How to plan a hip arthroplasty

Abstract

A method of planning hip arthroplasty for a subject is described, the method comprising: receiving at least one image of the subject while the subject is in an upright position, the image being obtained substantially from a sagittal plane; calculating at least one spinopelvic metric from the at least one image; and calculating a hip arthroplasty risk profile for the subject based on the calculated spinopelvic metric. A method of determining an acetabular cup orientation angle range for an acetabular cup implant in the subject is further described, and a computer-implemented method of determining an orientation angle range for an acetabular cup implant in the subject is further described.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a method for planning a hip arthroplasty.In another example, the present invention relates to a method for determining the range of angular orientation of an acetabular cup. [Background technology]

[0002] Hip arthroplasty is a surgical procedure in which a subject is implanted with a prosthesis to replace the hip joint. The prosthesis typically mimics the natural ball-and-socket hip joint with the femoral head rotating within an acetabular cup. Summary of the Invention [Problem to be solved by the invention]

[0003] In some cases, subjects experience hip pain, dislocation, or poor function after surgery, which can lead to ongoing problems and possibly require revision of the surgery.

[0004] A surgeon may strive to place the acetabular cup within a range of angles generally considered to produce acceptable results, but even within this range, the subject may experience problems such as pain or dislocation.

[0005] According to one example, a method of planning a hip arthroplasty for a subject is provided, comprising: receiving at least one image of the subject obtained from a substantially sagittal plane while the subject is in a standing position; calculating at least one spinopelvic metric from the at least one image; calculating a hip arthroplasty risk profile for the subject based on the calculated spinopelvic metrics; Includes:

[0006] According to another example, there is provided a method for determining an acetabular cup orientation angle range for an acetabular cup implant in a subject, the method comprising: receiving at least one image of the subject obtained from a substantially sagittal plane while the subject is in a standing position; before Twist receiving an angle range; receiving a tilt angle range; Calculated spinopelvic metrics, received before Twist determining an acetabular cup orientation angle range for the subject's acetabular cup implant based on the angle range and the received tilt angle range; Includes:

[0007] According to another example, a computer-implemented method for determining an orientation angle range for an acetabular cup implant in a subject is provided, comprising: before Twist receiving an angle range; receiving a tilt angle range; receiving the subject's spinopelvic metrics; and determining an acetabular cup orientation angle range for the subject's acetabular cup implant.

[0008] Embodiments may be implemented according to any one of the dependent claims 2-14, 16-23 or 24-27.

[0009] It should be understood that the terms "comprise," "comprises," and "comprising" can, in various jurisdictions, be of either an exclusive or an inclusive meaning. For purposes of this specification, unless expressly stated otherwise, these terms are intended to have an inclusive meaning. That is, these terms are to be taken to mean including the listed components, both by direct reference and when used to reference other unspecified components or elements.

[0010] No reference in this specification to any document that forms part of the prior art or common general knowledge that may be formally combined with another document is admitted.

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the general description of the invention given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. [Brief explanation of the drawings]

[0012]

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[0013] The methods described herein utilize patient-specific information to assess risk and determine optimal acetabular cup orientation for a particular patient. The inventors have found that patient-specific spinopelvic metrics are associated with the likelihood that an arthroplasty recipient will suffer a future adverse outcome, such as dislocation. The inventors have also found that patient-specific spinopelvic metrics may impose additional constraints on the optimal placement orientation for the acetabular cup, in addition to universal (i.e., non-patient-specific) orientation restrictions that a surgeon may operate under differently. This additional patient-specific constraint may indicate a narrower range in particularly suitable acetabular cup orientations for a given patient. The size of this narrower range may be another indicator of risk.

[0014] Spinopelvic metrics may be obtained from one or more sagittal plane images of the patient in an upright position. The term "sagittal plane" and the description of images taken in the sagittal plane are not intended to require precise adherence to a nominal sagittal plane orientation or position in the subject. This is rarely achievable due to skeletal differences, inaccuracies in the subject's position during imaging, and other factors. In fact, this terminology generally refers to images taken from the side of the patient, and the image plane is generally aligned with a plane through the subject's anterior and posterior sides.

