Femoral trial kit and assembly

Abstract

A femoral trial kit and method for assessing acetabular cup orientation during left and right hip joint surgery is described. The kit includes a trial femoral head having an inner wall defining a cavity extending along a head axis and a visual alignment guide on an outer surface of the trial femoral head; and a trial femoral neck having a tapered portion at a free end, the tapered portion being receivable within the cavity. One of the tapered portion and the inner wall has first and second anti-rotation features, the first and second anti-rotation features being angled, and the other of the tapered portion and the inner wall has a third anti-rotation feature. The trial femoral head is attachable to the trial femoral neck in a first angular configuration corresponding to the right hip joint with the third anti-rotation feature and the first anti-rotation feature engaged, and the trial femoral head is attachable to the trial femoral neck in a second angular configuration corresponding to the left hip joint, wherein the third anti-rotation feature and the second anti-rotation feature are engaged.

Description

[0001] This application is a divisional application of PCT patent application PCT / EP2018 / 059065 (international application date is April 9, 2018, priority date is April 12, 2017, Chinese national application number is 201880039140.6, invention name is “Femoral Test Kit and Assembly”) which entered the Chinese national phase on December 12, 2019. Technical Field

[0002] The present invention relates to hip surgery and, in particular, to trial components that may be used during a trial of a hip joint and methods of using such trial components. Background Art

[0003] Various methods of hip surgery are well known. The hip joint can generally be viewed as a ball-and-socket joint, wherein the head of the femur articulates within the acetabulum of the pelvis. Some methods of hip surgery may involve replacing one or more parts of the hip joint with one or more prosthetic components. This can be used to replace damaged, worn, diseased, or otherwise defective parts of the hip joint, including the corresponding articulating surfaces of the acetabulum and / or the femoral head.

[0004] Different surgical procedures may involve replacing a portion of the acetabulum or the femoral head or both. Some operations (sometimes referred to as surface remodeling operations) may involve replacing only the articular motion surface of the femoral head. Other operations may involve replacing the entire femoral head. Such operations also typically use a femur or stem component that is implanted in the resected femur and has a neck to which the femoral head is attached. In some operations, a prosthetic cup may be implanted in the prepared acetabulum cavity to provide a cavity in which the femoral head or a prosthetic femoral head can articulate when the joint is repositioned. A surgical procedure in which at least a portion of the femoral head and the acetabulum are replaced with a prosthetic component is typically referred to as a total hip replacement.

[0005] During hip surgery, some surgeons sometimes use one or more trial components that have the same geometry and dimensions as the intended prosthetic components. This allows the surgeon to test the joint before ultimately implanting one or both of the prosthetic components. For example, the surgeon may use the trial components to verify that the size, position, or orientation of one or more of the components are appropriate. Other surgeons may choose not to use trial components or may occasionally use them based on their professional judgment.

[0006] One of the considerations in hip surgery is the angular orientation of the acetabular cavity. When replacing the acetabulum with an acetabular cup, the surgeon typically aims to place the cup so that it points in a generally preferred direction or range of directions. The orientation of the cup is typically defined in terms of abduction or inclination and anteversion.

[0007] A variety of methods have been used to try and assess the angular orientation of an acetabular cup (whether trial or prosthetic) after placement in the acetabular cavity.

[0008] An anatomical approach may be used, in which the surgeon uses their experience and / or an instrument to measure, by inspection or instrumentation, the angular orientation of the acetabular cup relative to one or more anatomical features of the patient's pelvis. However, access to the surgical site is often limited, particularly for minimally invasive approaches, and therefore this is often not easy or accurate.

[0009] Other methods may use markings or other features on the trial or prosthetic component to measure the angular orientation of the acetabular cup relative to the patient's pelvis.

[0010] For example, Lucas, David H. and Scott, Richard D., in an article titled "The Ranawat Sign: A Specific Maneuver to Assess Component Positioning in Total Hip Arthroplasty," published in the Journal of Orthopaedic Techniques, Volume 2, Issue 2, June 1994, describe a method for intraoperatively assessing the orientation of components in total hip arthroplasty. With the patient in the correct lateral position, the femur is internally rotated without hip flexion until the flat underside of the prosthetic head (roughly perpendicular to the femoral neck) is coplanar with the rim of the acetabular cup. The amount of internal rotation required to achieve this position is called the Ranawat sign and is related to the combined anteversion of the acetabulum and femoral components of the joint. For example, a Ranawat sign of 45° may correspond to a cup anteversion of 30° and a femoral anteversion of 15°. However, any knee laxity or deformity may affect the interpretation of this value. In addition, it may be difficult to assess the actual magnitude of the angle of internal rotation. Additionally, different surgeons may have different methods of manipulating a patient's leg, and any one surgeon's method may not be easily replicated from patient to patient, by the same surgeon or other surgeons.

[0011] WO 2009 / 108683 describes another method in which markers are applied to the femoral head and in which the surgeon again applies a certain amount of internal rotation to the patient's leg during a trial reduction so that the angle between the rim of the acetabular cup and the various markers on the femoral head indicates the angular position of the acetabular cup relative to the patient's pelvis. A leg position is used in which the patient's leg is in a fully relaxed, extended state with zero degrees of abduction, zero degrees of anteversion, and approximately 15° of internal rotation, or otherwise internally rotated by an amount equal to that of the native femoral neck or the pattern of the artificial femoral neck. Therefore, this method also requires the surgeon to apply a specific amount of internal rotation to the patient's leg. Again, it may be difficult to apply the correct amount of internal rotation, may be inaccurate due to the deformity of the patient's leg, and the surgical technique may be difficult to reproduce and / or reliably learn. This is especially true for the relatively small angle of 15°, as even a relatively small error in the amount of internal rotation (e.g., 5°) accounts for a large portion (33%) of the target internal rotation.

[0012] Other methods and associated instruments are described in US2005 / 0107799. An attachment for implanting a hip cup includes a steerable cup, a steering head having a hemispherical portion, and a circular rim surrounding the steering head for aligning the steerable cup in the acetabulum. A device is provided for securing the aligned position of the steerable cup and allowing a guide to be provided for aligning a bone drill and a driver tool for reaming the acetabular cavity and placing the cup. In another method, the steerable cup is positioned in the acetabulum and its orientation is adjusted by a handle until the lip of the steerable cup is parallel to the equator on the femoral head or the plane opposite the femoral head

[0013] Therefore, a device and / or method that makes accurate intraoperative assessment of acetabular cup placement simpler, easier, and / or more reliable would be beneficial. Summary of the Invention

[0014] A first aspect of the present invention provides a femoral trial kit for evaluating acetabular cup orientation during left hip surgery and right hip surgery, comprising: a trial femoral head having an inner wall defining a cavity extending along the head axis and a visual alignment guide on the outer surface of the trial femoral head; and a trial femoral neck having a tapered portion at a free end, the tapered portion being receivable within the cavity, wherein one of the tapered portion and the inner wall has a first anti-rotation feature and a second anti-rotation feature, the first anti-rotation feature and the second anti-rotation feature being inclined, and the other of the tapered portion and the inner wall has a third anti-rotation feature, and wherein the trial femoral head can be attached to the trial femoral neck corresponding to a first angular configuration of the right hip joint, wherein the third anti-rotation feature and the first anti-rotation feature are engaged, and the trial femoral head can be attached to the trial femoral neck corresponding to a second angular configuration of the left hip joint, wherein the third anti-rotation feature and the second anti-rotation feature are engaged.

