US3262452A - Goniometer apparatus for brain surgery - Google Patents

Description

July 26, 1966 w. HARDY ETAL 3,262,452

GONIOMETER APPARATUS FOR BRAIN SURGERY Filed April 1.7, 1963 5 Sheets-Sheet 1 I N V EN TORS W6 Y! #620 Y wan/7M A guy uvmv Y July 26, 1966 w. HARDY ETAL GONIOMETER APPARATUS FOR BRAIN SURGERY Filed April 1.7, 1963 5 Sheets-Sheet 2 July 26, 1966 w. HARDY ETAL GONIOMETER APPARATUS FOR BRAIN SURGERY Filed April 17, 1963 5 Sheets-Sheet 5 R mm miw WW2 MM W M United States Patent GUNIOMETER APPARATUS FOR BRAIN SURGERY This invention relates to surgical apparatu and, more specifically, to goniometric apparatus used in connection with brain surgery. Various neurological diseases characterized by tremors and rigidity are markedly improved when a small area of the brain is treated. This treatment consists of limited destruction by mean of cutting or lesioning, electrocautery, ultrasound, freezing, or by introduction of chemicals. to such use, for the sake of simplicity and the simplification of terminology, the apparatus of this invention will be described in connection with lesioning. This lesioning process is accomplished by passage of a cannula to the specific area of the brain.

The lesioning process itself is relatively simple and well understood. Likewise, the actuallesioning itself requires very little time. The time consuming and, therefore, relatively expensive portion of the procedure has always been to locate the precise area on any given patient to be lesioned. Thi has been necessitated by the fact that the precise area within the brain cavity varies from patient to patient, and by the pronounced differences in the configuration of human skulls.

The surgery is performed through a small trephine or hole in the cranium; and the exact area to be lesioned is a definite area within the brain. The lesion area of the brain may be located by X-ray; however, since the brain is not a plane surface, the area must be located in both the anterio-posterior and the medio-lateral directions. It is obviou that, in order to insert a cannula through the trephine in the cranium and precisely reach the target area, the cannula must be precisely guided in both anterio-posterior and medio-later-al directions. This has been done in the past by various apparatus; all of which required a progressive series of check X- rays because the devices were not accurate enough to be precisely adjusted from the initial X-rays. The old procedure Was time consuming to the surgeon as well as causing unnecessary discomfort to the patient.

One object of the present invention is to provide an apparatus for precisely guiding the axis of a cannula to coincide with the axis through a trephine in the cranium and a precise area of the brain, in both anterioposterior and mediadateral directions from two X-ray films taken before surgery, one of which was taken in the anterio-posterior and the other in the medio-lateral position; the apparatus being set from the X-ray films.

Another object of the present invention is to reduce the number and the frequency of the X-ray requirements in the course of the surgery.

Still another object of the present invention is to provide an apparatus which, when removably joined to the patients cranium, may be set precisely to the determinations made on the X-ray films.

A still further object of the present invention is to provide a goniometer having the highest degree of accuracy, and which is nearly fool-proof in its use.

Additional objects, advantages and features of the invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention as will appear from the following description and accompanying drawings wherein:

FIG. 1 is a plan view, in reduced scale, of the goniometer.

FIG. 2 is a reduced scale side elevation, partially in section, taken along line 2-2 of FIG. 1 and rotated 90 to the left.

Although not limited FIG. 3 is a plan section on line 33 of FIG. 2 showing an azimuth scale.

FIG. 4 is a plan section on line 4-4 of FIG. 2 with the upper swivel plate omitted and showing the method of link-ing the cannula guide to the adjusting micrometers.

FIG. 5 is a vertical section on line 5'5 of FIG. 3.

FIG. 6 is a front elevation of the base.

FIG. 7 is a rear elevation of the base showing a drainage passage.

FIG. 8 is an exploded perspective of a portion of the cannula guide and the elements linking it to the adjusting micrometers.

FIG. 9 is a perspective of the goniometer, and

FIG. 10 illustrates the method for determining the correct setting of the goniometer from an X-ray negative by using a transparent overlay,scale.