[0015] By assessing patient risk at an individual level, patients can be stratified into risk levels. This allows higher-risk patients to receive more comprehensive pre-operative imaging and analysis in preparation for surgery, while lower-risk patients do not require such extensive pre-operative procedures. This can improve efficiency and outcomes by reducing overall costs and directing resources to patients most in need.

[0016] By taking into account patient-specific constraints in the placement orientation of the acetabular cup, the placement angle can be better tailored to the individual patient, which may result in improved surgical outcomes.

[0017] FIG. 1 illustrates an exemplary method 10 for assessing risk associated with a prospective hip arthroplasty. The method 10 includes receiving an image of a subject. The image is taken in a sagittal plane of the subject 11. The image may be one of a variety of suitable types of images. The image may include a depiction of the subject's skeletal structures, such as the spine, pelvis, and femur. In one example, the image is an X-ray image. Alternatively, the image may be obtained by other forms of radioimaging, such as gamma radioimaging, or by ultrasound imaging or other suitable techniques capable of imaging bones. In other examples, other imaging techniques that do not directly image bones may be used if the orientation and / or position of the bones can be inferred from the image.

[0018] Based on the images, one or more spinopelvic metrics are then calculated 12. Spinopelvic metrics relate to geometric characteristics of the skeletal structure, including the spine, pelvis, and femur. Spinopelvic metrics can be indicative of a subject's kinematics and balance. These metrics can include, for example, lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), acetabular anterior tilt (AI), and pelvic-femoral angle (PFA), as set out in the table below.

[0019] [Table 1]

[0020] These metrics are illustrated in Figures 4 and 5. Figure 4 is an X-ray image of a subject in a standing position taken in the sagittal plane. Figure 5 is an X-ray image of a subject in a sitting position taken in the sagittal plane. These metrics are constructed based on the placement of the spine 41, pelvis 42, and femur 43 in each position.

[0021] The metrics can be measured based on anatomical landmarks. These landmarks can be identified based on user input. For example, a user can review an image on a computing device and place markers on relevant landmarks. Alternatively, these landmarks can be automatically located using computer software. The computer software can include object recognition and labeling algorithms to identify landmarks and calculate metrics. The computer software can be an artificial intelligence system. In one example, the artificial intelligence system is based on a machine learning model. The machine learning model is trained on a dataset related to a particular surgeon to learn the surgeon's preferences or techniques.

[0022] Combinations of these metrics can be used to construct other metrics for use in the risk assessment method 10. For example, sagittal balance is defined as PI-LL. As shown in FIG. 11, patients who experienced anterior or posterior dislocation after arthroplasty tended to have higher PI-LL values ​​than patients who did not experience dislocation. In this graph, bar 101 indicates the frequency of dislocation (or lack of dislocation) as a function of PI-LL. Furthermore, the same metric can be measured in different postures. A combination of the metric values ​​in different postures can be used as a metric for risk assessment. For example, the difference in LL values ​​(ΔLL) between standing and sitting postures can be useful for determining stability or instability.

[0023] The subject's risk profile for hip arthroplasty is then calculated from the metric. 13 As mentioned above, the metrics can be used individually or in combination to determine the risk profile. The risk profile may take on a range of values ​​representing the significance of the risk, or may result in a distinct risk classification, such as "low risk" or "high risk." The risk profile itself may be used as a marker that a subject is at particular risk for poor surgical outcome. In one example, an instability metric is used to classify patients as high or low risk. The instability metric can be sagittal balance (PI-LL). In one example, the risk classification is based on subjects having PI-LL values ​​significantly greater than 0°, greater than about 2°, or greater than about 10°. Subjects with PI-LL in these ranges can be classified as high risk. These subjects may be at increased risk of suffering dislocation after hip arthroplasty. Another instability metric that can be used is ΔLL. Risk classification can be based on subjects having ΔLL values ​​significantly below 40° or below approximately 29°. Subjects with ΔLL in these ranges can be classified as high risk. Another metric that can be used is PFA. Very large or small PFA values ​​can indicate risk due to difficulty in placing the acetabular cup in the preferred orientation. For example, if a postoperative combined sagittal index (CSI) is required to be within a certain range, it may be difficult to place the acetabular cup in an orientation that would result in a postoperative CSI within the required range when the PFA is very large or very small. CSI is described in more detail with reference to FIG. 2.

