Needle insertion is the most common procedure of minimally invasive interventions. During insertion into a soft tissue, the needle with bevel tip can deflect due to the asymmetric forces acting on the tip of the needle. In this paper, a mechanics-based model is developed to predict the needle deflection. In the model, the needle is considered as a cantilever beam supported by a series of nonlin...

A numerical study was performed to reveal the temperature distributions in tissues around the GB38 acupoint during the warm (moxa-heated) needle treatment (WNT). The proposed WNT model involves a needle, needle handle and the calf section around the GB38 acupoint. For validating the numerical results, measurement using the calibrated infrared (IR) camera was also conducted. Our aim was to calcu...

Acupuncture needle manipulation gives rise to "needle grasp," a biomechanical phenomenon characterized by an increase in the force necessary to pull the needle out of the tissue (pullout force). This study investigates the hypothesis that winding of connective tissue, rather than muscle contraction, is the mechanism responsible for needle grasp. We performed 1) measurements of pullout force in ...

Suturing is a ubiquitous sub-task in surgery. To explore supervised automation of multi-throw suturing in Robot-Assisted Minimally Invasive Surgery, we present a novel mechanical needle guide design and an optimization framework to optimize needle size, needle trajectory and control parameters for two arms using sequential convex programming. We also develop a model-based needle tracking system...

BACKGROUND For surgical suturing, a Webster needle holder uses wrist supinating with supinator and extrinsic muscles, whereas a pen needle holder uses finger twisting with intrinsic and extrinsic muscles. Because the latter is better suited to microsurgery, which requires fine suturing with less forearm muscle movement, we have recently adopted an enlarged pen needle holder scaled from a micro ...

BACKGROUND AND PURPOSE Although ultrasonography-guided percutaneous nephrostomy is relatively safe, a number of factors make it challenging for inexperienced operators. A computerized needle navigation technique using tracked ultrasonography snapshots was investigated to determine whether performance of percutaneous nephrostomy by inexperienced users could be improved. METHODS Ten operators p...

The needle length of the Yersinia spp. injectisome is determined by Yop secretion protein P (YscP), an early substrate of the injectisome itself. There is a linear correlation between the length of YscP and the length of the needle, suggesting that YscP acts as a molecular ruler. However, it is not known whether one single molecule of YscP suffices to control the length of one needle or whether...

Salmonella and other pathogenic bacteria use the type III secretion system (T3SS) to inject virulence proteins into human cells to initiate infections. The structural component of the T3SS contains a needle and a needle tip. The needle is assembled from PrgI needle protomers and the needle tip is capped with several copies of the SipD tip protein. How a tip protein docks on the needle is unclea...

Real-time ultrasound guidance for any intervention relies on visualization of needle advancement towards a target. Unfortunately, correct identification of the needle tip is not straightforward, as artifacts always distort the image. The ultrasonic appearance of the needle is often degraded by reverberation, comet tail, side-lobe, beam-width, or bayonet artifacts, which can easily confuse an un...