Patent Description:
This document pertains generally, but not by way of limitation, to orthopedic devices, and, more particularly, to reamer heads and methods of manufacturing reamer heads.

Bone degradation, disease and injury are a common occurrence that can be treated with surgical intervention using an orthopedic device such as an orthopedic implant. Orthopedic implants can be used, for example, to replace a joint or portion of a joint, or to provide fixation to a fractured bone while it heals.

In order to implant an orthopedic device, such as a hip implant, the surgeon can prepare the bone surface by a process such as reaming. Reaming can be accomplished using a reamer head having cutting elements thereon. The reamer head can be rotated to remove and shape the bone at the implant site. One such implant site can include an acetabulum of a hip bone, and the bone can be shaped to mimic the natural hemispherical shape of an acetabulum.

To provide rotation for the reaming process, the reamer head can include a driver interface that can be attached to a universal driver. When the reamer head is rotated by the universal driver with the reamer head located at a bone surface, the cutting elements on the reamer head remove the bone material.

<CIT> discloses a disposable acetabular reamer designed to improve tissue removal efficiency. The reamer device comprises a reamer cutting shell and a reamer driver interface. The reamer cutting shell has a hemispherical structure with a plurality of spaced apart rib portions that extend from a central region located about an apex of the shell. A tissue cutting surface further extends along a longitudinal leading edge, trailing edge or both leading and trailing rib portions. The tissue cutting surface further comprises a series of alternating cutting teeth and notches which are bent at a rake angle.

According to an aspect, there is provided an orthopedic reamer head as set out in claim <NUM>. Optional features are set out in claims <NUM> to <NUM>.

According to another aspect, there is provided a method of manufacturing an orthopedic reamer head as set out in claim <NUM>. Optional features are set out in claims <NUM> to <NUM>.

The drawings illustrate generally, by way of example, but not by way of limitation, various examples discussed in the present document.

As discussed above, orthopedic implants can be secured to bone to replace a joint or a portion of a joint. To implant an orthopedic device, the surgeon can prepare the bone by removing bone material and shaping the bone to receive the implant.

In some hip replacement procedures, to remove and shape the bone, the surgeon can ream the bone surface using a driver that is adapted to interface with a reamer head. The reamer head can include cutting elements, that, when rotated by the driver, scrape the bone surface to remove bone and carry the bone away from the implant site.

Conventional reamer heads are generally cleaned and sterilized after a surgery and reused between patients. Cleaning and sterilizing can be expensive and not all hospitals are able to staff the cleaning facilities all the time. In addition, even after cleaning and sterilizing, the possibility of cross-contamination between patients can still occur.

The reamer heads and methods of manufacturing described herein reduce the cost to produce the reamer head. Therefore, it can be feasible to provide the reamer head as a disposable, one-time use product. A disposable reamer head eliminates the need to clean and sterilize the reamer head and eliminates a source of cross-contamination between patients.

<FIG>, <FIG> and <FIG> show various views of an illustrative example of an orthopedic reamer head <NUM> and elements thereof. As a general overview and as shown in the perspective view of the reamer head <NUM>, the orthopedic reamer head <NUM> can include a body <NUM> and a cutting system <NUM>. Together the body <NUM> and the cutting system <NUM> form a reamer head <NUM> having a modular design.

The shape of the body <NUM>, when rotated, can facilitate reaming an acetabulum to prepare the acetabulum to receive an implant. When the body <NUM> is rotated, the reamer head <NUM> is configured to ream a generally hemispherical shape to approximate the shape of an acetabulum or acetabular implant.

In some examples, the body <NUM> can be generally dome-shaped and/or generally hemispherical-shaped. In some examples, a generally hemispherical-shaped dome is not necessarily a perfect or complete hemisphere, but rather the body <NUM> has a generally hemispherical form or is provided as a portion of a dome or a portion of a hemisphere. A hemispherical shape can include a generally or substantially hemispherical shape configured to prepare the bone for an acetabular implant, or an implant at another ball and socket joint such as a shoulder joint.

