Plaque Contact Surface Area and Flow Lumen Volume Predict Stroke Risk in Extracranial Carotid Artery Stenosis

The standard indication for intervention in asymptomatic disease is currently percent stenosis in the internal carotid artery as measured by the NASCET method, which remains limited in discriminating power. CT angiography (CTA) is widely used to calculate NASCET stenosis but also offers the opportunity to analyze carotid artery plaques from a morphological perspective that has not been widely utilized. We aim to improve stroke risk stratification of patients with carotid artery stenosis using plaque 3D modeling and image analysis. Patients with CTAs appropriate for 3D reconstruction were identified from an NIH designated stroke center database, and carotid arteries were segmented and analyzed using software algorithms to calculate contact surface area between the plaque and blood flow (CSA), and volume of the flow lumen within the region of the plaque (FLV). These novel parameters factor in the 3D morphometry inherent to each carotid plaque. A total of 134 carotid arteries were analyzed, 33 of which were associated with an ipsilateral stroke. Plaques associated with stroke demonstrated statistically significant increases in average CSA and FLV when compared to those not associated with stroke. When compared to NASCET percent stenosis, CSA and FLV both demonstrated a larger area under the receiver operating characteristics curve (AUC) in predicting stroke risk in patients with carotid stenosis. The data presented here demonstrate morphological features of carotid plaques that are independent of NASCET criteria stratification and may present an improved method in assessing stroke risk in patients with carotid artery stenosis.

Comparison of Interface Pressure, Contact Surface Area, and Percent Area of Coverage Between Two Suture Configurations for Hill-Sachs Remplissage

Purpose: To compare maximum contact pressure, contact surface area, and the percent area of coverage of the bone-tendon interface in the remplissage procedure between two different suture configurations (independent mattress versus double-pulley). Methods: A sample size of seven specimens per group was defined by a 96% power analysis. Hill-Sachs lesions were created in all fourteen ex vivo ovine shoulders, corresponding to a 30% defect of the axial diameter of the humeral head (significant lesion according to literature). The defects were repaired using the remplissage technique applying one of the two randomly chosen suture configurations: two independent mattress sutures or a double-pulley. The contact pressure and contact surface area, as well as percent defect coverage, were recorded using a film sensitive to these parameters. Independent nonparametric tests (Mann-Whitney) were used for the statistical analysis. Results: The double-pulley group exhibited an average pressure of 0.128 ± 0.018 mPa, the contact surface of 0.199 ± 0.044 cm2, and 41.97 ± 9.8% defect coverage. The independent mattress group showed an average pressure of 0.102 ± 0.01 mPa, the contact surface of 0.081 ± 0.041 cm2, and defect coverage of 15.6 ± 8.1%. All three parameters were statistically superior in the double-pulley group (p=0.038, p=0.008, and p=0.008, respectively) Conclusion: The remplissage technique using the double-pulley configuration, presented superior biomechanical characteristics, in terms of contact pressure, contact area, and percent coverage of the defect, compared to the simple independent mattress configuration.

Effects of a Mini Implant’s Size and Site on its Stability Using Resonance Frequency Analysis

Aim: Temporary anchorage devices (TADs) have become the preferred method of skeletal anchorage in new-age orthodontics. Despite the remarkable success of mini implants in orthodontic treatment results, mini implants’ stability remains a vital issue that has to be resolved, due to the fact that failure rates are broadly variable and might be up to 25%. Objectives: To evaluate the effect of the diameter, implant bone surface contact, thickness of cortical bone, and implant insertion sites on mini implant stability using resonance frequency analysis (RFA). Materials and Method: CBCT of the dry skull was obtained. Buccal and lingual cortical plates of the maxillary and mandibular jaws were measured at 6 mm from the coronal part of the alveolar bone. After placing the implants, the stability was measured using resonance frequency analysis. Results: In the maxillary arch, Pearson correlation showed significant correlation of instability of the implant with the width of the buccal cortical plate and lingual cortical plate and implant contact surface area. In mandibular arch, Pearson correlation showed no significant effect of buccal/lingual cortical plate width, and implant surface contact area in primary stability of varied sized, mini implants. Conclusion: Statistically significant increases in the primary stability of mini implants with an increase in the implant bone contact surface area were found in the maxilla. In the mandible, no significant increase in mini implant stability was found with an increase in the implant contact surface area.