## Materials and Methods
### Data Reduction and Analysis  
We analyzed maximal values of the following joint kinematics at defined events of the gait cycle: frontal plane pelvic obliquity during mid-stance and mid-swing phases, hip flexion-extension during initial contact, terminal stance and mid-swing phases, hip adduction-abduction during mid-swing phase, knee flexion-extension and ankle dorsi-plantar flexion during initial contact, mid-stance, terminal stance and mid-swing phases and ankle dorsi-plantar flexion during foot off (Table 2).  
These values were chosen as they have been previously found to dynamically compensate for LLD [1; 3; 7; 8], by a significant difference in kinematical angles measured on the longer versus the shorter lower limb. Thus, kinematic asymmetry was assessed by calculating the difference between the longer and shorter lower limb's kinematic angles. Gait variables were normalized at 51 data points.  
Throughout the gait cycle, the functional leg length was measured by three separate DLLs, measuring the distance from the hip joint center to the heel marker (HDLL), to the ankle joint center (ADDL) and to the forefoot marker (FDLL) [7; 10; 11] respectively (Figure 1). The PGM ascertained the virtual trajectories of the hip and ankle joint centers.  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Kinematics** & **Gait Events** \\ \hline Pelvic obliquity & Mid-stance, mid-swing \\ Hip flexion-extension & Initial contact, terminal stance, mid-swing \\ Hip adduction-abduction & Mid-swing \\ Knee flexion-extension & Initial contact, mid-stance, terminal stance, mid-swing \\ Ankle dorsi-plantar flexion & Initial contact, mid-stance, terminal stance, mid-swing, foot off \\ \hline \hline \end{tabular}
\end{table}
Table 2: Maximal joint kinematic values analyzed at defined gait events.  
Clearance index was defined as the difference between the maximal DLLs measured during stance phase (right or left) and the minimal DLLs measured during the contralateral swing phase (left or right) [7]. Mid to terminal stance was defined as the stance phase; mid-swing was defined as the swing phase. These values are most critical in the gait cycle where the maximal functional leg length during stance is required to clear the contralateral side while the minimal functional length during the swing phase is required to clear the foot off the ground. A higher index value occurs during the longer limb swing phase due to excessive functional shortening and/or functional elongation of the shorter limb during the stance phase [7]. A lower index value may be present due to excessive functional shortening of the longer limb during the stance phase and/or decreased functional shortening of the shorter limb during the swing phase [7]. Thus, the clearance index allows quantifying the functional discrepancy, which is the difference between the right and left clearance index. The clearance index was identified according to the side of the swing limb and was found to be symmetrical among the 40 healthy participants evaluated in the same gait laboratory (Figure 2) [7; 11].  
Figure 1: DLLs during the gait cycle phases measured from hip joint center (HJC) to the heel marker (HEEL), to the ankle joint center (AJC) and to the forefoot marker (FF) ((**A**) initial contact, (**B**) mid stance, (**C**) pre-swing, (**D**) mid swing).  
Figure 2: A boxplot representation of the differences (in mm) between maximal DLLs throughout the stance phase and the contralateral minimal DLLs throughout the swing phase among 40 healthy controls from prior analysis made in the same gait laboratory.