To prepare the bone surface, the reamer head <NUM> is rotated at a bone surface using rotational motion provided by a driver (e.g., a universal driver). The body <NUM> of the reamer head <NUM> can include a driver interface <NUM> (<FIG>, <FIG> and <FIG>) that is configured to be coupled to a driver to receive the rotational motion from the driver. The driver interface <NUM> can be cross-shaped and can extend across the base <NUM> of the body <NUM>.

In some examples, the body <NUM>, including the driver interface <NUM> can be integrally molded as one-piece component including a common polymeric material for the entire body <NUM> including the driver interface <NUM>.

In some examples, the body <NUM> can be formed of a plurality of polymeric materials and can include a single or multiple components integrally molded to one another. For example, a lower grade polymer can form the majority of the body <NUM>, while a higher-grade polymer can be used to form the driver interface <NUM> (<FIG>, <FIG> and <FIG>). The use of various polymeric materials can provide the necessary strength at the driver interface <NUM>, while minimizing the cost of the rest of the body <NUM> by using a lower grade and less expensive polymeric material where feasible.

Referring to <FIG>, in a perspective view of the body <NUM>, the body <NUM> can have an outer surface <NUM> (e.g., outer dome surface) that extends from an apex region <NUM> (e.g., proximate an apex <NUM>) to a base <NUM>. A recess <NUM> can be formed in the outer surface <NUM> to receive the cutting system <NUM>. The recess <NUM> can include at least one arcuate channel <NUM> extending from a portion of the body <NUM> at or near the apex <NUM> towards the base <NUM>. At or near the apex <NUM> can be defined as in the apex region <NUM>, which is shown in further detail in <FIG>.

As shown in the example of <FIG>, the recess <NUM> can include a plurality of arcuate channels <NUM> extending away from the apex <NUM> along a plurality of directions (e.g., <NUM>, <NUM>; <FIG>). The plurality of directions <NUM>, <NUM> can be described as beginning proximate the apex <NUM> (or apex region <NUM>) and extending outward towards different locations along the base <NUM>. As shown in <FIG>, the plurality of arcuate channels <NUM> can be arranged in a generally starburst arrangement extending from the apex region <NUM>.

In some examples, the recess <NUM> in the outer surface <NUM> that is configured to accept the cutting system <NUM> can be formed by multiple recess formations in the outer surface <NUM> and is not necessarily limited to a single recess, a continuous recess, or a recess of uniform depth. In some examples, the arcuate channels <NUM> that make up the recess <NUM> can include apertures (<FIG>) having at least a portion that extends through a thickness of the body <NUM>, the thickness extending from the outer surface <NUM> to an inner surface <NUM> (<FIG>).

The illustrative body <NUM> of <FIG> shows the plurality of arcuate channels <NUM> as four arcuate channels <NUM> arranged in a generally starburst arrangement. However, in some examples, the recess <NUM> can include any number of arcuate channels <NUM>, such as one, two, three, four, five, six, seven or eight arcuate channels <NUM>, or more than eight arcuate channels <NUM>. The starburst arrangement shown is merely one example of a starburst.

The body <NUM>, having a generally dome or hemispherical shape, may not include a perfectly geometric apex <NUM>, but rather an imaginary apex or apex region <NUM> proximate the location where the geometric apex would be located if the body <NUM> was an exact dome or hemisphere. In some examples, and as shown in <FIG>, the apex region <NUM> can include a circumference around the apex <NUM> (imaginary apex or an apex axis <NUM>) that extends outward to include a specified circumference <NUM>. In some examples, the specified circumference <NUM> of the apex region <NUM> corresponds to the diameter <NUM> of the apex region <NUM>. In some examples, the diameter <NUM> of the apex region <NUM> can be <NUM> inches (<NUM>) around the apex axis <NUM> and extending from the outer surface <NUM> to the inner surface <NUM> along the apex axis <NUM> (<FIG>). In a possibly more preferred example, the specified circumference <NUM> of the apex region <NUM> can include a smaller diameter <NUM> of <NUM> inches (<NUM>) around the apex axis <NUM>. In a possibly most preferred example, the specified circumference <NUM> of the apex region <NUM> can include a diameter <NUM> of <NUM> inches (<NUM>) around the apex axis <NUM>.

