Femoral head repair

Abstract

A surgical instrument and method for assessing femoral head center restoration is provided. The instrument includes a body (100) having a first connector (104) for attaching the body to a femoral portion (442), the body defining a plurality of apertures (110, 112, 114, 116, 118) therein, each aperture corresponding to a respective femoral head center arising from a corresponding femoral neck; and a gauge (140) including a pin (142) at a first end and an arm (144) extending laterally from the pin, the pin being receivable in each of the plurality of apertures, the arm having a scale indicating distance from the pin. This approach seeks to provide a simple and / or easy approach for use in restoring natural femoral head position during a hip replacement surgical procedure.

Description

Technical Field

[0001] The present disclosure relates to surgical instruments and methods, and more particularly to surgical instruments and methods for use in restoring the center of the femoral head in hip replacement procedures.

Background Art

[0002] A variety of different hip replacement procedures are generally known. Some of these involve removing the natural femoral head and replacing it with an artificial femoral head. In many cases, a stem including an artificial femoral neck to which the artificial femoral head is attached is used. In some cases, an acetabular cup may be used to replace the natural acetabular fossa of the patient's pelvis. Specific details may vary depending on the implant system being used.

[0003] The positioning of the artificial components can be an important factor in the outcome of a hip replacement procedure. There are a variety of different concepts or approaches to implant placement, which can vary depending on the implant system and / or the individual circumstances of the patient.

[0004] One approach is a restoration approach in which the surgeon attempts to replicate or restore the patient's natural anatomy prior to a hip replacement procedure.

[0005] For example, preoperative images such as X-ray images or CT scans can be used to determine the anatomical structure of the patient's femur, and then the artificial implant components and their positioning can be planned in an attempt to restore the patient's natural anatomy. However, such an approach requires the availability of an imaging device, may take more time, may be more complex, and may require more surgeon experience or skill.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, a simpler approach to assist in restoring the natural anatomical structure would be beneficial. **Means for Solving the Problem**

[0007] The present disclosure is directed to surgical instruments, devices, kits of parts, and methods that may provide a simple and / or easy-to-use approach for restoring the natural femoral head position during hip replacement surgery.

[0008] A first aspect of the present disclosure is a surgical instrument for evaluating the restoration of the center of the femoral head, the instrument comprising: a body having a first connector for attachment to the femoral portion, the body defining a plurality of openings therein, each opening corresponding to a respective femoral head center originating from a respective corresponding femoral neck; a gauge comprising a pin at a first end and an arm extending laterally from the pin, the pin being receivable in each of the plurality of openings, the arm having a scale indicating the distance from the pin.

[0009] The plurality of openings may include openings corresponding to femoral necks having different medial-lateral offsets.

[0010] The plurality of openings may include openings corresponding to femoral necks having different stem-neck angles.

[0011] The plurality of openings may include openings corresponding to femoral necks having different leg lengths.

[0012] The body may have a front face, the front face including at least a first linear mark extending parallel to the medial-lateral axis, passing through at least a first opening of the plurality of openings, and corresponding to a first position on the superior-inferior axis.

[0013] The front face includes at least a second linear mark extending parallel to the medial-lateral axis, passing through at least a second opening of the plurality of openings, and corresponding to a second position on the superior-inferior axis.

[0014] The body may have a rear surface, which may include the same markings as the front surface and may be configured such that the same body can be used for the right and left hip joints.

[0015] The body may have a rear surface, which may define a rearward plane, and a front surface, which may define a forward plane, and the forward plane may be parallel to the rearward plane.

[0016] Each of the plurality of openings may include a channel that passes through the full thickness of the body. Each channel may pass from the front surface through the body or to the rear surface.

[0017] A second aspect of the present disclosure provides a surgical instrument system comprising the surgical instrument of the first aspect and a center finder. The center finder may include a plurality of markings configured to indicate the center of the center finder.

[0018] The center finder may comprise a circular ring. The plurality of markings may comprise a first pair of diametrically opposed markings and / or a second pair of diametrically opposed markings.

[0019] The surgical instrument system may further comprise a broach. The broach may include a second connector configured to engage a first connector for attaching the body to the broach.

[0020] The surgical instrument system may further comprise a plurality of femoral necks. Each neck may result in a different femoral head center position.

[0021] The plurality of femoral necks may include femoral necks having different offsets along the medial-lateral axis.