[0024] Alternatively or additionally, metrics can be Twist The metrics can be used in combination with other data, such as angle and inclination, to determine a risk profile. The metrics can be used as input to determine specific arthroplasty parameters, such as a preferred acetabular cup orientation angle range. This is described in more detail with reference to FIG. 2.

[0025] 2 presents a method for determining the orientation angle range of an acetabular cup implant. Method 20 may be used by itself or in combination with the method of FIG.

[0026] Before describing the method of FIG. 2 in detail, the relevant angles will be explained with reference to FIGS.

[0027] FIG. 6 is an x-ray image of a subject with a prosthetic hip joint implant 64. The image is in a coronal plane (i.e., taken from the front or back of the subject). The implant 64 includes a femoral head 63 and an acetabular cup 61, which together form a ball-and-socket joint that mimics the natural hip joint. The acetabular cup 61 has a circular rim 62. The rim 62 is shown as oval in the coronal image of FIG. 6 because it is angled relative to the coronal plane in this example. The base of the implant 64 is placed on the subject's femur 43, and the acetabular cup 61 is placed on the subject's pelvis 42. Two commonly used acetabular cup angles are radiographic tilt and radiographic anterior. Twist , is shown. The inclination of the cup, when projected onto the coronal plane, is the angle between the plane of the rim 62 and the subject's transverse plane (horizontal 66 in FIG. 6). Similarly, the inclination of the cup can be defined as the angle between the subject's longitudinal axis (vertical in FIG. 6) and the acetabular axis, when projected onto the coronal plane. The acetabular axis is the axis that passes through the center of the acetabular cup and is perpendicular to the plane of the rim 62. Anterior to the cup Twist is the angle between the plane of the circular rim and a line perpendicular to the coronal plane. Twist can be defined as the angle between the acetabular axis and the coronal plane. This is calculated from the eccentricity measured in an image of the rim, based on the recognition that the rim is an actual circle, e.g., based on the relative sizes of the major and minor axes in an elliptical image of the rim. In this example, the inclination of the cup is 40.5°, and the anterior aspect of the cup is Twist is 26°.

[0028] FIG. 7 is an X-ray image of the subject of FIG. 6 taken in the sagittal plane. This image shows the anterior tilt of the cup, which is the angle between horizontal line 72 and straight line 71. Straight line 71 is placed along or parallel to the major axis (i.e., the major axis) of the image of rim 62 in the sagittal plane. Similarly, the anterior tilt of the cup Twist can be defined as the angle between the subject's longitudinal axis (vertical in Figure 7) and the acetabular axis when projected onto the sagittal plane. In this example, the anterior tilt is 39.6°.

[0029] When planning a hip replacement, the surgeon usually Twist Consider the coronal and inclination angles of the anterior posterior vertex. Specifically, certain ranges of these angles are generally considered "safe" and have a low risk of adverse outcomes (e.g., dislocation). However, the surgeon should Twist Some judgment or personal preference may also be exercised for specific ranges in angle and inclination. However, some patients may still experience adverse outcomes due to particular configurations in the patient's skeletal structure when the acetabular cup is placed within those angle ranges. One measure of a patient's likelihood of suffering an adverse outcome is the combined sagittal index (CSI), which is defined as the sum of the PFA and the anterior inclination of the acetabular cup, i.e., CSI = PFA + AI(cup). The inventors have identified several anterior inclinations that can actually be considered "safe" for a given patient with a particular PFA value. Twist We found that values ​​of and slope result in CSI values ​​outside the optimal range. Twist This is because the slope and the angle are related to AI. In particular, the inventors have determined that these are related as follows:

[0030]

number

[0031] This relationship is shown in the graphs of Figures 8 and 9. In Figure 8, line 81 indicates the Twist 9, line 91 represents a constant value slope curve. These are plotted on the X and Y axes as tilt and forward tilt, respectively. Twist and forward tilt are plotted, respectively.

