VirtualHip user guide

About the silent demo

The VirtualHip demo on the products page has no speech, music, or meaningful audio. It presents the 28 guide screens described below, beginning with a title screen, moving through case submission and results, and ending with measurement definitions. Reading this page provides the same instructional information in the same sequence without requiring vision, hearing, or video playback.

Contents

1. Cases and case history
2. Search and submit from the electronic medical record
3. Upload and submit local images
4. Results and analysis tabs
5. Anatomy and two-dimensional maps
6. Acetabular and coverage measurements
7. Femoral measurements
8. Sacropelvic alignment
9. Dynamic impingement
10. Dynamic instability and coverage

Screens 2 and 3: cases and case history

After login, the Cases page displays completed, running, and pending cases. Each row can include accession number, medical record number, first and last name, age, sex, image modality, analyzed side, analysis creation date, study date, number of images, and status.

• Select the results control to open a completed case.
• Pending means the case is queued for analysis. A loading indicator appears while a case is being analyzed. Use refresh to obtain the current status.
• The PDF control opens the current case file in a new browser tab.
• Use an add-case control to submit a new case.
• Select a column header to sort the table.
• Use a column's filter menu to run an advanced search, hide that column, or manage the displayed columns.

An accession number uniquely identifies one imaging study and is generally the best value for locating the intended images. The accession number for a study is available in Synapse. A medical record number identifies the patient and can be associated with more than one imaging study.

Screens 4 to 6: search and submit from the electronic medical record

Search for imaging

For an authorized Boston Children's Hospital user, Add Case from EMR opens Search Medical Imaging Data, which is linked to the hospital radiology database in PACS and Synapse. Search fields include medical record number, accession number, first name, and last name. Results do not appear automatically; activate the search control after entering criteria.

• When searching by patient name, include both first and last name for a faster and more accurate query.
• A generic query, such as only the first name James, may return a warning. Narrow the search criteria when possible.
• If either Query Service or Pipeline Service is offline, submission cannot continue. Use the application support channel shown within the authorized VirtualHip system.
• Users outside Boston Children's Hospital do not have access to the hospital radiology search and must use the local image submission path.

Select a search result

The results table can include accession number, medical record number, patient name, sex, study date, image modality, date of birth, number of images, and age. Select one row to reveal the continue control. Selecting a different row changes the active case.

• Only one case can be selected at a time.
• The 2024 guide identifies CT as the available modality for this workflow.
• Select a hip CT scan.
• For best results, select a full field-of-view scan that contains the complete pelvis and femur. Analysis may run without the femoral condyles, but results may be inaccurate because the imaging position may differ from the neutral position.

Submit the request

The submission screen presents patient and study details. Go back if the selected case is incorrect. If it is correct, choose the hip side, optionally enter diagnosis, symptoms, prior hip surgery, and treatment plan, then submit. A confirmation appears, the system returns to Cases, and the new case is added to the table. Optional clinical fields can support assessment of VirtualHip efficacy and performance.

Screens 7 and 8: upload and submit local images

Add Case from Local Images opens upload instructions. Choose one ZIP file containing one set of medical images in DICOM format.

• For de-identified images, retain the Series Description DICOM tag, 0008,103E. If the tag was cleared, use pelvis for the pelvis series. If the condyle region is stored separately, use knee for the series containing the condyle. A missing Series Description tag causes an analysis error.
• Follow the CT imaging protocol available within the authorized application. Deviations may produce inaccurate measurements or processing errors.
• Upload one set of CT scans per entry as a single ZIP file.

After the upload finishes, the submission page displays details extracted from the images. Complete the required patient and study fields, verify the image, choose the hip side, add any optional diagnosis, symptom, prior-surgery, or treatment-plan details, and submit. The case appears in Cases using the information entered during submission. Retain the entered information for your own reference.

Screens 9 and 10: results and analysis tabs

A completed case opens a results page with a three-dimensional viewer, an anatomical measurement summary, two-dimensional maps, and analysis tabs.

