SHAVER HANDPIECE AND TERMINAL ACCESSORIES, PARTICULARLY FOR USE IN ARTHROSCOPY
DESCRIPTION
5 This patent concerns medical instruments, and particularly the instruments comprising a handpiece and related interchangeable blades and burs, specifically for use in arthroscopy. Certain surgical operations and manoeuvres demand the use of small blades or burs rotated by an electric motor. Surgical tools are known that comprise a handpiece and related interchangeable accessories-tools. The handpiece is composed of a grip containing an electric motor connected to the power supply by means of a suitable cord. At the opposite end of the handpiece, the accessories-tools needed for a given procedure are fitted as necessary. The end of the electric motor inside the handpiece is consequently connected, either directly or by means of gears, to a female coupling. This female coupling has a coaxial hole communicating radially with a chamber inside the handpiece, which can be connected to a suction system. The various accessories-tools include a tubular body, designed to be connected to the body of the handpiece, which contains a rotating arbor that carries the working tip (bur or blade) at one end and a male coupling at the other end for connecting it to the handpiece. To be more precise, the end of the tubular body of the accessory-tool where the working tip is attached is closed at its end and open at the side, while the working tip is basically spoon-shaped, with cutting edges that can only resect and/or shave tissue laterally. The arbor rotating inside the tubular body has a coaxial hole placing the working tip in communication with the male coupling, in such a
way as to enable the suction of the irrigation fluids and of the debris ablated by the working tip.
The accessory-tool and handpiece are connected together by various means, e.g. a collet or bayonet coupling, to prevent any accidental detachment of the accessory-tool from the handpiece and to keep the male and female couplings engaged.
The male and female, accessory-tool and handpiece couplings are normally hexagonal or square, so as to form a stable connection and ensure the transmission of the shaft's rotary motion with no slack or slipping. These handpieces and accessories-tools have various drawbacks.
The simple attachment of the accessory-tool to the handpiece does not necessarily coincide with an immediate connection and transmission of the rotary motion from the electric motor in the handpiece to the arbor carrying the accessory-tool's working tip. In fact, the male and female, handpiece and accessory-tool couplings rarely slot straight into place when they are axially aligned, so it becomes necessary to turn the electric motor or the arbor of the accessory-tool to complete the attachment of the accessory-tool to the handpiece, correcting the respective positions of the male and female couplings. Given the hexagonal or square shape of the male and female couplings between the handpiece and the accessory-tool, the working tip on the accessory-tool does not always occupy the same position, it may assume one of six or four, or numerous positions depending on the symmetry of the coupling obtained. The handpiece and accessory-tool are fitted with a further male-female connection in order to prevent the tubular body of the accessory-tool from turning, or rather to prevent the accessory-tool's tubular body from turning with respect to the handpiece. As a result, the working side of the accessory-tool is
always situated on the same side of the handpiece: above, below, right, left. The surgical manoeuvres required may make it necessary for the working side of the accessory-tool to lie on a different side, in which case the surgeon is obliged to turn the handpiece, which consequently comes to be held in an unnatural and uncomfortable position.
The electric motor in the handpiece is operated by a footswitch. This footswitch is for switching the motor on and off, and for selecting any intermediate electric motor turning speed, or for continuously modulating the motor's turning speed. To avoid all the above-outlined drawbacks, a new handpiece with terminal accessories (blades and burs) has been designed and implemented, particularly for arthroscopy, with a self-centering coupling that guarantees a constant positioning of the accessories, and with turning speed and power control. The aim of the new handpiece with terminal accessories is to ensure a rapid, direct coupling of the accessories-tools on the handpiece without having to align the male and female couplings either manually or by turning the motor.
Another aim of the new handpiece with terminal accessories is to couple each accessory-tool on the handpiece so as to guarantee the position of the working tip of the accessory-tool. A further aim of the new handpiece with terminal accessories is to enable the coupling of the accessory-tool on the handpiece in different, stable angular positions without having to turn the handpiece to move the working side of the accessory-tool towards the part to treat.
Another aim of the new handpiece with terminal accessories is to enable a continuous control over the turning speed of the motor and working tip. Another aim of the new handpiece with terminal accessories is to enable the adjustment and modulation of the motor's and working tip's force and power of rotation.
Another aim of the new handpiece with terminal accessories is to eliminate the encumbrance deriving from the handpiece's electric connection cord, which can become damaged with time.
Another aim of the new handpiece with terminal accessories is to automatically place the working tip in a safe angular position when the tool is not in use.
These and other, direct and complementary aims, are achieved by the new shaver handpiece with terminal accessories (blades and burs), particularly for use in arthroscopy, comprising a handpiece and accessories-tools having a male coupling on the handpiece motor shaft comprising a central spindle with round cross-section and with two radial pins on either side, and a female coupling on the accessory-tool arbor comprising a cylinder with a coaxial hole and two radial grooves at one end, with two sloping walls that come together to form a concave V shape. The handpiece motor's round central spindle fits into the accessory-tool arbor's coaxial hole, while the two radial pins on either side of the motor's male coupling fit into the grooves on the sloping walls of the accessory-tool's female coupling. When the accessory-tool is fitted on the handpiece, the sliding walls of the accessory-tool's coupling are guided by the radial pins on either side of the handpiece's male coupling, so that the female coupling is made to turn and the grooves in the sloping walls come into line with the radial pins.
