Surgical knife with retractable blade and depth of cut control

• US 5,620,453 A
• Filed: 01/13/1995
• Issued: 04/15/1997
• Est. Priority Date: 11/05/1993
• Status: Expired due to Fees

• Current Assignee: Ravi Nallakrishnan
• Original Assignee: Ravi Nallakrishnan
• Inventors: Nallakrishnan, Ravi
• Primary Examiner(s): Buiz, Michael Powell
• Assistant Examiner(s): LEWIS, WILLIAM W
• Application Number:
  US08/372,849
• Time in Patent Office: 823 Days
• Field of Search: 606/166, 606/167, 606/170, 606/172, 30/164.92, 30/164.93, 30/164.95, 30/293, 30/335
• US Class Current: 606/166
• CPC Class Codes: A61B 2090/033 Abutting means, stops, e.g. abutting on tissue or skin
• CPC Class Codes: A61B 2090/062 penetration depth
• CPC Class Codes: A61F 9/0133 Knives or scalpels specially adapted therefor

Abstract

A surgical knife for use in ophthalmic surgery includes a bladeholder assembly holding a surgical cutting blade, with the bladeholder assembly sliding into and out of a hollow knife handle, and a plunger mechanism manually operable to move said bladeholder assembly to a position where the cutting blade is exposed and usable for surgery. The knife also includes a depth of cut control which sets the depth to which the blade is used to make an ocular incision and which allows the plunger mechanism to extend and retract the bladeholder assembly without changing the depth of cut. A modified micrometer scale allows the depth of cut to be conveniently changed by a given distance without recalculating the cutting depth.

Claims

1. A surgical knife, said knife comprising:

a substantially straight, hollow, generally cylindrical handle terminating in first and second ends and having a central, axially-extending passageway;

a plunger assembly positioned within and axially moveable along said passageway to an extended position and a retracted position;

a blade holder assembly to which a surgical cutting blade is mounted,

said blade holder assembly positioned within said passageway,

said blade holder assembly axially moveable along said passageway responsive to the movement of said plunger assembly to extend said cutting blade from said first knife handle end and to retract said cutting blade into said knife handle;

a footplate attached to said first knife handle end;

means for setting a depth of cut of said cutting blade; and

means to retain said blade holder assembly in said extended position,

said retaining means includes means formed on said plunger assembly for engaging mating means formed on an interior surface of said knife handle.

2. A surgical knife, said knife comprising:

a hollow, generally cylindrical handle terminating in first and second ends and having a central, axially-extending passageway;

a blade holder assembly axially moveable along said passageway to extend said cutting blade from said first handle end and to retract said cutting blade into said handle;

a surgical cutting blade mounted to said blade holder assembly,

a footplate attached to said first handle end; and

means for setting a depth of cut of said cutting blade by extending or retracting said cutting blade to a desired distance beyond said footplate,

said depth setting means including a micrometer thimble in threaded engagement with the exterior surface of said handle at said second handle end, whereby rotation of said thimble causes said cutting blade assembly to move in an axial position within and relative to said handle;

said depth setting means further including a base line scribed on said knife handle,

said base line extending in an axial position along said knife handle; and

a scale scribed on said thimble, said thimble scale including a series of scale lines regularly spaced about the periphery of said thimble and extending in said axial direction,

said thimble scale lines arrayed to bring successive of said lines into alignment with said base line as said thimble is rotated,

said scale lines numbered about said thimble periphery to form a numerical depth scale and a numerical increment scale parallel one to another,

said depth scale being numbered from 0 to 50 and said increment scale being numbered in identically-spaced increments from 50 to 100, with the numbers 0 on the depth scale and 50 on the increment scale coinciding.

3. A surgical knife, said knife comprising:

a substantially straight, hollow, generally cylindrical handle terminating in first and second ends and having a central, axially-extending passageway;

a plunger assembly positioned within and axially moveable along said passageway to an extended position and a retracted position;

a blade holder assembly to which a surgical cutting blade is mounted,

said blade holder assembly positioned within said passageway,

said blade holder assembly axially moveable along said passageway responsive to the movement of said plunger assembly to extend said cutting blade from said first knife handle end and to retract said cutting blade into said knife handle;

a footplate attached to said first knife handle end;

means for setting a depth of cut of said cutting blade by extending or retracting said cutting blade to a desired distance beyond said footplate,

said depth setting means further including a base line scribed on said knife handle,

said base line extending in an axial position along said knife handle; and

a scale scribed on said thimble, said thimble scale including a series of scale lines regularly spaced about the periphery of said thimble and extending in said axial direction,

said thimble scale lines arrayed to bring successive of said lines into alignment with said base line as said thimble is rotated,

said scale lines numbered about said thimble periphery to form a numerical depth scale and a numerical increment scale parallel one to another,

said depth scale being numbered from 0 to 50 and said increment scale being numbered in identically-spaced increments from 50 to 100, with the numbers 0 on the depth scale and 50 on the increment scale coinciding; and

means to retain said blade holder assembly in said extended position,

said retaining means includes means formed on said plunger assembly for engaging mating means formed on an interior surface of said knife handle.