• Anatomy: three-dimensional evaluation of hip-joint morphology with comparisons to age- and sex-matched normative data from 24,000 asymptomatic hips.
• Impingement Map: dynamic evaluation of hip impingement over a personalized range of motion, including hip translation intended to simulate glide, joint laxity, and soft-tissue deformation.
• Coverage Map: dynamic evaluation of instability through global and regional femoral-head coverage over a personalized range of motion, including hip translation.
• Treatment Planning: a described future area for AI-assisted personalized diagnosis and surgical or nonsurgical planning using advanced patient matching and historical clinical data. The 2024 guide states that this tab is inactive in the beta-testing version.

Screens 11 and 12: anatomy and two-dimensional maps

Three-dimensional viewer

The viewer displays models reconstructed from medical images. Controls change each model's visibility and transparency. A solid green line represents the average acetabular-rim position in a large group of age- and sex-matched controls. Green shading represents the 90 percent confidence interval for normal acetabular-rim position.

Anatomical measurement summary

The summary places the patient's measurements against normative values from 24,000 asymptomatic hips, including males and females from birth through adulthood. Green represents the 10th through 90th percentile of controls. Orange represents values below the 10th or above the 90th percentile. Red represents a value outside the range observed in the control population. The software flags values outside the green range as abnormal.

Two-dimensional maps

• Epiphyseal map: an oblique view highlighting peripheral cupping and the epiphyseal tubercle. Height is measured from the nadir of the capital epiphysis, normalized to femoral-head diameter, and reported as a percentage.
• Acetabular rim height map: an oblique view highlighting acetabular-rim development. Height is measured from the bottom of the acetabulum, normalized to acetabular diameter, and reported as a percentage.
• Joint-space-width map: an oblique view reporting the space between the acetabular lunate surface and femoral head in millimeters.

On the clock-face convention used by these maps, 3 o'clock is anterior and 12 o'clock is superior.

Screens 13 to 16: acetabular, coverage, and joint-space measurements

Acetabular geometry

• Diameter: the diameter of the sphere best fitted to the concave acetabular surface.
• Depth: the distance between the average position of the 3, 6, 9, and 12 o'clock rim points and the midpoint of the concave surface.
• Width: the distance between 3 and 9 o'clock.
• Height: the distance between 6 and 12 o'clock.

Acetabular version

Version is measured at proximal or cranial, middle or central, and distal or caudal levels. It is the angle between a line connecting anterior and posterior rim points and that line's projection on the sagittal plane.

• Cranial: the average version at superior clock pairs 10 to 2 and 11 to 1.
• Central: version at the middle 9 to 3 o'clock section.
• Caudal: the average version at inferior clock pairs 7 to 5 and 8 to 4.

Hip coverage

At each clock position, the center-edge angle is the angle between a line from the femoral-head center to the acetabular clock point and that line's projection on the sagittal plane through the femoral-head center. The calculation occurs on the corresponding clock plane containing both lines. Femoral-head migration is measured in the coronal view as AC divided by AB and reported as a percentage.

The Tönnis angle is measured in the coronal view between the line from the most inferior point to the most lateral point of the sclerotic acetabular sourcil and a horizontal line. Because the coordinate system is aligned, the horizontal line is parallel to the line connecting the bases of the acetabular teardrops.

Joint-space width

Joint-space width is the distance between the acetabular lunate surface and the femoral head. Median width is calculated for the entire lunate surface and for three regions: anterior from 2 to 5 o'clock, superior from 10 to 2 o'clock, and posterior from 7 to 10 o'clock.

Screens 17 to 23: femoral measurements

Femoral version

Femoral version is the axial-view angle between a proximal reference axis and the posterior-condylar axis. The Murphy method uses a femoral head-shaft reference axis connecting the femoral-head center to the femoral-shaft center. The Reikerås method uses the three-dimensional femoral-neck axis.

Neck-shaft angle and head offset

Femoral neck-shaft angle is the coronal-view angle between the neck axis and shaft axis. Femoral-head offset is the perpendicular coronal-plane distance between the femoral-head center and femoral-shaft axis.