[0022] The plurality of femoral necks may include femoral necks having different stem-neck angles.

[0023] The plurality of femoral necks may include femoral necks having different leg lengths along the superior-inferior axis.

[0024] The femoral neck can be a trial neck or an artificial neck.

[0025] A third aspect of the present disclosure provides a method for evaluating the repair of the center of the femoral head of a patient's femur. The method includes determining the center of the natural femoral head of the patient's femur, marking the position of the center of the natural femoral head on the natural femoral head, using a known separation along the medial-lateral axis from the center of the natural femoral head to mark the position on the greater trochanter of the femur at the same position as the center of the natural femoral head along the superior-inferior axis, excising the natural femoral neck, attaching a body to the excised femoral neck, where the body defines a plurality of openings, each opening corresponding to a respective femoral head center arising from a respective corresponding femoral neck, attaching a gauge including a scale to the body using a first opening of the plurality of openings, using the gauge to determine whether the femoral head center arising from the first femoral neck corresponding to the first opening of the plurality of openings repairs the natural femoral head center, and may include one or more of the above.

[0026] The method may further include attaching a gauge to the body using a second opening of the plurality of openings and using the gauge to determine whether the femoral head center arising from the second femoral neck corresponding to the second opening of the plurality of openings repairs the natural femoral head center.

[0027] The method may further include aligning the gauge with a linear mark on the body that is parallel to the medial-lateral axis of the femur.

[0028] The method may further include using the scale on the gauge to determine whether the femoral head center arising from the femoral neck corresponding to the one of the plurality of openings has a separation that repairs the known separation.

[0029] The method may further include determining and / or marking the center of the natural femoral head using a center discovery guide disposed on the natural femoral head.

Brief Description of the Drawings

[0030] Hereinafter, embodiments will be described in detail for illustrative purposes only with reference to the accompanying drawings.

Figure 1

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Figure 10

Modes for Carrying Out the Invention

[0031] In the drawings, similar features in various figures are given common reference numerals unless otherwise indicated.

[0032] Referring to FIG. 1, a side view of the first portion 100 of the bone center repair device is shown. The first portion of the device 100 provides the body of the bone center repair device. The body includes a main portion 102 and a connecting portion 104, and during use, the body 100 can be attached to the femur portion by the connecting portion 104, as will be described in more detail below.

[0033] The main portion 102 of the body 100 defines a plurality of openings therein. In the illustrated embodiment, five openings 110, 112, 114, 116, 118 are defined by the body. Each of the openings passes completely through the full width of the main portion of the body 102 and also needs to have an opening on both sides of the body. The five openings are merely an example, and it will be understood that in other embodiments, more or fewer openings may be provided. As will be described in more detail below, the position of each opening corresponds to the center of the femoral component when attached to the corresponding femoral neck, particularly the corresponding neck. Thus, in the illustrated embodiment, since there are five openings, there are also five femoral necks. Each femoral neck has a geometry corresponding to a slightly different position of the center of the femoral component when attached to its respective neck. The femoral necks can have different stem-neck angles, such as 125° or 135°, and / or different medial-lateral offsets, and / or different leg lengths.

[0034] For example, the fourth opening 116 may correspond to a fourth femoral neck that can be considered a standard or reference femoral neck. The standard femoral neck has a stem-neck angle of 125° and can result in the center of the femoral component in a standard position with respect to the medial-lateral offset and leg length. The standard femoral stem can be said to provide a low femoral head position.

[0035] The third opening 114 can similarly be associated with a third femoral neck having a stem-neck angle of 125°. However, the femoral neck results in the center of the femoral component that produces a lateral offset of the femur with respect to the pelvis. For example, the amount of increased lateral offset can be about 7 mm.

[0036] The fifth opening 118 may also correspond to a fifth femoral neck having a neck-stem angle of 125°. However, the femoral neck results in a center of the femoral component having a reduced distance in the medial-lateral direction and corresponding to the medial offset of the femur relative to the pelvis. The amount of medial offset can be, for example, about 5 mm.

[0037] The second opening 112 may correspond to a second femoral neck having a stem-neck angle of 135°. The second femoral neck may result in a center of the femoral head that has the same medial-lateral direction position as a standard femoral neck but results in an increased leg length in the inferior-superior direction. For example, the amount of increase in leg length can be about 5 mm.

