Honeybee stinger-based biopsy needle and influence of the barbs on needle forces during insertion/extraction into the iliac crest: A multilayer finite element approach

Bone marrow biopsy (BMB) needles are frequently used in medical procedures, including extracting biological tissue to identify specific lesions or abnormalities discovered during a medical examination or a radiological scan. The forces applied by the needle during the cutting operation significantly impact the sample quality. Excessive needle insertion force and possible deflection might cause tissue damage, compromising the integrity of the biopsy specimen. The present study aims at proposing a revolutionary bioinspired needle design that will be utilized during the BMB procedure. A non-linear finite element method (FEM) has been used to analyze the insertion/extraction mechanisms of the honeybee-inspired biopsy needle with barbs into/from the human skin-bone domain (i.e., iliac crest model). It can be seen from the results of the FEM analysis that stresses are concentrated around the bioinspired biopsy needle tip and barbs during the needle insertion process. Also, these needles reduce the insertion force and reduce the tip deflection. The insertion force in the current study has been reduced by 8.6% for bone tissue and 22.66% for skin tissue layers. Similarly, the extraction force has been reduced by an average of 57.54%. Additionally, it has been observed that the needle-tip deflection got reduced from 10.44 mm for a plain bevel needle to 6.3 mm for a barbed biopsy bevel needle. According to the research findings, the proposed bioinspired barbed biopsy needle design could be utilized to create and produce novel biopsy needles for successful and minimally invasive piercing operations.

Extraction force, energy and nail deformation for 1.5 m versus 1.0 m intramedullary femoral nail bow design: A biomechanical investigation

BACKGROUND

The impact of the nail radius of curvature, as one of the most important design features in modern femoral nails on the ease of nail removal, remains unknown. Therefore, the aim of this study was to investigate force, energy, and nail deformation of different nail designs.

METHODS

Nail insertion and extraction was performed on six pairs of fresh-frozen human cadaveric femora on a material testing machine with two different nail systems - Trochanter femoral nail ADVANCED™ Nailing System with a radius of curvature of 1.0 m and Proximal Femoral Nail Antirotation System with a radius of curvature of 1.5 m. Deformation was measured after insertion (plastic and elastic deformations) and extraction (plastic deformations).

FINDINGS

The peak force during nail removal was significantly lower in the first group (274.5 ± 130.4 N) compared to the second group (695.2 ± 158.8 N, p = 0.001). Plastic deformation was observed in all implants, being significantly larger in the Proximal Femoral Nail Antirotation System (p = 0.027). There was a strong positive correlation between the first peak force during nail removal and nail insertion (r = 0.802, p = 0.002) as well as between extracting energy and insertion energy (r = 0.943, p < 0.001).

INTERPRETATION

The results from this study showed that a radius of curvature of 1.0 m is easier to remove from the set of cadaver femora. Furthermore, our findings support the idea of further reducing the nail radius of curvature below 1.0 m in order to more closely match the anatomy of populations with strong-bowed femora.

Comparison of polyvinyl chloride and elastic stannum stylet extraction forces with various lubricants: a simulation study

Background

Stylets are the most frequently used devices for tracheal intubation, but can be a source of postoperative pharyngeal pain or hoarseness. In this study, we evaluated extraction forces between polyvinyl chloride (PVC) and stannum (Sn) stylets with various lubricants.

Findings

Using a manikin, we compared extraction forces between PVC and Sn stylets under four different conditions: without lubricant, 3 ml of water (water), three sprays of 8 % lidocaine (lidocaine), and olive oil. A force measuring device was used to accurately measure the extraction force for stylet removal. The extraction force was significantly smaller with the Sn stylet compared to the PVC stylet, regardless of the lubricant used for all three tracheal tubes with different diameters tested (P < 0.05). In comparisons by lubricant, lidocaine and olive oil resulted in significantly lower extraction forces than with no lubricant or water with the PVC stylet for all tracheal tubes tested. In contrast, there were no significant differences in extraction force by lubricant for the Sn stylet across all tracheal tubes tested.

Conclusions

The Sn stylet required less extraction force compared to the PVC stylet, regardless of the lubricant used.