Semi-automated digital workflow to design and evaluate patient-specific mandibular reconstruction implants.

The reconstruction of large mandibular defects with optimal aesthetic and functional outcomes remains a major challenge for maxillofacial surgeons. The aim of this study was to design patient-specific mandibular reconstruction implants through a semi-automated digital workflow and to assess the effects of topology optimization on the biomechanical performance of the designed implants. By using the proposed workflow, a fully porous implant (LA-implant) and a topology-optimized implant (TO-implant) both made of Ti-6Al-4V ELI were designed and additively manufactured using selective laser melting. The mechanical performance of the implants was predicted by performing finite element analysis (FEA) and was experimentally assessed by conducting quasi-static and cyclic biomechanical tests. Digital image correlation (DIC) was used to validate the FE model by comparing the principal strains predicted by the FEM model with the measured distribution of the same type of strain. The numerical predictions were in good agreement with the DIC measurements and the predicted locations of specimen failure matched the actual ones. No statistically significant differences (p < 0.05) in the mean stiffness, mean ultimate load, or mean ultimate displacement were detected between the LA- and TO-implant groups. No implant failures were observed during quasi-static or cyclic testing under masticatory loads that were substantially higher (>1000 N) than the average maximum biting force of healthy individuals. Given its relatively lower weight (16.5%), higher porosity (17.4%), and much shorter design time (633.3%), the LA-implant is preferred for clinical application. This study clearly demonstrates the capability of the proposed workflow to develop patient-specific implants with high precision and superior mechanical performance, which will greatly facilitate cost- and time-effective pre-surgical planning and is expected to improve the surgical outcome.

[Familial Wolfram syndrome]. / Syndrome de Wolfram familial.

Wolfram syndrome (WS) is a rare autosomal recessive progressive neurodegenerative disorder, and it is mainly characterized by the presence of diabetes mellitus and optic atrophy. Other symptoms such as diabetes insipidus, deafness, and psychiatric disorders are less frequent. The WFS1 gene, responsible for the disease and encoding for a transmembrane protein called wolframin, was localized in 1998 on chromosome 4p16. In this report, we present a familial observation of Wolfram syndrome (parents and three children). The propositus was a 6-year-old girl with diabetes mellitus and progressive visual loss. Her family history showed a brother with diabetes mellitus, optic atrophy, and deafness since childhood and a sister with diabetes mellitus, optic atrophy, and bilateral hydronephrosis. Thus, association of these familial and personal symptoms is highly suggestive of Wolfram syndrome. The diagnosis was confirmed by molecular analysis (biology), which showed the presence of WFS1 homozygous mutations c.1113G>A (p.Trp371*) in the three siblings and a heterozygote mutation in the parents. Our observation has demonstrated that pediatricians should be aware of the possibility of Wolfram syndrome when diagnosing optic atrophy in diabetic children.