Referring to the drawings and, in particular, to FIG. 1, FIG. 2 and FIG. 9, the goniometer 11 has abase 12 which in use is joined to the patients cranium in a manner to be hereinafter described. The balance of the goniometer, referred to as indexinghead 15, is removably and rotatably mounted onbase 12. As will be better understood from a further reading of the specification, the terms removable and removably mounted or joined are to be differentiated from disassembable, in that there is a distinct function to be performed by the base when the indexing head is removed from the base; namely, to prevent body fluids flowing from the trephine in the patients skull and through the base from entering and encrusting on the indexing head, which if they did, would hinder the operation of the apparatus and would also form a site for infection. The indexinghead 15 has for its more essential elements, a base collar orring 14, a first quadrant means 18, a second quadrant means 16 at right angle to the first quadrant means, acannula guide 20, a first threaded adjusting means ormicrometer 24 and a second threaded adjusting means ormicrometer 22.

FIG. 10 represents an X-ray negative of the patient on which a transparent scale 26 (shown fragmentarily) has been positioned for a purpose to be hereinafter described. The goniometer (exceptcannula guide 20 which is shown in section) has most of its elements shown in phantom lines to indicate that the major portions are made of aluminum, magnesium or other materials which do not completely shield the penetration of X-rays. Thebase 12 is attached to the patients skull, and the indexinghead 15 is properly positioned and oriented on the base before the X-ray is taken. The goniometer has an azimuth scale, to be described hereinafter, to assure that the indexing head may be repeatedly oriented to the same position on the base. Thebase 12 has aflange 28, the lower face of which is contoured to the general shape of the human skull in the general area shown. The base is positioned to locate its vertical axis over the center of thetrephine 30, which had been previously formed, where it is held in position bypin 32 andscrew 34 which engage the skull.

Referring to FIG. 5, FIG. 6 and FIG. 7, thebase 12, in addition toflange 28, has acircular boss 36 having a passage axially passing through the boss and flange and having aspherical seat 38 at the free end of the boss. One element of the azimuth scale previously mentioned is scribed on the upper part of the boss. The scribed element of the azimuth scale is best shown on FIG. 3 as scribedindex line 40. As best shown on FIG. 5 and FIG. 7, the base also contains apassage 41 for the natural drainage of fluids from the tissues within the patients skull throughtrephine 30. As best shown on FIG. 3, the second element of the azimuth scale is shown onbase ring 14 as scribedindex 42, which is graduated through the full 360 of the circle. The azimuth scale provides a convenient means for repeatedly orienting the indexinghead 15 to any position on the patients skull, where it is releasably held in place bylock screw 43. It is obvious that the azimuth scale may be reversed with the scribedindex line 40 on thebase ring 14 and theindex 42 on thebase 12.

Each of quadrant means 16 and 18 has an arcuate crown containing an elongatedlinear slot 16a and 18a as best shown on FIG. 9. The slots are of such width as to provide a free fit for retaining and guiding the upper end of thecanriula guide 20 as shown. The lower open yoke end of each quadrant means is pivotally joined tobase ring 14 by means ofscrews 44 as best shown on FIG. and FIG. 9. Other pivoting means may be used; the important consideration being to provide a quadrant structure consisting of two means pivotally mounted at substantially 90 to each other and having superimposed crowns each arcuately movable in relation to the other. In order to provide ideal movement of components, the pivot axis of the first and second quadrant means should substantially be on a plane normal to the longitudinal passage through the cannula guide and passing through the geometrical center of thespherical seat 38 inbase 12 when the indexing head is joined to the base.

As best shown on FIG. 10, the cannula guide is an elongated hollow tube having aball end 46 at the lower end, and having asimilar ball 48 at the mid section. Theball end 46 andball 48 may be directly formed as shown; or, if desired, they may be made of ball elements and brazed in place.Ball end 46 is pivotally seated inseat 38 ofbase 12 as'best shown on FIG. 5. As best shown on FIG. 2, joined tocannula guide 20 is awasher 50 providing a spring saddle forcompression spring 52 which is disposed betweenwasher 50 and quadrant means 18 to bias the cannula guide toward thebase 12.

Referring in particular to FIG. 8 and FIG. 9,spindle 22a onmicrometer 22 andspindle 24a onmicrometer 24 each have aball end 54 joined to the free end thereof by means ofpin 56. Two triangular-shapedswivel plates 58, having holes in each corner area, are so placed oncannula guide 20 that one swivel plate is on each side ofball 48 on the cannula guide while the holes 60 in the other corner areas of the swivel plates engage theballs 54 onball ends 54. All holes in the swivel plates may be straight holes; or, they may be contoured to the form of the respective balls. As best shown on FIG. 2 and FIG. 8, the upper and lowerswivel plates 58 are resiliently held together to engageball ends 54 by means ofscrew 62,compression spring 63 andnut 64.

