Effects of surgical errors on small fragment screw fixation

Area of Science:

• Orthopedic surgery
• Biomechanical testing
• Surgical technique optimization

Background:

• Small fragment screw fixation is crucial in orthopedic surgery.
• Technical errors during screw application can compromise fixation strength.
• Understanding the impact of errors is vital for successful surgical outcomes.

Purpose of the Study:

• To evaluate the biomechanical effects of technical errors in small fragment screw fixation.
• To determine the salvageability of screw holes after technical deviations.

Main Methods:

• Screw pullout strength was tested using a bone substitute model on a universal testing instrument.
• Nine sets of screws were tested, with seven sets employing intentionally altered techniques.
• Techniques evaluated included incorrect pilot hole drilling, improper tapping, screw exchanges, and overtightening.

Main Results:

• Drilling an oversized pilot hole (3.5mm for 3.5mm screw) and overtightening/stripping screws reduced pullout strength by 76% and 82% respectively (P<0.01).
• Using the incorrect tap decreased pullout strength by 11-12% (P<0.01).
• Inserting screws without tapping unexpectedly increased pullout strength by 4% (P<0.01).

Conclusions:

• Deviations from recommended techniques for orthopedic screw placement have variable effects on fixation strength.
• Certain technical errors, such as incorrect tapping, may allow for salvage of the screw hole.
• Maintaining surgical vigilance and adhering to sound principles are recommended to prevent fixation complications.