP provided the highest combined sensitivity and specificity at cut-off point 2 below the normal value for the detection of both OL and OD.

Keywords

weight distribution platform - lameness evaluation - objective assessment - stance evaluation

Author Contributions

All authors contributed to conception of study, study design, and acquisition of data and data analysis and interpretation. All authors also drafted, revised and approved the submitted manuscript.

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