The handpiece is fitted with batteries or electric storage units for driving the motor, a circuit for controlling the turning speed and the force and power of the motor, and a radio receiver circuit connected to said control circuit. The batteries do away with the electric cord for powering the motor, while a transmitter, installed outside the handpiece, enables the handpiece motor's speed, force and power of rotation to be set and adjusted, and these adjustments are transmitted by radio to the handpiece.
The motor in the handpiece is of the encoder memory type, so it always comes to be in the same position when it is switched off. The end of the tubular body of the accessory-tool that is coupled to the handpiece has several equidistant grooves, lying parallel to each other and to the axis of the tubular body, cut into the rounded surface of the accessory-tool's tubular body. Likewise, the handpiece seat that houses the accessory-tool is fitted with several rotation-preventing steady rests that can move only radially and are complete with an elastic element designed to guide them towards the center of said seat. The accessory-tool can consequently be attached to the handpiece in various angular positions, but any rotation of the accessory-tool's tubular body in its seat in the handpiece is prevented.
The characteristics of the new shaver handpiece with terminal accessories (blades and burs), particularly for use in arthroscopy, will be better clarified in the following description with reference to the drawings attached, provided only as an illustrative and not restrictive example.
Figure 1 shows the handpiece (A) and the accessory-tool (U), while figure 2 shows a cross-section of the handpiece (A) and the accessory-tool (U). Figure 3 is an axonometric representation of the male coupling (M) on the handpiece (A) and of the female coupling (F) on the accessory-tool (U). Figure 4 illustrates the accessory-tool (U) and the spindle on the handpiece (A), showing cross-sections of the male coupling (M) of the spindle on the handpiece (A) and the female coupling (F) of the accessory-tool (U). The male coupling (M) comprises the round spindle (M1 ) with two radial pins (M2) on either side near its end. These radial pins (M2) shall have a preferably circular cross-section.
Said male coupling (M) may form an integral part of the shaft of the motor in the handpiece (A), or it may be keyed onto the shaft.
The female coupling (F) comprises a cylinder (F1) with two radial grooves (F3) at the end, with two walls (F4) that slope towards each other to form a concave V shape. Each groove (F3) has wails lying parallel to each other and the same distance apart as the thickness of each of the radial pins (M2) on either side of the male coupling (M).
A coaxial hole (F6) in the cylinder (F1) in the female coupling (F) extends from the sloping walls (F4) to the inside of said cylinder (F1 ).
Another coaxial hole (F2) runs from the opposite end of the cylinder (F1) up to the sloping walls (F4) and radial grooves (F3) in the cylinder (F1). The two coaxial holes (F2, F6) are not in communication with each other.
The cylinder (F1) in the female coupling (F) has a further radial hole (F5), communicating with the coaxial hole (F2) opposite the grooves (F3). The above-described female coupling (F) can be mechanically connected to the central arbor in the accessory-tool (U), and the arbor in the accessory-tool (U) has a radial hole suitable for the suction of debris ablated by the working tip and of the irrigation fluids, or it may form an integral part, or be the terminal part of the central arbor in the accessory-tool (U), in which case it has a radial hole for said suction of the debris ablated by the working tip and of the irrigation fluid. The above-described male (M) and female (F) couplings are associated or connected with, or form an integral part of the arbor inside the accessory-tool (U) and of the spindle of the motor in the handpiece (A).
When the accessory-tool (U) is attached to the handpiece (A), the female coupling (F) on the accessory-tool (U) encounters the male coupling (M) on the handpiece (A) at a random angle, very probably with the grooves (F3) misaligned with respect to the radial pins (M2) on either side of the male coupling (M).
The round central spindle (M1) of the male coupling (M) is fitted into the coaxial central hole (F6) of the female coupling (F), while the radial pins (M2) encounter,
at a slanting angle, the sloping walls (F4) at the end of the female coupling (F). Given the round cross-section of the radial pins (M2) and their angle with respect to the sloping walls (F4), further insertion of the accessory-tool (U) in the handpiece (M), i.e. bringing the male coupling (M) and the female coupling (F) together, makes the radial pins (M2) slide along the sloping walls (F4) and makes the central spindle (M1 ) turn in the coaxial hole (F6) of the female coupling (F). This rotation continues as the accessory-tool (U) is inserted in the handpiece (A), until the radial pins (M2) come into line with, and thus slot into the grooves (F3) in the female coupling (F). In this position, the central spindle (M1 ) on the male coupling (M) remains inserted in the coaxial hole (F6) in the female coupling (F), while the radial pins (M2) come to be exactly and completely inserted in the grooves (F3) in the female coupling (F). In short, whatever the initial position in which the radial pins (M2) encounter the female coupling (F), the insertion of the accessory-tool (U) in the handpiece (A) causes a rotation of the central spindle (M1 ) and of the radial pins (M2) on the male coupling (M) until said radial pins (M2) fit into and remain engaged in the grooves (F3) in the female coupling (F). As a result, whatever the angular position of the arbor (F) in the accessory-tool (U), when it is attached to the handpiece (A), said arbor (F) in the accessory-tool (U) comes to occupy the only possible position in which the radial pins (M2) can fit into the grooves (F3) in the female coupling (F), thereby placing the working tip of the accessory-tool (U) in a guaranteed position. The subsequent turning of the electric motor in the handpiece (A) instantaneously turns the arbor in the accessory-tool (U), with no need to adjust the position or tighten the connection. The accessory-tool (U) is fitted to the handpiece (A) by means of a known
mechanism, e.g. a collet (Ag), thereby preventing any accidental detachment of the accessory tool (U) from the handpiece (A).
