[Translated article] Validation of patient-specific 3D impression models for pelvic oncological orthopedic surgery.

INTRODUCTION: Pelvic ring tumours pose a challenge due to the difficulty in obtaining adequate surgical margins. Tools such as surgical navigation or 3D printing for the fabrication of patient-specific surgical positioning templates help in preoperative planning and intraoperative execution. Their correct positioning is essential in complex locations such as the pelvis, so it is necessary to identify positioning errors. The aim of this study is to demonstrate the reliability of 3D template placement for pelvic ring osteotomies. MATERIAL AND METHODS: Experimental study in cadaver with 10 hemipelvis. CT was performed to obtain the three-dimensional model, planning of osteotomies, design of positioning templates in ischiopubic (I), iliopubic (P), supracetabular (S) and iliac crest (C) branches; and a positioning marker (rigid-body) on the C and S templates for navigation. The templates and rigid-body are 3D printed and positioned according to pre-planning. Navigation allows the final position of the inserts and osteotomies to be checked. RESULTS: The positioning of the templates with respect to the preoperative planning varied depending on the location, being greater the error in those of the iliac crest. Using navigation the mean error of distance to the cutting plane is 3.5mm, except in pubis (5-8mm), being conditioned by the position of the rigid body. CONCLUSION: The use of patient-specific templates printed in 3D is a reliable tool for performing osteotomies in pelvic cancer surgery.

Validation of patient-specific 3D impression models for pelvic oncological orthopedic surgery. / Validación de los modelos de impresión 3D paciente-específicos para cirugía ortopédica oncológica pélvica.

INTRODUCTION: Pelvic ring tumors pose a challenge due to the difficulty in obtaining adequate surgical margins. Tools such as surgical navigation or 3D printing for the fabrication of patient-specific surgical positioning templates help in preoperative planning and intraoperative execution. Their correct positioning is essential in complex locations such as the pelvis, so it is necessary to identify positioning errors. The aim of this study is to demonstrate the reliability of 3D template placement for pelvic ring osteotomies. MATERIAL AND METHODS: Experimental study in cadaver with 10 hemipelvis. CT was performed to obtain the three-dimensional model, planning of osteotomies, design of positioning templates in ischiopubic (I), iliopubic (P), supracetabular (S) and iliac crest (C) branches; and a positioning marker (rigid-body) on the C and S templates for navigation. The templates and rigid-body are 3D printed and positioned according to pre-planning. Navigation allows the final position of the inserts and osteotomies to be checked. RESULTS: The positioning of the templates with respect to the preoperative planning varied depending on the location, being greater the error in those of the iliac crest. Using navigation the mean error of distance to the cutting plane is 3.5mm, except in pubis (5-8mm), being conditioned by the position of the rigid body. CONCLUSION: The use of patient-specific templates printed in 3D is a reliable tool for performing osteotomies in pelvic cancer surgery.

Serum melatonin concentration in the child with non-organic failure to thrive: comparison with other types of stress.

Human beings must adapt both to novel, unfavourable conditions and to circumstances of physical or psychological isolation. The initial response to stress depends fundamentally on the activation of the HPA axis. In regaining homeostatic equilibrium, melatonin plays a role due to its synchronising and anti-stress properties. To study the role of melatonin and the pineal gland in the organic and/or behavioural response to acute or chronic stress, 311 children were divided into two large groups: 1) Control Group - 121 healthy children classified, in turn, into 4 control subgroups, one for each pathology being studied; 2) Problem Groups, classified as traumatic stress (n=58), surgical stress (n=38), psychic stress (n=64) and febrile stress (n=30), according to pre-established clinical criteria. These groups were sub-classified according to the degree (low or high) and duration (acute or chronic) of the stress. This study used a case controlled, cross sectional design. Serum melatonin was measured by radioimmunoassay (RIA). In all the situations of acute stress, melatonin increased at a rate directly proportional to the severity and/or duration of the stress-causing stimulus. In contrast, in chronic stress, i.e. the Affective Deprivation Syndrome (or Psychological Dwarfism) with or without non-organic failure to thrive, resulted in the opposite response with a significant reduction of melatonin. In conclusion, in acute stress an increase in the bioavailability of melatonin could contribute to maintaining homeostatic balance. The lack of an appropriate response to acute stress could make some groups of patients (Affective deprivation syndrome with or without growth failure) predisposed to suffer depressive symptoms associated with a wide range of neurological, endocrinological or immunological consequences.