[0015] The visual alignment guide may comprise only a single marking.The visual alignment guide may be a single line or strip.

[0016] The visual alignment guide may be tilted relative to the head axis. The visual alignment guide may define a plane, and the plane and the head axis may subtend an acute angle in the range of about 20° to 40°. The acute angle may be about 31°.

[0017] The single marking may be in the form of a band having a first color. The surface of the test head may have a second color. The first color and the second color may be different colors. The first color may be a darker color than the second color.

[0018] The individual markings may have a width of at least 3 mm. The individual markings may have a width in the range of 3 mm to 5 mm. Preferred values ​​for the width of the individual markings include 3.5 mm and 4 mm.

[0019] The trial femoral neck may include a neck marker. The neck marker may be used as an angular position reference. The trial femoral head may include a first head marker and / or a second head marker on the outer surface of the trial femoral head. The first head marker and the second head marker may be positioned around the head axis so that when the trial femoral head is attached to the trial femoral neck in a first angular configuration, the first head marker is aligned with the neck marker, and / or when the trial femoral head is attached to the trial femoral neck in a second angular configuration, the second head marker is aligned with the neck marker. The neck marker may be or include a line. The first head marker may be a right marker and / or may be or include an R and / or a short line. The second head marker may be a left marker and / or may be or include an L and / or a short line.

[0020] Neck markings may be located on the superior and / or lateral surfaces of the trial femoral neck.

[0021] The trial femoral neck may include a first neck marker and a second neck marker on opposite sides of the trial femoral neck. The trial femoral head may include a first head marker and a second head marker on an outer surface of the trial femoral head. The first head marker and the second head marker may be positioned around the head axis respectively so that when the trial femoral head is attached to the trial femoral neck in a first angular configuration, the second head marker is aligned with the second neck marker, and when the trial femoral head is attached to the trial femoral neck in a second angular configuration, the first head marker is aligned with the first neck marker.

[0022] The first neck mark and the second neck mark can be visually distinguishable. The first head mark and the second head mark can be visually distinguishable. The first neck mark and the first head mark can be visually related, similar, or identical. The second neck mark and the second head mark can be visually related, similar, or identical.

[0023] The first neck mark, the second neck mark, the first head mark and the second head mark can all be the same shape. For example, they can all be triangular.

[0024] The first neck mark and the first head mark can be the same first color. The second neck mark and the second head mark can be the same second color. The first color and the second color can be different colors. The first color can be white and the second color can be black.

[0025] One of the tapered portion and the inner wall may have a fourth anti-rotation feature. The fourth anti-rotation feature may be angled relative to the first and second anti-rotation features. The other of the tapered portion and the inner wall may have a fifth anti-rotation feature. The fifth anti-rotation feature may be angled relative to the third anti-rotation feature. In a first angular configuration corresponding to a right hip joint, the fifth anti-rotation feature and the fourth anti-rotation feature may engage. In a second angular configuration corresponding to a left hip joint, the first and fifth anti-rotation features may engage.

[0026] The conical portion may have a free end and an outer portion. The or each anti-rotation feature may be provided at the free end of the conical portion. The outer portion of the conical portion may have a cylindrical form. The inner wall defining the cavity may have an outer portion and an inner portion. The inner portion may provide the or each anti-rotation feature. The outer portion may have a cylindrical form.

[0027] The femoral trial kit may further comprise a retaining mechanism arranged to releasably attach the trial femoral head to the tapered portion.

[0028] The retaining mechanism can be configured to provide a friction fit between the tapered portion and the cavity. The retaining mechanism can include an O-ring. The O-ring can be made of a compliant material such as rubber, silicone, or the like. The O-ring can be disposed around the tapered portion and can be located in a groove extending around the tapered portion.

[0029] The retaining mechanism may include a clamp. The clamp may be arranged to interact between the tapered portion and the cavity. The clamp may be in the form of a C-clip or a C-ring. The C-clip may be disposed in a groove extending around the band, and a corresponding groove may be disposed in a wall defining the trial femoral head cavity. The C-clip or C-ring may be made of a metal such as stainless steel.

[0030] The or each anti-rotation feature may be a surface. The surface may be a flat surface, a curved surface, or an irregularly shaped surface. The or each surface on the tapered portion and the or each surface within the cavity may be configured so that the surface on the tapered portion will mate, engage, or abut with the surface within the cavity. The mating surfaces may provide better anti-rotation control.

[0031] The anti-rotation feature may be a male feature and / or a female feature. The or each anti-rotation feature of the tapered portion may be a male feature, and the or each anti-rotation feature of the cavity may be a female feature. The or each anti-rotation feature of the cavity may be a male feature, and the or each anti-rotation feature of the tapered portion may be a female feature.

[0032] The trial femoral head may comprise a first gripping feature and / or a second gripping feature in an outer surface.The first gripping feature and / or the second gripping feature may be provided on the same side of the trial femoral head.

[0033] The first gripping feature and / or the second gripping feature may be in the form of a recess.The or each recess may be adapted or configured to receive a fingertip of a user in use.

[0034] When the trial femoral head is mounted on the trial neck on the stem component within the patient's femur, with the trial hip joint reduced and in a neutral position, the visual alignment guide can be positioned on the outer surface of the trial femoral head to correspond to an inclination angle of less than 45° of the acetabular cup in the patient's pelvis. The visual alignment guide can be positioned on the outer surface of the trial femoral head to correspond to an inclination angle of between approximately 20° and approximately 40° of the acetabular cup. The visual alignment guide can be positioned on the outer surface of the trial femoral head to correspond to an inclination angle of approximately 40° of the acetabular cup. The visual alignment guide can be positioned on the outer surface of the trial femoral head to correspond to an anteversion angle of between approximately 10° and approximately 20° of the acetabular cup. The visual alignment guide can be positioned on the outer surface of the trial femoral head to correspond to an anteversion angle of approximately 20° of the acetabular cup.

[0035] The anti-rotation feature can be configured such that the trial femoral head rotates less than 180° in the first configuration compared to the second configuration. The anti-rotation feature can be configured such that the trial femoral head rotates less than 150° in the first configuration compared to the second configuration. The anti-rotation feature can be configured such that the trial femoral head rotates approximately 144° in the first configuration compared to the second configuration.

[0036] The femoral trial kit may also include a femoral component to which the base of the trial femoral neck is releasably attached. The neck angle when the trial femoral neck is attached to the femoral component may be greater than or less than 135°. The femoral component may be a stem, a drill, a rasp, or the like.

[0037] A second aspect of the invention provides a femoral trial assembly comprising the components of the femoral trial kit of the first aspect of the invention, including any preferred features thereof.

[0038] A third aspect of the present invention provides a method for assembling a trial femoral component, which includes a trial femoral head having an inner wall defining a cavity and a trial femoral neck having a tapered portion receivable in the cavity, the method comprising: determining whether the component is for testing a left hip or a right hip; and attaching the trial femoral head to the trial femoral neck in a first angular configuration corresponding to the right hip joint, or attaching the trial femoral head to the trial femoral neck in a second angular configuration corresponding to the left hip joint.