The accessory tool (U) has two concentric tubes (U1, U2); the outside tube (U1) is attached with the collet (Ag) to the handpiece (A), while the inside tube (U2) is connected to the female coupling (F). The outside tube (U1 ) has a cigar-shaped or semispherical working tip (U1p) and lacks a portion of side wall. The working tip (U2p) on the inside tube (U2), which carries the cutting heads of the bur or blade, is generically spoon-shaped and sized so as to be contained exactly and turn inside the end of the working tip (U1p) on the outside tube (U1). The central part of the working tip (U2p) on the inside tube (U2) has a coaxial hole (U2o) connected to the coaxial hole (F2) in the female coupling (F) for the suction of irrigation fluids and of the debris resected and shaved by the working tip. Each complete turn of the working tip (U2p) on the inside tube (U2) induces a complete obstruction of the side opening in the tip (U1p) on the outside tube (U1) by the back of the spoon-shaped blade (U2p) and a complete opening of the opening in the tip (U1p) of the outside tube (U1) when the cutting edge of the spoon-shaped blade (U2p) comes into line with the opening in the tip (U1p) of the outside tube (U1). The end of the outside tube (U1) on the accessory-tool (U) that is coupled to the handpiece (A) has a series of equidistant grooves (U1s) on its outer surface, which run parallel to each other and to the axis of the outside tube (U1). Likewise, the seat in the handpiece (A) that houses the accessory-tool (U) is fitted with a series of rotation-preventing steady rests (A1 ), amounting to the same number as the grooves (U1s) in the end of the outside tube (U1) of the accessory-tool (U), or to a smaller number.
Said rotation-preventing steady rests (A1 ) lie equidistant from each other inside the seat in the handpiece (A).
Each rotation-preventing steady rest (A1 ) is fitted in the seat in the handpiece (A) so that it can move radially, i.e. it can move from a position in which it emerges from the seat to a position in which it is fully withdrawn in its cavity in the walls of the seat. Each rotation-preventing steady rest (A1 ) is preferably equipped with an elastic element designed to push it towards the center of the seat. When the accessory- tool (U) is inserted in the seat in the handpiece (A), said rotation-preventing steady rests (A1 ) slide and slot into the grooves (U1s) in the end of the accessory-tool (U). As a result, any rotation of the accessory-tool (U) in the seat in the handpiece (A) is prevented by the coupling between the rotation-preventing steady rests (A1 ) in the handpiece (A) and the grooves (U1s) on the accessory- tool (U).
The motor (G) installed in the handpiece (A) is of the type with an encoder memory, so each time it is switched off its shaft (Ga) returns to a specific angular position. Each time the motor (G) in the handpiece (A) is switched off, the male coupling (M) consequently always comes back to the same angular position. When the accessory-tool (U) is attached to the handpiece (M), the spoon-shaped blade (U2p) (the working tip) on the inside tube (U2) on the accessory-tool (U) always comes to be in a safe position, i.e. in a position such that the sharp blade (U2P) is enclosed inside the working tip (Up) of the accessory-tool and the opening in the working tip (U1 p) on the outside tube (U1 ) on the accessory-tool (U) is closed by the back of the spoon-shaped blade (U2p) of the working tip (U1 p) on the inside tube (U2). In addition to the electric motor (G), the handpiece (M) is also fitted with a connection for the suction of irrigation fluids and ablation debris (V), complete with a lever-type valve (Ve). The handpiece (M) can be fitted with batteries or electric storage units for
powering the motor (G), with a circuit for adjusting the speed and the force and power of rotation of said motor (G), and with a radio receiver circuit connected to said control circuit. The batteries enable the motor (G) to be powered without having to resort to a clumsy electric cord. The control circuit and receiver circuit are operated by a transmitter device positioned outside the handpiece that enables the speed, force and power of rotation of the motor (G) in the handpiece (A) to be adjusted and said adjustments to be sent by radio to the handpiece (A).
The accessory-tool (U) can carry optical fibres within the thickness of the working tip (Up), for lighting and viewing the operating field.
Predictably, the accessory-tool (U) will be angled as illustrated in figure 5.
This is a schematic outline sufficient to enable the expert to construct the invention, so in practical application there may be some variations without this affecting the fundamental innovative concept. Therefore, with reference to the previous description and the enclosed drawings, the following claims are put forth.