It Is Time to Reduce Free-Hand Manipulation: Case Report of Our Proposal for an Innovative 1-Step Cranioplasty.

BACKGROUND: Cranioplasty is a well-known procedure, and autologous graft bone is usually considered the best choice in this procedure, but it cannot be used in conditions such as bone-infiltrating tumors, spheno-orbital en plaque meningiomas, and bone infections. Polymethylmethacrylate (PMMA) offers great possibility of intraoperative adaption. We describe a case of 1-step cranioplasty performed in a patient with a meningeal fibrosarcoma using a custom-made silicon mold. CASE DESCRIPTION: A 48-year-old man was admitted to our department for a left temporo-parietal subcutaneous tumefaction that grew for a few months on the site of a previous osteodural decompression. After a biopsy that was diagnostic for meningeal fibrosarcoma, we planned tumor asportation, considering the bone infiltration of the tumor and the necessity of a cranioplasty. Before the intervention, we performed the craniotomy on a gypsum powder head phantom created based on a computed tomography scan. Then, using a computer-assisted design technique, a silicon mold was created and sterilized for the intervention. The edges of the preoperative simulated craniectomy were reproduced during the intervention using a rigid rail on the patient's scalp. The craniectomy was performed, and the tumor was removed. Then, a PMMA bone flap was made using a silicon mold and was fixed to the skull by miniscrews. Aesthetic results were considered excellent by the patient. CONCLUSIONS: We performed a 1-step cranioplasty after resection of a meningeal fibrosarcoma that infiltrated bone with a new technique to reproduce during intervention a preoperative simulated craniectomy and a computer-assisted design PMMA flap.

Surgical results of cranioplasty with a polymethylmethacrylate customized cranial implant in pediatric patients: a single-center experience.

OBJECTIVE Cranioplasty is a reconstructive procedure used to restore skull anatomy and repair skull defects. Optimal skull reconstruction is a challenge for neurosurgeons, and the strategy used to achieve the best result remains a topic of debate, especially in pediatric patients for whom the continuing skull growth makes the choice of material more difficult. When the native bone flap, which is universally accepted as the preferred option in pediatric patients, is unavailable, the authors' choice of prosthetic material is a polymethylmethacrylate (PMMA) implant designed using a custom-made technique. In this paper the authors present the results of their clinical series of 12 custom-made PMMA implants in pediatric patients. METHODS A retrospective study of the patients who had undergone cranioplasty at Gaslini Children's Hospital between 2006 and 2013 was conducted. A total of 12 consecutive cranioplasties in 12 patients was reviewed, in which a patient-specific PMMA implant was manufactured using a virtual 3D model and then transformed into a physical model using selective laser sintering or 3D printing. All patients or parents were administered a questionnaire to assess how the patient/parent judged the aesthetic result. RESULTS Patient age at craniectomy ranged from 5 months to 12.5 years, with a mean age of 84.33 months at cranioplasty. The mean extension of the custom-made plastic was 56.83 cm(2). The mean time between craniectomy and cranioplasty was 9.25 months. The mean follow-up duration was 55.7 months. No major complications were recorded; 3 patients experienced minor/moderate complications (prosthesis dislocation, granuloma formation, and fluid collection). CONCLUSIONS In this patient series, PMMA resulted in an extremely low complication rate and the custom-made technique was associated with an excellent grade of patient or parent satisfaction on long-term follow up.

A new design of a Nitinol ring-like wire for suturing in deep surgical field.

The present work proposes a new suturing procedure based on self-accommodating suture points. Each suture point is made of a commercial NiTi wire hot-shaped in a single loop ring; a standard suture needle is then fixed at one end of the NiTi suture. According to this simple geometry, several NiTi suture stitches have been prepared and tested by tensile test to verify the closing force in comparison to that of commercial sutures. Further experimental tests have also been performed on anatomic samples from animals to verify the handiness of the NiTi suture. Moreover, surface quality of sutures has been carefully investigated via microscopy. Results show that the NiTi suture expresses high stiffness and a good surface quality. In addition, the absence of manual knotting allows for a simple, fast and safe procedure.

Design and thermo-mechanical analysis of a new NiTi shape memory alloy fixing clip.

In this work, a new NiTi shape memory alloy (SMA) bone fixator is proposed. Thanks to the shape memory effect, this device does not need any external tool for the fixation, as the anchorage is obtained only by the self-accommodation of the clip during the parent transformation. Calorimetry and thermo-mechanical tests were used to evaluate the phase transformation temperatures and to estimate the forces generated both during the fixing surgical procedure and after the surgical operation. An application on animal anatomical sample was also performed; an appropriate mechanical tightness as well as a good handiness has been found.

A finite element model of the L4-L5 spinal motion segment: biomechanical compatibility of an interspinous device.

The biomechanical compatibility of an interspinous device, used for the "dynamic stabilization" of a diseased spinal motion segment, was investigated. The behaviour of an implant made of titanium based alloy (Ti6Al4V) and that of an implant made of a super-elastic alloy (Ni-Ti) have been compared. The assessment of the biomechanical compatibility was achieved by means of the finite element method, in which suitable constitutive laws have been adopted for the annulus fibrosus and for the metal alloys. The model was aimed at simulating the healthy, the nucleotomized and the treated L4-L5 lumbar segment, subjected to compressive force and flexion-extension as well as lateral flexion moments. The computational model has shown that both the implants were able to achieve their main design purpose, which is to diminish the forces acting on the apophyseal joints. Nevertheless, the Ni-Ti implant has shown a more physiological flexural stiffness with respect to the Ti6Al4V implant, which exhibited an excessive stiffness and permanent strains (plastic strains), even under physiological loads. The computational models presented in this paper seems to be a promising tool able to predict the effectiveness of a biomedical device and to select the materials to be used for the implant manufacturing, within an engineering approach to the clinical problem of the spinal diseases.