Development of a stereotactic frame for neurosurgery targeting: A prospective pre-clinical study

Current commercial stereotactic frames have several limitations and are geometrically complex. They utilize imaginary, physically unreachable reference points, and they are expensive. We designed a three-dimensional, low-cost, and easy-to-assemble frame that can both visualize and physically reach the reference point at (0, 0, 0). Our frame allows simultaneous bilateral targeting via distinct trajectories, thereby reducing operative time while providing wider facial exposure for airway protection.

In a prospective phantom experiment (August-October 2025), five operators each performed five passes at four radiopaque intracranial targets (100 attempts). Before every pass, the frame was physically re-zeroed to the reference point. For each attempt, we recorded the three-dimensional Euclidean target registration error (TRE) and the signed axis-specific offsets. Linear mixed-effects modelling with operator and target location as random factors, intraclass correlation, and Bland-Altman agreement were utilized for statistical analyses.

All 100 trajectories contacted their intended target. Mean±SD TRE was 0.19 ± 0.07 mm. Every attempt fell within 1 mm of the target (100 %, 95 %CI 96.4-100 %). Axis-wise biases were negligible (Δx = 0.01 mm, Δy = -0.01 mm, Δz = -0.01 mm; all p > 0.33). Bland-Altman limits of agreement were ±0.23 mm (x), ±0.24 mm (y), and ±0.24 mm (z) with no trend across the measurement range. Mixed-effects modelling attributed 12.5 % of the residual variance to operators, 7.1 % to target location, and 80.4 % to unexplained (within-trial) error; the adjusted ICC was 0.20, indicating low between-operator variability relative to total variance. Neither repetition order (p = 0.38) nor location (p = 0.08) influenced TRE. The mean setup-to-trajectory time was under 10 min per operator.

Our stereotactic system delivered reproducible, near-millimeter accuracy in phantom testing while simplifying setup, reducing operative time, and eliminating expensive software dependency. These findings justify advancing to cadaveric studies and early clinical trials to broaden access to frame-based stereotaxy for urgent procedures, such as external ventricular drain placement, across diverse healthcare environments.