Summary/Abstract:
Our long-range goal is to develop a novel semi-autonomous, minimally-invasive, image-guided neurosurgical
robotic workstation that consists of a robotic positioning mechanism, a continuum manipulator, flexible
instruments, and flexible implants (i.e., flexible pedicle screws (FPSs)) to enable the next generation of minimally-
and less-invasive spinal interventions. By providing access to regions within vertebral body, which currently are
not accessible utilizing conventional rigid surgical instruments, this neurosurgical robotic workstation will enable
surgical treatment of various bone defects in spine such as compression on the spinal cord and/or nerve roots,
metastatic bone disease, and vertebral compression fractures due to severe osteoporosis. For this project, we
mainly will focus on the mechanical design, development, basic control, and assessment of the subsystems of
this novel robotic system with the goal of minimally invasive spinal fusion of osteoporotic vertebrae.
Approximately 54 million Americans age 50 and older have osteoporosis causing an estimated two million
broken bones per year in the US only. Vertebral fractures are the most common type of osteoporotic fractures
(about 47%), which can lead to back pain, loss of height, and further vertebral and non-vertebral fractures. Failure
of non-surgical treatments often leads to a spinal fusion surgery to restore stability of the spine using Rigid
Pedicle Screws (RPSs). However, anatomical constraints and rigidity of instruments and screws force the
surgeon to typically implant the screw inside the low bone mineral density (BMD) regions of the vertebrae in an
osteoporotic spine. This results in an increased risk of screws loosening, pullout, and subsequently a surgical
failure.
It is our central hypothesis that utilizing the proposed minimally-invasive robotic system, the success rate of
spinal fusions with RPSs can be significantly improved. This improvement will happen by (i) developing a
biomechanical analysis module to plan a curved drilling trajectory based on the spatial (3D) BMD in the vertebra
obtained by QCT scans; (ii) increasing the reachability of the surgeons and enabling them to drill in high-BMD
regions of vertebra using a steerable drilling robot and the curved-drilling technique; (iii) selectively
implanting/anchoring the FPSs within the pre-planned drilled curved trajectories inside the high-BMD regions,
which can improve the pullout strength and stability of fusion; (iv) Biomechanical analysis of the fusion with FPS
and/or bone cemnet to optimize the spine stability, prevent vertebral collapse, and a need for revision surgery.
The proposed contribution is significant, high impact, and innovative since it offers to eliminate the
aforementioned complications of current spinal fusion surgery by proposing novel and innovative techniques. To
our knowledge, robotically-assisted techniques utilizing a steerable drilling robot and FPSs have not been
developed for a minimally invasive spinal fusion of osteoporotic vertebrae. Our goal is to demonstrate that the
proposed system can significantly improve the current treatment of osteoporotic vertebrae and shift the current
clinical paradigm.