[0038] The first opening 110 may similarly correspond to a first femoral neck having a neck-stem angle of 135°. The first femoral neck results in a femoral head center having an increased leg length relative to a standard neck and also results in an increased lateral offset relative to a standard neck. The amount of increase in leg length can be about 5 mm, and similarly, the amount of lateral offset can be about 7 mm.

[0039] The first femoral neck and the second femoral neck may be referred to as "high" femoral necks, and the third, fourth, and fifth femoral necks may be referred to as "low" femoral necks.

[0040] As shown in FIG. 1, various indicia and markings may be provided on the front face 120 of the main body portion 102 to indicate to the user the femoral neck associated with each of the respective openings. Similar markings may also be provided on the rear face of the body, as illustrated in FIG. 1, which is generally parallel to the front face. Thus, since it is essentially symmetric with respect to a central plane parallel to the front and rear faces of the body, the same body can be used for the right hip joint and the left hip joint, or for a front or posterior approach.

[0041] As also illustrated in FIG. 1, a first linear mark 122 and a second linear mark 124 are also provided on the front face 120. The first linear mark 122 passes through the first opening and the second opening and extends generally along the medial-lateral axis of the patient's anatomical structure when the body 100 is worn on the patient's femur during use. Similarly, the second linear mark 124 extends through the third opening, the fourth opening, and the fifth opening, and also extends generally parallel to the medial-lateral axis of the patient's anatomical structure when the body 100 is worn on the patient's femur during use.

[0042] The connection or foot portion 104 defines a peg 130 and a cavity 132 and provides a first attachment mechanism and a second attachment mechanism for removably attaching the body 100 to the femoral component during use. The provision of the peg and cavity helps to ensure that the body 100 is correctly attached to the femoral portion during use.

[0043] FIG. 2 shows a perspective view of the gauge 140 portion of the bone center repair instrument. The gauge 140 has a pin 142 at a first end. The pin 142 is dimensioned to fit snugly into any one of a plurality of openings in the body 100. As illustrated in FIG. 2, the peg has a generally straight cylindrical form.

[0044] The gauge 140 also includes an arm or member 144 that extends generally transverse to the longitudinal axis of the pin 142. The arm includes a plurality of marks on a first surface 146 and also on an opposite surface 148. As illustrated in FIG. 2, the marks provided on the arm 144 provide a scale indicating the distance or separation between a starting point defined by the position of the pin 142 and a lateral distance along the longitudinal axis of the arm 144.

[0045] In some embodiments, as illustrated in FIG. 2, the scale may also provide a ruler and include numbers indicating the magnitude of the distance. For example, 10, 20, 30, 40, 50, 60 mm. However, in other embodiments, the gauge may not be in the form of a ruler and may simply include any markings that allow for a visual assessment of the distance between a point on the arm 144 and the position of the pin 142.

[0046] FIG. 3 shows a perspective view of a bone center repair instrument 150 including a gauge 140 attached to a body 100. As illustrated in FIG. 3, the pin 142 is received within a first opening 110. The longitudinal axis of the pin extends substantially transverse to the plane of the front face 120 of the body. As also illustrated in FIG. 3, the longitudinal axis of the arm 144 is substantially parallel to a first linear mark 122.

[0047] The configuration of the body and gauge illustrated in FIG. 3 corresponds to the relative positions of the body and gauge during use, as will be described in more detail below.

[0048] FIG. 4 shows a flowchart illustrating a general method of use of the bone center repair instrument 150 illustrated in FIG. 3 as part of a hip replacement procedure. Various parts of the hip replacement procedure are generally known to those of ordinary skill in the art and are therefore not shown in the flowchart illustrated in FIG. 4. Thus, FIG. 4 shows only a subset of the surgical method so as not to obscure the description of the present invention. Here, the method 200 illustrated in FIG. 4 will be described in more detail with further reference to FIGS. 5-10.

[0049] FIG. 5 shows an anterior-posterior view of an adjacent portion of a patient's femur 300. Line 302 is generally parallel to the anatomical axis of the femur 300. The proximal portion of the femur 300 generally includes a natural femoral head 304, a natural femoral neck 306, and a natural greater trochanter 308.

