Tiny 'wrist' to assist needle surgery

A tiny flexible wrist component for needle-sized surgical equipment could enable surgeons to perform operations in tiny spaces which would involve incisions so small that they could be sealed just with surgical tape, rather than sutures. Less than 2mm in diameter, the wrist, which would form part of the suite of equipment for a type of minimally invasive technique known as needlescopic surgery, has ben developed by engineers at Vanderbilt University in Nashvile, Tennessee.

Needlescopic surgery, also known as mico-laproscopy, uses instruments about the size of a sewing needle inserted through incisions that are typically 5-10mm long. It causes less pain to patients, reduces tissue damage and scarring, and speeds up recovery times; and is particularly useful for operations in the head and neck. But such tiny instruments are difficult to control.

The Vanderbilt team, led by mechanical engineer Robert Webster, is developing a surgical robot for needlescopic surgery, which a surgeon would operate remotely, like the Da Vinci robot which is now mainly used for abdominal operations such as prostate surgery. “The da Vinci uses a wire-and-pulley system that is extremely difficult to miniaturise any further, so it won’t work in smaller spaces like the head and neck,” said Webster. Instead of Da Vinci’s rigid rods tipped with pulley-operated instruments, Webster’s team is working on a robot whose ‘arms’ are steerable needles made from a memory metal called nitinol. These needles are curved, and nested inside each other in a telescoping configuration. By extending the telescoping sections and rotating them, the surgeon can move the tip of the needle to the site of surgery with great accuracy.