Gear drive mechanisms for surgical instruments

A surgical instrument includes a handle assembly having a gear drive mechanism. The gear drive mechanism includes a variable radius gear to provide a desired mechanical advantage to a user during actuation of a movable handle of the surgical instrument.

BACKGROUND

Technical Field

This disclosure relates to gear drive mechanisms for surgical instruments. More particularly, the disclosure relates to gear drive mechanisms having a variable gear for use with handle assemblies of surgical instruments.

Description of Related Art

Several types of surgical instruments include a handle assembly that relies on mechanical action between a movable handle and a stationary handle to provide the forces necessary to perform the desired functions of the surgical instrument. Additionally, many surgical instruments utilize a single movable handle to provide multiple functions.

Generally, such movable handles used on surgical instruments are one of two types. One type is a simple pivoted handle that provides a near constant mechanical advantage throughout its stroke, and which is useful in many surgical situations. The second type of handle includes an additional link to provide a geometrically increasing mechanical advantage toward the end of its stroke to help provide a larger force, which may be desired to compress tissue or to deploy a surgical clip into tissue, for example.

However, many surgical instruments have different mechanical advantage requirements based on the functions a particular surgical instrument provides, where a constant mechanical advantage or a geometrically increasing mechanical advantage may not be the ideal solution.

SUMMARY

The disclosure relates to a surgical instrument including a handle assembly, an elongated shaft, a drive member, and a drive gear mechanism. The handle assembly includes a housing and a movable handle pivotally connected to the housing. The elongated shaft extends distally from the handle assembly and defines a longitudinal axis. The drive member extends at least partially through the elongated shaft and is movable along the longitudinal axis relative to the elongated shaft. The drive gear mechanism is disposed at least partially within the housing, and includes a first gear disposed in mechanical cooperation with the movable handle, a second gear disposed in mechanical cooperation with the first gear, a third gear disposed in mechanical cooperation with the second gear, and a fourth gear disposed in mechanical cooperation with the third gear and with the drive member. The third gear defines more than one radius.

In embodiments, the third gear defines a first radius and a second radius, where the first radius of the third gear is the same as a radius of the second gear. It is also disclosed that the second radius of the third gear is the same as a radius of the fourth gear.

It is further disclosed that a first radius of the third gear is from about 0.17 inches to about 0.55 inches (e.g., about 0.375 inches), and a second radius of the third gear is from about 0.75 inches to about 1.25 inches (e.g., about 1.0 inches).

In disclosed embodiments, the first gear is formed on the movable handle and the fourth gear is formed on the drive member.

The present disclosure also relates to a drive gear mechanism for use with a surgical instrument, including a first gear, a second gear, a third gear, and a fourth gear. The first gear defines a radius and includes a plurality of teeth. The second gear defines a radius and includes a plurality of teeth configured to engage the plurality of teeth of the first gear. The third gear includes a first portion defining a first radius, a second portion defining a second radius that is different from the first radius, and a plurality of teeth. The plurality of teeth of the first portion of the third gear is configured to engage the plurality of teeth of the second gear. The fourth gear includes a plurality of teeth and is disposed in mechanical cooperation with a drive member of the surgical instrument. The plurality of teeth of the fourth gear is configured to engage the plurality of teeth of the second portion of the third gear.

In embodiments, the first radius of the third gear is the same as a radius of the second gear. It is also disclosed that the second radius of the third gear is the same as a radius of the fourth gear.

It is further disclosed that the first radius of the third gear is from about 0.17 inches to about 0.55 inches (e.g., about 0.375 inches), and the second radius of the third gear is from about 0.75 inches to about 1.25 inches (e.g., about 1.0 inches).

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of gear drive mechanisms, in accordance with the disclosure, will now be described in detail with reference to the figures wherein like reference numerals identify similar or identical structural elements. As shown in the drawings and described throughout the following description, as is traditional when referring to relative positioning on a surgical instrument, the term “proximal” refers to the end of the apparatus which is closer to the user and the term “distal” refers to the end of the apparatus which is farther away from the user.

With initial reference toFIG.1, a surgical instrument is shown and is generally designated as reference number10. Surgical instrument10generally includes a handle assembly100, and an elongated assembly200defining a longitudinal axis “A-A” and extending distally from handle assembly100. Handle assembly100includes a housing110, a movable (e.g., pivotable) handle120, and a stationary handle130. An end effector, which is not explicitly shown in the accompanying figures, is coupled to a distal end of elongated assembly200. As the gear drive mechanisms described herein are usable with various types of surgical instruments having various types of end effectors, particular end effectors are not shown.

