The Number of Gait Cycles Necessary to Obtain a Representative Measure of Knee Joint Loads in Individuals With Lower Limb Amputation

It is unknown how many gait cycles are necessary to assess medial tibiofemoral joint contact forces (mTJCF) for individuals with lower limb amputation. The purpose of this study was to determine the number of gait cycles necessary to achieve a representative measure, and to determine the reliability of intact limb mTJCF. Gait data were extracted from 14 individuals with transtibial amputation; simulations were performed using OpenSim. A sequential analysis technique was used to determine the number of gait cycles to achieve a representative measure using thresholds derived from the literature, and another using 0.25 standard deviation of the data. Reliability of the continuous set of gait cycles was also determined using an intraclass correlation coefficient analysis. Using the literature-derived thresholds, 3 gait cycles were necessary to achieve a representative measure of all 3 variables. Using the more stringent 0.25 standard deviation threshold, 9 gait cycles were required. All mTJCF variables demonstrated excellent reliability (ρ > .99). Our results suggest when analyzing mTJCF, ≥3 gait cycles are necessary to achieve a representative measure, though 9 gait cycles improve precision by >75%. The results of the study provide guidance to researchers toward selecting the number of gait cycles to analyze based on their research objectives.