[0039] One of the tapered portion and the inner wall may have first and second anti-rotation features, the first and second anti-rotation features being inclined, and the other of the tapered portion and the inner wall may have a third anti-rotation feature.

[0040] The third anti-rotation feature and the first anti-rotation feature may be engaged in the first angular configuration.

[0041] The third anti-rotation feature and the second anti-rotation feature may be engaged in the second angular configuration.

[0042] The method may also include: disconnecting the trial femoral head from the trial femoral neck; rotating the trial femoral head around the neck axis of the trial femoral neck by an angle greater than or less than 180°; and reattaching the trial femoral head to the trial femoral neck in the other of the first angular configuration and the second angular configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Embodiments of the present invention will now be described in detail, by way of example only, and with reference to the accompanying drawings, in which:

[0044] Figure 1 A coronal view of the femur is shown;

[0045] Figure 2 Shown Figure 1 Sagittal view of the femur;

[0046] Figure 3 Shown Figure 1 and Figure 2 Transverse view of the femur;

[0047] Figure 4 shows a view of the femur in a plane parallel to the anatomical axis and neck of the femur;

[0048] Figure 5 A coronal view of the pelvis is shown;

[0049] Figure 6 Shown Figure 5 Sagittal view of the pelvis;

[0050] Figure 7 Shown Figure 5 and Figure 6 Transverse view of the pelvis;

[0051] Figure 8 Shown along Figure 5 A perspective view of a partial section of the pelvis along line AA;

[0052] Figure 9 A perspective view of the pelvis is shown;

[0053] Figure 10 Shown include Figures 1 to 4 femur and Figures 5 to 9 Coronal view of the pelvis and hip;

[0054] Figure 11 Shown along Figure 10 A partial cross-sectional perspective view of the pelvis along line CC;

[0055] Figure 12 showing views of left and right hip trial assemblies having a first geometry;

[0056] Figure 13 showing views of left and right hip trial assemblies having a second geometry;

[0057] Figure 14 shows a perspective view of a kit of parts according to the present invention;

[0058] Figure 15 showing an end view of a trial femoral head and a trial femoral neck of the kit of parts of the assembly in a first right hip configuration;

[0059] Figure 16 showing an end view of a trial femoral head and a trial femoral neck of the kit of parts of the assembly in a second left hip configuration;

[0060] Figure 17 A perspective view of the trial assembly is shown illustrating anteversion of the neck, anteversion of the cup, and cup tilt;

[0061] Figure 18 A second embodiment of a right hip trial assembly is shown; and

[0062] Figure 19 The second embodiment is shown as a left hip trial assembly.

[0063] Unless otherwise indicated, similar items in different drawings are shown with common reference numerals. DETAILED DESCRIPTION

[0064] Before describing the apparatus and / or method of the present invention, the geometry of the hip joint will be generally discussed. Hereinafter, the right hip joint is described, but it will be understood that a similar discussion applies to the left hip joint. In addition, the following discussion is intended to relate to both the natural hip joint or native hip joint before surgery, and the artificial hip joint or prosthetic hip joint. Therefore, although the magnitude of the various angles may vary between the native hip joint and the prosthetic hip joint, the definition of these angles may be roughly the same for the native hip joint and the prosthetic hip joint and may be determined by the position and / or orientation of the various parts that constitute the native hip joint and the prosthetic hip joint, respectively.

[0065] refer to Figures 1 to 4 , showing various views of the right femur 100. Specifically, Figure 1 A coronal view along the anterior-posterior direction (generally AP direction in this article) is shown. Figure 2 A sagittal view along the medial-lateral direction (generally the ML direction in this article) is shown. Figure 3 shows a transverse view in the up-down direction, and Figure 4 Shown is the view of the femur in the plane parallel to the anatomical axis of femur and the neck of femur, as described in more detail hereinafter.Preoperatively, the proximal portion of femur 100 comprises native femoral neck and native femoral head.Intraoperatively and postoperatively, the proximal portion of femur can comprise various trial parts or prosthetic parts or provide the parts of trial or prosthetic femoral neck and femoral head.Following content will be related to femoral neck and femoral head as a whole, and is intended to comprise native, trial or prosthetic femoral neck and femoral head.

[0066] Specific reference Figure 1 and Figure 2 , the proximal portion 102 of the femur 100 includes a femoral head 104 (represented by a sphere) attached to a femoral neck 126, as shown Figure 4, the femoral neck has a neck axis extending generally in the direction of arrow 106. The femur 100 has a epicondylar axis 108 extending between a lateral femoral epicondyle 110 and a medial femoral epicondyle 112. The femur 100 also has an anatomical axis 114 extending between, for example, a distal femoral intercondylar notch 116 and the piriformis fossa proximal to the medial aspect of the greater trochanter. The femur 100 also has a mechanical axis 120 extending between, for example, proximal to the distal femoral intercondylar notch 116 and the center of the femoral head 104. In other embodiments, the anatomical axis 114 and the mechanical axis 120 of the femur 100 may be defined by other anatomical points.

[0067] refer to Figure 3 The femoral neck anteversion angle 124 can be defined as the angle in the transverse plane formed by the femoral neck axis 106 and the epicondylar axis 108. In practice, the femoral neck anteversion angle of the native neck is typically in the range of about 12° to 15°, but can have other values. The neck anteversion angle 124 is a measure of the anteversion of the femoral neck relative to the local anatomy of the femur 100.

[0068] Figure 4 Shown in parallel with Figure 3 1. A view of the femur 100 in the plane of line BB, which is parallel to the femoral neck axis 106 and the anatomical axis 114 and which more clearly shows the femoral neck 126. Figure 4 Also shown is a neck angle 128 formed between the femoral neck axis 106 and the anatomical axis 114 of the femur. The native neck angle 128 varies from patient to patient, but is typically about 130°. Unless the implant is adjustable, the neck angle 128 of a trial or prosthetic implant is typically fixed by the implant design and is typically intended to approximately reproduce the native geometry, and therefore may also be about 130°. Hereinafter, a neck angle 128 of 130° may be used as an example, but it will be understood that in other embodiments, other neck angle values ​​may be used.

[0069] Thus, during hip surgery in which a prosthetic femoral component is used, one of the variables is the femoral neck anteversion 124, which generally measures the degree to which the femoral neck 126 points forward compared to the medial-lateral axis of the femur.

[0070] refer to Figures 5 to 9 , showing various views of the pelvis 200 and the right acetabulum. Specifically, Figure 5 A coronal view along the anterior-posterior direction (generally AP direction in this article) is shown. Figure 6 A sagittal view along the medial-lateral direction (generally the ML direction in this article) is shown. Figure 7 shows a transverse view in the up-down direction, Figure 8 Shown along Figure 5 A partial cross-sectional view of line AA, and Figure 9 A perspective view of pelvis 200 is shown, wherein the anterior pelvic plane (APP) is vertical, and the transverse axis is roughly horizontal. Before the operation, pelvis 200 includes the acetabulum providing a native socket, and the native femoral head is received in this native socket and performs joint motion therein. Intraoperatively and / or postoperatively, the pelvis may include various trial implants or prosthetic implants, such as trial acetabular cups or prosthetic acetabular cups (with or without lining, depending on the specific implant system used). The following content will relate to acetabulum or acetabular cups as a whole, and is intended to include native acetabulum and trial components or prosthetic components.

