Tool holding mechanism for a motor driven surgical instrument

Abstract

A surgical instrument has a housing which contains a motor that drives a spindle. A tool bit is attached to the motor by a holder that includes a body with a first end portion connected to the spindle, a central portion with a cavity therein, and a second end portion having an aperture through which a shaft of the tool bit passes into the cavity. A pair of lock pawls are pivotally mounted in the cavity with each one having a first tab that enters a slot in the shaft when the lock pawls are in a first position to hold the tool bit in the instrument. The first tabs retract from the slot when the lock pawls are in a second position for changing the tool bit. The lock pawls have second tabs that engage a restrainer only in the second position to prevent the body from rotating. A ring extends around the body and pivots the lock pawls between the first and second positions when the ring moved longitudinally along the body. A manually operable shift lever is pivotally coupled to the housing and move the ring longitudinally along the body.

Description

BACKGROUND OF THE INVENTIONThe present invention relates to motor driven surgical instruments; and specifically to mechanisms for releasably attaching a variety of different tool bits to the surgical instrument.Orthopedic and neurological surgeons frequently use a power driven surgical instrument to cut, shape and drill into bone. Such an instrument utilizes a small pneumatically driven motor contained in a cylindrical housing which is held by the surgeon during use. A hose from the source of compressed air attaches to one end of housing. A tool bit is received by a fitting at the other end of the housing and is rotated by the motor when compressed air is applied to the instrument.A wide variety of different shaped and sized tool bits are available for drilling into, cutting, and shaping bone as needed during a surgical procedure. Thus, the surgical instrument must be able to accept various kinds and sizes of tool bits.One common surgical instrument of this type used a collet to con...

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