[0050] FIG. 5 also shows a guide component 400 that can optionally be used to improve the overall accuracy of the procedure. The guide component 400 includes a center-finding portion 402, a first arm 404, and a second arm 406. The center-finding portion 402 generally has a circular ring structure. Thus, because it is generally in the form of a circular ring, when the center-finding portion 402 is mounted on the generally spherical femoral head 304, the center-finding portion 402 naturally seats with its center generally aligned with the center of the natural femoral head 304. The first arm 404 is aligned to be positioned parallel to the anatomical femoral shaft 302. The length of the first arm 404 and the angle between the second arm 406 and the first arm 404 are pre-defined to indicate a preferred resection height and angle for excising the natural femoral neck 306. The upper edge 408 of the second arm 406 can be used to define a first resection height (a standard resection height), and the lower edge 410 can be used to define a second resection height (corresponding to a high-neck resection).

[0051] In 202, the guide 400 is positioned and oriented on the natural femoral head such that, as illustrated in FIG. 5, the first arm 404 is generally parallel to the anatomical axis of the femur 302. Then, in 204, as illustrated in FIG. 6, the second arm 406 can be used to mark the resection height and angle on the natural femoral neck. For example, a chisel instrument 420 can be positioned on the femoral neck using the upper edge 408 of the second arm 406 and used to mark the height and angle of the neck resection on the natural femoral neck 306.

[0052] Next, the guide 400 is used at 206 to mark approximately the center of the natural femoral head 304. As illustrated in FIGS. 5 and 6, the annular ring 402 of the guide component 400 includes four marks, e.g., 412, each in the form of an arrow. The first pair of marks or markings defines a first axis that is substantially parallel to the axis of the first arm 404, or the inferior - superior axis of the patient's femur. The second pair of markings is substantially perpendicular to the first axis and the longitudinal axis of the first arm 404, and defines a second axis that is generally parallel to the medial - lateral axis of the patient's femur. Thus, the second pair of markings defines a second axis that is generally parallel to the medial - lateral axis of the natural femur. Thus, at 206, the surgeon can mark approximately the center of the natural femoral head by drawing a first line 414 between the first pair of markings and a second line 416 between the second pair of markings. Since the markings of each pair of markings are diametrically opposed, the intersection of the two lines generally corresponds to the center of the annular ring 402 and thus also generally corresponds to approximately the center of the natural femoral head 304.

[0053] After the center of the femoral head is marked, the guide 400 may be removed. FIG. 7 shows the natural femur after removal of the guide 400 and shows markings on the natural femoral neck 422 indicating the preferred neck resection height and angle. At 208, a mark is formed on a portion of the natural femur, and this mark remains after resection of the natural femoral head. The marking may be formed at any suitable portion of the remaining femur and, as illustrated in FIG. 7, is generally in the region of the greater trochanter. As illustrated in FIG. 7, the marking on the greater trochanter is formed at a known distance from the marked center of the natural femoral head. The marking may be formed by placing a gauge 140, or a ruler, or the like adjacent to the natural femoral head 304 and generally aligned with the second line 416 and thus with the medial-lateral axis of the natural femur. The marking 424 on the greater trochanter 308 includes a first line 425 generally parallel to the medial-lateral axis and a second line 427 perpendicular to the first line that clearly indicates the separation between the marking 424 on the greater trochanter 308 and the center of the natural femoral head 304. The distance along the medial-lateral axis is arbitrary, and the position of the vertical marking 427 may be more importantly determined by which portion of the greater trochanter is more accessible. The position of the vertical marking 427 need not correspond to any particular distance value. This is simply that the vertical marking provides a fixed separation from the center of the natural femoral head and that distance is known. For example, as illustrated in FIG. 7, the distance between the center of the natural femoral head and the marking 424 is about 4 cm.

[0054] After the greater trochanter is marked, at 210, the femoral neck may be resected using the neck resection marking 422 to achieve the desired neck resection height and angle. The intramedullary canal of the femur may then be formed as is generally known in the art. Forming the intramedullary canal may involve using various cutting instruments such as rasps and broaches. Finally, a final broach may be used if the cavity is the desired size for the intended artificial implant.

[0055] FIG. 8 illustrates the femur, shows the marking 424 in the remaining portion of the natural femur, and also shows the final broach 440 located within the intramedullary canal. As illustrated in FIG. 8, the final broach 440 includes a male attachment formation 442 extending therefrom, and also includes a female attachment formation (not shown) positioned and configured to mate with the male attachment formation 130 on the body 100. In other embodiments, the attachment formations on the broach and on the body may be exchanged. For example, if a female broach is used instead, a male attachment formation is provided on the body to engage therewith.

