System for controlling a motor driven surgical cutting instrument

• US 6,245,084 B1
• Filed: 10/20/1998
• Issued: 06/12/2001
• Est. Priority Date: 10/20/1998
• Status: Expired due to Term

• Current Assignee: Suros Surgical Systems Incorporated (Hologic Incorporated)
• Original Assignee: Promex SA (Uzinsider SA)
• Inventors: Miller, Michael E., Mark, Joseph L., Kara, Miklos T., McCary, Brian, Henry, Daniel John
• Primary Examiner(s): TRUONG, KEVIN THAO
• Application Number:
  US09/175,293
• Time in Patent Office: 966 Days
• Field of Search: 606/167, 606/170, 606/171, 606/176, 606/180
• US Class Current: 606/167
• CPC Class Codes: A61B 17/32002 with continuously rotating, oscillating or reciprocating cutting instruments
• CPC Class Codes: A61B 2017/00017 Electrical control of surgical instruments
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect

Abstract

A system is provided for controlling the stopping position of a surgical cutting tool relative to a tissue entrance location of a cannula housing the cutting tool. A signal processor is responsive to a motor activation signal to provide a motor activation signal to a motor control unit for driving a motor, which activates the cutting tool positioned in a cannula. The signal processor is responsive to a motor stop signal and to a stop position signal to stop the cutting tool relative to the tissue entrance location of the cannula to thereby avoid trapping a portion of the tissue base between the cutting tool and a boundary of the cannula opening.

Claims

1. A tissue cutting apparatus comprising:

an elongated housing configured for insertion into a body site, said housing having a first end defining an opening adjacent thereto;

a tissue cutting tool disposed within said housing and defining at least one cutting surface configured for movement relative to said housing adjacent said opening to thereby excise tissue extending into said opening;

a motor driving a drive shaft extending therefrom and coupled to said cutting tool, said motor operable to drive said cutting tool at a cutting speed to excise tissue at said opening;

means for sensing a predefined position of said drive shaft relative to said housing and producing a stop position signal corresponding thereto, said predefined position corresponding to a position of said at least one cutting surface relative to said opening to avoid trapping unexcised tissue therebetween;

means for generating a motor stop signal when it is desired to stop said cutting tool; and

a control circuit responsive to said motor stop signal to deactivate said motor with said drive shaft at a position prior to said predefined position so that said motor stops with said drive shaft substantially at said predefined position.

2. The tissue cutting apparatus of claim 1, wherein said motor is a brushed DC motor.

3. The tissue cutting apparatus of claim 1 wherein said motor is responsive to a motor activation signal provided by said control circuit to rotationally drive said drive shaft.

4. The tissue cutting apparatus of claim 3 wherein said drive shaft is connected to said cutting tool to thereby drive said cutting tool rotationally about a longitudinal axis defined by said elongated housing.

5. The tissue cutting apparatus of claim 3 further including transmission means disposed between said motor and said cutting tool for converting rotary motion from said rotating drive shaft to reciprocating linear motion of said cutting tool to thereby drive said cutting tool in a linearly reciprocating fashion relative to a longitudinal axis defined by said elongated housing.

6. The tissue cutting apparatus of claim 3 wherein said means for sensing a predefined position of said drive shaft relative to said housing includes:

a mark associated with said drive shaft; and

a sensor operable to sense passage thereby of said mark and produce said stop position signal.

7. The tissue cutting apparatus of claim 6 wherein said mark is a magnetized identifier attached to said drive shaft.

8. The tissue cutting apparatus of claim 7, wherein said sensor is a Hall effect sensor attached to said housing.

9. The tissue cutting apparatus of claim 3 wherein:

said motor activation signal is a variable motor speed signal; and

further including a motor control circuit disposed between said control circuit and said motor, said motor control circuit responsive to said variable motor speed signal to drive said motor at a corresponding rotational speed.

10. The tissue cutting apparatus of claim 9 wherein said motor control circuit includes:

a pulse width modulation (PWM) signal generator responsive to said motor speed signal to produce a corresponding PWM signal; and

a motor driver circuit responsive to said PWM signal to drive said motor at a corresponding rotational speed.

11. The tissue cutting apparatus of claim 1 further including a vacuum unit coupled to said housing for creating a vacuum therein.

12. The tissue cutting apparatus of claim 11 further including a vacuum control circuit disposed between said control circuit and said vacuum unit, said vacuum control circuit responsive to at least one vacuum control signal provided by said control circuit to control said vacuum unit.

