IMPROVED MICRO-SURGICAL SCISSORS

Abstract: Micro-surgical scissors comprise a movable blade (1) extending from a cylindrical end portion (1A) attached to a shaft (1B) fixed to a tubular shaft (5) driven by known means to oscillate within a tubular body portion (4) having an end portion (4A) terminating in a fixed blade (2). Contacting surfaces (1C, 2C) of the blades (1, 2) are partly cylindrical and are lapped into each other to ensure close contact between blades (1, 2). A seal is created between the movable blade (1) and the tubular shaft (5) by means of an annular seat (4B) formed in the body portion (4) and co-operating annular surface (1D) formed on the end portion (1A). The seat (4B) and the surface (1D) are extensions of contacting surfaces (1C, 2C) of the blades (1, 2). Shaft (5) is supported by a bearing (9) acting as a locator for compression spring (13) which bears against spring locator (9') held in position on shaft (5) by joint (10) and has means (12) by means of which oscillatory drive motion is transmitted to shaft (5). The seal is maintained by compression spring (13) arranged between a housing (8) and spring locator (9').

Description: TITLE: IMPROVED MICRO-SURGICAL SCISSORS This invention relates to improvements in micro-surgical scissors, particularly intra-ocular scissors, although the invention should not be regarded as being restricted to micro-surgical scissors for that purpose. Micro-surgical scissors in which the movable blade is formed at the end of a shaft which is manually or motor driven to oscillate over a fixed blade formed at the end of a tubular instrument body suffer from the problem that body fluids often penetrate between the tube and the drive shaft during surgery. Where the scissors are used for intra-ocular surgery, the vitreous fluids are found to be extremely difficult to remove from the instrument after surgery. It is an object of the present invention to provide improved micro-surgical scissors in which the above problem is at least substantially reduced. The invention provides micro-surgical scissors comprising a tubular body portion 4A having a fixed blade component 2 extending from its free end, a shaft 5 located within said tubular body portion 4A and driven to oscillate therewithin, said shaft 5 having an end portion 1A from which a movable blade component 1 extends to co-operate with said fixed blade component 2 to define the micro-surgical scissors, the free end of said tubular body portion 4A being formed to define an annular seat 4B and said end portion 1A of said shaft 5 being formed to define a closely co-operating annular surface ID , and biassing means 13 for holding said annular surface ID in close contact with said annular seat 4B to form a seal between said end portion 1A and said tubular body portion 4A . The annular surface ID is preferably lapped into said annular seat 4B to increase the degree to which a seal is created between the respective surfaces. The annular surface on the end portion may therefore be regarded as being similar to a valve in an internal combustion engine which is lapped into its valve seat to ensure that an appropriate seal is created against the combustion gases when the valve is closed. The seat is preferably arranged at an angle of 35 to the axis of the tubular body portion although other angles may be used with equally successful results. The blade components are preferably as defined in greater detail below. It is a preferred object of the present invention to provide micro-surgical scissors having an improved blade arrangement which reduces the extent to which sharpening is required. To this end, the fixed blade component 2 and said movable blade component 1 have co-operating surfaces which define part of a cylindrical surface of revolution, said blade components 2, 1 extending at an acute angle to the axis of said body portion 4A , said biassing means 13 holding said co-operating surfaces in contact as said blade components 2, 1 move during cutting. The working surface of said movable blade component is preferably lapped into the working surface of said fixed blade component to ensure that the respective surfaces are closely complementary. The cutting edges of the respective blade components are defined in the usual manner by machining in a direction substantially perpendicular to the working surfaces . Because the respective working surfaces are closely complementary, the blades are substantially self-sharpening and require little or no maintenance during their working life. The drive shaft is oscillated by a suitable oscillatory drive mechanism and the drive mechanism is' preferably such as to cause the blades to open by approximately 20 . A preferred form of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional elevation of micro-surgical scissors embodying the invention; Figure 2 is an enlarged plan view of the cutting blades of the scissors, and Figure 3 is a sectional end view through the blades. The micro-surgical scissors will be seen to comprise a movable blade 1 extending from a cylindrical end portion 1A attached to a shaft IB fixed to a tubular drive shaft 5 driven by a known drive means to oscillate within a tubular body portion 4 having an end portion 4A formed from hardened steel and terminating in a fixed blade portion 2 . The blade portion 2 extends at an angle of 35° to the axis of the shaft 5 and the contacting surfaces of the blades 1 and 2 are partly cylindrical so that the movable blade 1 may be oscillated over the fixed blade 2 . To ensure close contact between the respective blades, the movable blade 1 has its contacting surface lapped into the contacting surface of the fixed blade 2 . As is usual, the cutting edges of the blades are defined by grinding surfaces IC and 2C which are perpendicular to the aforementioned contacting surfaces. To create a seal ' between the movable blade and the tubular body portion 5 , the end portion 4A of the tubular body portion 4 is formed with an annular seat 4B while the end portion 1A of the driven shaft 5 is formed with a co-operating annular surface ID . The annular seat is formed at an angle of 35 to the axis of the shaft 5 and it will be appreciated that the respective blades 1 and 2 form extensions of those surfaces. Thus, the annular surface IB is similarly lapped into the seat 4B to ensure that a relatively tight seal is formed between the respective surfaces. The tubular housing portion 4 is. supported by a sleeve which is in turn secured to a housing 8 which is adapted for threaded attachment to the drive housing (not shown) of a known oscillatory drive mechanism (for example see Australian Patent Specification AU-A 32501/78) . The drive shaft 5 is supported by a bearing 9 which also acts as a locator for compression spring 13 which bears ■ against a similar spring locator 9' which is held in position on the drive shaft 5 by an end fitting 11 which is attached to the drive shaft 5 by solder joint 10 and has means 12 for receiving a drive key by means of which oscillatory drive motion is transmitted to the shaft 5 in the usual manner. It will be appreciated that the compression spring 13 biasses the drive shaft 5 rearwardly which in turn holds the annular surface ID and the co-operating surface of the movable blade 1 in close contact with the co-operating surface of the fixed blade 2 and the seat 4B to not only ensure that the respective blade surfaces are in intimate contact but also that the required seal is established between the end portion 1A and the end portion 4A . As indicated in Figure 1, the loading established by the compression spring 13 is approximately 140 grams and this is found to provide the necessary contact between the surfaces of the blades - 1 , 2 and to establish a satisfactory seal such as to avoid the abovementioned problems of the prior art. OMPI