[0056] In 214, the body 100 is attached to the broach 440, as illustrated in FIG. 9. If desired, the marking 424 may have a vertical line extending generally parallel to the anatomical femoral axis, as illustrated in FIG. 9. Then, in 216, the gauge 140 can be attached to the body 100 by inserting a pin 142 into each one of the openings 110 - 118, each corresponding to a different femoral neck. As illustrated in FIG. 10, the pin 142 is inserted into the first opening 110 and thus corresponds to a femoral neck having a stem-neck angle of 135° and being a high neck compared to the standard neck. The arm 144 is aligned with the first linear mark 122 so as to be generally parallel to the medial-lateral axis. As illustrated in FIG. 10, the arm 144 of the gauge generally overlaps the horizontal line of the marking 424. Thus, this shows the user that the femoral neck corresponding to the currently used opening results in a center of the femoral head that substantially reproduces the position of the center of the natural femoral head in the inferior-superior direction.

[0057] Thus, at 218, the surgeon uses the gauge 140 to evaluate which of the openings in the body 100 can most closely position the prosthetic femoral head closest to the center of the natural femoral head for repairing the natural femoral head. At 218, the surgeon can look at the scale of the gauge 140 and evaluate the position in the medial-lateral direction. For example, if the scale on the arm 144 indicates that the separation in the medial-lateral direction is about 5 cm, and it has been determined that the preferred separation between the center of the femoral head and the marking on the trochanter was about 4 cm previously, the surgeon may determine at 220 that the femoral neck corresponding to the first opening may not be appropriate. Thus, at 220, if the surgeon determines that the femoral neck corresponding to the currently used opening may not be appropriate, the method returns to step 218 as illustrated by the process flow line 222. At 218, the surgeon can remove the gauge 140 from the body 100 and engage the pin 142 with another one of the plurality of openings. For example, if the surgeon positions the gauge with the pin 142 in the second opening 112, this reduces the medial-lateral offset of the femoral head disposed on the corresponding femoral neck. As discussed above, the second opening 112 may correspond to a femoral neck that results in a reduced separation in the medial-lateral direction of about 7 mm. Thus, the surgeon positions the gauge 140 in alignment with the first linear mark 122 and may determine using the scale on the gauge that the resulting separation is about 4.3 cm. Since it is determined that the ideal separation initially determined for repairing the natural femoral head is about 4 cm, this may be considered acceptable at 220. Thus, at step 220, an acceptable femoral neck is identified, the center of the natural femoral head is substantially repaired, and thus the remainder of the neck replacement procedure can continue at 224.

[0058] Additionally or alternatively, at 220, since the gauge offsets from the marking 424 when aligned with the linear mark 122, the femoral neck corresponding to the currently selected aperture within the body may be determined to position the femoral head in an incorrect position in the inferior - superior direction. Thus, the surgeon may select another one of the apertures, for example aperture 116, and attach the gauge with its pins in that aperture such that the arm of the gauge 144 is aligned with the second linear mark 124. The surgeon may then visually inspect the marking 424 to evaluate whether the corresponding femoral neck results in a femoral head position that is sufficiently close in the inferior - superior and medial - lateral directions. If the arm of the gauge 144 is sufficiently close to the horizontal portion of the marking 424 and the vertical portion of the marking 424 corresponds to a sufficiently close separation on the medial - lateral axis, the surgeon may accordingly select the corresponding femoral neck.

[0059] Accordingly, using the plurality of apertures of the body 100 and the gauge 140, it is possible to determine which of the plurality of femoral necks results in a replacement femoral head having a center that most closely coincides with the center of the natural femoral head. This is accomplished by providing markings on the remaining portion of the natural femur 424 having a known positional relationship to the center of the natural femoral head. Thus, the gauge 144 and the apertures and the linear marks 122, 124 enable the surgeon to compare the resulting leg length and the medial - lateral offsets resulting from the various femoral necks corresponding to the various apertures of the body.

[0060] The use of a scale and measuring specific distances has been described above, but it will be understood that this is not essential. Rather, the scale may simply use different markings indicating different amounts of separation. The absolute value of the distance is not essential.

[0061] Also, as described above, the embodiments described use five openings each corresponding to a different femoral neck, but more or fewer openings corresponding to the femoral neck may be used. Also, the specific geometric shapes of the femoral necks described are not essential with respect to their stem-neck angle and leg length variations and medial-lateral direction offsets.

