For surgeons · technical file
Everything you need to prepare a patient-specific implant.
Imaging protocol, design logic, material, manufacturing and inspection: the technical framework behind every IME TECH implant, from the request to the operating theatre.
- Imaging
- CT ≤ 1 mm
- Format
- Native DICOM
- Alloy
- Ti-6Al-4V ELI
- Process
- Laser fusion
01
Imaging protocol
The quality of the implant depends first on the quality of the scan. These parameters allow faithful segmentation of thin bone (orbital floor, defect edges) and a design without extrapolation.
| Parameter | Cranioplasty | Orbit · maxillofacial |
|---|---|---|
| Modality | CT | CT; CBCT possible if the field of view covers the whole area |
| Slice thickness | ≤ 1 mm, ideally 0.5 to 0.625 mm | ≤ 1 mm, ideally 0.5 to 0.625 mm |
| Increment | Equal to or less than the thickness (contiguous slices) | Equal to or less than the thickness (contiguous slices) |
| Field of view | Whole skull, from vertex to base, not truncated | Complete facial skeleton with both orbits, from the orbital roof to the chin |
| Gantry tilt | 0° | 0° |
| Reconstruction kernel | Bone (plus soft tissue if the aesthetic contour matters) | Bone (plus soft tissue if the aesthetic contour matters) |
| Export | Uncompressed DICOM, complete native axial series | Uncompressed DICOM, complete native axial series |
| Conditions | Scan taken after the last surgery on the area | Teeth in intercuspal occlusion, removable appliances taken out |
MPR or 3D reconstructions alone are not enough: the native axial series is essential. Files can be attached directly to the request form.
02
Study and planning
Each case goes through a feasibility study and then an online planning session with the lead engineer. Decisions are made by the surgeon and recorded.
Segmentation
3D extraction of bone from the slices, checking thin areas and artefacts.
Defect analysis
Extent, quality of the bone edges, thickness available for fixation.
Strategy
Mirroring of the healthy side or curvature blending; resection margins for tumours.
Decision points
Screw positions, overlap, thickness, restoration of the temporal contour.
03
Design rules
The parameters below are adapted to each patient. The values quoted are measured on the implants shown on this site, not constants.
R01
Anatomical reference
Unilateral defect: mirroring of the healthy side across the midsagittal plane. Bilateral or midline defect: reconstruction by continuity of curvature with the healthy bone at the edges.
R02
Thickness
Set according to the area and the loads. On the cases shown: ≈ 2 to 2.5 mm for the vault, ≈ 0.45 mm for the orbital floor.
R03
Perforations
Weight reduction, fluid drainage and soft-tissue adhesion. Diameter and layout chosen at design (Ø ≈ 3.9 mm on the FIG. 01 case).
R04
Fixation
Holes placed on healthy bone, away from thin or sinus areas, sized for the surgeon’s screw system (Ø ≈ 2.5 mm on FIG. 01).
R05
Edges and contour
Rounded edges to protect the covering tissues. Contour restored, including the temporal region, to limit visible hollowing.
R06
Identification
Identification engraving on the part (visible on the implants shown) and traceability back to the manufacturing batch.
04
Material: Ti-6Al-4V ELI
Extra-low-interstitial grade (ELI, grade 23) of the titanium-aluminium-vanadium alloy, the reference for bone implants. Its low oxygen content improves ductility and fracture toughness.
Chemical composition (% by mass)
| Aluminium (Al) | 5.5 – 6.5 % |
|---|---|
| Vanadium (V) | 3.5 – 4.5 % |
| Iron (Fe) | ≤ 0.25 % |
| Oxygen (O) | ≤ 0.13 % |
| Carbon (C) | ≤ 0.08 % |
| Nitrogen (N) | ≤ 0.05 % |
| Hydrogen (H) | ≤ 0.012 % |
| Titanium (Ti) | Balance |
Properties
| Tensile strength | ≥ 860 MPa | standard minimum |
|---|---|---|
| Yield strength | ≥ 795 MPa | standard minimum |
| Elongation at break | ≥ 10 % | standard minimum |
| Density | 4.43 g/cm³ | typical value |
| Elastic modulus | ≈ 110 GPa | typical value |
| Thermal conductivity | ≈ 6.7 W/m·K | typical value |
| Magnetism | Non-ferromagnetic | alloy property |
Follow-up imaging
Far fewer CT artefacts than with steels. Non-ferromagnetic alloy: MRI is usually possible, under the conditions specified for the device.
Stiffness
Modulus ≈ 110 GPa, higher than cortical bone: the geometry (thickness, perforations) governs the overall stiffness of the part.
Thermal sensation
Conductivity ≈ 6.7 W/m·K, low for a metal: limits the transmission of heat and cold through a thin plate.
Composition and mechanical minima: requirements of the ASTM F136 / F3001 specifications. The values of each batch appear on the material certificates in the manufacturing file.
05
Manufacturing and inspection
From powder to delivered part, every operation is recorded. The part is shipped only after inspection against the approved model.
