The Impact of Craniotomy and Surgical Fixation Devices on the Efficacy of Tumor Treating Fields in Glioblastoma Treatment

Glioblastoma is increasingly treated with Tumor Treating Fields (TTFields), but how post-craniotomy anatomy and fixation hardware alter delivered fields is unclear. We used finite-element modeling in a realistic head model to simulate TTFields after a standard bone flap with either a non-penetrating fixation plate or a penetrating skull clamp, and compared results to an intact-skull baseline across a range of clinically used array layouts. Bone gaps increased mean brain electric-field magnitude by [~]10-20%. Non-penetrating plates caused only minimal, localized changes relative to the bone-gap condition. In contrast, penetrating clamps produced strong but spatially confined increases: local mean fields were [~]6-8x higher within 5-10 mm of the device, with [≥] 50% enhancement extending [~]50-60 mm depending on whether the gap was modeled as healed scalp (soft-tissue-like) or healed bone; this enhancement decayed with distance. These simulations, performed in a single head model with literature-based tissue conductivities, suggest that penetrating hardware can substantially modulate local TTFields delivery, whereas non-penetrating plates have minimal impact. Accounting for post-surgical anatomy and hardware in TTFields planning may improve dose targeting.