Dynamic craniotomy: translational development, biomechanical validation, and early clinical experience of an adaptive cranial bone flap fixation platform

Postoperative cerebral swelling, recurrent hemorrhage, and the trade-off between rigid bone flap fixation and decompressive craniectomy remain unresolved problems in cranial neurosurgery. The authors describe the translational development, biomechanical validation, and early clinical implementation of dynamic craniotomy using the NuCrani reversibly expandable plate and the KTC PEEK telescopic burr hole cover, and position this platform within the contemporary innovation continuum of cranial fixation devices.

The authors synthesized the device development pathway for dynamic craniotomy, integrating 1) the unmet clinical need and engineering rationale; 2) cadaveric intracranial pressure (ICP)-control studies and biomechanical static compression, static shear, and fatigue testing; 3) a first-in-human technical report; 4) a 25-patient consecutive series in traumatic brain injury (TBI); 5) a propensity score-matched comparison of dynamic versus fixed craniotomy in TBI; 6) a comparative series in spontaneous intracerebral hemorrhage; and 7) a posterior fossa case series. Outcomes examined included ICP control, bone flap migration behavior, midline shift, reoperation rate, wound complications, cranioplasty avoidance, and Glasgow Outcome Scale score at 3 months.

Cadaveric and biomechanical testing demonstrated greater ICP buffering (120-mL volume challenge: ICP rise from 2.8 to 13.4 mm Hg with dynamic craniotomy vs 11.4 to 100.1 mm Hg with fixed craniotomy, p = 0.04), a peak inward displacement load resistance of 643.3 ± 26.1 N, an expansion tolerance up to 71.6 mm, and zero failure across 500 fatigue cycles at 15 mm of excursion. Across the clinical series (≥ 60 patients), outward bone flap migration ≥ 5 mm occurred in 84%-100% of cases with worsening edema, with reciprocal decreases in midline shift; ≥ 8 mm migration occurred in approximately 40%-56%. No fixation failures, paradoxical sinking, rescue craniectomies, or cranioplasty procedures were required. In the propensity score-matched TBI cohort, dynamic craniotomy was associated with lower postoperative midline shift, lower mortality, and a higher proportion of favorable outcomes than fixed craniotomy. Because these comparative data derive from small, single-center, retrospective cohorts, they should be interpreted as preliminary and hypothesis generating.

Dynamic craniotomy is an adaptive, pressure-responsive cranial reconstruction platform that bridges the gap between fixed-plate craniotomy and decompressive craniectomy. Its translational pathway from concept and biomechanics to early clinical experience supports its feasibility and preliminary safety; however, because the comparative clinical data are limited, retrospective, single center, and generated by the device developers, the reported outcome advantages over conventional fixation remain unproven and require confirmation in prospective, independently conducted, multicenter studies. The platform nonetheless exemplifies a stepwise, low-disruption model for neurosurgical device innovation.