Validation of an optical, computer-assisted technique for intraoperative tracking of 3-dimensional canine stifle joint motion

Background: Cranial cruciate ligament (CCL) rupture is the most common orthopedic pathology in dog and in men. In human, optical computer-assisted technique is considered as a repeatable and reliable method for the biomechanical assessment of joint kinematics and laxity in case of CCL surgery. Aim: To evaluate the repeatability and reliability afforded by clinical tests in terms of laxity measured by means of a computer-assisted tracking system in two canine CCL conditions: CCL-Intact, CCL-Deficient. Methods: Fourteen fresh frozen canine stifles were passively subjected to Internal/External (IE) rotation at 120\ub0 of flexion and Cranial drawer test (CC). To quantify the repeatability and the reliability, intra-class correlation coefficient (ICC) and the mean percent error were evaluated (\u394 r %). Results: The study showed a very good intra-class correlation, before and after CCL resection for kinematics tests. It was found a minimum ICC = 0.73 during the IE rotation in CCL-Intact and a maximum value of ICC = 0.97 for the CC displacement in CC-Deficient. IE rotation with CCL-Intact is the condition with the greatest \u394 r % = 14%, while the lowest \u394 r % = 6% was obtained for CC displacement in CCL-Deficient. Conclusion: The presented work underlined the possibility of using a computer-assisted method also for biomechanical studies concerning stifle kinematics and laxity

preliminary study of inkjet printed sensors for monitoring cell cultures

Abstract An extremely promising methodology able to obtain feedbacks from cell cultures is represented by the direct integration within culture substrates of specific sensitive elements capable to provide information related to cell adhesion, migration, differentiation and growth. At present, the most common materials used in the implementation of sensors monitoring 2D cell culture are noble metals. However, printed electronics allow instead an innovative approach, from both sensor realization technique and utilization of sensitive materials. This project aims to develop and test 2D ink-jet printed sensors, focusing on biocompatible substrates and conductive inks. Both biocompatibility and printability of two different sensor designs were evaluated, followed by electronic measurements that estimate fibroblast adhesion. Preliminary findings show a good biocompatibility of the Kapton® substrate coupled with PEDOT:PSS ink. This solution allowed us to correlate cell adhesion with an increase of impedance module, in agreement with the optical observation. On-going works rely on the evaluation of different materials used for both substrates and inks, addressing the possibility to monitor cardiomyocyte activity

Screen-Printed Biosensors for the Early Detection of Biomarkers Related to Alzheimer Disease: Preliminary Results

Abstract Alzheimer disease (AD), despite representing the most common type of dementia in elderly, is still lacking reliable methodologies for early diagnosis. A potential biomarker associated to AD development has been recently identified in the open isoform of p53, redox sensitive protein, currently quantified using a specific blood-based enzyme-linked immunosorbent assay (ELISA). In order to overcome ELISA limitations (level of detection, standardization and reliability), this study aimed to realize a low cost highly sensitive portable point-of-care (PoC) testing system based on screen printed electrochemical sensors (SPES). The study specifically reported the design of the platform, including the sensing probe and the electronic circuit devoted to the conditioning of the electric signal. Preliminary results were obtained from circuit testing by using controlled concentrations of electrolytic solutions and from an initial calibration stage by using Anodic Stripping Voltammetry (ASV) measurements. Future works will address the quantification of unknown concentration of unfolded p53 in peripheral blood samples, thus to validate the here-presented low cost, easy to use and highly precise platform

Advanced microscopy analysis of the micro-nanoscale architecture of human menisci

The complex inhomogeneous architecture of the human meniscal tissue at the micro and nano scale in the absence of artefacts introduced by sample treatments has not yet been fully revealed. The knowledge of the internal structure organization is essential to understand the mechanical functionality of the meniscus and its relationship with the tissue’s complex structure. In this work, we investigated human meniscal tissue structure using up-to-date non-invasive imaging techniques, based on multiphoton fluorescence and quantitative second harmonic generation microscopy complemented with Environmental Scanning Electron Microscopy measurements. Observations on 50 meniscal samples extracted from 6 human menisci (3 lateral and 3 medial) revealed fundamental features of structural morphology and allowed us to quantitatively describe the 3D organisation of elastin and collagen fibres bundles. 3D regular waves of collagen bundles are arranged in “honeycomb-like” cells that are comprised of pores surrounded by the collagen and elastin network at the micro-scale. This type of arrangement propagates from macro to the nanoscale

Hamstring grafts for anterior cruciate ligament reconstruction show better magnetic resonance features when tibial insertion is preserved