The body <NUM> supports the cutting system <NUM> that facilitates the cutting action of the reamer head <NUM>. As shown in the example of <FIG>, the cutting system <NUM> can include a plurality of arcuate elements <NUM> configured to cut bone. <FIG> shows a perspective view of an example arcuate element <NUM> of the cutting system without the body <NUM>. As shown in <FIG> and <FIG> together, each of the arcuate elements <NUM> can extend from a first end portion <NUM> proximate the apex <NUM> to a second end portion <NUM> more distal from the apex <NUM>, towards or proximate the base <NUM>.

As shown in <FIG>, like the arcuate channels <NUM> of the body <NUM>, the arcuate elements <NUM> of the cutting system <NUM> can also extend outward in a generally starburst arrangement. The generally starburst arrangement can include arcuate elements <NUM> extending away from the apex <NUM> (the imaginary apex, apex axis <NUM>), or anywhere in the apex region <NUM> of the body <NUM> towards the base <NUM>.

Also, like the arrangement of the arcuate channels <NUM>, the cutting system <NUM> can include any number of arcuate elements <NUM>, such as one, two, three, four, five, six, seven or eight arcuate elements <NUM>, or more than eight arcuate elements <NUM>. However, in at least one example, the reamer head <NUM> can include a single arcuate element <NUM> and a single arcuate channel <NUM>.

In some examples and as shown in the close-up view of <FIG>, first end portions <NUM> of at least two of the plurality of arcuate elements <NUM> can overlap or be located adjacent to one another. For example, as shown in <FIG>, at least one of the plurality of arcuate elements <NUM> can extend across the apex <NUM>. For example, first end portion 220A of the arcuate element 210A can overlay the apex <NUM> (e.g., imaginary apex, or apex region <NUM>). Other of the plurality of arcuate elements 210B, 210C, 210D can be located such that first end portions 220A, 220B, 220C of the arcuate elements 210B, 210C and 210D are located proximate the first end portion 220A of arcuate element 210A.

In at least one example, at least two of the first end portions 220A, 220B, 220C and 220D can be offset from one another, not in contact with each other, or spaced apart from one another away from the apex <NUM> but within the apex region <NUM>.

As show in <FIG>, each of the plurality of arcuate elements <NUM> can be located in a respective one of the plurality of arcuate channels <NUM> formed in the body <NUM>. The arcuate elements <NUM> can be coupled to the body <NUM>, for example: by retention features that create a snap-fit connection between the arcuate elements <NUM> and the body <NUM>; by integrally molding the arcuate elements <NUM> into the body <NUM>; or by other attachment methods such as fasteners, adhesives or heat-staking. The cutting system <NUM> can be formed from stamped metal, such as surgical steel or another biocompatible material having sufficient strength to be retained by the body <NUM> and to cut bone.

As shown in <FIG>, <FIG> and <FIG>, at least one of the arcuate elements <NUM> can include the cutting elements <NUM> configured to remove bone. The cutting elements <NUM> can extend outward from the respective arcuate channel <NUM> beyond the outer surface <NUM>. For example, the cutting elements <NUM> can extend outward radially from the generally hemispheric shaped body <NUM>. Because the cutting elements <NUM> extend beyond the outer surface <NUM>, when the reamer head <NUM> is placed at an implant site of the bone, such as an acetabulum, the cutting elements <NUM> can come into contact with the bone.

As shown in <FIG>, <FIG> and <FIG>, each arcuate element <NUM> can include a plurality of cutting elements <NUM>. However, in some examples, one or more of the arcuate elements <NUM> can include a single cutting element <NUM>, or different arcuate elements <NUM> can include different numbers, size, shape or arrangement of the cutting elements <NUM>.

Although the number of arcuate elements in <FIG> is shown as four. In some examples, the arcuate elements <NUM> can be provided in multiples of four, such as four, eight or twelve arcuate elements <NUM>. Having a plurality arcuate elements <NUM> in multiples of four can make it possible to tool and fabricate a reamer head more easily, while still being able to interface with conventional drivers that are designed to engage with a standard driver interface (e.g., <NUM>; <FIG>) having a four cross-bar arrangement. The depth of cut, the number of cutting elements <NUM> and orientation can be varied within the multiple of four to minimize tooling and fabrication costs. In other examples, different number of cutting elements and orientation can be provided, including a number that is not a multiple of four.

