All posts by Esther de Kater

Spinal bone anchor fixation by molding to the pedicle

During spinal fusion surgery, multiple vertebrae are fused by fixating them together. The fixation of the vertebrae is achieved by placing screws through the pedicles of the vertebrae that are connected to rods. The fixation strength of the screw mainly relies on the contact area between the screw and the outer bone layer of the vertebra. This contact can only be achieved within the pedicle of the vertebra. However, even in the pedicle, this contact is limited due to the hourglass shape and oval cross-section of the pedicle.

In this graduation project, you will design a bone anchor that can adapt its shape in 3D to the pedicle of the vertebra to fixate to increase the contact area between the anchor and the cortical outer layer of the pedicle.

Interested? Contact Esther de Kater, E.P.dekater@tudelft.nl

Design of an internal fixation system for spinal fusion surgery

During spinal fusion surgery multiple vertebrae are fused by fixating them together. The fixation of the vertebrae is achieved by placing screws through the pedicles of the vertebrae that are connected to rods. The rods run along the vertebrae and are embedded in the surrounding soft tissue. This can result in pain and irritation for the patient.

The vertebra grow together and form one bony mass in the first six months after surgery. During this period the forces acting on the fixation are substantial during daily activities. If the screw loosen during this period, the desired fusion cannot be achieved.

In this graduation project we will set the first steps in the direction of a new fixation method that is mainly located within the vertebra. The graduation projects focuses on the development of a drilling and/or anchoring system that can be used to create the desired fixation.

Interested? Contact Esther de Kater, E.P.dekater@tudelft.nl

Design of a Bone Marrow Harvesting Device (CLOSED)

Bone marrow is a soft and fatty tissue located within the porous bone structure at the centre of the larger bones. During bone marrow biopsies, also called trephine biopsies, a 1-2 cm long sample of the bone and bone marrow is taken to check, amongst others, for blood cell abnormalities. A Jamshidi needle is used to collect the bone marrow by pushing the needle through the rigid cortical outer layer of the bone such that it will be located within the softer cancellous bone. During retrieval of the needle, the biopsy sample sometimes remains inside the incision. This requires manual removal of the sample using forceps, and possibly a second biopsy has to be taken.

During this project, you would first look into current instruments used to perform a bone marrow biopsy after which you will design a novel device that could be used for harvesting bone marrow samples.

Interested? Contact Esther de Kater, e.p.dekater@tudelft.nl

Wasp Inspired Steerable Bone Drill

Parasitoid wasps can drill through relatively hard material such as wood with their ovipositor, a very thin structure through which the wasp transports its eggs. The ovipositor consists of three valves that slide one-by-one deeper in the wood to drill. Not only can the parasitoid wasp drill with this very thin structure through hard material but the wasp is also able to steer during drilling. It is still not fully known how the wasp can do this, but there are multiple hypotheses. Multiple steerable needles were designed based on the wasp ovipositor. The goal of this graduation project is to design a steerable wasp inspired bone drill.

Interested? Contact Esther de Kater: E.P.deKater@tudelft.nl

Entry point detection for spinal fusion surgery (CLOSED)

Multiple diseases can require patients to undergo spine surgery. At the BITE group, we are developing a novel probe that allows for the surgeon to steer through the bone along a secure drilling trajectory, avoiding nerves and blood vessels that run along the spinal column. To help the surgeon find and maintain the right trajectory, an optical sensing system based on Diffuse Reflectance Spectroscopy (DRS) will be integrated into the probe to differentiate the tissue ahead of the tool tip, thereby providing positional feedback for the surgeon in real time.

In the scope of the proposed graduation project, a probe prototype will be designed that enables the surgeon to sense the correct entry point for spine drilling procedures. Its usability for guidance will be assessed through drilling tests on a bone phantom/ex-vivo animal bone.

This assignment will be available from September 2021. Interested? Contact Esther de Kater, e.p.dekater@tudelft.nl or Merle Losch, m.s.losch@tudelft.nl.

Design of a bone phantom (CLOSED)

Spinal fusion is the surgical procedure of stiffening parts of the spinal column to reduce back pain for patients affected by multiple diseases. At the BITE group, we are developing a novel drill that allows for the surgeon to steer through the bone along a secure drilling trajectory, avoiding nerves and blood vessels that run along the spinal column.

To help the surgeon find and maintain the right trajectory, an optical sensing system based on Diffuse Reflectance Spectroscopy (DRS) will be integrated into the drill to differentiate the tissue ahead of the tool tip, thereby providing positional feedback for the surgeon in real time.

In the scope of the proposed graduation project, a bone tissue-simulating phantom will be designed that mimics both mechanical and optical properties of human bone. This phantom will allow for mechanical testing of the steerable drill, as well as for optical testing of the sensing system. Eventually, it will also provide a training environment where surgeons can become accustomed to the novel tool.

This assignment will be available from March/April 2021. Interested? Contact Merle Losch, m.s.losch@tudelft.nl.

Design of a steerable bone screw (CLOSED)

During spinal fusion surgery multiple vertebrae are fused by fixating them together with an internal brace. The brace is connected to a vertebra with pedicle screws. The inside of the bone (cancellous bone) is too weak to achieve sufficient grip. Therefore, screw fixation mainly relies on locations where the screw is in direct contact with the surrounding  layer of the much harder cortical bone. We are developing a steerable bone drill in order to increase the contact area of screws and cortical bone by drilling along the cortical bone layer. An optical sensing system that can differentiate the two types of bone tissue will help the surgeon find and maintain the right drilling trajectory. Furthermore, a novel anchoring device that is flexible during insertion, but becomes rigid once in place will replace straight pedicle screws.

There are multiple graduation projects available related to optical sensing, bone drilling and anchoring.

  • Development of a bone phantom for testing of a steerable drill or screw
    Contact: Merle Losch, m.s.losch@tudelft.nl
  • Design of a drill prototype to provide directional feedback
    Contact: Merle Losch, m.s.losch@tudelft.nl
  • Design of  flexible screw that can become incredibly stiff in order to transfer the forces acting of the screw
    Contact: Esther de Kater, e.p.dekater@tudelft.nl

  • Design of a flexible screw that adheres to the bone surface in order to transfer the forces acting on the screw
    Contact: Esther de Kater, e.p.dekater@tudelft.nl

NWO – Spine Stabilization

This research project is funded by the Netherlands Organization for Scientific Research NWO and conducted in collaboration with Philips Research, DEAM, Karolinska University Hospital in Sweden, Amsterdam University Medical Center and Reinier de Graaf Hospital in Delft.

Spinal fusion is the surgical procedure of stiffening parts of the spinal column with screws and rods to, among others, reduce back pain for patients affected by multiple diseases. Vertebrae have an outer layer of hard cortical bone surrounding the softer core that consists of cancelous bone. The strength of the connection between vertebra and screw mainly relies on the contact area with the cortical bone, but drilling close to this cortical bone layer is risky, as it can lead to cortical breaches. These breaches can have severe complications, especially since important neural and vascular structures run along the spinal column.

This research will focus on creating a better fixation of the screws and preventing complications that can arise due to cortical breaches by developing a steerable bone drill with an optical sensing system in the tip. This allows the surgeon to drill a curved path along the cortical bone layer while getting real time information about the location of the drill. Regular stiff screws will not fit this curved hole, thus a new anchoring device will be developed that is flexible when introduced to the curved hole and that can become rigid to generate the needed fixation.