Design Concept and Rationale

Design Concept

The Scissor Stopper is a device that serves as a physical divider between the legs of a patient with a scissor gait to prevent the legs from crossing while the patient walks (Figure 3). Its frame is an L-shape, with the longer side resting between the legs of the user and the shorter side attaching to the frame of the walker on the supporting bar parallel to the ground. The Scissor Stopper attaches to the walker by a clamp that clamps around the bar of the walker and attaches to a metal bar with a flange. The L-shape frame can easily be screwed into the metal bar and lay on the flange by using screws to attach them, allowing for vertical adjustability to account for the different builds of its users. The section of the frame resting between the user's legs is padded to make the device more comfortable. Finally, there is a crossbar that rests at the inner corner of the L-shaped frame, parallel to the ground, that prevents the device from swinging in line with the movement of the walker. The crossbar allows for the device to attach more securely to the walker.

For measurements of our device, see Appendix I: Dimensionalized Sketches.
For instructions of construction and use and materials used, see Appendix J: Instructions of Construction and Appendix K: Instructions of Use.

Figure 3

Figure 3: Overall design of Scissor Stopper

The following sections describe the components of our device – clamp, flanged rail, L-shaped frame, and crossbar – as well as the rationale for each component.

Clamp

Specifications and use
We used a vibration-damping loop clamp with a 1 inch diameter (Figure 4) that will loop around the top horizontal bar (Figure 5). This clamp will attach to the metal with the flange, which will support the whole device.

Figure 4

Figure 5

Figure 4: Dimensions of clamp

Figure 5: Clamp on Walker

Rationale
The clamp is ultimately how the Scissor Stopper attaches to the walker. It serves as an essential attachment point to the walker. During mockup testing, we realized that a clamp would provide the most stability for attaching our device to the walker (Appendix H). Additionally, we noticed that in order for the protruding divider to be centered, we would need to offset the clamp about 1 inch from the center of the walker (Figure 5) because of the flanged rail. The molded cushion of the clamp provides a more secure fit so that the clamp can attach to walkers that are different sizes. Additionally, with the cushioning, the clamp can still be secure even if the clamp is around something that is not perfectly circular, especially if the clamp is offset from the middle of the walker.

Aluminum was chosen for the material of the clamp because it has good corrosion resistance and can be easily cleaned. Neoprene was chosen for the material of the cushioning since it offers strong resistance to tears and cuts. Neoprene is also resistant to damage caused by abrasion, flexing and twisting, and has good adhesion to fabrics and metals. The neoprene creates a tighter fit around the walker for the clamp, which is essential because it serves as the only attachment point of the device to the walker.

Flanged Rail

Specifications and use
The rail (metal without the flange) dimensions are 1½ x 12 x 1½ inches, while the flange has a width of 1½ inches and a length of 12 inches (Figure 6). The flanged rail attaches to the clamp and is oriented vertically, with the flange centered at the middle of the walker. The rail has bolt holes on all four sides that are 1½ inches apart from each other.

Figure 6

Figure 6: Flanged rail

Rationale
The bolt holes on the flanged rail allow for easy connectivity to the clamp and the L-shaped frame. The flanged rail acts as the main connector between the device and the clamp on the walker. The consistently spaced bolt holes allow for multiple mounting options of the L-shaped frame to the flanged rail, creating the adjustable feature of our device (Appendix G). Also, the bolt holes allow for easy tightening and loosening of the flanged rail from the L-shaped frame so the device can be adjusted conveniently without a screwdriver or wrench.

The flange is important because it creates a support that the vertical part of the L-shaped frame can lay on (Appendix G). This will enhance the stability of our device. During client testing, our overall design was not stable or secure, causing it to move around as the walker was moved. Therefore, in our final design, we choose a flange as an extra support.

Aluminum was chosen for the flanged rail because it is lightweight and resistant to corrosion, allowing it to withstand multiple uses (Appendix A). Since aluminum is lightweight, it will not hinder the patient from using our device (Appendix G). Additionally, aluminum can be easily cleaned, which is beneficial since we expect our device to be used by different patients for several years.

L-shape Frame

Specifications and use
The L-shape frame acts as the body of the device. The vertical bar is 1½ x 12 x 1½ inches while the horizontal bar is 1½ x 30 x 1½ inches (Figure 7). The horizontal bar acts as the divider between the legs. Each of the bars have consistently spaced bolt holes that are 1½ inches apart. They are connected using a corner bracket. Additionally, there is padding on the horizontal bar.

Figure 7

Figure 7: L-shape frame

Figure 8: Corner bracket for L-Frame

Rationale
We used aluminum for the frame since it is lightweight, durable. and has resistance to corrosion (Appendix G). During client testing, our client told us that the barrier, which had a length of 22 inches, should be longer and extend past the walker (Appendix F). This is because even though patients typically stand close to the walker, they do not step all the way inside/to the front of the walker. Therefore, in our final design, we made the barrier length 30 inches.

The vertical and horizontal portions are connected by a corner bracket, which will combine them into a L-shape frame (Figure 8). The bolt holes on the vertical portion of the L-frame can mount to any holes on the flanged rail, which allows the frame to be placed at multiple heights. This creates a barrier that can be placed at adjustable heights, and therefore, fit multiple users. The padding on the barrier allows for comfort when the patient utilizes the device, since many existing solutions lack comfort.

Crossbar

Specifications and use
The crossbar is made of the same material as the L-shape frame. The dimensions of the crossbar is 1½ x 26 x 1½ inches. The cross bar lays on the inner corner of the L-shape frame and will stop the device from swinging as the patient moves the walker (Figure 9). This will add more security for the device to the walker and stop the device from wobbling.

Figure 9

Figure 9: Crossbar on L-shape frame

Rationale
The crossbar is made from the same aluminum material as the L-shape frame for the same reason: it is lightweight and durable (Appendix A). During client testing, our client told us that the crossbar was effective on smaller walkers, but would not work well with a wider (bariatric) walker (Appendix F). The crossbar was originally 22 inches, so we made it 26 inches in the final design. Additionally, our client told us that the crossbar needed a permanent attachment or else it would fall off the frame, so we decided to screw it to the frame so that it would move as a whole complex.