Robotic spine surgery system and methods
A robotic system and methods for performing spine surgery are disclosed. The system comprises a robotic manipulator with a tool to hold a screw and to rotate the screw about a rotational axis. The screw is self-tapping and has a known thread geometry that is stored by a controller. A navigation system tracks a position of a target site. Movement of the robotic manipulator is controlled to maintain the rotational axis of the surgical tool along a planned trajectory with respect to the target site based on the tracked position of the target site. In autonomous or manual modes of operation, the rotational rate of the screw about the rotational axis and/or an advancement rate of the screw linearly along the planned trajectory is controlled to be proportional to the known thread geometry stored in the memory.
1. A method of placing a screw in a target site using a surgical robotic system comprising a robotic manipulator, a navigation system, a robotic controller in communication with the robotic manipulator and the navigation system, and a surgical tool coupled to the robotic manipulator to rotate the screw about a rotational axis, the method comprising:
holding the screw with the surgical tool, the screw being self-tapping and having a known thread geometry;
storing the known thread geometry in a memory of the robotic controller;
tracking a position of the target site with the navigation system;
controlling movement of the surgical tool to maintain the rotational axis along a planned trajectory with respect to the target site based on the tracked position of the target site;
autonomously controlling a rotational rate of the surgical tool to rotate the screw about the rotational axis and an advancement rate of the surgical tool to linearly advance the screw along the planned trajectory wherein the rotational rate of the surgical tool and advancement rate of the surgical tool are proportional to the known thread geometry stored in the memory.
2. The method of claim 1 , further comprising defining the planned trajectory by a haptic object.
3. The method of claim 2 , wherein defining the planned trajectory by a haptic object comprises defining the planned trajectory by a line haptic object and wherein controlling movement of the surgical tool further comprises generating haptic feedback to the user with the robotic controller to indicate that the screw has reached the planned insertion depth at the target site.
4. The method of claim 1 , comprising autonomously controlling movement of the surgical tool to place the rotational axis along the planned trajectory.
5. The method of claim 1 , comprising determining a torque being applied to drive the screw and stopping the surgical tool from advancing and rotating the screw once the torque meets or exceeds a torque threshold.
6. The method of claim 1 , comprising tracking a pose of the rotational axis relative to the planned trajectory.
7. The method of claim 1 , comprising displaying information relating to a location of the screw relative to the planned insertion depth at the target site.
8. The method of claim 1 , wherein the rotational rate of the surgical tool and advancement rate of the surgical tool are proportional to the known thread geometry according to a relationship
δ
θ
δ
t
=
δ
D
δ
t
*
Pitch
2
π
,
wherein
δ
θ
δ
t
is the rotational rate of the surgical tool,
δ
D
δ
t
is the advancement rate of the surgical tool, and Pitch is a number of threads per unit length of the screw.
9. A method of placing a screw in a target site using a surgical robotic system comprising a robotic manipulator, a navigation system, a robotic controller in communication with the robotic manipulator and the navigation system, and a surgical tool coupled to the robotic manipulator to rotate the screw about a rotational axis, the robotic manipulator comprising a sensor, the method comprising:
holding the screw with the surgical tool, the screw being self-tapping and having a known thread geometry;
storing the known thread geometry in a memory of the robotic controller;
tracking a position of the target site with the navigation system;
autonomously controlling movement of the surgical tool to maintain the rotational axis along the planned trajectory with respect to the target site based on the tracked position of the target site;
detecting, with the sensor, a force applied by a user;
controlling one of a rotational rate of the surgical tool to insert the screw about the rotational axis or an advancement rate of the surgical tool to insert the screw linearly along the planned trajectory based on the force applied by the user to implant the screw into the target site; and
controlling, autonomously, the other of the advancement rate of the surgical tool or the rotational rate of the surgical tool so that the advancement rate of the surgical tool and the rotational rate of the surgical tool are proportional to the force applied by the user and to the known thread geometry stored in the memory.
10. The method of claim 9 , wherein the sensor comprises a force/torque sensor arranged on the surgical tool to detect the applied force.
11. The method of claim 9 , comprising autonomously controlling movement of the surgical tool to place the rotational axis along the planned trajectory.
12. The method of claim 9 , wherein the surgical tool comprises a trigger, the trigger is coupled to the sensor and is configured to generate a signal indicative of a user's input.
13. The method of claim 12 , wherein controlling one of the rotational rate of the surgical tool or the advancement rate of the surgical tool comprises controlling the rotational rate of the surgical tool based on the signal, and controlling, autonomously, the advancement rate of the surgical tool to be proportional to the rotational rate of the surgical tool and the known thread geometry according to a relationship
δ
θ
δ
t
=
δ
D
δ
t
*
Pitch
2
π
,
wherein
δ
θ
δ
t
is the rotational rate of the surgical tool,
δ
D
δ
t
is the advancement rate of the surgical tool, and Pitch is a number of threads per unit length of the screw.
14. The method of claim 12 , wherein controlling one of the rotational rate of the surgical tool or the advancement rate of the surgical tool comprises controlling the advancement rate of the surgical tool based on the signal, and controlling, autonomously, the rotational rate of the surgical tool to be proportional to the advancement rate of the surgical tool and the known thread geometry according to a relationship
δ
θ
δ
t
=
δ
D
δ
t
*
Pitch
2
π
,
wherein
δ
θ
δ
t
is the rotational rate of the surgical tool,
δ
D
δ
t
is the advancement rate of the surgical tool, and Pitch is a number of threads per unit length of the screw.