Each micrometer may be axially adjusted on its re spective quadrant means during instrument calibration by means of adjustingnuts 66 shown on FIG. 9. The calibration scale shown on each micrometer may be graduated to show the angular displacement of the cannula guide from its vertical zero position. During instrument calibration each micrometer is axially adjusted to read 0 on the calibration scale when the cannula guide is in its true vertical zero position. The particular scale used is a function of the distance between ball end 46 andball 48 on the cannula guide, and the pitch of the micrometer thread. Micrometers calibrated to read linear measurements may be used, but such use requires a mental conversion of linear readings to angular equivalents on the cannula guide. The arrangement of elements is such that the axis through the cannula guide may be set to any simple or compound angle from the vertical zero position.

After the patient has been prepared andbase 12 attached to the patients skull as indicated on FIG. 10, the indexing head is joined to the base and oriented in azimuth to place the axes of the micrometers into the anterio-posterior and medic-lateral planes on which the X- rays are to be taken; where it is held in place bylock screw 43. The azimuth reading is made of record in order that the indexing head may subsequently be returned to the initial position. The goniometer is set to have the axis of the cannula guide on the vertical zeroaxis 68 shown on FIG. 10. The patient, with goniometer attached, is then X-rayed; taking at least one picture in both the anterio-uosterior and medic-lateral positions. The indexing head is then removed, leaving the base on the patients skull.

After the X-ray films have been developed, the films are used to determine the correct compound angle of the cannula guide in order for the cannula to reach thelesion area 70 within the patients brain. FIG. 10 which represents an X-ray film in the anterio-posterior position shows thehypothetical lesion area 70 in that one plane of the film. The transparent scale 26 is superimposed over the film with the center of the scale over the ball end of the cannula guide as shown and the 0 line coinciding with the vertical zeroaxis 68 passing through the cannula guide when the X-ray was taken. Thelesion area 70 is shown to be on the 5 line etched on the scale and indicates the correct required angular displacement of the cannula guide from its vertical Zero position in the anterio-posterior plane in order to make the axis pass through thelesion area 70. When the cannula guide is displaced the required 5 by adjustingmicrometer 22, the axis through the cannula guide will coincide with the 5 position on the scale and will be in proper alignment in the anterio-posterior plane. The procedure is repeated on the film taken in the medic-lateral direction; that adjustment being made withmicrometer 24. It is obvious that the compound angle of the cannula guide is now properly positioned to place the axis throughlesion area 70 in the patients brain.

The scale 26 is graduated in degrees on both sides of the 0 line as shown. For clarity, only each fifth degree line is shown full length on the drawing. Also on the scale, as shown, are a series of arcuate lines radiating from the scale center. These arcs may he graduated in inches as shown, or in the metric system. The arcuate lines are useful in estimating the distance of thelesion area 70 from such reference surface as the upper end of the cannula guide. It is obvious that the scale 26 may be superimposed on the film with the 0 line passing througharea 70; in which case the necessary angular adjustment would be read onaxis 68.

It is to be understood that the embodiment of the present invention as shown and described is to be regarded as illustrative only, and that the invention is susceptible to variations, modifications and changes within the scope of the appended claims.

We claim:

1. A goniometer having an angularly adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base having an upper and a lower end with an axial bore extending through said ends, the lower end being contoured and adapted for externally joining in a fixed non-rotating manner to a convex surface and the upper end having a seat coaxial with said bore, and an indexing head removably joined to said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head; said indexing head comprising a base collar removably joined to said base, a cannula guide the lower end of which engages with the seat in said base when said indexing head is joined to said base, a first quadrant means pivotally joined at the lower end to said base collar and slidably engaging the upper portion of said cannula guide, a second quadrant means pivotally joined at the lower end to said base collar to be superimposed at substantially to said first quadrant means and slidably engaging the upper portion of said cannula guide,

a first adjusting means joined to said first quadrant means and pivotally moving said cannula guide on said base and pivoting said second quadrant means on said base collar, and a second adjusting means joined to said second quadrant means and pivotally moving said cannula guide on said base and pivoting said first quadrant means on said base collar.

