Ratchet locking mechanism for surgical instruments

• US 5,176,702 A
• Filed: 02/07/1992
• Issued: 01/05/1993
• Est. Priority Date: 04/04/1991
• Status: Expired due to Term

• Current Assignee: Symbiosis Corporation (Boston Scientific Corporation)
• Original Assignee: Symbiosis Corporation (Boston Scientific Corporation)
• Inventors: Slater, Charles R., Smith, Kevin W., Bales, Thomas O., Scarfone, Frank A., Murphy, Gregory J.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): AKERS, SCOTT
• Application Number:
  US07/833,840
• Time in Patent Office: 333 Days
• Field of Search: 128/749, 128/751, 606/167, 606/170, 606/176, 606/205, 606/206, 606/207, 606/208, 74/575, 74/577, 74/577 M, 74/578, 81/318, 81/319, 81/320, 81/321, 81/322, 81/323, 81/324, 81/328, 81/415
• US Class Current: 606/208
• CPC Class Codes: A61B 10/06 Biopsy forceps , e.g. with cup-shaped jaws
• CPC Class Codes: A61B 17/29 Forceps for use in minimally invasive surgery
• CPC Class Codes: A61B 17/2909 Handles
• CPC Class Codes: A61B 17/320016 Endoscopic cutting instruments, e.g. arthroscopes, resectoscopes A61B10/0233, A61B17/29, A61B17/3207 take precedence
• CPC Class Codes: A61B 17/3201 Scissors for biopsy A61B10/02
• CPC Class Codes: A61B 18/1445 at the distal end of a shaft, e.g. forceps or scissors at the end of a rigid rod
• CPC Class Codes: A61B 2017/0023 disposable
• CPC Class Codes: A61B 2017/0046 with a releasable handle; with handle and operating part separable
• CPC Class Codes: A61B 2017/0088 ceramic
• CPC Class Codes: A61B 2017/2837 with a locking ratchet
• CPC Class Codes: A61B 2017/2926 Details of heads or jaws
• CPC Class Codes: A61B 2017/2929 with a head rotatable about the longitudinal axis of the shaft
• CPC Class Codes: A61B 2017/2939 Details of linkages or pivot points
• CPC Class Codes: A61B 2018/00077 high, i.e. electrically conducting
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00107 Coatings on the energy applicator
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/1412 Blade
• CPC Class Codes: A61B 2018/1415 multiple blades
• CPC Class Codes: A61B 2018/1455 having a moving blade for cutting tissue grasped by the jaws
• CPC Class Codes: A61B 2018/146 : Scissors
• CPC Class Codes: Y10T 74/2133 : Pawls and ratchets
• CPC Class Codes: Y10T 74/2136 : Pivoted pawls
• CPC Class Codes: Y10T 74/214 : Multiple tooth
• CPC Class Codes: Y10T 74/2152 : Hollow rod, lubricated

Abstract

Releasable ratchet mechanism for medical instruments such as endoscopic instruments are disclosed. The ratchet mechanism includes: a leaf spring with a locking barb which is located on a handle of the medical instrument; a ratchet on a lever arm of the medical instrument which lever arm is pivotally engaged to the handle; and a latch on the handle of the medical instrument. The latch on the handle engages and resiliently deforms the leaf spring to cause engagement of the locking barb in a groove of the ratchet when the latch is in a first position. When in a second position, the latch releases the locking barb from the ratchet groove. Preferably, the locking barb has an extending edge surface on an axis which is substantially parallel to the pivoting axis of the handle and lever arm, and the teeth of the ratchet have extending edge surfaces on axes substantially parallel to the extending edge surface of the locking barb. Also, preferably, the edge surfaces of said teeth of the ratchet are located along an arc of a cylinder having the handle/lever arm pivot axis as its center line.

