Fig 1.
Demonstration of analysis region relative to the gait cycle.
The analysis region was from toe off of the involved limb to contralateral heel strike and is shown in the shaded box. The timeline at the top of the figure shows analysis region percentages matched to important gait events (i.e., 0% of the analysis region occurs at 60% of the typical gait cycle, or at the time of involved limb toe-off). A full gait cycle was unable to be obtained due to limited ground reaction forces provided by the set-up of the force plates.
Fig 2.
A: Diagram of femur on acetabulum resultant joint contact forces (JCFs) in the pelvic reference frame.
B: Assistive diagram showing proposed variables: theta (Θ) and phi (Φ) in respective right-triangles formed in a planar (2D) view. Fres = Resultant JCF; POS = posterior; ANT = anterior; LAT = lateral; MED = medial; SUP = superior.
Table 1.
Demographic representation of participants in the FAIS and healthy control groups. Data were reported as mean ± standard deviation for continuous measures and median (interquartile range) otherwise.
Table 2.
Maximum involved limb strength values normalized to body mass and presented as measured force (N/kg) and torque (Nm/kg) for individuals with femoroacetabular impingement syndrome (FAIS) and healthy controls. Data are presented as median (interquartile range).
Table 3.
Post hoc SnPM paired t-test results for the resultant joint contact force (JCF) and the average of the difference between conditions across the analysis region. Direction of difference compares each strength condition to default. Significant differences with the specified p-value occurred over the listed range of the analysis region.
Fig 3.
A: Timeseries curves for the resultant joint contact force (JCF) of the default, 50% and 75% conditions;
B: Timeseries curves for the resultant joint contact force (JCF) of the default, 125%, and 150% conditions; C: Differences in JCF magnitude between each scaled condition and the default. Analysis region begins at swing and ends at terminal stance (TS) as indicated on the x-axis.
Table 4.
Post hoc SnPM paired t-test results for the anterior, superior, and medial components of the joint contact force (JCF). Direction of difference compares each strength condition to default. Significant differences with the specified p-value occurred over the listed range of the analysis region.
Fig 4.
Timeseries curves for the anterior, superior, and medial components of the joint contact force (JCF) for the default, 50% and 75% conditions (column 1), the default, 125%, and 150% conditions (column 2), and the difference in JCF magnitude between each scaled condition and the default (column 3).
A1-3: Data for the anterior JCF. B1-3: Data for the superior JCF. C1-3: Data for the medial JCF. Analysis region begins at swing and ends at terminal stance (TS) as indicated on the x-axis.
Fig 5.
Theta (Θ) vs Phi (Φ) joint contact force (JCF) vector path of increased and decreased strength conditions in comparison to default condition (100%).
Gait event labels are placed for orientation at beginning and end of vector path: TO = involved toe off (start of the analysis region), IC = initial contact, MS = midstance, TS = terminal stance (end of the analysis region). Color-coordinated circles represent regional loading centers of each condition calculated per least squares algorithm.
Fig 6.
3D plots comparing resultant joint contact force (JCF) magnitude (Force [BW]) between the default and each strength condition.
Gait cycle events are labeled in A and correspond to all plots. A: 50% vs default (100%) condition. B: 75% vs default condition. C: 125% vs default condition. D: 150% vs default condition. TO = involved toe off, IC = involved initial contact, MS = involved midstance, TS = involved terminal stance.