[0032] Figure 10 shows the frequency of posterior and anterior hip dislocations after arthroplasty as a function of standing CSI. Bar 101 represents the number of patients who experienced (or did not experience) each type of dislocation. As can be seen, patients who experienced anterior dislocations tended to have higher CSI values ​​than patients who did not experience dislocations, and patients who experienced posterior dislocations tended to have lower CSI values ​​than patients who did not experience dislocations.

[0033] FIG. 12 shows the patient's cup tilt and the front of the cup. Twist Specific patient values ​​are represented by dots 121 and shaded according to their CSI value. Also shown are the overall accepted tilt angle and Twist The box-shaped outline of the area 122 corresponds to the "safe" value of the angle. The area 122 is bounded by a lower limit 124a and an upper limit 124b of the slope, and Twist As noted, there are some patients within region 122 who have CSI values ​​less than 200° or greater than 245°.

[0034] In the method 20 of Figure 2, an image in the sagittal plane of a subject in a standing position is received 21. The image in the sagittal plane may be as described with reference to Figure 1.

[0035] Based on the images, one or more spinopelvic metrics are calculated 22. This metric can indicate the subject's expected instability after surgery. One suitable metric for method 20 is PFA, which can be particularly useful for imposing constraints on the optimal acetabular cup placement angle.

[0036] Method 20 Twist The method also includes receiving a range of angles. 23 These angles may be predetermined or based on the surgeon's judgment or preference and may include determining the angles previously considered suitable for placing the acetabular cup. Twist The angle range may be expressed. In one example, the range may be centered around approximately 20°. In one example, a range of 20°±10° (i.e., 10-30°) is accepted.

[0037] The method also includes receiving a tilt angle range. Twist When angles are used, they may be predetermined or based on the surgeon's judgment or preference. They represent a range of inclination angles considered suitable for placing the acetabular cup. In one example, this range may be approximately a median of around 40°. In one example, it may be in the range of 40° + 10° (i.e., 30-50°).

[0038] Spinopelvic metric, anterior Twist Based on the angle range and the inclination angle range, the orientation angle range of the acetabular cup is determined 25. In one example, the angle range of the acetabular cup is determined based on the angle range of the acetabular cup before receiving the TwistThe range and tilt range are angles at which the subject's CSI, when installed in the subject, falls within an acceptable CSI range. In one example, the acceptable CSI ranges are 200°±10° and 245°±10° in a standing posture. The acceptable CSI range may be established based on experimental data, computer simulation / modeling, or other research. The acceptable range may also be established based on the surgeon's skill level, preference, or judgment. The acceptable range may also be based on the level of risk acceptance or aversion. The subject's measured PFA can be used to determine a range of AI(cup) values ​​that lead to a CSI within the acceptable range. The determined acetabular cup orientation angle can be an angle consistent with the determined range of AI(cup) values ​​that lead to an acceptable CSI value. In particular, the AI ​​range may be selected based on the following formula: CSI = PFA + ΔPFA + AI (cup) Here, ΔPFA is the expected change in PFA after hip arthroplasty, which categorizes CSI as ranging from 200° ± 10° to 245° ± 10°. ΔPFA can be established clinically preoperatively, typically within the range of 2–10°. ΔPFA can also be given as a fixed value, such as 5°.

[0039] As can be seen from this relationship, the PFA value for a particular subject imposes a constraint on the optimal AI value. When determining the preferred angle range for the acetabular cup, the output angle should be determined based on this constraint, as well as the received Twist The angle may be an angle that satisfies the angle range and the tilt angle range.