13. The tissue cutting apparatus of claim 1, wherein:

said motor includes motor terminals for receiving signals from said control circuit; and

said control circuit includes a relay spanning said motor terminals and operable in response to said motor stop signal to cause a short circuit across said terminals.

14. A tissue cutting apparatus comprising:

an elongated housing configured for insertion into a body site, said housing having a first end defining an opening adjacent thereto;

a tissue cutting tool disposed within said housing and defining at least one cutting surface configured for movement relative to said housing adjacent said opening to thereby excise tissue extending into said opening;

a motor driving a drive shaft extending therefrom and coupled to said cutting tool, said motor operable to drive said cutting tool at a cutting speed to excise tissue at said opening;

a control circuit operable to generate a motor activation signal, wherein said motor activation signal is a variable motor speed signal; and

a motor control circuit disposed between said control circuit and said motor, said motor control circuit responsive to said variable motor speed signal to drive said motor at a corresponding rotational speed,

wherein said motor control circuit includes;

a power amplifier providing a current signal to said motor; and

a current sensor sensing the current provided to said motor and providing a current feedback to said power amplifier, whereby said power amplifier is responsive to said current feedback to control the current signal provided to said motor.

15. The tissue cutting apparatus of claim 14, wherein said motor control circuit includes a switch disposed between said current sensor and said power amplifier operable to disable said current feedback in response to said motor stop signal.

16. A tissue cutting apparatus comprising:

an elongated housing configured for insertion into a body site, said housing having a first end defining an opening adjacent thereto;

a tissue cutting tool disposed within said housing and defining at least one cutting surface configured for movement relative to said housing adjacent said opening to thereby excise tissue extending into said opening;

a motor driving a drive shaft extending therefrom and coupled to said cutting tool, said motor operable to drive said cutting tool at a cutting speed to excise tissue at said opening;

means for sensing a predefined position of said drive shaft relative to said housing and producing a stop position signal corresponding thereto, said predefined position corresponding to a position of said at least one cutting surface relative to said opening to avoid trapping unexcised tissue therebetween;

means for generating a motor stop signal when it is desired to stop the cutting apparatus; and

a control circuit responsive to said motor stop signal to drive said motor at a predefined motor speed substantially less than said cutting speed and thereafter responsive to said stop position signal to deactivate said motor with said drive shaft at said predefined position.

17. The tissue cutting apparatus of claim 16, wherein said motor is a brushed DC motor.

18. A tissue cutting apparatus comprising:

an elongated housing configured for insertion into a body site, said housing defining a cutting opening sized to receive tissue therethrough;

a cutting member operatively disposed within said housing and defining a cutting surface adjacent said cutting opening configured to excise tissue projecting through said opening;

a brushed DC motor having a rotating output shaft coupled to said cutting member and operable to drive said cutting member at a cutting speed sufficient to excise tissue, said brushed DC motor generating a resistance torque in a direction opposite to the direction of rotation of said output shaft;

a position identifier mark associated with either of said output shaft or said cutting member;

a position sensor mounted in said housing in alignment with said position identifier mark, said sensor having a predetermined position relative to said cutting opening so that when said position identifier mark is immediately adjacent said position sensor, said cutting surface is disposed relative to said opening so that tissue projecting through said cutting opening is not trapped by said cutting surface; and

means for generating a stop signal when it is desired to stop operation of said cutting member; and

a motor controller providing power to said brushed DC motor and having means for controlling the operation of said motor, said means operable in a first state to control said motor at said cutting speed, in a second state to control said motor at a reduced speed sufficient only to overcome said resistive torque in response to said stop signal, and a third state to terminate power to said motor immediately after the second passage of said position identifier mark by said position sensor.

19. The tissue cutting apparatus according to claim 18, wherein said motor controller includes:

a power amplifier providing a current signal to said motor;

a current sensor sensing the current provided to said motor and providing a current feedback to said power amplifier, whereby said power amplifier is responsive to said current feedback to control the current signal provided to said motor; and

a switch disposed between said current sensor and said power amplifier operable to disable said current feedback to said power amplifier in response to said stop signal.

20. The tissue cutting apparatus of claim 19, wherein:

said motor includes motor terminals for receiving signals from said control circuit; and

said motor controller includes a relay spanning said motor terminals and operable in response to said stop signal to cause a short circuit across said terminals.