### RESULTS: Angular Kinematics

Segment angle. The absolute angle of the trunk was analyzed for one complete crutch-gait cycle for both the Hope and Standard crutches. The range of motion when the subject used the Hope crutches (15.3 degrees) was 1.6 degrees smaller than the 16.9 degree range of motion exhibited when the subject used the Standard crutches. Similarly, the maximum and minimum angles for the Hope crutches (7.91 and -7.35 degrees respectively) were 1.82 and 0.23 degrees smaller than the maximum and minimum angles for the Standard crutches (9.73 and -7.12 degrees respectively). The gait using the Standard crutches had a slightly higher maximum angle, while the minimum angle with the Hope crutches was only minimally smaller than that of the Standard crutches.

 Figure 3. Trunk segment angle during Hope-crutch gait (left) and Standard-crutch gait (right). The trunk segment angle is calculated as the angular difference from the vertical. Anatomical position corresponds to 0 degrees. Increasing values represent clockwise rotation from the vertical.

Joint angle 1. The range of motion at the hip joint when the subject used the Hope crutches (53 degrees) was 13 degrees smaller than the 66 degree range of motion for the hip joint exhibited in the Standard-crutch gait. The maximum angle for the Hope crutches (201 degrees) was 8 degrees smaller than the maximum angle for the Standard crutches (209 degrees). The minimum angle for the Hope crutches (148 degrees), however, was 5 degrees larger than the minimum angle for the Standard crutches (143 degrees). Maximal extension values of the hip for the Hope and Standard crutches were obtained at 51.3% and 64.1% of the stride cycle, respectively. The smallest angle using the Standard crutches was obtained at 97.4% of the stride cycle. On the other hand, the smallest angle when using the Hope crutches was obtained at 79.5% of the stride cycle.

 Figure 4. Hip joint angles during Hope-crutch gait (left) and Standard-crutch gait (right). The hip joint angle is calculated as the lateral angle between the thigh and trunk. Anatomical position corresponds to 180 degrees. Increasing values represent extension.

Joint angle 2. The pattern of the knee joint angles varied little between the two crutch movements. The maximum angle (178.9 deg) and range of motion of the knee (58.2 deg) for the Hope-crutch gait were slightly greater than the maximum angle (176.1 deg) and the range of motion (51.3 deg) for the Standard-crutch gait. However, the smallest angle of the knee joint was greater in the Standard-crutch gait (124.8 deg) then in the Hope-crutch gait (120.7 deg). Further, the timing of both movement patterns was similar. In fact, the percentage of total movement time of the Hope-crutch gait (95% of the total movement time) and the Standard-crutch gait (95% of the total movement time) was the same. Peak knee flexion also occurred at similar times for the Hope-crutch gait (77% of total movement time) and Standard-crutch gait (74% of total movement time).

 Figure 5. Knee joint angles during Hope-crutch gait (left) and Standard-crutch gait (right). The knee joint angle is calculated as the lateral angle between the thigh and lower leg. Anatomical position corresponds to 180 degrees. Increasing values represent extension.

Joint velocity. The Hope-crutch gait (340 m/s) had a higher maximum joint velocity then the Standard-crutch gait (307 m/s). Further, the Hope crutch gait (-348 m/s) and a greater minimum joint velocity then the Standard crutch (-296 m/s). The knee reached a maximum joint velocity in the Hope-crutch when the movement was 93% complete, while the maximum joint velocity occurred in the Standard-crutch gait when the movement was 85.7% complete. Like the timing of the maximum joint velocity, the timing of the minimum joint velocity in both movements was also similar. In the Hope-crutch the minimum joint velocity occurred when the movement was 64.1% complete, while the minimum joint velocity in the Standard-crutch gait occurred when the movement was 67% complete.

 Figure 6. Knee joint velocity during Hope-crutch gait (left) and Standard-crutch gait (right). Positive values represent extension.

Angle-Angle Plot. Coordination between the knee and the hip joints differed slightly between the two crutch-gaits. The differences occurred during the end of the crutch-gait cycle. With the Hope crutches, the coordination between hip and knee joints was almost sequential for the last 27.5% of the crutch-gait cycle. In contrast, during this same period of time with the Standard crutches, the coordination between hip and knee was coupled. In both crutch gaits, the first 50% of the movement consists primarily of hip extension with little change in knee angle.

 Figure 7. Coordination of hip joint and knee joint angles in the Hope-crutch gait (left) and Standard-crutch gait (right). The hollow square on each graph represents the beginning of the movement. The graph is read in a clockwise direction beginning at this square and continuing through the full circle.