Techniques for 3D foot bone orientation angles in weight-bearing from cone-beam computed tomography.

BACKGROUND: For the diagnosis and treatment of foot and ankle disorders, objective quantification of the absolute and relative orientation angles is necessary. The present work aims at assessing novel techniques for 3D measures of foot bone angles from current Cone-Beam technology. METHODS: A normal foot was scanned via weight-bearing CT and 3D-model of each bone was obtained. Principal Component Analysis, landmark-based and mid-diaphyseal axes were exploited to obtain bone anatomical references. Absolute and relative angles between calcaneus and first metatarsal bone were calculated both in 3D and in a simulated sagittal projections. The effects of malpositioning were also investigated via rotations of the entire foot model. RESULTS: Large angle variations were found between the different definitions. For the 3D relative orientation, variations larger than 10 degrees were found. Foot malposition in axial rotation or in varus/valgus can result in errors larger than 5 and 3 degrees, respectively. CONCLUSIONS: New measures of foot bone orientation are possible in 3D and in weight-bearing, removing operator variability and the effects of foot positioning.

Correlations between weight-bearing 3D bone architecture and dynamic plantar pressure measurements in the diabetic foot.

BACKGROUND: Measurements of plantar loading reveal foot-to-floor interaction during activity, but information on bone architecture cannot be derived. Recently, cone-beam computer tomography (CBCT) has given visual access to skeletal structures in weight-bearing. The combination of the two measures has the potential to improve clinical understanding and prevention of diabetic foot ulcers. This study explores the correlations between static 3D bone alignment and dynamic plantar loading. METHODS: Sixteen patients with diabetes were enrolled (group ALL): 15 type 1 with (N, 7) and without (D, 8) diabetic neuropathy, and 1 with latent autoimmune diabetes. CBCT foot scans were taken in single-leg upright posture. 3D bone models were obtained by image segmentation and aligned in a foot anatomical reference frame. Absolute inclination and relative orientation angles and heights of the bones were calculated. Pressure patterns were also acquired during barefoot level walking at self-selected speed, from which regional peak pressure and absolute and normalised pressure-time integral were worked out at hallux and at first, central and fifth metatarsals (LOAD variables) as averaged over five trials. Correlations with 3D alignments were searched also with arch index, contact time, age, BMI, years of disease and a neuropathy-related variable. RESULTS: Lateral and 3D angles showed the highest percentage of significant (p < 0.05) correlations with LOAD. These were weak-to-moderate in the ALL group, moderate-to-strong in N and D. LOAD under the central metatarsals showed moderate-to-strong correlation with plantarflexion of the 2nd and 3rd phalanxes in ALL and N. LOAD at the hallux increased with plantarflexion at the 3rd phalanx in ALL, at 1st phalanx in N and at 5th phalanx in D. Arch index correlated with 1st phalanx plantarflexion in ALL and D; contact time showed strong correlation with 2nd and 3rd metatarsals and with 4th phalanx dorsiflexion in D. CONCLUSION: These preliminary original measures reveal that alteration of plantar dynamic loading patterns can be accounted for peculiar structural changes of foot bones. Load under the central metatarsal heads were correlated more with inclination of the corresponding phalanxes than metatarsals. Further analyses shall detect to which extent variables play a role in the many group-specific correlations.

Radiographic angular measurements of the foot and ankle in weight-bearing: A literature review.

BACKGROUND: For the diagnosis and treatment of the foot and ankle, bone alignments have long been evaluated using planar radiographs in weight-bearing conditions and a large number of measurements have been reported. The present survey reviews the major radiographic angles that are currently present in the literature for a possible better comprehension and classification of them. METHODS: PubMed and Google Scholar were used to retrieve technical and clinical papers related to these angles, and were classified based on five typologies and the three projection planes. These angles were grouped into one definition if they described similar concepts, regardless of their anatomical references and names. A corresponding original definition and diagrammatic representation are offered. RESULTS: Thirty-one conceptual radiographic angles were identified across all descriptions from the literature: 18 in the sagittal plane, 9 in the transverse, and 4 in the coronal. Most angular measures represent relative bone orientations; absolute orientations, bone morphology and joint lines are less frequently used or reported. CONCLUSIONS: The present survey reveals a confused scenario of angular measures, particularly in terms of anatomical references and names. It is therefore recommended to establish common relevant techniques and terminology.

Weight-bearing CT Technology in Musculoskeletal Pathologies of the Lower Limbs: Techniques, Initial Applications, and Preliminary Combinations with Gait-Analysis Measurements at the Istituto Ortopedico Rizzoli.

Musculoskeletal radiology has been mostly limited by the option between imaging under load but in two dimensions (i.e., radiographs) and three-dimensional (3D) scans but in unloaded conditions (i.e., computed tomography [CT] and magnetic resonance imaging in a supine position). Cone-beam technology is now also a way to image the extremities with 3D and weight-bearing CT. This article discusses the initial experience over a few studies in progress at an orthopaedic center. The custom design of total ankle replacements, the patellofemoral alignment after medial ligament reconstruction, the overall architecture of the foot bones in the diabetic foot, and the radiographic assessment of the rearfoot after subtalar fusion for correction of severe flat foot have all taken advantage of the 3D and weight-bearing feature of relevant CT scans. To further support these novel assessments, techniques have been developed to obtain 3D models of the bones from the scans and to merge these with state-of-the-art gait analyses.

A Nanostructured PLGA System for Cell Delivery of a Tetrathiahelicene as a Model for Helical DNA Intercalators.

A novel nanoconstruct based on poly(lactic-co-glycolic acid) nanoparticles loaded with a tetrathiahelicene molecule conjugated to a fluorescent rhodamine probe was prepared and characterized. Because helicenes are known to be very promising DNA intercalators, the tetrathiahelicene was selected for this study as a model therapeutic cytotoxic molecule. The ability of the nanoconstruct to internalize the tetrathiahelicene and deliver it intracellularly in a safe manner has been investigated by means of cytotoxicity and cell uptake tests on Balb/3T3 clone A31 fibroblasts. The outcomes of this study suggest the suitability of the developed nanoconstruct to act as a vector for the intracellular delivery of hydrophobic small molecules, such as helicenes, thus contributing to their possible future exploitation as novel therapeutics.

SPION-Smac mimetic nano-conjugates: putative pro-apoptotic agents in oncology.

Non-covalent (NP-1/3) and covalent (NP-A-1/3) pro-apoptotic SPION-Smac mimetic nano-conjugates antitumor agents are reported. The solution synthesis of key Smac mimetics, their support onto SPIONs through non-covalent adsorption (NP-1/3) or APTES-mediated covalent binding (NP-A-1/3), the analytical characterization of SPION-Smac mimetic conjugates, their target affinity in cell-free assays, and their cytotoxicity against tumor cells are thoroughly described.

Magnetic iron oxide nanoparticle functionalization: isocyanate moiety as a suitable monodentate anchoring group.

A new strategy for anchoring organic molecules onto superparamagnetic iron oxide nanoparticles (SPIONs) using isocyanate containing linkers has been realized. This functional group easily and efficiently reacts with the hydroxyl residues of the nanoparticle surface, leading to the formation of a stable carbamate bond, as confirmed by means of spectroscopic and analytical data.