Claims

1. In a medical instrument having end effectors and a handle means and a lever arm means each coupled to at least one of said end effectors, said handle means and lever arm means being pivotably fixed relative to each other by a pivot means, wherein pivoting of said lever arm means relative to said handle means around said pivot means effects relative movement between said end effectors, an improvement comprising:

a releasable ratchet mechanism having

a) a resilient member with opposite first and second opposite ends, said first end held in cantilever engagement with one of said handle means and said lever arm means, and with its second end extending away from said one of said handle means and said lever arm means with which said resilient member is in cantilever engagement toward the other of said handle means and said lever arm means, said resilient member having a locking element extending therefrom remote from its cantilevered engagement;

b) a ratchet means extending from said other of said handle means and lever arm means toward said cantilever engagement of said resilient member, said ratchet means being axially displaced relative to said locking element along an axis perpendicular to said pivot means but in closely adjacent opposed relationship to said locking element, said ratchet means having a plurality of teeth defining a plurality of grooves wherein each groove is adapted to individually receivably engage said locking element of said resilient member;

c) latching means movably coupled to said one of said handle means and lever arm means with which said resilient means is in cantilever engagement, said latching means for engaging and resiliently deforming said resilient member to cause engagement of said locking element in a groove of said ratchet means when said latching means is in a first position, and said latching means for either substantially disengaging said resilient means or for reducing the deformation of said resilient member when in a second position such that said locking means is substantially free from said ratchet means.

2. In a medical instrument according to claim 1, wherein:

said pivot means has a pivot axis;

said locking element has an extending edge surface on a second axis substantially parallel said pivot axis; and

said plurality of teeth have extending edge surfaces on third axes substantially parallel said second axis.

3. In a medical instrument according to claim 2, wherein:

said edge surfaces of said teeth of said ratchet means are located along an arc of a cylinder having said pivot axis as its center line.

4. In a medical instrument according to claim 1, wherein:

said resilient member comprises a leaf spring, and said locking element comprises a first punched out barb extending from said leaf spring.

5. In a medical instrument according to claim 4, wherein:

said punched out barb is at a substantially forty-five degree angle relative to said leaf spring.

6. In a medical instrument according to claim 1, wherein:

said resilient member comprises a leaf spring including an engaging means for fixedly engaging at its cantilevered end said one of said handle means and lever arm means with which said resilient means is in cantilever engagement.

7. In a medical instrument according to claim 1, wherein:

said handle means and said lever arm means comprise scissor type handle loop elements, and said resilient member is coupled to said one of said handle means and lever arm means and said ratchet means is coupled to the other of said handle means and lever arm means at locations on said loop elements remote from said pivot means.

8. In a medical instrument according to claim 1, wherein:

said handle means and lever arm means are comprised of plastic,

said ratchet means is formed as a unitary plastic component with the other of said handle means and said lever arm means, wit

said teeth being formed in said ratchet means in a recessed cutout with the other of said handle means and said lever arm means, with said teeth being formed in said ratchet means in a recessed cutout fashion.

9. In a medical instrument according to claim 8, wherein:

said pivot means has a pivot axis,

said ratchet means has a first width along an axis parallel to said pivot axis, and

said teeth have a second width along said axis parallel to said pivot axis, wherein said second width is smaller than said first width.

10. In a medical instrument according to claim 1, wherein:

said handle means and lever arm means are comprised of plastic,

said ratchet means is a metal component in locked engagement with the other of said handle means and said lever arm means.

11. In a medical instrument according to claim 3, wherein:

each of said teeth have a first angled surface making an approximately forty-five degree angle relative to radii defining said arc.

12. In a medical instrument according to claim 11, wherein:

each of said teeth have a second angled surface making an approximately ten degree angle relative to said radii defining said arc

13. In a medical instrument according to claim 1, wherein:

said latching means comprises a camming lever means having a pivot pin pivotably engaging said one of said handle means and lever arm means with which said resilient means is in cantilever engagement, said camming lever having a bearing end adjacent said resilient means at a location toward said free end from where said resilient means is held in cantilever engagement, said bearing end having a first bearing surface, with said first bearing surface engaging and resiliently deforming said resilient member a first amount to cause engagement of said locking element in a groove of said ratchet means when said latching means is in said first position.

