Anatomy and mobility in the adult cadaveric craniocervical junction.

Genetic diseases with craniofacial malformations can be associated with anomalies of the craniocervical joint (CCJ). The functions of the CCJ are thus impaired, as mobility may be either limited by abnormal bone fusion causing headaches, or exaggerated in the case of hypermobility, which may cause irreparable damage to the spinal cord. Restoring the balance between mobility and stability requires surgical correction in children. The anatomy and biomechanics of the CCJ are quite unique, yet have been overlooked in the past decades. Pediatric evidence is so scarce, that investigating the adult CCJ is our best shot to disentangle the form-function relationships of this anatomical region. The motivation of the present study was to understand the morphological and functional basis of motion in the CCJ, in the hope to find morphological features accessible from medical imaging able to predict mobility. To do so, we have quantified the in-vitro kinematics of the CCJ in nine cadaveric asymptomatic adults, and estimated a wide range of mobility variables covering the complexity of spinal motion. We compared these variables with the shape of the occipital, the atlas and the axis, obtained using a dense geometric morphometric approach. Morphological joint congruence was also quantified. Our results suggest a strong relationship between bone shape and motion, with the overall geometry predicting best the primary movements, and the joint facets predicting best the secondary movements. We propose a functional hypothesis stating that the musculoligamental system determines movements of great amplitude, while the shape and congruence of joint facets determine the secondary and coupled movements, especially by varying the geometry of bone stops and the way ligaments are tensioned. We believe this work will provide valuable insights in understanding the biomechanics of the CCJ. Furthermore, it should help surgeons treating CCJ anomalies by enabling them to translate objectives of functional and clinical outcome into clear objectives of morphological outcome.

Intentional craniofacial remodelling in Europe in the XIXth century: Quantitative evidence of soft tissue modifications from Toulouse, France.

Intentional skull deformations have been practiced by every human population, from the prehistoric times until the XXth century. In Europe, they were specifically prevalent in the region of Toulouse, France. The soft-tissue modifications due to such practices are not well characterized in the literature due to the rarity of photographic data. Most studies on skull deformations are thus based on skeletal remains. Here we performed a controlled geometric morphometric assessment of 31 frontal pictures and 70 lateral pictures of individuals from Toulouse with intentional deformations extracted from two XIXth century historical French photographic archives. We also measured the forces exerted on the skull vault by the traditional deformation device from Toulouse using a 3D-printed skull and pressure sensors. We showed that individuals with Toulouse deformations have distinctive facial features, caused by moderate forces exerted on the skull vault. Our results exhibit and quantify for the first time the real face of intentional skull deformations, which are a ubiquitous and distinctive feature of the human species.

3D-printed suture guide for thoracic and cardiovascular surgery produced during the COVID19 pandemic.

Emergency 3D-printing of medical devices came out as a potential solution to tackle shortages during the COVID-19 pandemic. Manufacturing medical devices in small series within hospitals is an exciting perspective in crisis management. Health professionals and additive manufacturing technology are ready for this revolution but regulative adaptations are still required. Here we present the design and production of a suture guide for cardiac surgery as a case study for a 3D-printed medical device manufactured during the COVID-19 pandemic.