Claims: Claims : 1. Micro-surgical scissors comprising a tubular body portion (4A) having a fixed blade component (2) extending from its free end, a shaft (5) located within said tubular body portion (4A) and driven to oscillate therewithin, said shaft (5) having an end portion (1A) from which a movable blade component (1) extends to co-operate with said fixed blade component (2) to define the micro-surgical scissors, the free end of said tubular body portion (4A) being formed to define an annular seat (4B) and said end portion (1A) of said shaft (5) being formed to define a closely co-operating annular surface (ID) , and biassing means (13) for holding said annular surface (ID) in close contact with said annular seat (4B) to form a seal between said end portion (1A) and said tubular body portion (4A) . 2. The scissors of claim 1, wherein said annular surface (ID) is lapped into said annular seat (4B) to increase the degree to which a seal is created between the respective surfaces. 3. The scissors of claim 1 or claim 2, wherein said annular surface (ID) and said seat (4B) are arranged at about 35 to the axis of said tubular body portion (4A) . 4. The scissors of claim 1 wherein said fixed blade component (2) and said movable blade component (1) have co-operating surfaces which define part of a cylindrical surface of revolution, said blade components (2, 1) extending at an acute angle to the axis of said body portion (4A) , said biassing means (13) holding said co-operating surfaces in contact as said blade components (2, 1) move during cutting. 5. The scissors of claim 1, wherein said co-operating surfaces are lapped to ensure that they are closely complementary. 6. The scissors of claim 5, wherein said co-operating surfaces are extensions of said annular seat (4B) and said annular surface (ID) . 7. The scissors of claim 6, wherein the cutting edges (IC, 2C) of the blades (1, 2) are defined by flat surfaces extending substantially perpendicular to said co-operating surfaces. 8. Micro-surgical scissors substantially as hereinbefore described with reference to the accompanying drawings. OMPI

Inventors: CROCK GERRARD WILLIAM, PERICIC LJUBOMIR, CROCK, GERRARD, WILLIAM, PERICIC, LJUBOMIR
Applicants: UNIV MELBOURNE, THE UNIVERSITY OF MELBOURNE
Application year: 1983
Main classification: A61B17
IPC codes: A61B17