[0040] Figures 13 and 14 show the nomograms for two different subjects, A (Figure 13) and B (Figure 14). These nomograms show the results of the pre- and post-treatment evaluations in a single plot. Twist , inclination, and anterior tilt, which are useful for determining the orientation angle of the preferred acetabular cup placement, and at the same time, Twist , tilt, and forward tilt constraints. Line 133 is a constant value slope curve. TwistThe tilt value is measured along the X axis and the forward tilt value is measured along the Y axis.

[0041] These figures show a shaded area 134 of tilt values, which corresponds to the range of tilt values ​​received. This range is between a lower limit 135a and an upper limit 135b. In this example, the range is 30-50°. The shaded area 131 represents the received front Twist This corresponds to the angle range. This range is between lower limit 132 and upper limit 132b. In this example, the range is 5 to 25°. In Figures 13 and 14, ranges 131 and 134 are the same for subjects A and B because they are not based on measurements of the subjects.

[0042] Also shown in FIG. 13 is a shaded region 136 corresponding to the range of anterior tilt (AI) values ​​determined for subject A. This range is determined based on the spinopelvic metrics of subject A, as described above. Range 136 is between lower limit 137a and upper limit 137b. In this example, the range is 0 to approximately 44°. Region 138 in FIG. 13 corresponds to the range of acetabular cup orientation angles that satisfy all constraints and are suitable for acetabular cup placement. This region 138 is formed for subject A by the overlap of regions 134, 131, and 136. Note that region 136 is subject-specific because it is based on the spinopelvic metrics of a particular subject. Point 139 corresponds to a particular combination of cup orientation angles within range 138 that may be considered suitable for acetabular cup placement without a high likelihood of failure. In the method of FIG. 2, the range of determined acetabulum values ​​may correspond to region 138 of subject A.

[0043] In FIG. 14 , region 141 corresponds to the range of determined anterior tilt values ​​for subject B. This region 141 is between lower limit 142a and upper limit 142b. In this example, the range for subject B is 15 to 40°. Region 143 corresponds to the range of acetabular cup orientation angles that satisfy all constraints and are suitable for acetabular cup placement. This region is formed by the overlap of regions 134, 131, and 141 for subject B. Note that this region is different from and smaller than region 138 in FIG. 13 . Point 144 corresponds to a specific combination of cup orientation angles suitable for acetabular cup placement for subject B.

[0044] In some cases, tilt and / or forward Twist The preferred angular ranges may be small based on the spinopelvic metrics of a particular subject. The size of any of these ranges may be used to characterize a subject's risk. For example, subjects with small ranges may be classified as higher risk than subjects without small ranges. In one example, the tilt or anterior tilt of the acetabular cup may be used to characterize the risk of a particular subject. Twist If either or both of the determined ranges are less than or equal to 10°, the subject is classified as high risk. In this example, if both ranges are greater than 10°, the subject may be classified as low risk. The size of the ranges used to classify risk may be varied depending on factors such as a particular surgeon's risk threshold or taking into account other risk factors for the subject. Risk characteristics may also be proportional to the size of the range, with multiple individual risk characteristics or a continuous scale risk characteristic.

[0045] Depending on the risk profile, patients may be recommended for accurate 3D planning in preparation for surgery. This may be recommended only for subjects characterized as high risk. This may involve generating a 3D model of the patient's hip bone from a CT or MRI scan. Alternatively, these may be reconstructed from coronal and sagittal X-ray data. During 3D planning, software may be used to generate a subject-specific anterior planar view.Twist and slope range are calculated based on the patient-specific Twist and tilt range; before acetabular cup and stem Twist combination; or before maximizing hip range of motion Twist If the user customizes the cup angle in the software, which may be calculated based on a further optimized combination of angle and tilt angle, the software can provide a warning when the angle exceeds any of the above ranges.

[0046] On the other hand, if the subject is characterized as low risk, standard 2D templating may be recommended.

