Inroads Toward Robot-Assisted Internal Fixation of Bone Fractures Using a Bendable Medical Screw and the Curved Drilling Technique

Internal fixation is a common orthopedic procedure in which a rigid screw is used to fix fragments of a fractured bone together and expedite the healing process. However, the rigidity of the screw, geometry of the fractured anatomy (e.g. femur and pelvis), and patient age can cause an array of complications during screw placement, such as improper fracture healing due to misalignment of the bone fragments, lengthy procedure time and subsequently high radiation exposure. To address these issues, we propose a minimally invasive robot-assisted procedure comprising of a continuum robot, called ortho-snake, together with a novel bendable medical screw (BMS) for fixating the fractures. We describe the implementation of a curved drilling technique and focus on the design, manufacturing, and evaluation of a novel BMS, which can passively morph into the drilled curved tunnels with various curvatures. We evaluate the performance and efficacy of the proposed BMS using both finite element simulations as well as experiments conducted on synthetic bone samples.

Plan in 2D, execute in 3D: An augmented reality solution for cup placement in total hip arthroplasty

Reproducibly achieving proper implant alignment is a critical step in total hip arthroplasty (THA) procedures that has been shown to substantially affect patient outcome. In current practice, correct alignment of the acetabular cup is verified in C-arm X-ray images that are acquired in an anterior-posterior (AP) view. Favorable surgical outcome is, therefore, heavily dependent on the surgeon's experience in understanding the 3D orientation of a hemispheric implant from 2D AP projection images. This work proposes an easy to use intra-operative component planning system based on two C-arm X-ray images that is combined with 3D augmented reality (AR) visualization that simplifies impactor and cup placement according to the planning by providing a real-time RGBD data overlay. We evaluate the feasibility of our system in a user study comprising four orthopedic surgeons at the Johns Hopkins Hospital, and also report errors in translation, anteversion, and abduction as low as 1.98 mm, 1.10 degrees, and 0.53 degrees, respectively. The promising performance of this AR solution shows that deploying this system could eliminate the need for excessive radiation, simplify the intervention, and enable reproducibly accurate placement of acetabular implants.