[0062] Furthermore, specific guides are illustrated as being used in FIGS. 5 and 6 to determine the approximate center of the natural femoral head, but the use of such guides is not essential. Any device that can be used to approximately identify the center of the femoral head can be used. The identification of the preferred neck resection height and angle is merely incidental and not essential to achieve the advantage of approximately restoring the center of the femoral head.

[0063] In this specification, exemplary embodiments have been presented with respect to a selected set of details. However, those skilled in the art will understand that many other exemplary embodiments, including different sets of these selected details, can be practiced. The following claims are intended to cover all possible exemplary embodiments.

[0064] Unless a particular order is explicitly stated, any instructions and / or flowchart steps can be executed in any order. Also, while one exemplary set of instructions / methods has been considered, those skilled in the art will recognize that the content herein can be variously combined to yield other examples and should be understood within the context provided by this detailed description.

[0065] Although the present disclosure is suitable for various modifications and alternative forms, specific matters thereof have been shown in the drawings and described in detail for purposes of illustration. However, it should be understood that other embodiments besides the specific embodiments described are also possible. All modifications, equivalents, and alternative embodiments included within the scope of the appended claims are likewise covered.

[0066] [Embodiment] (1) A surgical instrument for evaluating the repair of the center of the femoral head, comprising: A main body having a first connector for attaching the main body to the femoral portion, the main body defining a plurality of openings in the main body, each opening corresponding to a respective femoral head center originating from a respective corresponding femoral neck, a main body; A gauge including a pin at a first end and an arm extending laterally from the pin, the pin being receivable in each of the plurality of openings, the arm having a scale indicating a distance from the pin, a gauge; (2) The surgical instrument according to Embodiment 1, wherein the plurality of openings include openings corresponding to femoral necks having different medial-lateral offsets. (3) The surgical instrument according to Embodiment 1 or 2, wherein the plurality of openings include openings corresponding to femoral necks having different stem-neck angles. (4) The surgical instrument according to any one of Embodiments 1 to 3, wherein the plurality of openings include openings corresponding to femoral necks having different leg lengths. (5) The surgical instrument according to any one of Embodiments 1 to 4, wherein the main body has a front surface, the front surface extending parallel to the medial-lateral axis, passing through at least a first opening of the plurality of openings, and including at least a first linear mark corresponding to a first position on the superior-inferior axis.

[0067] (6) The surgical instrument according to Embodiment 4, wherein the front surface extends parallel to the medial-lateral axis, passes through at least a second opening of the plurality of openings, and includes at least a second linear mark corresponding to a second position on the superior-inferior axis. (7) The surgical instrument according to Embodiment 5 or 6, wherein the main body has a rear surface, the rear surface includes the same marks as the front surface, and the same main body is configured to be usable for the right hip joint and the left hip joint. (8) The surgical instrument according to any one of Embodiments 1 to 7, wherein each of the plurality of openings includes a channel passing through the entire thickness of the main body. (9) A surgical instrument system, comprising: the surgical instrument according to any one of Embodiments 1 to 8; and a center finder including a plurality of marks configured to indicate the center of the center finder. (10) The surgical instrument system according to Embodiment 9, wherein the center finder includes a circular ring, and the plurality of marks include a first pair of marks facing each other in the diameter direction and a second pair of marks facing each other in the diameter direction.

[0068] (11) A broach, comprising a second connector configured to engage with the first connector for attaching the body to the broach. The surgical instrument system according to Embodiment 9 or 10, further comprising a plurality of femoral necks, each neck resulting in a different femoral head center position. (12) The surgical instrument system according to Embodiment 11, wherein the plurality of femoral necks include femoral necks having different offsets along the medial-lateral axis. (13) The surgical instrument system according to Embodiment 11 or 12, wherein the plurality of femoral necks include femoral necks having different stem-neck angles. (14) The surgical instrument system according to any one of Embodiments 11 to 13, wherein the plurality of femoral necks include femoral necks having different leg lengths along the superior-inferior axis. (15) A method for evaluating the restoration of the femoral head center for a patient's femur, comprising: determining the center of the natural femoral head of the femur of the patient; marking the position of the center on the natural femoral head; using a known separation along the medial-lateral axis from the center of the natural femoral head to mark the position on the greater trochanter of the femur relative to the center of the natural femoral head at the same position along the superior-inferior axis as the center of the natural femoral head; excising the natural femoral neck. Attaching the body to the excised femoral neck, wherein the body defines a plurality of openings, and each opening corresponds to a respective femoral head center arising from a respective corresponding femoral neck, the attaching; Attaching a gauge including a scale to the body using a first opening of the plurality of openings; Determining, using the gauge, whether the femoral head center arising from a first femoral neck corresponding to the first opening of the plurality of openings repairs the natural femoral head center, a method comprising.

