Orthopaedic Robot

I worked on this robot during my 2 years at Prosurgics, a UK-based medical robotics company. The robot was designed to assist guidewire placement in a Dynamic Hip Screw operation. Such a robot could reduce operation time, reduce the potential for human error and the need for supervision of junior surgeons. Patient outcome would be improved through better accuracy in screw placement, reduced damage to the bone from misplaced guidewire attempts and greatly reduced x-ray exposure.

The robot was a small device which could be clamped to the side of an OR table by a single person. The robot would be fitted with a sterile registration phantom which could be positioned near to the incision using an adjustable clamp. A single AP and single lateral x-ray would then be taken and the two images would appear on a draped touch-screen (the two images could be taken from anywhere and need not perfectly orthogonal). The surgeon would mark on the touchscreen the desired path and depth of the guidewire insertion.

The system would then use image processing for each x-ray image to identify the locations of x-ray opaque balls embedded in the registration phantom. Because of the unique configuration of the balls it was then possible calculate the location of each image and the 3-d location of the surgeon's guidewire trajectory, relative to the robot. A cannula could then be attached and the robot would move to align the cannula with the desired trajectory and inform the surgeon of the required guidewire depth.

Myself, a software engineer and the project manager tested the robot over a period of several months with a leading orthopeadic surgeon at Charing Cross hospital, London. The system was rather clunky and not as user-friendly as desired but it worked, delivering the guide wire to within a few mm of the desired target.

OR Table Clamp

I designed a novel, patented double-action clamp for mounting the robot to any size of OR table rail. The clamp had a unique mechanism for grasping any size of OR table rail from two directions by turning only a single handle on the top.

Other Medical Robots

During my time at Prosurgics I gained fantastic medical device experience. I was able to spend lots of time talking directly to surgeons about requirements, watching procedures, understanding the expectations of staff and becoming familiar with the practical requirements and demands of an OR environment.

Pathfinder

Pathfinder is a neurosurgical robot to assist with precise placement of electrodes for deep brain stimulation. The system was accurate to within 1mm which was not easy to achieve. I assisted with the robot calibration using an iterative estimation of kinematic parameters (An, Atkeson and Hollerbach). I designed a disposable, repositionable registration article for MR and CT imaging. The small, triangular shape was fixed to the skull using standard bone screws and the registration articles could be removed and precisely reattached so that the patient did not need to wear a cubersome stereotactic frame. The device was designed to be injection moulded.

Freehand

Freehand is a robotic laparoscope holder. The surgeon wears a matchbox-sized infra-red tracking device on his head and the robot moves the image (up/down, left/right, zoom etc) according to the motion of the surgeons head, when a foot pedal is depressed. I designed the OR table clamp, a mobile cart for transporting the system and the head-mounted tracking device. I also carried out testing for CE certification. The system was successfully CE marked and is currently on sale at www.freehandsurgeon.com .