Authors: Anna King, Gregory Macke, Jackson Romelli, and Lillie Orians

The body powered hook is a below the elbow prosthetic made to aid the user in pushing, pulling, grasping, and manipulating objects. The device was developed in response to the need of a more precise and functional 3D printed prosthetic option for youth performing every day activities.

Link to instructions: https://docs.google.com/document/d/13281-W6-YRYGgkORF4zv3KMnJTb92k0P/edit?usp=sharing&ouid=100673832100116241344&rtpof=true&sd=true

Link to bill of materials: https://docs.google.com/spreadsheets/d/1by01Mh6XaCK4AFNxpAwo9bxICZA4PbFz/edit?usp=sharing&ouid=100673832100116241344&rtpof=true&sd=true

The body powered hook is made up of four main parts. It can be adapted to work for users in need of both sides or one. The first system is the hooks of which there are currently two designs. The J-hook is placed on the dominant side of the user. The J-hook is designed for fine motor skills and grabbing and manipulating small objects. The it can be used to hook around and push/pull objects or it can be opened to grab ahold of objects. The second design is the rounded hook which is placed on the non-dominant side of the user. The hook is designed to complement the J-hook and is best suited to grab hold of rounded objects or larger ones that don’t fit in the narrower grasp of the J-hook. The hooks are anchored into the socket interfacing block using a bolt and nut. This mechanism allows the hooks to be loosened, replaced, and for the angle of the hook to be adjusted within the confines of the cable position. The silicone grip covers slide over the end of each hook arm to provide grip to the hooks and aide in picking up objects. The hooks are made of a strong polycarbonate material that can flex slightly to not break under stress.

The second system is the socket. The socket fits over the arm of the user to comfortably hold the prosthetic hooks on the arm. The socket can be tightened by pulling on the Velcro straps which causes the leaves of the socket to flex and tighten around the arm. The socket can be anchored to the harness using one or two additional straps which attach via slits on the top of the socket. The socket is made of flexible material for increased comfort and to allow it to be tightened down by the user. The socket is the most customizable part of the body powered hooks. It is likely that the socket will need to be customized and remodeled for each unique patient. A silicone sock is slid over the arm and then the socket. This is the best found way to pad the socket for user comfort while not allowing the socket to easily slide off.

The third system is the figure eight harness. The harness fits around the shoulders of the user similar to a backpack. It connects the cable mechanism to the body and helps control the opening and closing of the hooks using the movement of the user. The harness is made of nylon straps and is held together with adjustment clips so that it can be sized to the user.

The fourth system is the cable mechanism. The cable mechanism consists of a combination of nylon strap and metal cable running from the middle of the back to the end of the hook. It runs through the tricep guide and guide holes on the socket. The cable mechanism maintains a fixed length and as the user pushes forward with their arm it creates tension which pulls on the mobile side of the hook to open it. The cable mechanism is made of metal hardware components, colored nylon straps (different colors help with strap management), Teflon tubing, and a flexible TPU tricep guide.