It is technically demanding and requires rich experience to insert the translaminar facet screw(TFS) via the paramedian mini-incision approach. It seems that it is easy to place the TFS using computer-assisted design and rapid prototyping(RP) techniques. However, the accuracy and safety of these techniques is still unknown. The aim of this study is to assess the accuracy and safety of translaminar facet screw placement in multilevel unilateral transforaminal lumbar interbody fusion using a rapid prototyping drill guide template system. A patient-matched rapid prototyping translaminar facet screw guide was examined in fourteen cadaveric lumbar spine specimens. A three-dimensional (3D) preoperative screw trajectory was constructed using spinal computed tomography scans, from which individualized guides were developed for the placement of translaminar facet screws. Following bone tunnel establishment, the 3D positioning of the entry point and trajectory of the screws was compared to the preoperative plan as found in the Mimics software.Among 60 trajectories eligible for assessment, no cases of clinically significant laminar perforation were found. The mean deviation between the planned and the actual starting points on spinous process was 1.22 mm. The mean tail and submergence angle deviation was found to be 0.68°and 1.46°, respectively. Among all the deviations, none were found to have any statistical significance. These results indicate that translaminar facet screw placement using the guide system is both accurate and safe.

Objectives: Stakeholder co-production in design of public health programmes may reduce the 'implementation gap' but can be time-consuming and costly. Prototyping, iterative refining relevant to delivery context, offers a potential solution. This evaluation explored implementation and lessons learnt for a 12-week referral-based weight-management programme, 'Momenta', along with feasibility of an iterative prototyping evaluation framework.
Design: Mixed methods evaluation: Qualitative implementation exploration with referrers and service users; preliminary analysis of anonymised quantitative service data (12 and 52 weeks).
Setting: Two leisure centres in Northumberland, North East England.
Participants: Individual interviews with referring professionals (n=5) and focus groups with service users (n=13). Individuals (n=182) referred by healthcare professionals (quantitative data).
Interventions: Three 12-week programme iterations: Momenta (n=59), Momenta-Fitness membership (n=58) and Fitness membership only (n=65).
Primary and Secondary Outcome Measures: Primary outcome: Qualitative themes developed through stakeholder-engagement. Secondary outcomes included preliminary exploration of recruitment, uptake, retention, and changes in weight, body mass index, waist circumference and psychological well-being.
Results: Service users reported positive experiences of Momenta. Implementation gaps were revealed around the referral process and practitioner knowledge. Prototyping enabled iterative refinements such as broadening inclusion criteria. Uptake and 12-week retention were higher for Momenta (84.7%, 45.8%) and Momenta-Fitness (93.1%, 60.3%) versus Fitness only (75.4%, 24.6%). Exploration of other preliminary outcomes (completers only) suggested potential for within-group weight loss and increased psychological well-being for Momenta and Momenta-Fitness at 12 weeks. 52 week follow-up data were limited (32%, 33% and 6% retention for those who started Momenta, Momenta-Fitness and Fitness, respectively) but suggested potential weight loss maintenance for Momenta-Fitness.
Conclusions: Identification of issues within the referral process enabled real-time iterative refinement, while lessons learnt may be of value for local implementation of 'off-the-shelf' weight management packages more generally. Our preliminary data for completers suggest Momenta may have potential for weight loss, particularly when offered with a fitness membership.
(© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY. Published by BMJ.)

Zygomatic fractures account for 10% to 15% of all facial fractures. The surgical management of isolated zygomatic arch fractures usually requires open reduction treatment without fixation through an intraoral access. Therefore, the main problem in the non-fixed treatment of zygomatic arch fractures is related to the difficulty in obtaining a stable reduction for a period long enough to guarantee the physiological bone healing process. We propose an innovative "in-house" rapid prototyping (RP) protocol for the 3D-zygoma mask manufacture of a patient-specific protective device to apply after zygomatic arch fracture reduction. Our study includes 16 consecutive patients who underwent surgical open reduction for an isolated zygoma fracture without fixation between January 2017 and February 2018. The patients received regular postoperative checks at weeks 1 and 2. Before the device was removed, a multiple choice questionnaire was administered to measure the degree of wearability of the mask. The estimated cost of the production is around &OV0556;5 per case and the construction time is around 90 minutes. Based on the encouraging results, obtained in our experience, we hope that other studies can be conducted to confirm our procedure and improve its functionality in the field of facial trauma.

Background: Restoring the orbital cavity integrity in orbital floor defects is a challenging issue due to the anatomical complexity of the floor's surface. This is a showcase for technical description of a novel "in house" rapid prototyping protocol aimed to customize implant for orbital floor reconstruction.
Methods: The authors present 4 cases to show our Computer-aided-design and Computer-aided-manufacturing digital workflow. The system was based on a 3D-printed press that; through a virtually designed mold, was used to conform a patient specific titanium mesh for orbital floor reconstruction.
Results: The merging procedure analysis by iPlan Cranial 3.0 (Brainlab, Munich, Germany) highlighted a 0.71 ± 0.23 mm (P <0.05) discrepancy in a point-to-point superimposition between the digital planned reconstruction and the real in vivo result.
Conclusions: The authors expect that this technique will reduce operative time and cost however further study and larger series may better define the applicability in everyday surgical practice.

Purpose: To explore 3D printing for rapid development of prototype thin slab low-Z/density ionization chamber arrays viable for custom needs in radiotherapy dosimetry and quality assurance (QA).
Materials and Methods: We designed and fabricated parallel plate ionization chambers and ionization chamber arrays using an off-the-shelf 3D printing equipment. Conductive components of the detectors were made of conductive polylactic acid (cPLA) and insulating components were made of acrylonitrile butadiene styrene (ABS). We characterized the detector responses using a Varian TrueBeam linac at 95 cm SSD in slab solid water phantom at 5 cm depth. We measured the current-voltage (IV) curves, the response to different energy beam lines (2.5 MV, 6 MV, 6 MV FFF) for various dose rates and compared them to responses of a commercial Exradin A12 ionization chamber. We measured off-axis ratio (OAR) for several small field static multi-leaf collimators field sizes (0.5-3 cm) and compared them to OAR data obtained for commissioning of stereotactic radiotherapy.
Results: We identified the printing capability and the limitations of a low-cost off-the-shelf 3D printer for rapid prototyping of detector arrays. The design of the array with sub-millimeter size features conformed to the 3D printing capabilities. IV-curve for the array showed a strong polarity effect (8%) due to the design. Results for the parallel plate and the array compared well with A12 chamber: monitor unit (MU) dependence for the array was within a few % and the response to different energy beam lines was within 1%. Off-axis dose profiles measured with the array were comparable to dose profiles obtained in water tank and stereotactic diode after accounting for the size of the chambers. Dose error was within 2% at the center of the profile and slightly larger at the penumbra.
Conclusions: Rapid prototyping of ion chambers by means of low-cost 3D printing is feasible with certain limitations in the design and spatial accuracy of the printed details.
(© 2019 American Association of Physicists in Medicine.)