[0047] FIG. 3 illustrates a computer-implemented method for determining an orientation angle range of an acetabular cup. In this method, a computing device Twist The computer device receives an angle range 31, which may be predetermined or based on the surgeon's judgment preference as described above. The computer device also receives an inclination angle range 32, which may also be predetermined or based on the surgeon's judgment or preference. The computer device also receives one or more spinopelvic metrics associated with the subject 33. Based on this information, the computer device determines an orientation range for the acetabular cup 34. This may be accomplished by the procedures detailed above.

[0048] The computing device may be any suitable computing device having one or more interfaces, memory, and processing circuitry for receiving and outputting information. In one example, the computing device is a mobile phone. The computer-implemented method may be performed by the computing device operating according to a set of instructions that constitute a computer program. The computer program may be in the form of an application on the mobile phone.

[0049] The computer program may include instructions for carrying out the procedures outlined above, in particular the methods described with reference to Figures 1 and 2.

[0050] 15 and 16 outline one exemplary method 150 from arthroplasty recommendation to 2D or 3D templating. First, it is determined that the patient requires a total hip arthroplasty 151. A coronal x-ray is taken 152, and the surgeon determines the coronal cup angle range 153. The coronal cup angle range is determined based on the specific anterior pos ... Twist The cup angles and metrics are passed to a dislocation risk classification step 160, which is shown in more detail in FIG. 16. If the subject is classified as low risk, 2D templating is performed 157. If the subject is classified as high risk, 3D templating is performed 158.

[0051] The risk classification 160 can be based on the procedure detailed above. In particular, the surgeon's coronal cup angle 153 and the subject's sagittal measurement 156 are used and cross-referenced using a nomogram 161 as detailed above. The acetabular cup angle safe zone is then determined 162 as the area that satisfies all constraints. The determined acetabular cup angle range (anterior Twist The size of each of the ranges (angle and inclination) is compared to a threshold, in this case 10°. If both ranges are greater than 10°, the subject is classified as low risk 164. If one or both ranges are less than 10°, the subject is classified as high risk 165. Other thresholds may be used, such as 20°, 15°, or 5°. Thresholds may be set based on experimental data, computer simulation / modeling, or other research. Thresholds may also be set based on the surgeon's skill level, preference, or judgment. Thresholds may also be based on the level of risk acceptance or aversion.

[0052] While the present invention has been illustrated by the description of its embodiments and those embodiments have been described in detail, it is not the applicant's intention to restrict the scope of the appended claims to such details or to impose any limitations thereon. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from these details without departing from the spirit or scope of applicant's general inventive concept.

Claims

1. A computer-implemented method for assessing risks associated with hip arthroplasty for a subject, comprising: receiving, by the computer, at least one image of the subject obtained from a sagittal plane while the subject is in a standing position; the computer calculates at least one spinopelvic metric from at least one of the images, the spinopelvic metric including at least a pelvic-femoral angle and an anterior tilt; and determining a hip arthroplasty risk classification for the subject by calculating a post-operative standing composite sagittal index from at least the pelvic-femoral angle and the anterior tilt based on the calculated at least one spinopelvic metric; The subject's risk classification for hip arthroplasty is high if the standing composite sagittal index after surgery is less than 190° or if the standing composite sagittal index after surgery is greater than 255°; A method for assessing the risks associated with hip arthroplasty for a subject.

2. receiving at least one image obtained from a sagittal plane while the subject is in a seated position; calculating at least one said spinopelvic metric from at least one said image; Including, 2. The method of claim 1, wherein the subject's risk classification for hip arthroplasty is further based on at least one image obtained from a sagittal plane when the subject is in an upright position and at least one image obtained from a sagittal plane when the subject is in a sitting position.

3. 3. The method of claim 1 or 2, further comprising indicating one or more orientations for an acetabular cup implant based on the calculated at least one spinopelvic metric, and determining the subject's risk classification for hip arthroplasty is further based on the one or more orientations for the acetabular cup implant.