[0071] like Figure 5 As shown, the acetabulum 202 can be represented by a hemisphere or semi-spherical cup that generally has a position and orientation. The orientation or direction of the acetabulum can generally be defined by two angles. The first angle indicates the degree to which the acetabulum points forward or backward relative to the pelvis (when pointing forward, it is generally referred to as antevertion, and when pointing backward, it is generally referred to as retroversion). The second angle indicates the degree to which the acetabulum points downward or along the inferior axis relative to the pelvis (generally referred to as tilt or abduction). The orientation of the acetabulum can be defined by Figure 9 The acetabular axis 204 is best shown in FIG. 2 and is defined as passing approximately through the center of the ostium of the acetabulum and perpendicular to the plane of the ostium of the acetabulum.

[0072] Pelvis 200 includes a transverse axis 206 passing between right and left anterior superior iliac spines (ASIS) 208 and 210. An anterior pelvic plane 212 (hereinafter generally referred to as APP) is defined by transverse axis 206 and first and second points 214 and 216 on the pubic symphysis.

[0073] like Figure 5 As best shown, the inclination angle of the acetabulum or acetabular cup 202 can be defined by an angle 220 subtended by the transverse axis 206 and a long axis or inclination axis 222 of the acetabular cup 202 in or parallel to the anterior pelvic plane 212. Figure 5 In FIG. 2 , the tilt angle 220 is shown to be approximately 40°. Figure 8 Shown along Figure 5 A cross-sectional view of the pelvis 200 is taken along line AA and in a direction along the long axis 222 of the acetabular cup 202. Thus, Figure 8 A plane generally perpendicular to the long axis 222 of the acetabular cup 202 is shown. Figure 8 In FIG. 2 , anteversion angle 224 can be defined as the angle subtended between a plane 226 of the ostium of the acetabular cup and a plane 228 perpendicular to the anterior acetabular plane 212. Figure 8 As shown, the acetabulum or acetabular cup 202 has an anteversion angle 224 of approximately 20°.

[0074] Therefore, if Figure 9As shown in the perspective view of the pelvis 200 in FIG. 1 , the acetabulum or acetabular cup 202 has an orientation corresponding to 40° of inclination and 20° of anteversion. These angles may be referred to as radiographic angles because they are based on Figure 5 An APP view of the pelvis is shown and is a view of the pelvis typically obtained by radiographic imaging or X-ray and commonly used by surgeons to assess acetabular orientation before, during, and / or after surgery.

[0075] refer to Figures 10 and 11 , showing various views of the right hip joint 300 formed by the femur 100 and the pelvis 200. Specifically, Figure 10 Shown with Figure 1 and Figure 5 A coronal view similar to the one in the anterior-posterior direction (usually AP in this article). Figure 10 , the femur has been placed in a neutral position, as described in more detail below. Figure 11 Shown along Figure 10 The partial cross section is viewed along the line CC and in the direction of the tilt axis 222 of the acetabular cup 202. Therefore, Figure 11 The plane is generally perpendicular to the direction of the tilt axis 222 of the acetabular cup.

[0076] like Figure 11 As shown, the acetabular cup 202 has an anteversion angle 224 of 20° in a plane perpendicular to the tilt axis 222 of the acetabulum. Figure 11 Also shown is the femoral anteversion angle 230 in a plane perpendicular to the tilt axis of the acetabulum and defined by the angle 230 subtended by the femoral neck axis 106 and the anterior pelvic plane 212 in that plane. Figure 11 As shown, the apparent femoral anteversion angle 230 is approximately 11°.

[0077] Thus, it can be seen that the overall geometry of the hip joint is caused by the orientation of the acetabulum relative to the pelvis and the orientation of the femoral neck relative to the femur. In the illustrated example, Figure 10 and Figure 11 The total or combined anteversion of the illustrated hip joint 200 is a combination of the acetabular anteversion (approximately 20°) and the amount of femoral anteversion projected into the same plane (approximately 11° in this example). Thus, the combined anteversion of the hip joint 300 in this plane is approximately 31°.

[0078] However, in practice, when surgeons discuss a combined anteversion of approximately 35°, this can be obtained by adding the absolute values ​​of the angles in the different planes (15° anteversion of the neck relative to the femur in a first plane and 20° anteversion of the acetabulum relative to the pelvis in a second, different plane) to arrive at approximately 35°. In practice, it is assumed that the combined anteversion is in the range of approximately 30° to 40°, such as typically greater than 30° and less than 40°, and that any measurement or assessment is likely to be accurate to plus or minus a few degrees anyway, and therefore the measurement of the angles in different non-parallel planes is not critical.

[0079] In this article, depending on the context, combined anteversion can refer to the general idea that the anteversion of the hip joint is the combined effect of the degree of anteversion of the femoral neck relative to the femur and the degree of anteversion of the acetabulum relative to the pelvis. More specifically, for non-extreme cases, combined anteversion can also refer to the general rule of thumb that the sum of the acetabular anteversion and femoral anteversion measured in the same plane should have a certain value, such as approximately 35°. Therefore, if one value is lower, the other value can be increased (or vice versa) to bring the combined anteversion closer to the target value.

[0080] refer to Figure 12 , shows views of a first trial hip joint 400 and a second trial hip joint 500. The first trial hip joint 400 is for a right hip joint and the second trial hip joint 500 is for a left hip joint. The first trial hip joint 400 includes a femoral component 402 and an acetabular component 404. The femoral component includes a stem component 410 in the form of a reamer or drill, a trial neck 412 releasably attached to the upper portion of the reamer, and a trial femoral head 414 releasably attached to the trial neck 412. The acetabular component 404 includes an acetabular cup 420 and an optional acetabular liner 422. The acetabular cup 420 is generally hemispherical and defines a hemispherical cavity in which the acetabular liner 422 can be received and which itself defines a generally hemispherical cavity in which the trial femoral head 414 can be received and articulated.

[0081] Similarly, second trial hip joint 500 includes a femoral component 502 and an acetabular component 504. The femoral component includes a stem component 510 in the form of a reamer or drill, a trial neck 512 releasably attached to an upper portion of the reamer, and a trial femoral head 514 releasably attached to the trial neck 512. The components of first trial hip joint 400 and second trial hip joint 500 may be the same components.

[0082] The acetabular component 504 includes an acetabular cup 520 and an acetabular liner 522. The acetabular cup 520 is generally hemispherical and defines a hemispherical cavity in which the acetabular liner 522 is received and which itself defines a generally hemispherical cavity in which the trial femoral head 514 can be received and articulated.

[0083] Figure 12 A view of the first and second trial hip joints is shown in a plane parallel to the plane of the body of the stem components 410, 510, and with the neck axis 416, 516 of the trial neck located in this plane. In use, the stem components will be located within a cavity within the patient's femur and the stem components will have a torsion angle (typically anteversion) relative to the femur, as discussed above.

