The thread design and larger core diameter are designed to minimize notch concentration and enhance its strength. (Import Screw Testing information from the Design Rationale.)

The screws were designed to optimize strength and stability of the implant. The enlarged area under the head of the screw is designed to provide additional cortical purchase as the screw seats to bone. Competitive designs have achieved market acceptance with even smaller thread designs (Synthes). See Design Rationale.

It is not uncommon to unintentionally overdrill the near cortex due to a "wobble" effect often associated with using power drills. The TRIGEN◊ screw was designed with expanded threads at the head to enhance bony purchase at the near cortex. The optimal size of the expanded threads was determined by balancing maximum bony purchase while minimizing the risk of micro-fractures.

The Knee Nail guide is designed to allow one transverse screw to be inserted medial to lateral, while the two oblique screws are inserted at 25° anterior to posterior to avoid important anatomical structures. The guide rotates 180° for added convenience in placing the second oblique screw.

Our clinical experiences, to date, have not indicated any problems in this area when the proper length screw is used. It is important not to exceed the measured length off the drill or screw length gauge. As with any screw, placing one into the bone that is too long can increase the risk of irritation. Current external fixation half pin designs with sharp tips are well-tolerated by patients, as are the TRIGEN◊ screws when properly measured.

(Import pictures and distances from the Design Rationale. See Knee Nail and FAN Fact Sheets to show pictures and distances.)