14. In a medical instrument according to claim 13, wherein:

said bearing end has a second bearing surface, with said second bearing surface resiliently deforming said resilient member a second amount when said locking means is in a second position, wherein said second amount can range from zero to an amount less than said first amount.

15. In a medical instrument according to claim 12, wherein:

said locking element is at a substantially forty-five degree angle relative to said resilient member such that when said latching means is in said first position with said locking element engaging said ratchet means, said handle means and said lever arm means can be squeezed together with said locking element riding on said first angled surface of respective teeth of said ratchet means and falling into grooves between said respective teeth.

16. In a medical instrument according to claim 3, wherein:

said resilient member comprises a leaf spring,

said locking element comprises a first punched out barb extending from said leaf spring at a substantially forty-five degree angle relative to said leaf spring, and

said leaf spring further comprises a second punched out barb which fixedly engages said said one of said handle means and lever arm means with which said resilient means is in cantilever engagement at the cantilevered end of said leaf spring.

17. In a medical instrument according to claim 16, wherein:

said handle means and said lever arm means comprise scissor type handle loop elements, and said resilient member is coupled to said one of said handle means and lever arm means and said ratchet means is coupled to the other of said handle means and lever arm means at locations on said loop elements remote from said pivot means.

18. In a medical instrument according to claim 17, wherein:

said latching means comprises a camming )ever means having a pivot pin pivotably engaging said one of said handle means and lever arm means with which said resilient means is in cantilever engagement, said camming lever having a bearing end adjacent said resilient means at a location toward said free end from where said resilient means is held in cantilever engagement, said bearing end having a first bearing surface, with said first bearing surface engaging and resiliently deforming said resilient member a first amount to cause engagement of said locking element in a groove of said ratchet means when said latching means is in said first position.

19. In a medical instrument according to claim 1, wherein:

said medical instrument comprises an endoscopic instrument having a longitudinally extending hollow outer tube with a proximal end, a distal end, and a longitudinal axis, a push rod extending through said outer tube and having proximal and distal ends, an actuating means for imparting reciprocal axial motion to said push rod relative to said outer tube, said actuating means comprised of said handle means which engages said outer tube and said lever arm means which is coupled to said proximal end of said push rod, and said end effectors which are coupled to said push rod at said distal end of said push rod and pivotally coupled to said outer tube, whereby said reciprocal axial motion of said push rod is translated to pivotal movement of said end effectors.

20. In a medical instrument according to claim 17, wherein:

said medical instrument comprises an endoscopic instrument having a longitudinally extending hollow outer tube with a proximal end, a distal end, and a longitudinal axis, a push rod extending through said outer tube and having proximal and distal ends, an actuating means for imparting reciprocal axial motion to said push rod relative to said outer tube, said actuating means comprised of said handle means which engages said outer tube and said lever arm means which is coupled to said proximal end of said push rod, and said end effectors which are coupled to said push rod at said distal end of said push rod and pivotally coupled to said outer tube, whereby said reciprocal axial motion of said push rod is translated to pivotal movement of said end effectors.

21. A medical instrument, comprising:

a) a hollow outer tube having a proximal end, a distal end, and a longitudinal axis;

b) a push rod extending through said outer tube and having proximal and distal ends;

c) an actuating means for imparting reciprocal axial motion to said push rod relative to said outer tube, said actuating means comprising a handle means and a lever arm means, said handle means and lever arm means being coupled to each other by a pivot means, with said handle means engaging said outer tube, said lever arm means engaging said push rod;

d) end effector means coupled to said push rod at said distal end of said push rod and pivotally coupled to said outer tube, whereby pivoting of said lever arm means relative to said handle means around said pivot means is translated to pivotal movement of at least one of said end effectors; and

