Firearms – Stocks – For pistols
Reexamination Certificate
2000-07-18
2003-08-26
Johnson, Stephen M. (Department: 3641)
Firearms
Stocks
For pistols
C042S007000
Reexamination Certificate
active
06609322
ABSTRACT:
BACKGROUND
Hand powered instruments useful for biting tissues, known as rongeurs are common in the field of surgery. While there are many variations designed for use by one hand, the most common by far, would be the Pituitary, Kerrison, and Leksell types.
Prior hand operated rongeurs of the pituitary type have been characterized by a scissors like construction, with thumb and index finger grip holes, or of the Kerrison type using the thenar-palm line and four fingered handle. In these and other available designs, the forefinger is used to actuate the instrument from a position offset from the actuating operating mechanism so that the force required to close and open the instrument also translates in part into an upward displacement of the operating shaft and tip of the instrument. Not infrequently the surgeon finds it necessary to post the tip of the instrument into healthy tissue in order to limit the movement of the tip before biting or cutting the tissue to be removed. This injures healthy tissue. Also, due to the orientation of the hand and fingers, the location of the tip of the instrument is difficult to be mentally perceived, much less controlled, by the surgeon.
There is, therefore, a need for an improved handle for surgical instruments.
SUMMARY OF THE PRESENT INVENTION
The present invention consists of a rongeur having a main body portion which is the longitudinal proximal extension of the working shaft of the instrument. The most rearward portion of the body portion extends for approximately one inch over the dorsum of the hand, specifically in the notch formed by the junction of the thumb and index finger to the hand. Just distal to the proximate end of the body member, is the rear arcuate handle, the arc facing the rear end of the instrument. This rear handle is affixed to the body portion at essentially 90 degrees to the long axis of the body portion and will anatomically conform to the shape of the thenar eminence (the prominence of the muscles of the thumb) when the hand is in the “Bang Bang”, “Fake Gun” or index finger pointing with the thumb extended position. In fact, the hand in grasping the instrument will, by means of said fixed proximal handle contour, be coaxed into assuming the desired position.
The lower portion of the rear handle continues, where it may either become convex or continue in line with the thenar portion, in which event said member would follow the shape of the thenar proximal, but would be more ulnar (towards the little finger side of the hand) such that in either case the ulnar border of the hand would be driven more proximal beneath the thenar's and with a tendency for the wrist, if unresisted, to assume a more extended (cocked-up) position. Spaced from the rear handle member of the instrument is a front downwardly disposed, pivotable arcuate handle member, of a length sufficient to accommodate the long, ring and little fingers of the hand. The lower portion of the front handle may be curved to facilitate finger placement and provide for a cradling of the lowest finger, thereby providing for a better feel and more control. A spring mechanism associated with the front handle, is utilized to urge the front handle to its original forward position. In alternative embodiments, the front handle may be fixed and provided with a trigger housing and mechanism for activating the rongeur. For example, if the rongeur is electrically powered, the trigger within the housing would activate the rongeur.
The instrument of the present invention is grasped quite differently from all other prior surgical instruments in that the index finger is separated from the remaining three fingers and is left extended along the main shaft of the instrument, pointing, while the three remaining fingers are wrapped around the unusually short front handle or trigger. The thumb is fully extended and may come to rest in more distal position, relative to its natural resting position and to the other fingers of the hand, as the shape of the rear handle urges the thumb portion of the hand forward and the wrist into a more extended (cocked-up) position. The part of the body portion coming to lie between the thumb and index fingers, which are relatively opposed, is called the “pinch pad” area of the body portion of the instrument.
The following advantages of the present invention are a product of the handle design and the induced finger, hand, and wrist positions:
1. Ambidextrous.
2. Anatomic to the working position profile of the inside of the partially closed hand.
3. Anatomic to and thus induces the optimal functional finger, hand and wrist positions.
4. Recruits the “Automatic Hand Effect” to optimize the instrument function. If no attempt is made to inhibit it, it can be observed that taking the fingers from the fully extended position with the hand straight out to the semi-closed finger grasping position, causes the wrist to go into the “cocked-up” position automatically. This effect is deliberately elicited by the handle design and is beneficial in at least two ways. Firstly, it allows for the proper alignment, discussed below, and secondly it improves the finger flexion function, as described below in Item 6.
5. While the handle design deliberately elicits the described wrist extension, this in fact results in the absolute longitudinal alignment of the surgical instrument through the hand and wrist with the forearm.
6. Finger flexion. The means of operating these instruments is facilitated by wrist extension. This is easily proven by assuming the opposite position and attempting to make a fist with the wrist fully flexed.
7. Elimination of the operating shaft/hand vertical displacement, increasing control.
8. Maximalization of hand contact is achieved for added control. The thumb and index fingers contact the body portion throughout their entire length. The palm engages the handle across its entire breadth, with the thenar engaging and almost encircling the rear handle portion. The three remaining fingers literally wrap around the front handle portion.
9. Minimalization of skin contact pressures.
10. Fits all size hands, because the lower three fingers wrap the pivotal front handle or trigger, and since it does not matter whether it is more proximally or distally, the handle will function well, and feel good to hands of all sizes.
11. Increased mechanism capacitance of springs and the like in the body portion.
12. The surgeon's hand is not exposed to any sharp or moving parts.
13. Enhanced instrument stability. The opposition of the thumb and index fingers on either side of the “pinch pad” stabilizes the instrument against side to side movement, while the instrument is also stabilized against any up and down movement by both the rear and front handles, which have both upper and lower contoured stops.
14. Ergonomic. The handle is biomechanically engineered to facilitate the human hand function in its operation.
15. Proprioceptive. Proprioception or kinesthetic sense is the ability to correctly spacially locate a bodily part without the use of vision. This allows one to easily place a finger in the ear or on the tip of the nose, even with the eyes closed. The index finger first, and the tactile pulp of the thumb secondly, are the most richly invested with this kinesthetic capacity. Prior rongeurs have failed to take advantage of this, and have allowed both the index finger and thumb to face away from the intended target, or to be curled up in and upon themselves. The present design aligns the index finger and thumb along the longitudinal axis of the instrument such that they always point exactly at the target, and thereby facilitate the accurate placement of the instrument by the operator, without the need to visually monitor that action. This is extremely important as it allows the surgeon to remain focused at the surgical site even as the instrument is passed into and away from that site, and without the need for the surgeon to perform continuing and repetitive disruptive reorientations.
16. The absence of reactive tip excursion. Since the typical rongeur pro
Johnson Stephen M.
Martin & Ferraro LLP
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