Key Takeaways
- Ti-6Al-4V trial implant printed for orthopaedic planning.
- Patient-specific geometry from medical imaging.
- Biocompatible titanium suited to implant trials.
- Improved pre-surgical fit and planning.
Background
A senior orthopaedic surgeon at a Mumbai tertiary hospital was planning a complex tibial plateau reconstruction for a patient with a high-energy tibial plateau fracture (Schatzker VI). Standard off-the-shelf implant trials did not fit the patient's anatomy — the fracture pattern created an unusual medial step and the surgeon wanted to physically rehearse the approach and verify implant positioning before the operation.
The hospital's biomedical engineering team contacted Layer X with a CT DICOM dataset and a request for a patient-specific titanium trial implant in Ti-6Al-4V that could be used intraoperatively for positioning verification (non-implanted, sterilised, single-use).
Regulatory and Quality Context
This part was a patient-matched instrument (PMI) — a single-use, non-implanted trial used intraoperatively to verify implant position before the definitive implant is placed. Under India's CDSCO regulations, PMIs used under a surgeon's clinical judgment as research tools do not require product registration if not commercially sold. Layer X produced this part under our documented quality management system with full batch record documentation for the hospital's quality file.
Technical Requirements
- Material: Ti-6Al-4V Grade 5 (ASTM B265 Grade 5 chemistry equivalent)
- Geometry: Patient-specific tibial plateau profile from CT segmentation, sized for standard tibial stem compatibility (12 mm stem diameter)
- Surface: Proximal (bone-contact) surface rough (Ra 6–12 µm as-printed, no additional finishing); distal surface and stem bore machined to smooth finish
- Sterility: Compatible with gamma irradiation sterilisation at the hospital
- Documentation: Material test report from powder supplier, dimensional report, sterilisation compatibility certificate
Geometry Workflow: DICOM to DMLS
CT Segmentation
The patient's CT DICOM dataset (0.6 mm slice thickness, 512×512 matrix) was imported into 3D Slicer (open source). The tibial plateau bone surface was manually segmented by Layer X's engineer working with the surgeon's annotations of the fracture lines and target implant zone. Segmentation produced a 3D model of the plateau surface in STL format.
Implant Design
Using Fusion 360, Layer X designed the trial implant as a conforming shell that matched the patient's tibial plateau curvature on the proximal surface and had a flat distal face with a 12 mm cylindrical stem bore for standard tibial nail compatibility. The medial step created by the fracture pattern was incorporated into the proximal geometry to ensure seating stability during the surgical trial.
Total design time: 8 hours (segmentation + design + customer review cycle). The surgeon reviewed and approved the 3D model render before build approval.
DMLS Build and Post-Processing
Ti-6Al-4V was built with 30 µm layer height for maximum resolution on the proximal surface features. Supports were positioned exclusively on the distal face (which would be machined). Post-processing:
- Stress relief anneal: 800°C for 2 hours in argon atmosphere
- Support removal
- CNC machining: distal face flatness to within 0.1 mm, stem bore to H7 (12.000–12.018 mm)
- CMM inspection: 14 critical dimensions including plateau width, A-P length, and stem bore diameter — all within drawing tolerance
- Cleaned, bagged, and gamma sterilisation compatibility validated
Surgical Outcome
The trial implant was used intraoperatively during the tibial plateau reconstruction. The surgeon confirmed accurate anatomic fit with the fracture-reduced bone surface during the case. The implant trial identified that a standard size-5 tibial implant would require 2 mm of additional medial-side bone grafting — information that would not have been apparent from imaging review alone.
The definitive implant was placed correctly on the first attempt, and the surgeon reported a 25-minute reduction in surgical time compared to his previous experience with similar cases requiring intraoperative size adjustment. The patient had a successful outcome at 6-month follow-up.
Timeline
| Step | Time |
|---|---|
| DICOM dataset received by Layer X | Day 0 |
| CT segmentation complete | Day 1 |
| Design complete, surgeon approval | Day 2 |
| DMLS build complete | Day 4 |
| Post-processing and machining | Day 6–7 |
| CMM inspection and documentation | Day 8 |
| Part shipped to Mumbai hospital | Day 9 |
| Surgical procedure | Day 14 |
Key Learnings
DMLS Ti-6Al-4V enables patient-specific implant trials that were previously unavailable to Indian orthopaedic surgeons without 6–8 week international procurement lead times. The 9-day turnaround from DICOM to sterilised implant trial, at a cost of ₹45,000, makes patient-matched surgical planning economically accessible at Indian tertiary hospital budgets.
Layer X provides medical DMLS services for hospitals and med-tech companies under documented, biocompatible-material quality management. Contact us for surgical guide and patient-matched instrument production in Ahmedabad.