- 1
Preparation
Part orientation, supports and fusion parameters defined for the geometry.
- 2
Laser powder-bed fusion
Layer-by-layer build under inert atmosphere, with a traced powder batch.
- 3
Heat treatment
Relief of the residual stresses from fusion.
- 4
Finishing
Support removal, deburring and surface finishing.
- 5
Cleaning
Removal of powder and manufacturing residues.
- 6
Inspection
Visual and dimensional inspection against the model approved by the surgeon.
- 7
Record
Part identification, material batch, parameters and inspection results.
06
In theatre
The procedure has been prepared: the shape, the bearing areas and the fixation points are known before the incision.
Deliverables
- ImplantIdentified, with its manufacturing file
- Placement planPositioning views and screw locations
- Anatomical modelOptional, to check the fit before surgery
- Cutting guidesIf a resection is planned
Before surgery
- Check the part identification and that it matches the patient
- Check the fit on the anatomical model if supplied
- Prepare the screw system planned at design
- Follow the packaging and sterilisation instructions in the file
07
Cranial reconstruction options
A summary of the characteristics generally reported for the main options. The choice depends on the patient, the defect and the team’s experience: it rests with the surgeon.
| Option | Fit | Strength | Imaging | Key points |
|---|---|---|---|---|
| Autologous bone (stored flap) | Original anatomy | That of bone | No artefact | Biological and no material cost; subject to resorption, especially in children and with large flaps. |
| PMMA shaped in theatre | Depends on manual moulding | Moderate, brittle under impact | Radiolucent | Low cost; exothermic polymerisation, longer operating time, less reproducible contour. |
| Patient-specific PEEK | Designed on the CT scan | High | Radiolucent, artefact-free | Well tolerated and easy imaging follow-up; no osseointegration, thicker part than titanium. |
| Stock titanium mesh | Shaped in theatre | Good, depends on shaping | Limited artefacts | Immediately available; contour depends on shaping, edges to watch under thin tissues. |
| Patient-specific printed titanium | Designed on the CT scan | High at low thickness | Limited artefacts | Free geometry (perforations, contour, integrated fixation), thin part; requires design and manufacturing lead time. |
08
Measured cases
Values taken directly from the manufacturing files of the five cases illustrated on this site.
FIG. 01 · technical plate
Left fronto-temporo-parietal cranioplasty
Large vault defect, peripheral fixation with 8 screws
- Overall size
- 107 × 107 × 32 mm
- Thickness
- ≈ 2.9 mm
- Mass
- ≈ 125 g
- Volume
- 28.3 cm³
- 52 perforations Ø ≈ 3.6 mm
- 8 screws Ø 1.5 × 15 mm
- Bone support ≈ 470 mm²
Hero · home page
Fronto-temporo-parietal cranioplasty
Extensive lateral vault defect
- Overall size
- 154 × 119 × 53 mm
- Thickness
- ≈ 2.1 mm
- Mass
- ≈ 142 g
- Volume
- 32.1 cm³
- 69 perforations Ø ≈ 3.9 mm
- 17 fixation holes Ø ≈ 2.5 mm
- Identification engraving
Animation · process
Bifrontal cranioplasty
Frontal defect crossing the midline
- Overall size
- 130 × 102 × 88 mm
- Thickness
- ≈ 2.5 mm
- Mass
- ≈ 156 g
- Volume
- 35.3 cm³
- Distributed perforations
- Bilateral curvature blending
- Identification engraving
FIG. 02
Orbitozygomatic reconstruction
Floor, lateral rim and body of the zygoma
- Overall size
- 40 × 38 × 64 mm
- Thickness
- ≈ 0.45 mm
- Mass
- ≈ 5 g
- Volume
- 1.1 cm³
- Mirrored design from the healthy side
- Frontal and malar fixation
- Contoured floor
FIG. 03
Orbital roof reconstruction
Oculoplastic surgery, fixation on the superior rim
- Overall size
- 28 × 21 × 12 mm
- Thickness
- ≈ 0.6 mm
- Mass
- ≈ 1.2 g
- Volume
- 0.26 cm³
- 3 screws Ø 1.5 × 8 mm
- Screw spacing 6.2 mm
- Planned screw axes
Thickness: median distance between opposite faces. Mass: mesh volume × 4.43 g/cm³.
09
Standards
The main regulations and standards governing the design and additive manufacturing of patient-specific implants.
- Regulation (EU) 2017/745
- Framework for medical devices, including custom-made devices (Article 52(8), Annex XIII).
- ISO 13485
- Quality management systems for medical devices.
- ISO 14971
- Application of risk management to medical devices.
- ISO 10993-1
- Biological evaluation of medical devices.
- ASTM F3001 · ASTM F136
- Ti-6Al-4V ELI: powder-bed fusion and wrought form for implants.
- ISO/ASTM 52900 · 52904
- Additive manufacturing: terminology and metal laser fusion for critical applications.
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