2. A goniometer having an angularly adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base and ,an indexing head removably joined to said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to a convex surface, a boss extending upward from said flange, and a bore coaxially passing through said boss and said flange and forming a seat at the free end of said boss; said indexing head comprising a base collar removably joined to said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing :body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head, a cannula guide the lower end of which engages with the seat at the free end of the boss on said base when said indexing head is joined to said base, a first quadrant means pivotally joined at the lower end to said base collar and slidably engaging the upper portion of said cannula guide, a second quadrant means pivotally joined at the lower end to said base collar to be superimposed at substantially 90 to said first quadrant means and slidably engaging the upper portion of said cannula guide, a first adjusting means joined to said first quadrant means and engaging said cannula guide for pivotally moving said cannula guide on said base and pivoting said second quadrant means on said base collar, and a second adjusting means joined to said second quadrant means and engaging said cannula guide for pivotally moving said cannula guide on said base and pivoting said first quadrant means on said base collar.

3. A goniometer having an angularly adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patientsbrain with a cannula or other instrument guided by the cannula guide and comprising: a base and an indexing head removably and rotatably joined to said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to a convex surface, a circular boss extending upward from said flange, and a bore coaxially passing through said boss and said flange and forming a seat at the free end of said boss; said indexing head comprising a base ring removably and rotatably joined to the circular boss on said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head, a hollow cannula guide the lower end of which engages with the seat at the free end of the circular boss on said base when said indexing head is joined to said base, a first quadrant means pivotally joined at the lower end to said base ring and slidably engaging the upper portion of said hollow cannula guide, a second quadrant means pivotally joined at the lower end to said base ring to be superimposed at substantially 90 to said first quadrant means and slidably engaging the upper portion of said hollow cannula guide, a first adjusting means joined to said first quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said second quadrant means on said base ring, and a second adjusting means joined to said second quadrant means 6 and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said first quadrant means on said b-asetring.

4. A goniometer having an angularly adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base and an indexing head removably and rotatably joined to said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to a convex surface, a circular boss extending upward from said flange, and a bore coaxially passing through said boss and said flange and forming a seat at the free end of said circular boss; said indexing head comprising a base ring removably and rotatably joined to the circular boss on said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head, a hollow cannula guide the lower end of which engages with the seat at the free end of the circular boss on said base when said indexing head is joined to said base, a first forked quadrant means straddling and pivotally joined at the lower open end to said base ring and slidably engaging the upper portion of said hollow cannula guide, a second forked quadrant means straddling and pivotally joined at the lower open end to said base ring to be superimposed at substantially to said first quadrant means and slidably engaging the upper portion of said hollow cannula guide, a first adjusting means joined to said first quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said second quadrant means on said base ring, a second adjusting means joined to said second quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said first quadrant means on said base ring, and a biasing means disposed between said hollow cannula guide and said first quadrant means for biasing said hollow cannula guide against the seat in said base. I

5. A goniometer having an angularly adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base and an indexing head removably and rotatably joined to said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to a convex surface, a circular boss extending upward from said flange, and a bore coaxially passing through said boss and said flange and forming a seat at the free end of said circular boss; said indexing head comprising a base ring removably and rotatably joinedto the circular boss on said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head, a hollow cannula guide the lower end of which engages with the seat at the free end of the circular boss on said base when said indexing head is joined to said base, a first forked quadrant means having an arcuate crown' with an elongated longitudinal slot slidably engaging the upper upper portion of said hollow cannula guide and having the lower open end straddling and pivotally joined to said base ring, a second forked quadrant means having an arcuate crown with an elongated longitudinal slot slidably engaging the upper portion of said hollow cannula guide and having the lower open end straddling and pivotally joined to said base ring to be superimposed at substantially 90 to said first quadrant means, a first adjusting means joined to said first quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said second quadrant means on said base ring, and a second adjusting means joined to said second quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said first quadrant means on said base ring.