4. 4. The method of assessing risk associated with hip arthroplasty for a subject according to any one of claims 1 to 3, wherein the at least one spinopelvic metric is one or more of the group consisting of sagittal index, sacral obliquity, pelvic-femoral angle, lumbar lordosis, and overall sagittal balance.

5. 5. The method of claim 1, further comprising determining a range of acetabular inclination or anteversion angles, wherein the subject's risk classification for hip arthroplasty is high if the determined acetabular inclination or anteversion angle range is less than 20°.

6. 6. The method of claim 5, wherein the subject's risk classification for hip arthroplasty is high if the determined acetabular inclination angle or anteversion angle range is less than 10°.

7. 7. The method of assessing risk associated with hip arthroplasty for a subject according to any one of claims 1 to 6, wherein at least one said spinopelvic metric is calculated using anatomical landmarks received from a user.

8. 8. The method of assessing risk associated with hip arthroplasty for a subject according to any one of claims 1 to 7, wherein at least one said spinopelvic metric is calculated using anatomical landmarks, the method comprising locating said anatomical landmarks.

9. A computer-implemented method for determining an acetabular cup orientation angle range for an acetabular cup implant in a subject, comprising: receiving, by the computer, at least one image of the subject obtained from a sagittal plane while the subject is in a standing position; said computer calculating at least one spinopelvic metric from at least one of said images; the computer receiving an anteversion angle range; receiving a tilt angle range from the computer; determining an acetabular cup orientation angle range for the subject's acetabular cup implant based on the calculated at least one spinopelvic metric, the received anteversion angle range, and the received tilt angle range; The acetabular cup orientation angle range is determined so that a calculated post-operative standing composite sagittal index is greater than or equal to 190° and less than 255°. A method for determining an acetabular cup orientation angle range for an acetabular cup implant in a subject.

10. 10. The method of claim 9, wherein at least one of the spinopelvic metrics is calculated using anatomical landmarks received from a user.

11. 11. A method for determining an acetabular cup orientation angle range for an acetabular cup implant in a subject, as described in claim 9 or 10, wherein at least one of the spinopelvic metrics includes one or more of the group consisting of sagittal index, sacral tilt, pelvic-femoral angle, lumbar lordosis, and overall sagittal balance.

12. 12. A method for determining an acetabular cup orientation angle range for an acetabular cup implant in a subject, as described in any one of claims 9 to 11, wherein at least one of the spinopelvic metrics is calculated using anatomical landmarks, and the method includes positioning the anatomical landmarks.

13. A method for determining an acetabular cup orientation angle range for an acetabular cup implant in a subject, as described in any one of claims 9 to 12, wherein the acetabular cup orientation angle range is determined such that a calculated post-operative standing composite sagittal index is greater than 200° and less than 250°.

14. 1. A computer-implemented method for determining an orientation angle range for an acetabular cup implant in a subject, comprising: the computer receiving an anteversion angle range; receiving a tilt angle range from the computer; receiving, by the computer, at least one spinopelvic metric for the subject; and the computer determines an acetabular cup orientation angle range for the acetabular cup implant in the subject based on at least one of the spinopelvic metric, the received anteversion angle range, and the received tilt angle range; The orientation angle range of the acetabular cup is determined so that the calculated post-operative standing composite sagittal index is greater than or equal to 190° and less than 255°. A computer-implemented method for determining an orientation angle range for an acetabular cup implant in a subject.

15. 15. The computer-implemented method for determining an orientation angle range for an acetabular cup implant in a subject of claim 14, wherein the spinopelvic metrics include one or more of the group consisting of sagittal index, sacral tilt, pelvic-femoral angle, lumbar lordosis, and overall sagittal balance.

16. A computer-implemented method for determining an orientation angle range for a subject's acetabular cup implant, as described in claim 14 or 15, wherein the orientation angle range of the acetabular cup is determined such that the calculated post-operative standing composite sagittal index is greater than 200° and less than 250°.