How the Native Knee Flexes — teaching sequence
Source bone/cartilage geometry: Open Knee(s), specimen oks009, Open Knee(s) Development Team.
https://simtk.org/svn/openknee/oks/oks009/Geometry/
Source license: Creative Commons Attribution-ShareAlike 3.0 Unported.
https://creativecommons.org/licenses/by-sa/3.0/
Derived anatomy.glb and the 4K animation are distributed under CC BY-SA 3.0.
Modifications: welded/smoothed surfaces, mirrored left reference to right knee,
warm ivory materials, cartilage tint, sagittal section geometry, prescribed
0–120-degree medial-pivot motion, illustrative menisci, markers and lecture HUD.
No endorsement by the source authors is implied.

The animation is a prescribed teaching model, not an experimental recording,
patient-specific simulation, or validated joint-contact/meniscal mechanics model.
Numeric targets: medial 1 mm posterior, lateral 20 mm posterior, 20.2 degrees
coupled axial rotation by 120 degrees, with a 55 mm inter-marker distance.
The condylar-center and contact-patch concepts are distinct. Meniscal motion
and the early medial contact shift are illustrative, not measured from oks009.
Sagittal surfaces are sections extracted from the reference bone geometry.
Beyond 120 degrees is not animated.

Clinical sources:
Iwaki H, Pinskerova V, Freeman MAR. 2000. PMID 11132285.
Hill PF et al. 2000. PMID 11132286.
Johal P et al. 2005. PMID 15598453.
Freeman MAR, Pinskerova V. 2005. PMID 15598446.
Komistek RD, Dennis DA, Mahfouz M. 2003. PMID 12771818.
Hill and Komistek report variability that precludes a universal no-medial-motion claim.

Correction: added same-specimen fibula, revised posterior-facet rotation centers, and sampled surface-clearance guard. These are illustrative geometric adaptations.
Study illustrations: Pinskerova V, Vavrik P (2020), chapter14, Figures14.1 and14.4, reproduced unaltered under CC BY4.0. https://doi.org/10.1007/978-3-030-24243-5_14 ; https://creativecommons.org/licenses/by/4.0/

patient-hero-trochlea-v1.glb: reference-guided illustrative derivative for the
introductory camera orbit, CC BY-SA 3.0. The continuous anterior femoral
cartilage is broadened, raised asymmetrically and smoothed, with a shallow
sulcus blended into its supporting femoral surface. Tibia, fibula and tibial
cartilage remain unchanged. Shape guidance supplied by the user from an
UnderstandOrtho trochlea illustration; that reference image is not bundled.
This is an illustrative shape edit, not patient-specific measurement.

Restoration refinement, 2026-09-13:
The actual collateral ligament surfaces in oks009-collateral-ligaments.glb are
Open Knee(s) oks009 MRI segmentations, Open Knee(s) Development Team, CC BY-SA 3.0.
Source MCL: https://simtk.org/svn/openknee/oks/oks009/Geometry/oks009_MRG_MCL_SKC_03_LVTIT.stl
Source LCL: https://simtk.org/svn/openknee/oks/oks009/Geometry/oks009_MRG_LCL_SKC_LVTIT_01.stl
These are the tissue files paired with the bones by the source Connectivity.xml.
Adaptations: welded vertices, right-knee reflection, Y-up coordinates, neutral
ivory material, fine illustrative collagen relief, prescribed attachment-weighted
deformation for teaching. Shapes are scan-derived; deformation and tissue forces
are not a validated simulation. Derived meshes are distributed under CC BY-SA 3.0.
The native restoration cartilage is a single smoothed source shell, without the
previous clipped anterior overlay. The polished, higher-lateral femoral implant
is original reference-inspired illustrative geometry, not Zimmer Persona CAD.