6. A goniometer having an angularly adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base and an indexing head removably and rotatably joined to said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to a convex surface, a circular boss extending upward from said flange, and a bore coaxially passing through said boss and said flange and forming a seat at the free end of said circular boss; said indexing head comprising a base ring removably and rotatably joined to the circular boss on said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head, a hollow cannula guide the lower end of which engages with the seat at the free end of the circular boss on said base when said indexing head is joined to said base, a first forked quadrant means having an arcuate crown with an elongated longitudinal slot slidably engaging the upper portion of said hollow cannula guide and having the lower open end straddling and pivotally joined to said base ring, a second forked quadrant means having an arcuate crown with an elongated longitudinal slot slidably engaging the upper portion of said hollow cannula guide and having the lower open end straddling and pivotally joined to said base ring to be superimposed at substantially 90 to said first quadrant means, a first adjusting means joined to said first quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said second quadrant means on said base ring, a second adjusting means joined to said second quadrant means and engaging said hollow cannula guide for pivotally moving said hollow cannula guide on said base and pivoting said first quadrant means on said base ring, and a biasing means disposed between said hollow cannular guide and said first quadrant means for biasing said hollow cannula guide against the seat in said a base.

7. A goniometer having an angularly adjust-able cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base and an indexing head removably and rotatably joined to said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to, a convex surface, a circular boss extending upward from said flange, and a bore coaxially passing through said boss and said flange and terminating in a spherical seat at the free end of said circular boss; said indexing head comprising a base ring removably and rotatably joined to the circular boss on said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encrusting on said indexing head, an elongated cannula guide terminating at the lower end in a ball engaging the spherical seat in said base when saidindexing head is joined to said base and having a longitudinal passage therethrough, a first forked quadrant means having an arcuate WQWQ ith an elongated longitudinal slot slidably engaging the upper portion of said cannula guide and having the lower open end straddling and pivotally joined to said base ring, a second forked quadrant means having an arcuate crown with an elongated longitudinal slot slidably engaging the upper portion of said cannula guide and having the lower open end straddling and pivotally joined to said base ring to be superimposed at substantially to said first quadrant means, the pivot axis of said first and said second quadrant means being substantially on a plane normal to the longitudinal passage through said cannula guide when coaxial with the bore in said base to be in the vertical zero position and passing through the geometrical center of the spherical seat in said base when said indexing head is joined to said base; a first adjusting means joined to said first quadrant means and engaging said cannula guide for pivotally moving said cannula guide on said base and pivoting said second quadrant means on the second quadrant pivot axis, and a second adjusting means joined to said second quadrant means and engaging said cannula guide for pivotally moving said cannula guide on said base and pivoting said first quadrant means on the first quadrant pivot axis.

8. A goniometer as set forth inclaim 7 wherein said first and said second adjusting means are threaded adjusting means having a calibration scale to indicate the angular displacement of said cannula guide from the vertical zero position.

9. A goniometer as set forth inclaim 7 wherein said first and said second adjusting means are threaded adjusting means having a calibration scale to indicate the angular displacement of the cannula guide from the vertical zero position and each having adjusting means for lineally adjusting their joined position in said first and said second quadrant means, thus providing a means for setting the zero on the calibration scale to the vertical zero position of said cannula guide during instrument calibration.

10. A goniometer having an angular adjustable cannula guide and being adapted for attaching over a trephine in a patients skull, thus permitting a surgeon to reach a predetermined area of the patients brain with a cannula or other instrument guided by the cannula guide and comprising: a base and an indexing head removably and rotatably joined to said base, said base and said indexing head having a first and a second azimuth scale element indicating the azimuth of said indexing head on said base; said base comprising a flange contoured and adapted for externally attaching in a fixed non-rotating manner to a convex surface, a circular boss extending upward from said flange, a bore coaxially passing through said boss and said flange and terminating in a spherical seat at the free end of said circular boss, and the first of said azimuth scale elements scribed on said circular boss; said indexing head comprising a base ring removably and rotatably joined to the circular boss on said base for leaving said base in fixed position on the patient when said indexing head is removed and thus preventing body fluids flowing from the trephine in patients skull and through said base from entering and encnisting on said indexing head and having the second of said azimuth scale elements scribed thereon, an elongated cannula guide terminating at the lower end in a ball engaging the spherical seat in said base when said indexing head is joined to said base and having a longitudinal passage therethrough, a first forked quadrant means having an arcuate crown with an elongated longitudinal slot slidably engaging the upper portion of said cannula guide and having the lower open end straddling and pivotally joined to said base ring, a second forked quadrant means having an arcuate crown with an elongated longitudinal slot slidably engaging the upper portion of said cannula guide and having the lower open end straddling and pivotally joined to said base ring to be superimposed at substantially 90 to said first quadrant means, the pivot axis of said first and said second quadrant means being substantially on a plane normal to the longitudinal passage through said cannula guide when coaxial with the bore in said base to be in the vertical Zero position and passing through the geometrical center of the spherical seat in said base when said indexing head is joined to said base; a first threaded adjusting means joined to said first quadrant means and engaging said oannula guide for pivotally moving said cannula guide on said base and pivoting said sec-0nd quadrant means on the said second quadrant pivot axis, said first threaded adjusting means having a calibration scale to indicate the angular displacement of the cannula guide from the vertical zero position, and a second threaded adjusting means joined to said second quadrant means and engaging said cannula guide for pivotally moving said cannula guide on said base and pivoting said first quadrant means on the said first quadrant pivot axis, said second threaded adjusting means having a calibration scale to indicate the angular displacement of the cannula guide from the vertical zero position, said first and said second threaded adjusting means having adjusting means for setting the zero on the calibration scale to the vertical zero position of said cannula guide during instrument calibration.

