Endoscopic microdiscectomy at L4/L5, with the approach fitted to the bone
A full-endoscopic interlaminar microdiscectomy at L4/L5, built by script on open atlas anatomy. The working corridor was found by a search against the bone, not picked by eye.
Overview
How do you show a procedure that takes place inside a tube 7.5 mm wide? This sample is a 23-second cut from a 66-second film of a full-endoscopic interlaminar microdiscectomy at L4/L5: the endoscope goes down the working sheath, the ligamentum flavum is opened, the L5 root is held aside, the disc fragment comes out in two bites, and the root is released.
The scene is built by a script, not posed by hand. The approach comes from a search against the bone, so the sheath fits the window it is shown in, and the dural sac and the nerve roots give way to the fragment and the sheath by no more than they have to.
Because the scene is a script, another level, another approach or another instrument set is a new run of the same pipeline, and versions for other audiences come from the same scene. This film also exists with Arabic step cards and labels for patients and families.
The instruments are generic, so no manufacturer’s device is shown. The method note below says what was modelled and what was an artistic choice.
Film
Method note
- Modelled
- Vertebrae, discs, ligaments, limb nerves, skin and back muscles from the Z-Anatomy atlas; the L4/L5 disc trimmed to the intervertebral space and its nucleus reshaped
- Nerve roots of the cauda equina from my own root build on the same atlas
- Dural sac and root sleeves, which the atlas does not have at this level, built around its nerve roots from a signed-distance field on a 0.35 mm grid
- Right paracentral disc extrusion with an annular fissure and a two-lobed fragment in the lateral recess; sac and roots displaced by the smallest amount that clears the fragment (3.77 mm, found by bisection)
- Working corridor from a search over 192 directions against the vertebrae, the sacrum and the hip bones: 6 clear them, and the chosen one keeps its axis 4.63 mm from the nearest bone for a sheath radius of 3.75 mm. The window admits the sheath as it is, so no bone removal is shown
- Retraction of the L5 root and the sac by the bevel of the sheath: the smallest medial shift that clears the sheath (5.31 mm)
- Generic full-endoscopic instrument set (needle, guidewire, three dilators, bevelled 7.5 mm working sheath, working-channel endoscope, grasping forceps, bipolar probe); no manufacturer’s device
- Simplified: the back muscles do not deform around the dilators; forceps and probe run on the axis of the sheath, not in the endoscope’s off-centre working channel; the endoscope shaft is drawn 0.4 mm wider than the bore of the sheath; no epidural fat or veins
- Computed
-
Nothing in this piece was simulated.
- Artistic choices
- Colour palette and materials
- Where the section cuts run and when they open
- Camera path, lighting and depth of field
- Instrument timing
- Red glow on the compressed L5 root
- Tools
- Blender, Python, FFmpeg
- Credits
- Anatomy: Z-Anatomy, the libre 3D atlas of anatomy (CC BY-SA 4.0)
- BodyParts3D, The Database Center for Life Science (CC BY-SA 2.1 Japan)
- This video and the stills on this page are adapted from that anatomy and are licensed CC BY-SA 4.0