English 
Small Fragment (2.7mm / 3.5mm) & Large Fragment (4.5mm) Cortical and Cancellous Bone Screw Thread Profiles
Detailed dimensional guide to self-tapping cortical screws, partially/fully threaded cancellous screws, and StarDrive/hexagonal recess torque transmission.
On this page (2)
Precision thread pitch, core-to-outer diameter ratio, and cutting flute geometry determine insertion torque and axial pullout strength in cortical diaphyseal vs trabecular metaphyseal bone.
1. Dimensional Specifications Across Fragment Systems
| Screw Classification | Outer Thread Ø | Core Ø / Drill Bit | Thread Pitch | Hex / Star Recess |
|---|---|---|---|---|
| 2.7 mm Cortex Screw (Self-Tapping) | 2.7 mm | 1.9 mm / 2.0 mm drill | 1.0 mm | 2.5 mm Hex / T8 Star |
| 3.5 mm Cortex Screw (Self-Tapping) | 3.5 mm | 2.4 mm / 2.5 mm drill | 1.25 mm | 2.5 mm Hex / T15 Star |
| 3.5 mm Locking Screw | 3.5 mm | 2.9 mm / 2.8 mm drill | 0.8 mm (Double-lead) | 2.5 mm Hex / T15 Star |
| 4.0 mm Cancellous Screw | 4.0 mm | 1.9 mm / 2.5 mm drill | 1.75 mm | 2.5 mm Hex |
| 4.5 mm Cortex Screw (Large Frag) | 4.5 mm | 3.1 mm / 3.2 mm drill | 1.75 mm | 3.5 mm Hex |
| 6.5 mm Cancellous Screw (16/32mm) | 6.5 mm | 3.0 mm / 3.2 mm drill | 2.75 mm | 3.5 mm Hex |
2. Three-Flute Self-Tapping Tip Geometry
OrthoValley cortical and locking screws feature CNC-milled triple radial cutting flutes that clear bone chips into the flute reservoir during insertion, reducing thermal necrosis and eliminating separate tapping in normal cortical bone.
Dr. Tariq Mahmood
Implant Grade Titanium & ISO 5832-3 Metallurgy Advisor
Reviewed against ASTM F136 / ISO 5832-3 Ti-6Al-4V ELI titanium and ISO 5832-1 316LVM implant metallurgy, locking thread geometry, and AO trauma standards.