Are terminally threaded guide pins from cannulated screw systems dangerous?

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Surgical Safety

Background:

• Threaded and smooth pins are standard in orthopedic procedures.
• Aberrant pin placement can lead to soft tissue injuries, including nerve or vessel damage.
• Understanding pin behavior is crucial for preventing surgical complications.

Purpose of the Study:

• To compare the risk of nerve injury between threaded and smooth guide pins.
• To evaluate injury risk associated with over-drilling past the bone cortex.
• To assess the likelihood and magnitude of soft tissue entanglement with pins.

Main Methods:

• Porcine femurs were used to simulate bone drilling.
• Blindfolded participants drilled pins to assess over-drilling distance.
• Nerve entanglement was tested by drilling near simulated nerves at different angles, measuring wrapped nerve length.

Main Results:

• Threaded pins were over-drilled significantly more than smooth pins (16.9 mm vs. 4.6 mm).
• Nerve entanglement was more frequent and extensive with threaded pins in both perpendicular and parallel drilling positions.
• The tactile feedback for detecting bone cortex penetration was less reliable with threaded pins.

Conclusions:

• Threaded pins pose a higher risk of nerve injury due to increased over-drilling and soft tissue entanglement.
• The tactile sensation of bone cortex breakthrough is less precise with threaded pins.
• Smooth pins appear to offer a safer alternative regarding nerve and soft tissue protection in orthopedic applications.