Alpha angle and head-neck offset

The analysis intersects radial planes with the femur. Planes begin at 12 o'clock and rotate clockwise around the physeal-plane axis in 30-degree intervals. For each clock position, the alpha-angle control point is the first radial femoral location intersecting the circle fitted to the femoral head. The head-neck-offset control point is the corresponding position on a line parallel to the femoral-neck axis.

Alpha angle is the angle between the femoral-neck axis and a line from the femoral-head center to the alpha-angle control point. Head-neck offset is the distance between two lines parallel to the neck axis: one through the control point and one tangent to the best-fit femoral-head sphere. Offset is reported as a percentage of femoral-head diameter.

Head-neck angle and neck size

Head-neck angle is the angle between the normal vector of the physeal plane and the femoral-neck axis in coronal and axial views. To measure neck size, a cross-sectional plane is defined from the neck axis and the midpoint between the most medial and lateral neck surfaces. Neck diameter is the diameter of the best-fit circle through the plane's intersection points. Neck length is the distance between the centers of the medial and lateral surfaces.

Femoral-head size and normalized height

Minimum and maximum points in three directions determine femoral-head size. Depth, height, and width are the distances between maximum and minimum points along the Z, Y, and X directions in an oblique view. Diameter is the diameter of the sphere best fitted to the femoral head.

Peripheral cupping and the epiphyseal tubercle are evaluated in an oblique view. At each clock position, cupping height is the vertical distance from the clock position to a reference point at the center of the capital-epiphysis nadir. Tubercle height is the vertical distance from the tubercle peak to the same reference point. Both are reported as percentages of femoral-head diameter.

Screen 24: sacropelvic alignment

Three sagittal-view parameters describe sacropelvic alignment:

• Pelvic incidence: the angle between a line from the center of the S1 endplate to the femoral-head center and the axis perpendicular to the S1 endplate.
• Sacral slope: the angle between the S1 endplate and the horizontal anterior-posterior axis.
• Pelvic tilt: the angle between a line from the S1 endplate center to the femoral-head center and the vertical inferior-superior axis.

Screens 25 and 26: dynamic impingement analysis

Dynamic hip impingement is defined as bone-to-bone contact between the femur and pelvis during combinations of single-plane and multiplanar motion. The tested range extends from 50 degrees of extension to 150 degrees of flexion, 75 degrees of abduction to 75 degrees of adduction, and 75 degrees of external rotation to 75 degrees of internal rotation.

The impingement map highlights femoral and pelvic regions at high risk of contact. Users can view the entire tested range or select hip positions commonly examined in clinical settings. The impingement-free range for a position can be compared with age- and sex-matched controls.

The analysis can be repeated with different hip-translation values to simulate changes in the center of rotation caused by glide, joint laxity, or soft-tissue deformation. For example, a 2-millimeter translation range permits the center of rotation to move up to 2 millimeters in any direction during the test. The algorithm restricts hip dislocation and bone-to-bone penetration to prevent nonphysiological motions.

Screens 27 and 28: dynamic instability and coverage

Hip coverage is the area of the femoral-head surface covered by the acetabulum. Red shading on the three-dimensional model marks the covered region. Users can view coverage over the full tested range of motion or at selected clinical hip positions.

A solid green line shows normal femoral-head coverage for each position, based on the average from a large group of age- and sex-matched controls. Coverage is reported as a percentage of total femoral-head surface area, both overall and within quadrants:

• Anterior-superior: 12 to 3 o'clock.
• Anterior-inferior: 3 to 6 o'clock.
• Posterior-inferior: 6 to 9 o'clock.
• Posterior-superior: 9 to 12 o'clock.

In the guide, HEER means hyperextension plus external rotation. AB-HEER means abduction plus hyperextension plus external rotation.

Original file and support

Download the original 28-page PDF (legacy format). It is retained for visual reference; this structured HTML page is the primary accessible version.

For questions about public documentation, use the MDI² contact page. Do not email medical images, medical records, or other patient information. Authorized users should use approved application and hospital support channels for case-specific issues.