e) a releasable ratchet mechanism having

a resilient member engaged with and extending from a first of said handle means and said lever arm means, said resilient member having a locking element extending therefrom,

a ratchet means extending from the other of said handle means and said lever arm means said ratchet means being axially displaced relative to said locking element along an axis perpendicular to said pivot means but in closely adjacent opposed relationship to said locking element, said ratchet means having a plurality of teeth defining a plurality of grooves wherein each groove is adapted to individually receivably engage said locking element of said resilient member, and

latching means movably coupled to said first of said handle means and lever arm means, said latching means for engaging and resiliently deforming said resilient member to cause engagement of said locking element in a groove of said ratchet means when said latching means is in a first position.

22. A medical instrument according to claim 21, wherein:

said handle means and said lever arm means are pivotally engaged by said pivot means at a location adjacent said proximal end of said outer tube, and said handle means and lever arm means extend in an opposed relationship to respective remote ends which are at a substantially common distance away from said pivot means, and

said resilient member engages said first of said handle means and said lever arm means at the remote end thereof.

23. A medical instrument according to claim 21, wherein:

said latching means comprises a pivot arm having a first end and a second end, said latching means being pivotally engaged between its first end and its second end to said first of said handle means and lever arm means, and said pivot arm having two distinct bearing faces at its second end which are alternatively positionable to abut said resilient member upon pivotal movement of said first end of said pivot arm, a first of said bearing face when abutting said resilient member causing said resilient member to deform and causing engagement of said locking element and said ratchet means, and the other of said bearing faces when abutting said resilient member enabling disengagement of said locking element from said ratchet means.

24. A medical instrument according to claim 21, wherein:

said pivot means has a pivot axis;

said locking element has an extending edge surface on a second axis substantially parallel said pivot axis; and

said plurality of teeth have extending edge surfaces on third axes substantially parallel said second axis.

25. A medical instrument according to claim 24, wherein:

said edge surfaces of said teeth of said ratchet means are located along an arc of a cylinder having said pivot axis as its center line.

26. A medical instrument according to claim 21, wherein:

said resilient member comprises a leaf spring, and said locking element comprises a first punched out barb extending from said leaf spring.

27. A medical instrument according to claim 26, wherein:

said punched out barb is at a substantially forty-five degree angle relative to said leaf spring.

28. A medical instrument according to claim 22, wherein:

said handle means and said lever arm means comprise scissor type handle loop elements, and said resilient member is coupled to said first of said handle means and lever arm means and said ratchet means is coupled to the other of said handle means and lever arm means.

29. A medical instrument according to claim 21, wherein:

said handle means and lever arm means are comprised of plastic,

said ratchet means is formed as a unitary plastic component with the other of said handle means and said lever arm means, with said teeth being formed in said ratchet means in a recessed cutout fashion.

30. A medical instrument according to claim 29, wherein:

said pivot means has a pivot axis,

said ratchet means has a first width along an axis parallel to said pivot axis, and

said teeth have a second width along said axis parallel to said pivot axis, wherein said second width is smaller than said first width.

31. A medical instrument according to claim 21, wherein:

said handle means and lever arm means are comprised of plastic,

said ratchet means is a metal component in locked engagement with the other of said handle means and said lever arm means.

32. A medical instrument according to claim 25, wherein:

each of said teeth have a first angled surface making an approximately forty-five degree angle relative to radii defining said arc.

33. A medical instrument according to claim 32, wherein:

each of said teeth have a second angled surface making an approximately ten degree angle relative to said radii defining said arc.

34. A medical instrument according to claim 33, wherein:

said locking element is at a substantially forty-five degree angle relative to said resilient member such that when said latching means is in a first position with said locking element engaging said ratchet means, said handle means and said lever arm means can be squeezed together with said locking element riding on said first angled surface of respective teeth of said ratchet means and falling into grooves between said respective teeth.