Purpose: Comparing the MRI features of the grafts between a group of patients treated with an over-the-top anterior cruciate ligament reconstruction technique that preserves the hamstring attachment and a control group with a classical reconstruction technique. Methods: Patients were assigned to a standard reconstruction technique or an Over-the-top plus lateral plasty technique. All patients underwent preoperative, 4-months and 18-months MRI; together with a clinical evaluation with KOOS and KT1000 laxity assessment. MRI study involved different parameters: the \u201cGraft\u201d was evaluated with the continuity, Howell Grading system, presence of liquid and signal noise quotient. The \u201cTibial Tunnel\u201d was evaluated with the signal noise quotient, presence of edema or liquid and tunnel widening. All points assigned to each parameter formed a composite score ranging from 0\u201310. Tunnel and graft positioning were evaluated. Results: At 18-month 20 MRIs (10 each group) were available, demographics were not significantly different between groups. The non-detached group showed significantly less liquid within the graft at 4-months (p = 0.008) and 18-months (p = 0.028), the tunnel was significantly smaller (p < 0.05) and less enlarged at both follow-ups (p < 0.05), signal noise quotient of the intra-tunnel graft was lower at 18-months (p < 0.05). The total score of the non-detached group saw a significant improvement at 4-months (p = 0.006) that remained stable at 18-months (n.s.). Conclusions: Hamstring grafts, which tibial insertions were preserved, showed better MRI features at 4-and 18-months follow-up, especially in terms of liquid effusion, tunnel enlargement and signal noise quotient. Level of evidence: IV

No differences in knee kinematics between active and passive flexion-extension movement: an intra-operative kinematic analysis performed during total knee arthroplasty

Purpose: The objective of the present study was to acquire and compare by the use of a navigation system the intra-operative flexion-extension movement of the knee performed actively by the patient and passively by the surgeon before and after a total knee arthroplasty (TKA) implantation. Methods: A cohort of 31 patients with primary knee osteoarthritis (OA), candidate for TKA underwent intra-operative kinematics assessment with a commercial navigation system before and after the definitive implant positioning of a Cruciate Retaining (CR) Mobile Bearing (MB) prostheses. The kinematical data were acquired while surgeon performed the flexion-extension movement (passive ROM - pROM), and while the patient performed it (active ROM - aROM). Differences between pre- and post- implantation and between active and passive motions, were statistically analyzed using paired Student t-tests (p = 0.05). Results: No statistically significant difference were found between aROM and pROM with paired Student t-test regarding internal-external rotation and anterior-posterior translation of the femoral component with respect to the tibia during flexion-extension movement before and after TKA implant (p > 0.05). Conclusions: Active muscle contraction seems to not significantly affect TKA kinematics. The ROM performed by the surgeon during operation resemble the movement actively performed by the patient. The clinical relevance of this study further supports the use of CAS system in performing intra-operative analysis concerning knee biomechanics

Structural-mechanical characterization of human ligaments using a custom-made tensile test chamber combined with the Skyscan1176 system

Anterior cruciate ligament (ACL) injuries are one of the major and one of the most frequent clinical problems in orthopedics1. Connecting femur and tibia, the ACL decreases the joint degrees of freedom and maintaines joint stability under load conditions. Thus, ACL plays a fundamental role in the stability and functionality of the knee. When injured, the common approach lies on its surgical reconstruction by using several types of graft2. However, surgical or implant reconstruction techniques still show unsatisfactory long-term success. Therefore, the knowledge of the biomechanical, structural and morphological properties of native tissues is fundamental in order to reduce the need of surgical revision and the probability of early development of other pathologies, such as osteoarthritis. This better understanding of the properties of ACL could help to optimize the choice and the development of new grafts and scaffolds. Dense connective fibrous tissues, such as ACL, typically exhibit non-linear stress-strain characteristics related to fibers crimp, orientation and tension, which intrinsically define its functional properties. The behavior of ACL bundles in relation of its fibrous structure has already been studied under load, but considering only the outer surface and not the entire 3D structure3. Aim of this study was to design and test a dedicated setup able to acquire the volumetric fibrous microstructure of the ACL samples, under progressive increasing mechanical strain

Assessment of human soft tissue microstructure under tensile load by using the Skyscan 1176 system: preliminary results

This study aimed to analyse the changes given by different levels of strain in the 3D microstructure of a fibrous soft tissue by using a microtomography system (micro-CT, Bruker Skyscan 1176) integrated with a custom-made tensioning device. Without loss of generality, the proposed approach was applied to the Anterior Cruciate Ligament. Two different samples were specifically analysed: a cadaveric tissue harvested by a healthy donor and a specimen obtained by a patient, who underwent total knee arthroplasty. Analysis was carried out by means of standard microtomographic procedures and focused on fiber orientation and stress-strain characteristic. Findings highlighted a clear difference in terms of fibrous density and arrangement between the two specimens. Besides providing proper mechanomicrostructural fingerprints for each human ligament/tendon and increasing the understanding on the effects of osteoarthritis on joint soft tissues, this approach can be useful also in tissue engineering, since it suggests correlation between tissue arrangements and mechanical behaviou