[0069] (16) Attaching the gauge to the body using a second opening of the plurality of openings; Determining, using the gauge, whether the femoral head center arising from a second femoral neck corresponding to the second opening of the plurality of openings repairs the natural femoral head center, the method according to embodiment 15 further comprising. (17) Further comprising aligning the gauge with a linear mark on the body that is parallel to the medial-lateral axis of the femur, the method according to embodiment 15 or 16. (18) Further comprising determining, using the scale on the gauge, whether the femoral head center arising from the femoral neck corresponding to one of the plurality of openings has a separation that repairs the known separation, the method according to any one of embodiments 15 to 17. (19) Further comprising determining the center of the natural femoral head and / or marking the position of the center of the natural femoral head using a center finding guide disposed on the natural femoral head, the method according to any one of embodiments 15 to 18.

Claims

Claim 1. A surgical instrument system, comprising: a plurality of femoral necks, each femoral neck producing a different femoral head center position; a surgical instrument, comprising: a body having a first connector for attaching the body to a natural femoral portion, the body defining a plurality of openings therein, each opening corresponding to a respective femoral head center originating from a respective corresponding femoral neck of the plurality of femoral necks; a gauge including a pin at a first end and an arm extending laterally from the pin, the pin being receivable in each of the plurality of openings, the arm having a scale indicating a distance from the pin; a broach inserted into the intramedullary canal after the natural femoral neck has been resected and the intramedullary canal has been formed, the broach including a second connector; the first connector of the body engaging the second connector of the broach inserted into the intramedullary canal, such that the body is attached to the natural femoral portion via the broach; based on a distance between a specific location of the natural femur and the natural femoral head center measured prior to resection of the natural femoral neck, and a distance between the specific location and each of the plurality of openings measured by the scale when the pin is received in each of the plurality of openings with the body attached to the natural femoral portion via the broach, one opening closest to the natural femoral head center among the plurality of openings can be determined, and a femoral neck corresponding to the one opening can be selected. A surgical instrument system. Claim 2. The surgical instrument system according to claim 1, wherein the plurality of openings include openings corresponding to femoral necks having different medial-lateral offsets. Claim 3. The surgical instrument system according to claim 1 or 2, wherein the plurality of openings include openings corresponding to femoral necks having different stem-neck angles. Claim 4. The surgical instrument system according to any one of claims 1 to 3, wherein the plurality of openings include openings corresponding to femoral necks having different leg lengths. Claim 5. The surgical instrument system according to any one of claims 1 to 4, wherein the body has a front surface, the front surface extends parallel to the inner-outer axis, passes through at least a first opening of the plurality of openings, and includes at least a first linear mark corresponding to a first position on the up-down axis.

6. The surgical instrument system according to claim 5, wherein the front surface extends parallel to the inner-outer axis, passes through at least a second opening of the plurality of openings, and includes at least a second linear mark corresponding to a second position on the up-down axis.

7. The surgical instrument system according to claim 5 or 6, wherein the body has a rear surface, the rear surface includes the same marks as the front surface, and the same body is configured to be usable for the right hip joint and the left hip joint.

8. The surgical instrument system according to any one of claims 1 to 7, wherein each of the plurality of openings includes a channel passing through the entire thickness of the body.

9. A center finder, comprising a center finder including a plurality of marks configured to indicate the center of the center finder, the surgical instrument system according to claim 1.

10. The surgical instrument system according to claim 9, wherein the center finder includes a circular ring, and the plurality of marks include a first pair of diametrically opposed marks and a second pair of diametrically opposed marks.

11. The surgical instrument system according to claim 5, wherein the plurality of femoral necks include femoral necks having different offsets along the inner-outer axis.

12. The surgical instrument system according to claim 11, wherein the plurality of femoral necks include femoral necks having different stem-neck angles.

13. The surgical instrument system according to claim 5, wherein the plurality of femoral necks include femoral necks having different leg lengths along the up-down axis.

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