OLA

Case Study: 3D-Printed Spinal Cage with Porous Body & Anchored End

Pure Titanium (Ti-6Al-4V ELI) | SLM | FDA / CE / NMPA Compliant Spinal Implant

Orthopedic Implant Case Study

1. Background

A spine medical-device OEM was developing a next-generation interbody fusion cage for TLIF, PLIF, and ACDF procedures. The legacy PEEK cage required a separate HA coating step for bone ongrowth, and the smooth cylindrical body had a serious clinical limitation: post-operative cage migration and subsidence. Radiographic follow-up showed 6-8% of legacy cages migrated within the first 6 months, requiring revision surgery. A pure titanium cage with an integrated porous bone-ingrowth body AND a flared anchored end was needed to eliminate both problems in a single implant.

2. The Challenge

Design requirements included:

· Pure titanium (Ti-6Al-4V ELI) cage with integrated porous body for bone ingrowth — no separate HA coating

· Flared anchored end with anti-migration teeth / petals that grip the vertebral endplate on insertion

· Cervical / lumbar sizes from 10 mm to 14 mm height, with lordotic angle 0° / 6° / 12°

· Central bore through the porous body for bone graft packing and vascularization

· ASTM F136 / ISO 5832-3 material certification, full traceability per ASTM F2979

· Surface roughness Ra 4-6 μm on the porous lattice (validated for osteoblast attachment)

· Biocompatibility per ISO 10993-1, cytotoxicity / sensitization / irritation all pass

· Class III medical device, FDA 510(k), CE MDR, NMPA documentation all ready

· Single-piece monolithic construction — no welded or brazed anti-migration features

3. The Solution

The cage was redesigned with two integrated zones: a cylindrical porous body (600-800 μm lattice, 70% porosity) for vascularized bone ingrowth, and a flared anchored end with anti-migration petals that grip the vertebral endplate on insertion. Both zones were manufactured by Selective Laser Melting (SLM) in Ti-6Al-4V ELI powder (ASTM F136) as a single monolithic titanium part — no assembly, no coating, no adhesive, no welded anti-migration features. The central bore runs through the entire porous body for bone graft packing, and the end-face openings provide vascularization paths.

The flared anchored end was topology-optimized to maximize grip force on the vertebral endplate while staying within the insertion envelope of a standard TLIF/PLIF/ACDF delivery cannula. After printing, every cage was hot isostatic pressed (HIP) for 100% density in the load-bearing core, passivated per ASTM F86 for biocompatibility, gamma-sterilized, and serial-numbered with full material traceability back to the powder lot per ASTM F2979.

 

Figure 1: SLM-printed pure titanium spinal cage — end view of the flared anchored end, showing the anti-migration petals arranged around the central graft bore

 

Figure 2: Same cage from the side view — porous cylindrical body for bone ingrowth (top) integrated with the flared anchored end (bottom), all in a single monolithic Ti-6Al-4V ELI part

4. The Result

· 30% faster fusion — validated in preclinical — 6-8 months vs. 9-12 for PEEK + HA

· 0% cage migration — anti-migration petals grip endplate on insertion, no post-op migration observed

· 100% density core — HIP + CT scan verified, no porosity in load-bearing region

· ASTM F136 / ISO 5832-3 — full material certification, every powder lot traceable per ASTM F2979

· ISO 10993 biocompatibility — cytotoxicity, sensitization, irritation — all pass

· Multi-region regulatory — FDA 510(k), CE MDR, NMPA documentation all prepared

· Single-piece construction — no welded anti-migration features, no coating delamination risk

· Lead time: 6 weeks — from CAD to sterile-packed, certified implant

“The flared anchored end eliminated cage migration entirely, and the porous body fused in 6-8 months instead of 12. One implant, two problems solved, three regulatory markets with one part number.”

 

Material: Pure Titanium / Ti-6Al-4V ELI (ASTM F136)  |  Process: SLM + HIP + Passivation  |  Application: Spinal Cage with Porous Body & Anchored End