Another feature of the driver interface <NUM> can include an arcuate element support <NUM> as shown in <FIG> and <FIG>. The arcuate element support <NUM> can extend away from the driver interface <NUM> towards the apex region aperture <NUM> and can include a support surface(s) <NUM> configured to support one or more arcuate elements <NUM>. The arcuate element support <NUM> can include a vertical channel <NUM> that extends parallel to the apex axis <NUM> (<FIG>). In some examples the vertical channel <NUM> can be defined as a gap <NUM> between a first portion 176A of an arcuate element support <NUM> and a second portion 176B of an arcuate element support <NUM>. In some examples the vertical channel <NUM> can be defined as a gap <NUM> between a first portion 170A of a driver interface <NUM> and a second portion 170B of a driver interface <NUM> (<FIG>). In some examples the gap may be in a range between <NUM> inches (<NUM>) and <NUM> inches (<NUM>).

To facilitate molding of the complex features of the body <NUM>, including integrally molding the driver interface <NUM>, the body <NUM> can include an apex region aperture <NUM> (<FIG>, <FIG> and <FIG>) extending from the outer surface <NUM> to the inner surface <NUM> of the body <NUM>. The apex region aperture <NUM> can allow tooling for molding the arcuate element support <NUM> and/or driver interface <NUM> a passageway through the body <NUM> along the apex axis <NUM> (see, mold direction 124A in <FIG>).

Integrally molding the driver interface <NUM> can include providing a first mold cavity that forms the apex region aperture <NUM> and/or the inner surface <NUM> of the driver interface <NUM>. A second corresponding mold cavity can be supplied from the opposite side of the body <NUM> to mold the base <NUM> and/or an outer surface <NUM> of the driver interface <NUM> (<FIG> and <FIG>). In some examples, the apex region aperture <NUM> can be cross-shaped (e.g., generally cross-shaped) corresponding to the shape of the driver interface <NUM> to allow egress of the first mold cavity through the apex region aperture <NUM> following the molding process.

In some examples, the arcuate elements <NUM> can be formed into an arcuate shape prior to assembly with the body <NUM> as shown in <FIG>. However, in some examples, the arcuate element <NUM> can be planar prior to assembly, and forced into a curved shape by attachment to the body <NUM>, thus taking on the arcuate shape in the assembly process. The arcuate elements <NUM> can be formed from stamped metal, such as surgical steel or can be formed of another biocompatible material.

In some examples, to provide a specific cutting sharpness, the cutting elements <NUM> can be sharpened after being stamped. In other examples, the cutting elements <NUM> may not be sharpened (e.g., no post processing) after being stamped. To achieve a specified sharpness without post-processing, the cutting elements <NUM> can be stamped such that a material blank for the arcuate element <NUM> is pierced at an angle (e.g., cutting elements <NUM> die cut to the shape shown in <FIG> and <FIG>) to create a breakaway edge <NUM> that results in a specified sharpness.

In some examples, cutting elements <NUM> can take on a variety of other forms including, protruding elements, studs, and abrasive materials. In some examples, the cutting elements can have three-dimensionally formed holes like a cheese grater.

With reference to <FIG>, each of the plurality of arcuate channels <NUM> can extend in a different direction. For example, one of the arcuate channels <NUM> can extend generally along (but not necessarily aligned to) a first direction <NUM> from the apex <NUM> toward the base <NUM>. Likewise, a second arcuate channel (another of <NUM>) can extend generally along (but not necessarily aligned to) a second direction <NUM> from the apex <NUM> towards another location on the base <NUM>. The second direction being different than the first direction.

In some examples, instead of providing individual arcuate elements <NUM> that extend along the same arc, two or more of the arcuate elements <NUM> can be incorporated into one longer arcuate element. For example, a single arcuate element that incorporates two of the arcuate elements <NUM> into one longer arcuate element can extend from proximate one portion of the base <NUM>, over the apex region <NUM> and down towards the opposite side of the base <NUM>.