11. A goniometer as set forth inclaim 10 and having References Cited by the Examiner UNITED STATES PATENTS 2,697,433 12/ 1954 Zehnder l28-83 3,115,140 12/1963 Volkman 128-410 FOREIGN PATENTS 182,815 8/1955 Austria. 240,542 4/ 1946 Switzerland.

RICHARD A. GAUDET, Primary Examiner.

G. MCNEILL, Assistant Examiner.

Claims (1)

1. A GONIOMETER HAVING AN ANGUALRLY ADJUSTABLE CANNULA GUIDE AND BEING ADAPTED FOR ATTACHING OVER A TREPHINE IN A PATIENT''S SKULL, THUS PERMITTING A SURGEON TO REACH A PREDETERMINED AREA OF THE PATIENT''S BRAIN WITH A CANNULA OR OTHER INSTRUMENT GUIDED BY THE CANNULA GUIDE AND COMPRISING: A BASE HAVING AN UPPER AND A LOWER END WITH AN AXIAL BORE EXTENDING THROUGH SAID ENDS, THE LOWER END BEING CONTOURED AND ADAPTED FOR EXTERNALLY JOINING IN A FIXED NON-ROTATING MANNER TO A CONVEX SURFACE AND THE UPPER END HAVING A SEAT COAXIAL WITH SAID BORE, AND AN INDEXING HEAD REMOVABLY JOINED TO SAID BASE FOR LEAVING SAID BASE IN FIXED POSITION ON THE PATIENT WHEN SAID INDEXING HEAD IS REMOVED AND THUS PREVENTING BODY FLUIDS FLOWING FROM THE TREPHINE IN PATIENT''S SKULL AND THROUGH SAID BASE FROM ENTERING AND ENCRUSTING ON SAID INDEXING HEAD; SAID INDEXING HEAD COMPRISING A BASE COLLAR REMOVABLY JOINED TO SAID BASE, A CANNULA GUIDE THE LOWER END OF WHICH ENGAGES WITH THE SEAT IN SAID BASE WHEN SAID INDEXING HEAD IS JOINED TO SAID BASE, A FIRST QUADRANT MEANS PIVOTALLY JOINED AT THE LOWER END TO SAID BASE COLLAR AND SLIDABLY ENGAGING THE UPPER PORTION OF SAID CANNULA GUIDE, A SECOND QUADRANT MEANS PIVOTALLY JOINED AT THE LOWER END OF SAID BASE COLAR TO BE SUPERIMPOSED AT SUBSTANTIALLY 90* TO SAID FIRST QUADRANT MEANS AND SLIDABLY ENGAGING THE UPPER PORTION OF SAID CANNULA GUIDE A FIRST ADJUSTING MEANS JOINED TO SAID FIRST QUANDRANT MEANS AND PIVOTALLY MOVING SAID CANNULA GUIDE ON SAID BASE AND PIVOTING SAID SECOND QUADRANT MEANS ON SAID BASE COLLAR, AND A SECOND ADJUSTING MEANS JOINED TO SAID SECOND QUADRANT MEANS AND PIVOTALLY MOVING SAID CANNULA GUIDE ON SAID BASE AND PIVOTING SAID FIRST QUADRANT MEANS ON SAID BASE COLLAR.

Images