Quantitative assessment of cranial fixation stability using a sensor-equipped head fixation device in neurosurgical...

Reliable head fixation is essential for accuracy in cranial neurosurgical procedures, particularly when using neuronavigation systems. While traditional skull clamps are designed to ensure rigid immobilization, undiscovered movement of patient´s head under external forces can undermine surgical precision.

In this study, we investigate the biomechanical performance of a head fixation device equipped with force and angle sensors. Using seven cadaveric heads and an external force applicator, we quantified resistance against the external force, the axial force at each pin and angular displacement of the two-pin rocker. The movement of head across three clinically relevant head positions for craniotomy: prone, middle fossa, and pterional was optically recorded by a neuronavigation system.

In the pterional position, the horizontal orientation of the two-pin rocker resisted significantly higher external shear forces (575.1 N, SD: 202.3 N) than the vertical orientation (427.2 N, SD: 105.9 N; p = 0.0081). Correspondingly, angular displacement of the two-pin rocker was lower in the horizontal orientation (0.48°, SD: 0.65°) than in the vertical orientation (1.15°, SD: 0.76°; p = 9.92 · 10^-5). No statistically significant differences were observed in the prone or middle fossa positions for the external shear forces.

These results suggest that optimal two-pin rocker orientation can mitigate slippage and angular drift, improving intraoperative reliability. This study provides a foundation for developing a quantitative stability model and evidence-based recommendations for skull clamp application in neurosurgical practice.