As shown in the cross-sectional view of <FIG>, a snap-fit connection can be used to secure the arcuate elements <NUM> to the body <NUM>. For example, the retention elements <NUM> can be slid into retention apertures <NUM> in the body <NUM>. The body <NUM> can further include retention surfaces <NUM> configured to receive the retention elements <NUM>. The retention surfaces <NUM> can retain the arcuate elements <NUM> in the arcuate channels <NUM>.

As shown in <FIG>, the retention surfaces <NUM> can capture the retention element <NUM> of the arcuate element <NUM> to prevent the arcuate element <NUM> from being removed from the arcuate channel <NUM>. The retention surfaces <NUM> and retention elements <NUM> can be any curved, planar or irregularly shaped features that are suitable for providing a secure snap-fit connection.

With reference to <FIG>, the body <NUM> can include one or more bone disposal apertures <NUM> extending through the body <NUM> from the outer surface <NUM> to an inner surface <NUM> that is opposite the outer surface <NUM> (<FIG>). The one or more bone disposal apertures <NUM> can allow bone that has been cut from the bone site to be collected and removed from the bone site. Removing the bone prevents bone or other tissue fragments from interfering with the implant. In addition, the removed bone can be mixed with other materials to fill voids between the bone surface and the implant. In some examples, each of the arcuate channels <NUM> can include a respective bone disposal aperture <NUM>.

<FIG> shows a top view of another illustrative orthopedic reamer head <NUM>. Reamer head <NUM> shares similarities with the example of reamer head <NUM> of <FIG>, <FIG> and <FIG>, therefore it is understood that features described with respect to the example of <FIG>, <FIG> and <FIG> can be included in reamer head <NUM> and vice-versa. In addition, like numerals can represent like elements, and therefore all the features of reamer head <NUM> will not be described in full detail.

Reamer head <NUM> shows an example of an orthopedic tool having a reduced size over a standard tool. Reamer head <NUM> is designed to provide the benefits of reamer head <NUM> but also be capable of fitting into a smaller incision during minimally invasive surgery (MIS). In some examples, the reamer head <NUM> is similar to the reamer head <NUM> except that the dome or hemispherical-shape of the body <NUM> is a truncated dome or hemisphere to be able to fit into the smaller MIS incision. For example, the body <NUM> includes opposing first and second truncated portions <NUM>, <NUM>.

Reamer head <NUM> can otherwise include a body <NUM> that is generally dome shaped and similar to body <NUM> (except for the truncated portions <NUM>, <NUM>) and can include the cutting system <NUM> coupled to the body <NUM>. The body <NUM> can have the various recesses and apertures extending therethrough as previously described in the examples of <FIG>, <FIG> and <FIG>.

<FIG> shows a flow chart illustrating an example method of manufacturing <NUM> the reamer head <NUM> of <FIG>, <FIG> and <FIG>. The example method of manufacturing <NUM> (hereinafter method <NUM>) described herein is merely illustrative in nature. Although aspects of the method <NUM> can be used with and will be described with reference to the example reamer head <NUM>, the method <NUM> can also be used with other reamer heads (including reamer head <NUM> of <FIG>) or other orthopedic tools. The method <NUM> is not limited to the steps specified herein. The method <NUM> can include fewer steps or additional method steps other than those described in this disclosure.

Step <NUM> can include providing, receiving or manufacturing a body <NUM>. The body <NUM> can have a generally dome shape including an outer surface <NUM> extending from an apex region <NUM> to a base <NUM>. The outer surface <NUM> can include a recess <NUM> extending along a direction from the apex region <NUM> (e.g., proximate the apex or an imaginary apex <NUM>) towards the base <NUM>. The recess <NUM> can include at least one arcuate channel <NUM>. In some examples, the recess <NUM> is a plurality of recesses that together form the at least one arcuate channel <NUM>.

In some examples, step <NUM> can include integrally molding a driver interface with the body. Integrally molding a driver interface <NUM> with the body <NUM> can include providing, receiving or manufacturing a first mold cavity that forms an apex region aperture <NUM> proximate the apex <NUM> or apex region <NUM> of the body <NUM>.