[0084] Acetabular components 404, 504 have an orientation relative to the patient's pelvis, as described above, which can be defined by anteversion and inclination or abduction. Anteversion generally refers to the angle at which the cup rotates in a forward direction relative to the coronal plane of the patient's pelvis, and inclination generally refers to the angle at which the cup rotates in a downward direction relative to the transverse plane of the patient's pelvis. The direction of each acetabular cup can be defined by a corresponding acetabular cup axis 424, 524, which passes through the stem of the cup and is perpendicular to the cup opening plane and through the center of the roughly circular opening of the cup. Therefore, the acetabular cup orientation relative to the pelvis can be defined by the anteversion and inclination of the acetabular cup axis.

[0085] The trial femoral head 414, 514 is generally spherical and includes a trial cavity extending along the femoral head axis of the trial femoral head, which axis passes through the stem of the trial femoral head and coincides with the neck axis 416, 516. The trial cavity provides a receptacle into which the free end of the trial neck can be inserted as a connector to provide a releasable attachment mechanism for releasably attaching the trial femoral head 414, 514 to the trial neck 412, 512. The trial femoral head also includes at least one marking in the form of a color band 418, 518 on the surface of the trial femoral head, and the marking is Figure 1 The color bands 418, 518 are black in color and extend around the great circle or equator of the trial head but are oblique to and not perpendicular to the femoral head axis. The color bands 418, 518 can be used to visually assess the orientation of the acetabular components 402, 502 relative to the pelvis, as described in more detail below.

[0086] exist Figure 12 , the neck angle 430 between the longitudinal axis of the stem 432 and the trial neck axis 416 is 135°, and the acetabular cup has an inclination angle of 45°. The color band 418 is deflected relative to the neck axis 416. With the trial joint reduced and the patient's hip joint in a neutral position, the ostial plane of the acetabular cup is parallel to the color band 418, indicating that the acetabular cup has been placed in the patient's pelvis at an inclination angle of 45°.

[0087] The neutral position of the patient's hip joint can be defined as: the patient's leg is placed in an appropriate position to provide 0° flexion / extension, 0° abduction / adduction, and 0° internal / external rotation of the femur relative to the pelvis. Moreover, the rotation angle of the trial femoral head about the neck axis 416 is predetermined, for example by markings or some form of keying mechanism or timing mechanism. The inclination angle of the ribbon and the angular position about the neck axis are selected so that when the trial hip joint is reduced and the trial hip joint is in a neutral position, when the neck axis 416 has an anteversion angle of 15° relative to the femur and the acetabular cup has an anteversion angle of 20° and an inclination angle of 45° relative to the pelvis, the orifice plane of the acetabular cup will be parallel to the ribbon 418.

[0088] For a cup tilt angle of 45° and a neck angle 430 of 135°, as Figure 1 As shown, the geometry is such that the geometry of the left trial hip component 500 is completely similar to the geometry of the right trial hip component 400. Thus, the same trial components can be used for the right trial hip 400 and also for the left trial hip 500, except that the trial femoral head needs to be rotated 180° about the trial neck axis 416, 516 between use of the left trial hip 500 and the right trial hip 400.

[0089] However, for some patients and / or surgeries, an acetabular cup tilt angle of 45° may not be appropriate. If the cup tilt angle is changed from 45° (e.g., to 40°), then Figure 12 The methods shown in will no longer work. For example, Figure 13 A similar first right trial hip 450 and a second left trial hip 550 are shown, but in which the band on the trial head is tilted so that for the right trial hip, with the trial hip in a neutral position, the ostial plane of the acetabular cup is parallel to the band when the acetabular cup is at an inclination angle of less than 45° (e.g., 40°). In this case, if the trial femoral head is simply rotated 180° about the neck axis and then attached to the trial neck for the left hip, the acetabular cup of the left hip is positioned at the correct target inclination of 40°, as shown in FIG. Figure 13 If the test assembly 550 is shown in FIG, then its mouth plane will no longer be parallel to the ribbon, thereby indicating an incorrect cup orientation, which is not the case.

[0090] This can be avoided by using two different trial femoral heads, one with the ribbon correctly placed for the left hip and another with the ribbon correctly placed for the right hip. However, this will result in increased inventory and instrumentation. This may also increase the likelihood of error if the surgeon accidentally uses a trial femoral head constructed for the left hip on the right hip.

[0091] Alternatively, a single trial femoral head could be used to avoid the increase in inventory and instrumentation and have multiple bands, with a first band being used to assess acetabular cup orientation for the right hip and a second band being used to assess acetabular cup orientation for the left hip. However, this would make the surface of the trial head more visually complex and might require the surgeon to check or confirm which color band to use as a visual reference for the left or right hip. Moreover, the color bands may need to overlap and therefore be confused with each other. Additionally, if visibility is limited, for example due to the presence of other instruments and / or small incisions and / or the presence of blood or other body fluids or materials, it may be difficult to distinguish between the different color bands in the surgical site. Therefore, a simpler visual indication that could be used to assess cup placement for both the left and right hips might be beneficial.

[0092] Figure 14 A perspective view of a trial device 600 according to the present invention is shown, and includes a trial femoral neck 612 and a trial femoral head 614. The trial femoral neck 612 has a neck axis 616 extending along its longitudinal axis. The trial femoral neck 612 has a circular peg 652 extending from its lower surface and a closed cylindrical hole 654 extending from its lower surface, which can cooperate with corresponding corresponding concave and convex features on the upper surface of the drill 410 to releasably attach the trial neck to the drill during use. The upper lateral side 656 of the trial neck carries a marking in the form of a line 658 that extends along the middle of the neck width and parallel to the neck axis 616. The line 658 provides a visible reference that can be used to check the rotational position of the trial head 614 during use.

[0093] The trial neck 612 has a tapered portion 660 toward the free end. The sidewall of the tapered portion has a groove 662 extending around the neck axis 616 therein, and a C-ring or C-clamp 564 is retained in the groove 662. The C-ring can be made of any suitable compliant material (such as rubber, silicone or metal). When the compliance of the material is lower (such as metal), it is preferred to use a C-ring to help allow the C-ring to compress. The C-clamp interacts between the tapered portion and the corresponding groove extending around the inner wall of the trial head that defines the cavity 670. The C-clamp and the groove provide a retaining mechanism by which the trial femoral head can be releasably attached to the trial neck.

[0094] In other embodiments, the retaining mechanism may be provided in the form of a friction fit. For example, an O-ring of a suitable compliant material (such as rubber or silicone or the like) may be provided in the groove 662 of the tapered portion so as to interfere with a corresponding portion of the inner wall of the trial head defining the cavity 670.

[0095] The tapered portion 660 has a Figure 15 The complex shape is best shown, which shows an end view of the trial neck along the trial neck axis 616.

[0096] The trial femoral head 614 has a generally truncated spherical shape and has a hole 670 extending along a trial head axis 672 which passes through the stem of the trial femoral head, through the center of the spherical head and generally perpendicular to the plane of the lower truncated portion defined by the circular edge 674. Figure 14 The outer surface of the trial femoral head also includes first 676 and second 678 recesses or depressions to increase the user's grip when manipulating the trial head and are located on approximately the same side of the trial femoral head. These provide gripping elements to facilitate removal of the trial femoral head from the trial femoral neck during use.