Referring now toFIGS.2-4, internal portions of handle assembly100are shown including a drive gear mechanism300and a drive member400. Drive gear mechanism300includes a first gear310, a second gear320, a third gear or shell or nautilus gear330, and a fourth gear340. First gear310includes a plurality of teeth312and is associated with or forms part of movable handle120. Movable handle120, and thus first gear310, is pivotable or rotatable relative to housing110of handle assembly100about a first structure or pin315. Second gear320includes a plurality of teeth322, is disposed within housing110of handle assembly100, and is rotatable relative to housing110of handle assembly100about a second structure, hub or pin325. Teeth322of second gear320are configured to engage and mesh with teeth312of first gear310. Third gear330includes a plurality of teeth332, is disposed within housing110of handle assembly100, and is rotatable relative to housing110of handle assembly100about a third structure, hub or pin335. Fourth gear340includes a plurality of teeth342and is associated with or forms part of drive member400.

Generally, actuation of movable handle120relative to stationary handle130causes rotation of various portions of drive gear mechanism300relative to housing110of handle assembly100, which causes longitudinal translation of drive member400relative to housing110of handle assembly100. More particularly, and with specific reference toFIGS.3and4, actuation of movable handle120in the general direction of arrow “A” causes rotation of first gear310about first pin315in the general direction of arrow “B.” This rotation of first gear310causes a corresponding rotation of second gear320about second pin325in the general direction of arrow “C,” due to the engagement between teeth312of first gear310and teeth322of second gear320. This rotation of second gear320causes a corresponding rotation of third gear330about third pin335in the general direction of arrow “D,” due to the engagement between teeth322of second gear320and teeth332of third gear330. Finally, this rotation of third gear330causes longitudinal (e.g., distal) translation of drive member400in the general direction of arrow “E,” due to the engagement between teeth332of third gear330and teeth342of fourth gear340.

With more particular reference to drive gear mechanism300, first gear310, second gear320and fourth gear340each include a single radius, which may be the same or different from each other. For example, the radius of first gear310may be from about 0.6 inches to about 0.9 inches (e.g., equal to about 0.75 inches), the radius of second gear320may be from about 0.17 inches to about 0.55 inches (e.g., equal to about 0.375 inches), and the radius of fourth gear340may be from about 0.75 inches to about 1.25 inches (e.g., equal to about 1.0 inches). While particular ranges of radiuses are disclosed, first gear310, second gear320, and fourth gear340may have radiuses outside of these ranges without departing from the scope of the disclosure.

Third gear330is a variable-radius gear or nautilus gear. That is, a first portion336of third gear330(e.g., the portion that engages second gear320) has a first radius, while a second portion338of third gear330(e.g., the portion that engages fourth gear340) has a second radius. In the illustrated embodiment, the first radius (e.g., at first portion336) of third gear330is smaller than the second radius (e.g., at second portion338) of third gear330. For example, the first radius may be from about 0.17 inches to about 0.55 inches (e.g., equal to about 0.375 inches), and the second radius may be from about 0.75 inches to about 1.25 inches (e.g., equal to about 1.0 inches). Further, the first radius of first portion336of third gear330may be equal to the radius of second gear320, with which first portion336of third gear330engages, and the second radius of second portion338of third gear330may be equal to the radius of fourth gear340, with which second portion338of third gear330engages. While particular ranges of radiuses are disclosed, first portion336and second portion338of third gear330may have radiuses outside of these ranges without departing from the scope of the disclosure.

The variable-radius third gear330results in differing amounts of mechanical advantage provided by movable handle120during a single actuation stroke. For example, the mechanical advantage of the initial actuation of movable handle120may be about 0.75:1 for the first approximately 10° of actuation, which may distally advance drive member200about 2.0 inches. In furtherance of this example, the mechanical advantage of the subsequent actuation of movable handle120may be about 5:1 for the next approximately 30° of actuation, which may distally advance drive member400about 0.3 inches. In embodiments, the initial actuation of movable handle120may correspond with loading or advancing a surgical fastener or clip, and the subsequent actuation of movable handle120may correspond with firing, forming or deploying the surgical fastener or clip through or onto tissue. While particular mechanical advantages, stroke lengths, and advancement distances of drive member400are disclosed, other mechanical advantages, stroke lengths, and advancement distances of drive member400that are higher and/or lower than these values are contemplated without departing from the scope of the disclosure, for instance depending on the particular type of instrument, surgical procedure, type of fastener used, etc.

Thus, the variable-radius third gear330reduces the force that must be applied to movable handle120by a user, while ensuring that adequate force and advancement distance of drive member400is produced to complete the surgical task.

Additionally, drive gear mechanism300may include a total of three gears instead of four gears. In such embodiments, second gear320is absent, first gear310directly engages first portion336of third gear330, and second portion338of third gear330engages fourth gear340.

It should be understood that the foregoing description is only illustrative of the disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the disclosure is intended to embrace all such alternatives, modifications and variances. The embodiments described with reference to the attached drawing figures are presented only to demonstrate certain examples of the disclosure. Other elements that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure.