Anti-skiving Drill Bit Trajectory Control in Robotic Spinal Surgery
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Solution Overview
Problem
Spinal surgeries face challenges due to inaccurate drilling and screw placement, leading to potential damage to delicate areas like the spinal cord, caused by drill bit skidding and sub-optimal trajectories, which are influenced by the bone's structure and surrounding tissue, and current navigational systems' limitations.
Innovation Solution
The use of an anti-skiving drill bit with adjustable rotational characteristics, monitored by a robotic surgical system, which alters its speed and mode based on haptic feedback and medical image data to optimize the drilling trajectory, ensuring precise hole preparation by distinguishing between the hard outer layer and spongious interior of the bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a drill bit is used at a non-90 degree angle to the bone surface, then the drilling can access difficult-to-reach trajectories, but the drill bit tends to skid over the bone surface causing inaccurate hole placement
Solution Approach 1:
A pilot hole is drilled first at the intended entry point to establish an accurate trajectory before the main drill bit is inserted. The pilot hole acts as a guide that prevents skidding and ensures the main drill follows the correct path, resolving the contradiction between trajectory flexibility and placement accuracy.
Solution Approach 2:
A guide instrument or trajectory guide is used as an intermediary between the drill bit and bone surface. This guide establishes the correct entry point and angle, allowing the drill bit to maintain accurate trajectory even when drilling at non-90 degree angles, thus enabling both trajectory flexibility and precision.
2Productivity
If high rotational speed is used to drill through the hard outer layer of bone, then drilling efficiency is improved, but the drill bit may skid and deviate from the intended trajectory
Solution Approach 1:
The drilling process uses periodic alternation between high rotational speed for efficient bone penetration and lower speeds for trajectory correction. The system periodically reduces speed to allow the drill bit to self-correct its trajectory by engaging the bone surface properly, then increases speed again for efficient drilling, thus resolving the contradiction between productivity and precision.
Solution Approach 2:
The rotational speed of the drill bit is dynamically adjusted during the drilling process based on real-time feedback from force sensors and trajectory monitoring. The system automatically modulates speed to maintain optimal balance between drilling efficiency and trajectory accuracy, applying high speed when trajectory is stable and reducing speed when correction is needed.
3Ease of operation
If soft tissue pressure is applied on surgical instruments during drilling, then minimally invasive access is achieved, but the trajectory deviates from the planned path
Solution Approach 1:
Force sensors and trajectory monitoring systems provide real-time feedback on the position and orientation of the drill bit. When soft tissue pressure causes trajectory deviation, the system detects this through feedback signals and automatically adjusts the drill bit orientation or provides haptic feedback to the surgeon to correct the trajectory, thus maintaining both minimally invasive access and trajectory accuracy.
Solution Approach 2:
The system replaces manual mechanical control with robotic or computer-controlled guidance mechanisms. A robotic arm or guided instrument holder maintains the precise trajectory despite soft tissue pressure, substituting mechanical stability provided by manual holding with automated positional control that compensates for tissue movement and pressure.
4Device complexity
If medical images with insufficient contrast are used for trajectory planning, then the surgical planning process is simplified, but the selected trajectory may be sub-optimal and risk breaching sensitive areas
Solution Approach 1:
Contrast agents or radiopaque markers are introduced as intermediaries to enhance image contrast during trajectory planning. These markers are placed at critical anatomical locations or on guide instruments, allowing clear visualization of safe trajectories on imaging systems without requiring complex imaging equipment, thus resolving the contradiction between system simplicity and trajectory safety.
Solution Approach 2:
The imaging parameters are dynamically adjusted during the procedure, including switching between different imaging modes (X-ray, CT, MRI) or adjusting contrast enhancement levels. The system changes imaging parameters to optimize visualization of critical structures for trajectory planning, maintaining simple equipment while improving trajectory safety through parameter optimization.
Data Source
AI summary
Described herein are systems and methods for use in preparing holes in bones. In certain embodiments, the trajectory followed in preparing a hole in a bone is optimized by adjusting characteristics of rotation of a drill bit (e.g., an anti-skiving drill bit). In certain embodiments, a change in material is determined once a hard outer layer of a bone has been drilled. Subsequently, characteristics of rotation of a drill bit are altered to allow natural features of a patient's anatomy to guide the drill bit. In this way, certain hard walls of certain bones can act to redirect a drill bit. The change in material may be determined, and/or characteristics of rotation altered, by a surgeon or a robotic surgical system (e.g., automatically). In certain embodiments, a robotic surgical system notifies a surgeon of a change in material to prompt the surgeon to alter the characteristics of rotation.