[0097] The outer surface of the trial femoral head includes a single marking 618 in the form of a band that is a different color from the rest of the outer surface. The band 618 extends around the equator of the spherical head. The band 618 is tilted or inclined relative to the trial head axis 672 in that the plane of the band 618 is not perpendicular to the trial head axis 672. Furthermore, the band has an angular position that is rotated about the trial head axis 672. The values ​​of the angular position of the rotation and tilt of the band are selected to correspond to target values ​​for anteversion and tilt of the acetabular cup. For example, if the target values ​​for anteversion and tilt are 20° and 40°, respectively, the band will be tilted away from being parallel to the plane of the edge 674 at an angle of approximately 31° and form an acute angle of 59° with the trial head axis 672. The band 618 has a width of approximately 3.5 mm. The lowest point of the band is approximately midway between the "L" and "R" markings, as shown in FIG. Figure 15 , and thus forms an angle of approximately 72° relative to the "R" mark about the trial head axis 672. Trial heads of various sizes may be provided, for example having diameters of approximately 28 mm, 32 mm, and 36 mm, although other sizes may be used for other embodiments.

[0098] Likewise Figure 15 6, which shows a view of the underside of the trial femoral head along the trial femoral head axis 672, the inner wall of the trial head defines a cavity 670. The inner wall has an outer portion 681 and an inner portion, the outer portion defining the outer portion of the circular cavity and the inner portion defining the inner portion of the non-circular cavity. The outer portion 681 of the inner wall has a simple curved circular form.

[0099] The inner portion of the inner wall has a plurality of different sections and includes straight and curved sections. Specifically, the inner wall has a first curved section 680, a second curved section 682, a first straight section 684, and a second straight section 686. The first curved section 680 and the second curved section 682 are on opposite sides of the cavity, and the first straight section 684 and the second straight section 686 are on opposite sides of the cavity 670. The first curved section 680 extends at a greater angle than the second curved section 682, and therefore, the first straight section 684 and the second straight section 686 are not parallel.

[0100] The test femoral head also includes "R" 710 and a short line 712, which provide a mark for providing a rotational position reference for the test femoral head when used to test the right hip joint, i.e., the "right mark". An "R" and a short line mark are set adjacent to the edge 674 of the test femoral head at a first angular position. The test femoral head also includes "L" 714 and another short line 716, which provide a mark for providing a rotational position reference for the test femoral head when used to test the left joint, i.e., the "left mark". An "L" and a short line mark are set adjacent to the edge 674 of the test femoral head at a second angular position. The obtuse angle around the edge 674 between the left and right marks in the clockwise direction is approximately 216 °, and therefore the acute angle in the counterclockwise direction is approximately 144 °.

[0101] Similarly, the taper at the free end 660 of the trial neck has an outer portion 690 and an inner portion 692. The outer portion of the taper wall has a curved, slightly tapering circular wall sized to fit tightly within the outer portion of the trial head cavity.

[0102] The inner portion of the tapered wall defines an inner portion 692 of the tapered portion 660 and has a plurality of distinct sections, including straight and curved sections. Specifically, the inner tapered wall has a first curved section 694, a second curved section 696, a first straight section 698, a second 700 straight section, and a third straight section 702. The first curved section 694 and the second curved section 696 are located on opposite, generally upper and lower sides of the trial neck, and the first straight section 698 is located on the generally rear side of the trial neck, generally opposite the second straight section 700 and the third straight section 702, which are located on the generally front side of the trial neck. The second and third straight sections intersect to define an apex 704.

[0103] Figure 15 The rotational position of the test head 614 in corresponds to that also in Figure 14The rotational position shown, wherein when the tapered portion 660 is fully inserted into the cavity 670, will result in the "R" and dash mark being aligned with the line 658 on the upper surface 656 of the trial neck. In this right hip joint configuration, the trial head cavity straight wall portion 684 is adjacent to the tapered straight wall portion 698, and the trial head cavity straight wall portion 686 is adjacent to the tapered straight wall portion 700, thereby keying the rotation angle of the trial femoral head about the trial neck axis 616. The circular C-ring 664 forms a friction fit with the outer circular portion of the trial head cavity 670. In this first right hip configuration, the trial head and trial neck assembly can be used to evaluate the orientation of the acetabular cup of the right hip joint in a manner similar to that described in reference above. Figure 12 and Figure 13 The method was similar to that described above, but with target acetabular cup anteversion and inclination of 20° and 40°, respectively, and femoral neck anteversion of 15°, with the hip joint in a neutral position.

[0104] Figure 16 Shown with Figure 15 6, except that the trial femoral head has been rotated 144° clockwise about the trial head axis 672, or equivalently 216° counterclockwise, as shown. Figure 14 As shown by the curved double-headed arrow 720 in FIG.

[0105] Figure 16 The rotational position of the trial head 614 in is such that when the tapered portion 660 is fully engaged in the cavity 670, this will cause the "L" 714 and short line 716 markings to align with the line 658 on the upper surface 656 of the trial neck. In this left hip joint configuration, the trial head cavity straight wall portion 586 is adjacent to the tapered straight wall portion 598, and the trial head cavity straight wall portion 684 is adjacent to the tapered straight wall portion 702, thereby keying the rotation angle of the trial femoral head about the trial neck axis 616. Moreover, the circular C-ring 664 forms a friction fit with the outer circular portion of the trial head cavity. In this second left hip configuration, the trial head and trial neck assembly can be used to evaluate the orientation of the acetabular cup of the left hip joint in a manner similar to that of the above reference. Figure 12 and Figure 13 The method was similar to that described above, but with target acetabular cup anteversion and inclination of 20° and 40°, respectively, and femoral neck anteversion of 15°, with the hip joint in a neutral position.

[0106] Thus, the same trial head 614 and trial neck 612 may be used to trial one or both of the right and / or left hips, with a simple visual indication on the trial head surface of the target orientation of the acetabular cup.

[0107] Figure 17 Shows that when Figure 15The right hip trial assembly 750 is assembled with the trial head 614 and trial neck 612 mounted on the drill 410, and the acetabular cup 752 optimally positioned relative to the transverse plane 754, sagittal plane 756, and coronal plane 758 of the patient's pelvis, with the trial hip joint in a neutral position. Figure 17 As shown, the cup 752 is tilted at an angle 760 of 40° relative to the transverse plane 754 and at an angle 762 of 20° relative to the coronal plane 758. The body of the drill 410 is not coplanar with the coronal plane 758, but rather the trial neck axis is angled 15° subtending the coronal plane, corresponding to a neck axis angle of 15° relative to the femoral anteversion. The coincidence of the color band 618 with the plane of the mouth of the liner 753 of the cup 752 provides a visual indication that the cup has been positioned in the target orientation of 20° cup anteversion and 40° cup tilt. Furthermore, the combined anteversion of the femoral component and cup portion of the hip is approximately 35°.

