The Adjustable Cranial Plate: A Novel Implant Designed to Eliminate the Need for Cranioplasty Surgery Following a Hemicraniectomy Operation.

BACKGROUND: Decompressive hemicraniectomy (DHC) is performed to relieve life-threatening intracranial pressure elevations. After swelling abates, a cranioplasty is performed for mechanical integrity and cosmesis. Cranioplasty is costly with high complication rates. Prior attempts to obviate second-stage cranioplasty have been unsuccessful. The Adjustable Cranial Plate (ACP) is designed for implantation during DHC to afford maximal volumetric expansion with later repositioning without requiring a second major operation. METHODS: The ACP has a mobile section held by a tripod fixation mechanism. Centrally located gears adjust the implant between the up and down positions. Cadaveric ACP implantation was performed. Virtual DHC and ACP placement were done using imaging data from 94 patients who had previously undergone DHC to corroborate our cadaveric results. Imaging analysis methods were used to calculate volumes of cranial expansion. RESULTS: The ACP implantation and adjustment procedures are feasible in cadaveric testing without wound closure difficulties. Results of the cadaveric study showed total volumetric expansion achieved was 222 cm3. Results of the virtual DHC procedure showed the volume of cranial expansion achieved by removing a standardized bone flap was 132 cm3 (range, 89-171 cm3). Applied to virtual craniectomy patients, the total volume of expansion achieved with the ACP implantation operation was 222 cm3 (range, 181-263 cm3). CONCLUSIONS: ACP implantation during DHC is technically feasible. It achieves a volume of cranial expansion that will accommodate that observed following survivable hemicraniectomy operations. Moving the implant from the up to the down position can easily be performed as a simple outpatient or inpatient bedside procedure, thus potentially eliminating second-stage cranioplasty procedures.