Surgery – Instruments – Orthopedic instrumentation
Reissue Patent
2000-06-21
2001-09-04
Reip, David O. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S180000, C408S231000
Reissue Patent
active
RE037358
ABSTRACT:
BACKGROUND OF THE INVENTION
The 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 connect an end of the tool bit shaft to the spindle of the motor. This connection required a special collet wrench in order to replace the tool bit. In addition, the various tool bits had different sized shafts thus requiring different size collets. The need for corresponding sized collets and wenches not only made tool replacement time consuming and cumbersome, it required that additional items be stocked in the operating room. Further because a sterile environment was necessary for the surgical procedure, the different collets and wrenches have to be sterilized between the procedures.
SUMMARY OF THE INVENTION
The general object of the present invention is to provide a single mechanism which is capable of attaching a variety of different sized tool bits to a power driven surgical instrument.
Another object is to provide a mechanism for attaching tool bits which does not require the use of special wrenches to change tool bits.
A further object is to eliminate the use of separate collets for each tool bit of a different size.
Yet another object of the present invention is to provide a mechanism for attaching tools which prevents the motor spindle from rotating when the instrument is not in use. This feature inhibits the tool bit from accidentally rotating when the instrument is at rest.
A powered surgical instrument includes a housing that contains a motor and a restrainer, such as a ring gear, fixedly attached to said housing. The instrument also comprises a holder for attaching a variety of different tool bits to the motor. The holder has a body within the housing with a first end portion connected to the motor for rotation about an axis, a central portion with a cavity therein, and a second end portion that has an aperture which receives tool bit shafts of various sizes.
A pair of lock pawls are pivotally mounted in the cavity. Each lock pawl includes a first tab that projects toward the axis of rotation and a second tab that projects away from the axis of rotation. When each lock pawl is pivoted into a first position, its first tab enters a slot in the shaft of a tool bit inserted into the instrument. In this state the lock pawl prevents the shaft of the tool bit from being removed from the instrument. When the lock pawl is pivoted into a second position the first tab is retracted from the shaft slot enabling the tool bit to be removed.
The second tab engages the restrainer when the lock pawl is in the second position thereby preventing rotation of the body. This enables the tool bit to be replaced without the possibility of the motor accidentally rotating the body. In the first position of the lock pawl, the second tabs are disengaged from the restrainer thus allowing operation of the instrument.
A ring extends around the body and pivots the first and second lock pawls as the ring moves longitudinally along the body. A manually operable shift lever is pivotally coupled to the housing and causes longitudinal movement of the ring along the body, thereby pivoting the first and second lock pawls.
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Anspach, Jr. William E.
del Rio Eddy H.
Akerman & Senterfitt
Reip David O.
The Anspach Effort, Inc.
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