[0108] As mentioned above, the inclination of the ribbon 618 relative to the axis of the trial head is approximately 30°. This provides a trial head suitable for target cup positioning with a 40° inclination and 20° anteversion relative to the pelvis, and a combined anteversion of 35° for radiographic angles. This facilitates clinical assessment of cup position by X-ray or other radiographic imaging of the APP. It will be noted that in Figure 17 In the 3D image, the stem and cup anteversion are not in the same plane, and therefore the combined anteversion is not a true 35°. However, in the anatomical coordinate system, the stem and cup anteversion are equivalent.

[0109] It will be appreciated that for other target inclination angles of the acetabular cup, different angular spacings between the left and right markers and corresponding changes in the angular positions of the trial head linear walls 684 and 686, and the trial neck linear walls 700 and 702, will be made. Generally speaking, as the target inclination angle of the acetabular cup decreases from 45°, the angular spacing between the left and right markers in the clockwise direction will decrease from 180° and thus increase from 180° in the counterclockwise direction. The inclination angle of the band 618, the angular position of the band 618 about the trial head axis, and the angular spacing between the "L" and "R" markings will also vary accordingly.

[0110] Figure 18 shows an anterior-posterior view of yet another embodiment of a trial assembly in a right hip configuration 800, and Figure 19 A front-to-back view of yet another embodiment of a trial assembly is shown in a left-hand hip configuration 850. The trial assembly includes a trial head 814 and a trial neck 812 similar to those described above. However, the trial head 814 and trial neck 812 include different markings that are positioned differently to facilitate easy assembly of the trial head 814 and trial neck 812 in the right-hand 800 and left-hand 850 hip configurations.

[0111] The test head 814 includes a first marking 816 and a second marking 818, which are visually distinct and, when in use, are located near the edge of the test head and generally on the front side of the test head. As shown, the first marking 816 is in the form of a white triangle and the second marking 818 is in the form of a black triangle. In other embodiments, the test head markings 816, 818 can have other shapes and colors, as long as they are visually distinguishable from each other. The test head markings 816, 818 are angularly separated by approximately 36 degrees.

[0112] The trial neck 812 includes a first marking 820 and a second marking 822 that are visually distinct and located on opposite sides of the trial neck 812, corresponding to the front of the right hip 800 and the front of the left hip 850, respectively. The trial neck markings 820, 822 are positioned along the neck so as to be adjacent to the edge of the trial head 814 when assembled. As shown, the first trial neck marking 820 is in the form of a white triangle and the second trial neck 822 is in the form of a black triangle. In other embodiments, the trial neck markings 820, 822 may have other shapes and colors, as long as they are visually distinguishable from each other. However, the first trial head marking 816 and the first trial neck marking 820 are visually related, similar, or identical, and the second trial head marking 818 and the second trial neck marking 822 are visually related, similar, or identical.

[0113] Therefore, during use, if Figure 18 As shown, with the trial neck arranged for a right hip, the white triangle 820 on the front visible face of the trial neck is visible to the surgeon and can be used to assist in angular alignment of the trial head 814 via its white triangle 816 and also provide visual feedback to the surgeon that the trial head 814 has been correctly assembled on the trial neck for the right hip when the markings 816, 820 match. Similarly, as Figure 19 As shown, with the trial neck arranged for a left-hand hip, the black triangle 822 on the front visible face of the trial neck is visible to the surgeon and can be used to assist in angularly aligning the trial head 814 via its black triangle 818, and also to provide visual feedback to the surgeon when the markings 818, 822 match up that the trial head 814 has been correctly assembled on the trial neck 812 for the left-hand hip.

[0114] In addition to being able to use the same trial head and back neck for the left hip and / or the right hip, the trial neck 612, 812 and the trial heads 614, 814 also have many other advantages. For example, because the trial cone has a circular inner portion and the straight wall portions 698, 700, 702 are effectively cut away, a conventional trial femoral head with a simple reduced circular cavity can also be used with the trial neck 612. Therefore, there is no need to provide an additional trial neck for a conventional trial femoral head. By way of further example, because the trial head has straight wall portions 684, 686 in the inner portion of the trial head cone cavity 670, a conventional trial neck with a conventional cone cannot be properly used because the trial head 614 will not fully sit on the conventional neck cone. Therefore, the risk of the surgeon accidentally using the trial femoral head 614, 814 with a conventional trial neck is reduced.

[0115] The use of trial neck 612,812 and trial femoral head 614,814 is roughly as follows.After preparing the femur, and when final drill or reamer still remains in place, remove reamer or drill handle, and be attached to drill or reamer by trial neck 612, wherein upper surface 656 is along generally upward direction.After preparing acetabular cavity, acetabular cup and optional any liner are inserted into acetabular cavity with orientation having anteversion angle and inclination angle relative to patient's pelvis.Then select trial femoral head 614,814 with the diameter corresponding to the size of acetabular cup or liner.Determine whether the hip currently being replaced is left hip or right hip.

[0116] The trial femoral head 614 is then rotated to align the appropriate right markings 710, 712 or left markings 714, 716 with the markings 658 on the trial neck, and the trial femoral head 614 is placed on the trial neck 616 until the trial femoral head is fully seated on the tapered portion 660 and held in place by the friction fit provided by the C-ring 664. Optionally, the trial femoral head 814 is then rotated to align the appropriate right markings 816 or left markings 818 with the matching markings 820 or 822 on the front face of the trial neck 812, and the trial femoral head 814 is placed on the trial neck 816 until the trial femoral head is fully seated on the tapered portion 660 and held in place by the friction fit provided by the C-ring 664.

[0117] The trial joint is then reduced and the hip positioned as described above and as Figure 17618 is a graph showing the neutral position of the acetabular cup. The surgeon can then compare the curve of the visual assessment acetabular cup by the orientation of the mouth plane of the acetabular cup or liner with the black band 618 on the trial femoral head surface. If the black band 618 is parallel to the mouth of the cup or liner, this indicates that the acetabular cup has been placed in the target orientation, which in this example is an anteversion angle and an inclination angle of 20 ° and 40 °, respectively. The surgeon can simply use this information as real-time feedback, or can take further action, such as repositioning the acetabular cup and / or femoral component (if possible) to try and improve possible surgical results. Like this, the remainder of the surgical procedure is generally conventional.

[0118] If a double hip replacement is to be performed, then at the same stage of the procedure on the other hip, the same trial neck 612, 812 and trial head 614, 814 may be used, but in a second configuration with the trial head rotated 216° or 144° about the trial neck axis.

[0119] Therefore, by controlling the angular rotation of the trial head 614, 814 about the trial neck axis 616, i.e., by rotating the head to a specific angle other than 180°, the correct correction can be made when flipping between the right hip and the left hip. Figure 13 The error shown. Thus, a single trial head 614, 814 with a single strap 618 can be used for cup inclination angles other than 45° and / or neck angle configurations other than 135°. In the described embodiment, the trial component is configured for a 135° neck angle, with target cup radiographic inclination and anteversion values ​​of 40° and 20°, respectively, and an assumed natural femoral anteversion of 15°. In this case, the trial head rotation angle is a clockwise rotation of approximately 216° from right to left. In other embodiments, the trial head rotation angle will vary depending on the values ​​of the neck angle and / or cup inclination and / or cup anteversion and / or natural femoral anteversion.

