Internal View
Design Background
This device is a single use hand piece used for cutting cranial bone during endoscopic craniectomies for infants. Currently, surgeons use scissors to cut cranial bone in this context; the only powered option on the market is available exclusively for open surgeries. This device will help expedite minimally invasive craniectomies and increase accuracy and safety of this procedure.
Design Concept
Because it is single use, the motor housing was designed to be manufactured from gamma-sterilizable plastic, which will be ultrasonic welded during assembly. Using a worm gear set up to transfer rotary motion to the cutting bit keeps a low profile and drastically gears down the speed from the motor. This allows for transfer of a higher torque to the cutting bit, which is required to cut bone. Using laser welding at the seams of the cutting bit housing, which is made from stainless steel, allows for manufacturing of a single piece housing with a complex shape. Existing cutting bits currently used in craniectomies were adapted to interface with the hand piece.
Design Analysis
Extensive testing and surgeon feedback was required to source cutting bits sufficient for infant cranial bone. The motor housing was designed to be injection molded, including ultrasonic weld features for ease of assembly and manufacturing. In-depth design analysis was conducted to maintain a low profile for the cutting portion of the device, restrained by the endoscopic nature of the procedure. Input from the laser weld supplier was used to determine proper weld settings and callouts, which ensured the stainless steel housing would be properly welded.
Gear Interface View