Mean flexion-extension for the hip, stifle, and tarsal joints for a representative limb from each cat using the multiplane and sagittal plane kinematic models during the step cycle for gait.

<p>Cat 1 corresponds to the cat in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197837#pone.0197837.g004" target="_blank">Fig 4</a> and Cat 2 corresponds to the cat in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197837#pone.0197837.g005" target="_blank">Fig 5</a>.</p

Mean stifle joint kinematics for a representative hind limb using both stifle prediction techniques during the step cycle for gait.

<p>Technique 1 corresponds to the unadjusted tibia axis, and technique 2 corresponds to the adjusted tibia axis. Flexion-extension angles correspond to the absolute angle between the segments while positive values indicate external rotation and abduction, and negative values correspond to internal rotation and adduction. The dashed horizontal lines indicate 0° (neutral) on external-internal rotation and abduction-adduction graphs.</p

Mean (solid line) ± SD (dotted line) three dimensional joint coordinate system kinematics for the hip, stifle, and tarsal joints for a representative hind limb during the step cycle for gait.

<p>Flexion-extension angles correspond to the absolute angle between the segments while external rotation and abduction correspond to positive and internal rotation and adduction correspond to negative. The dashed horizontal lines indicate 0° on external-internal rotation and abduction-adduction graphs.</p

Cat kinematics experimental setup overhead view.

<p>Ten infrared motion capture tracking cameras (numbered 1–10) surrounded the walkway, and 2 synced video cameras (indicated with A and B) were placed on opposite sides of the walkway to record sagittal plane movements. Camera locations relative to the motion capture space origin are indicated in the table, and the walkway length and width are shown. The walkway was 1.0 m above the ground, and the motion capture space origin was on the surface of the walkway.</p

Lateral stifle virtual marker (dark sphere) projection techniques.

<p>Tibia axis 1 (light arrow along the tibia) was defined as the vector of length equal to the fibula length originating at the lateral malleolus projected through the vector marker. The femoral axis was defined as the vector of length equal to the femur length originating at the greater trochanter projected towards the fibula vector endpoint. The lateral stifle virtual marker was defined as the midpoint of the line connecting the endpoints of tibia axis 1 and the femoral axis. Tibia axis 2 (dark arrow along the tibia) was defined as the vector of length equal to the fibular length originating at the lateral malleolus projected towards the lateral stifle virtual marker determined previously.</p

Hip, stifle, and tarsal mean (solid line) ± SD (dotted line) kinematics for the <i>ex vivo</i> walking task using the transformed bony landmark marker set and the triad marker set.

<p>The horizontal dashed line indicates 0° on external-internal rotation and abduction-adduction graphs.</p

Hind limb specimen with bony landmark markers (gray circles) and marker triads (white circles at triangle vertices).

<p>Markers and marker triads are adhered along the pelvis and a single limb. The left hind limb was suspended to prevent obstruction of the right hind limb markers. The right hind limb was manipulated using the rigid extension (identified with a white arrow) attached to the metatarsal bones distal to the tarsus triad. Reflective markers can be seen at the stifle and anterior tibia, but these markers were not used in the current study.</p

Cat model anatomical coordinate systems and directional unit vector axes.

<p>Cat model anatomical coordinate systems and directional unit vector axes.</p

Bilateral mean and SD, maximum, and minimum joint angles, and range of motion (ROM) throughout the average step cycle for each joint rotation from a representative cat using the multiplane model.

<p>Bilateral mean and SD, maximum, and minimum joint angles, and range of motion (ROM) throughout the average step cycle for each joint rotation from a representative cat using the multiplane model.</p

Cat model anatomical coordinate systems.

<p>Anatomical coordinate systems were determined for the pelvis, femur, tibia, and tarsus.</p