[0120] In the described embodiments of the trial head and trial neck, the angular position and rotation angle are controlled by a series of planes on both the inner portion of the cavity taper geometry of the trial head cavity and the upper portion of the neck taper geometry. However, structures other than planes can be used to implement the keying behavior described herein. The design makes it possible for the trial head 614, 814 to fully engage with the trial neck 612, 812 only when rotated to the right hip configuration or the left hip configuration. In one embodiment, these two configurations are indicated by the "R" and "L" letters on the trial head surface, which can be aligned with the mark 658 on the upper lateral side 656 of the trial neck to help the surgeon correctly assemble the femoral trial. In another embodiment, these two configurations are represented by white and black triangles on the trial head surface, which can be aligned with the corresponding triangles in the white and black triangles on the front face of the trial neck to help the surgeon correctly assemble the femoral trial.

[0121] For alternative cup tilt and / or stem angle configurations, the planar geometry is simply modified to provide the appropriate rotation angles for right-hand and left-hand hip configuration angles.

[0122] Additionally, the described method facilitates the use of a conventional trial femoral head with the trial neck 612, 812, and also prevents the use of the trial head 614, 814 with a conventional trial neck.

[0123] Various changes, modifications, substitutions, and adaptations of the described embodiments will be apparent to those skilled in the art from the above description.

Claims

1. A femoral trial kit for use in evaluating acetabular cup orientation during left and right hip surgery, the femoral trial kit comprising: a trial femoral head having an inner wall defining a cavity extending along a head axis and a visual alignment guide on an outer surface of the trial femoral head, the visual alignment guide comprising only a single marking, wherein the inner wall of the trial femoral head has a first curved portion, a second curved portion, a first straight portion, and a second straight portion, the first curved portion and the second curved portion of the trial femoral head are on opposite sides of the cavity, the first straight portion and the second straight portion of the trial femoral head are on opposite sides of the cavity, the first curved portion of the trial femoral head extends at a greater angle than the second curved portion of the trial femoral head, and the first straight portion and the second straight portion of the trial femoral head are not parallel; as well as a trial femoral neck having a tapered portion at a free end, the tapered portion being receivable within the cavity, wherein a wall of the tapered portion of the trial femoral neck has a first curved portion, a second curved portion, a first straight portion, a second straight portion, and a third straight portion, the first curved portion and the second curved portion of the trial femoral neck being on opposite sides of the trial femoral neck, the first straight portion of the trial femoral neck being on an opposite side from the second and third straight portions of the trial femoral neck, and the second and third straight portions of the trial femoral neck intersecting to define an apex, wherein the first and second straight portions of the trial femoral head and the first, second and third straight portions of the trial femoral neck are anti-rotation features, and the first, second and third straight portions of the trial femoral neck are inclined, wherein the trial femoral head is attachable to the trial femoral neck in a first angular configuration corresponding to a right hip joint, in which the first straight portion of the trial femoral head engages the first straight portion of the trial femoral neck and the second straight portion of the trial femoral head engages the second straight portion of the trial femoral neck, and The trial femoral head is capable of being attached to the trial femoral neck in a second angular configuration corresponding to the left hip joint, in which the first straight line portion of the trial femoral head is engaged with the third straight line portion of the trial femoral neck, and the second straight line portion of the trial femoral head is engaged with the first straight line portion of the trial femoral neck.

2. The femur trial kit of claim 1, wherein the single marking is in the form of a band having a first color, and wherein the surface of the trial head has a second color, and wherein the first color and the second color are different colors.

3. The femoral trial kit of claim 1 or 2, wherein the visual alignment guide has a width of at least 3 mm.

4. A femoral trial kit according to claim 1 or 2, wherein the trial femoral neck includes a neck marker, and the trial femoral head includes a first head marker and a second head marker on the outer surface of the trial femoral head, and wherein the first head marker and the second head marker are respectively positioned around the head axis so that when the trial femoral head is attached to the trial femoral neck in the first angular configuration, the second head marker is aligned with the neck marker, and when the trial femoral head is attached to the trial femoral neck in the second angular configuration, the first head marker is aligned with the neck marker.

5. The femoral trial kit of claim 4, wherein the neck marking is located on the superior lateral surface of the trial femoral neck.

6. A femoral trial kit according to claim 1 or 2, wherein the trial femoral neck includes a first neck marker and a second neck marker on opposite sides of the trial femoral neck, and the trial femoral head includes a first head marker and a second head marker on the outer surface of the trial femoral head, and wherein the first head marker and the second head marker are respectively positioned around the head axis so that when the trial femoral head is attached to the trial femoral neck in the first angular configuration, the second head marker is aligned with the second neck marker, and when the trial femoral head is attached to the trial femoral neck in the second angular configuration, the first head marker is aligned with the first neck marker.

7. The femoral trial kit of claim 6, wherein the first neck marking and the second neck marking are visually distinguishable, the first head marking and the second head marking are visually distinguishable, the first neck marking and the first head marking are similar or identical, and the second neck marking and the second head marking are similar or identical. 8 . The femur trial kit according to claim 7 , wherein the first neck marker, the second neck marker, the first head marker, and the second head marker are all of the same shape.

9. The femur trial kit according to claim 7 or 8, wherein the first neck mark and the first head mark are the same first color, the second neck mark and the second head mark are the same second color, and wherein the first color and the second color are different colors.

10. A femoral trial kit according to claim 1 or 2, wherein the tapered portion has a free end and an outer portion, and wherein the anti-rotation feature or each anti-rotation feature is provided at the free end and the outer portion has a cylindrical form, and wherein the inner wall defining the cavity has an outer portion and an inner portion, and wherein the inner portion provides the anti-rotation feature or each anti-rotation feature and the outer portion has a cylindrical form.

11. A femoral trial kit according to claim 1 or 2, further comprising a retaining mechanism arranged to releasably attach the trial femoral head to the tapered portion.

12. The femoral trial kit of claim 11, wherein the retaining mechanism is configured to provide a friction fit between the tapered portion and the cavity.

13. The femoral trial kit of claim 11, wherein the retaining mechanism comprises a clamp.

14. The femoral trial kit of claim 1 or 2, wherein each anti-rotation feature is a flat surface.

15. The femoral trial kit according to claim 1 or 2, wherein the trial femoral head comprises a first gripping feature and / or a second gripping feature in the outer surface.

16. The femoral trial kit of claim 15, wherein the first gripping feature and / or the second gripping feature are in the form of a recess.

17. A femoral trial kit according to claim 1 or 2, wherein when the trial femoral head is mounted on a trial neck on a stem component within the patient's femur, with the trial hip joint reduced and in a neutral position, the visual alignment guide is positioned on the outer surface of the trial femoral head to correspond to an inclination angle of less than 45° of the acetabular cup in the patient's pelvis.

18. The femoral trial kit of claim 1 or 2, wherein the anti-rotation feature is configured such that the trial femoral head is rotated less than 180° in a first configuration compared to a second configuration.

19. The femoral trial kit of claim 1 or 2, further comprising a femoral component to which the base of the trial femoral neck is releasably attached, and wherein the neck angle of the trial femoral neck when attached to the femoral component is greater than or less than 135°.

20. A femoral trial assembly comprising components of the femoral trial kit according to any one of claims 1 to 19.

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