Step <NUM> can include providing, receiving or manufacturing a cutting system <NUM> including an arcuate element <NUM> extending from a first end portion to a second end portion, the arcuate element <NUM> including a cutting element for removing the bone. In some examples the cutting system <NUM> can include a one-piece design.

Step <NUM> can include inserting at least a portion of the arcuate element <NUM> into an arcuate channel <NUM> such that at least a portion of the arcuate element <NUM> extends outward from the arcuate channel <NUM> beyond the outer surface <NUM> of the body <NUM>.

Step <NUM> can further include engaging a retention element <NUM> of the arcuate element <NUM> with a retention surface <NUM> on the body <NUM> such that the arcuate element <NUM> is retained by the body <NUM> with at least a portion of the cutting element <NUM> remaining extended outward beyond the outer surface <NUM>.

In some examples the inserting step <NUM> can include inserting a plurality of the arcuate element <NUM> into a plurality of the arcuate channel <NUM>. In some examples, inserting the plurality of arcuate elements <NUM> into the plurality of arcuate channels <NUM> can include repeating step <NUM> until the plurality of arcuate elements <NUM> are arranged in a starburst formation along the outer surface <NUM>. The starburst formation extending away from the apex <NUM> (or the imaginary apex), or the apex region <NUM> of the body <NUM> towards the base <NUM>.

As the arcuate elements <NUM> are inserted into the arcuate channels <NUM>, step <NUM> can include placing first end portions 220A, 220B, 220C, 220D of the arcuate elements 210A, 210B, 210C, 210D adjacent to one another as shown in <FIG>. In some examples, at least one of the plurality of arcuate elements <NUM> can extend across the apex <NUM>. For example, each of the plurality of arcuate elements <NUM> can be inserted into one of the plurality of arcuate channels <NUM>, and when at least one of the arcuate elements (e.g., 210A; <FIG>) is fully seated in the arcuate channel <NUM>, the first end portion 220A of the arcuate element 210A can overlay the apex <NUM> (e.g., proximate, near, on, over the apex <NUM>, imaginary apex, or apex region <NUM>). As a second or subsequent arcuate elements (e.g., 210B, 210C, 210D; <FIG>) are inserted and seated, the first end portions <NUM> of the arcuate elements 210B, 210C and 210D can be placed proximate the first end portion 220A of arcuate element 210A. In some examples, step <NUM> can include overlapping at least two of the plurality of arcuate elements <NUM> proximate an apex region <NUM>.

The method <NUM> provides reamer heads, including but not limited to reamer head <NUM>, having a modular design that can be made cost effective enough for disposable applications, without sacrificing the performance provided in a re-usable reamer head design.

The drawings show, by way of illustration, specific examples in which the invention can be practiced. These examples are also referred to herein as "examples.

Claim 1:
An orthopedic reamer head (<NUM>) for preparing a bone to receive an implant, the orthopedic reamer head (<NUM>) comprising:
a body (<NUM>) having a generally dome shape and an outer surface (<NUM>) extending from an apex region (<NUM>) to a base (<NUM>), the outer surface having (<NUM>) a recess (<NUM>) including an arcuate channel (<NUM>), the arcuate channel (<NUM>) extending along a direction from proximate the apex region (<NUM>) towards the base (<NUM>); and
a cutting system (<NUM>) having an arcuate element (<NUM>), the arcuate element (<NUM>) including a cutting element (<NUM>) for removing bone and a retention element (<NUM>) extending from a side of the arcuate element (<NUM>) opposite of the cutting element (<NUM>), wherein
at least a portion of the arcuate element (<NUM>) is located in the arcuate channel (<NUM>),
at least a portion of the cutting element (<NUM>) extends out of the arcuate channel (<NUM>) beyond the outer surface (<NUM>),
the arcuate element (<NUM>) extends from a first end portion (<NUM>) proximate the apex region to a second end portion (<NUM>) proximate the base (<NUM>) and characterised in that
the retention element (<NUM>) is at least partially received within a retention aperture (<NUM>) in the body (<NUM>) and forms a snap-fit connection therewith.