Psychometric Evaluation of the Hill Assessment Index (HAI) and Stair Assessment Index (SAI) In High-functioning Transfemoral Amputees

The hill assessment index (HAI) and stair assessment index (SAI) were developed to objectively evaluate ramp and stair gait. This study's purpose was to determine the validity and reliability of these tests in a sample of persons with unilateral transfemoral amputation (TFA) using microprocessor prosthetic knee systems. All subjects were fit with a microprocessor knee system. After accommodation, subjects performed three trials ascending and descending a 5° ramp and a flight of stairs while being recorded on video. Sensitivity and specificity for the HAI was calculated against degree of asymmetry in step length using Dartfish video analysis software. Reliability was assessed using intraclass correlational coefficients calculated using Spearman's Rho (r_s). A priori significance level was set at p ≤ 0.05. Twenty (n = 20) individuals with TFA completed the study protocol. Sensitivity and specificity of the HAI were calculated at 88.0% and 75.0% during ascending conditions and 94.0% and 67.0% during descending conditions, respectively. Significant correlations for the HAI included r_s = 0.87 and r_s = 0.73 within raters uphill and downhill, respectively. Corresponding coefficients of r_s = 0.80 and r_s= 0.67 were calculated between raters. For the SAI, significant correlations included r_s = 1.00 for both comparisons within raters and in the comparison between raters in the ascending condition. A correlation of r_s = 0.89 was calculated for the between-rater comparison in the descending condition. The HAI showed moderate to excellent sensitivity and specificity but good to adequate reliability. The SAI showed excellent to good reliability.