By: 13 January 2016
Modular partial wrist implant may help ease the burden of arthritis

Modular partial wrist implant may help ease the burden of arthritis

Studies are under way to determine if a new modular partial wrist replacement will allow for better movement and last longer than traditional implants for people seeking relief from painful wrist arthritis. Although current options such as total wrist replacement and wrist fusion can alleviate pain, patients are often limited in performing certain activities after surgery.

“Wrist arthritis is one of the most common and debilitating conditions treated by hand surgeons,” explained Scott Wolfe, hand and upper extremity surgeon at the Hospital for Special Surgery in the USA, who developed the new device. “When conservative treatments fail to provide relief, patients often consider surgery. Because of the limitations of current surgical options, we set out to develop a better wrist replacement based on years of research into how the wrist moves.”

Wolfe and colleagues, along with Extremity Medical, have designed the modular partial wrist replacement to be a better anatomical match for a normal wrist. The new modular implant is the culmination of more than a decade of research funded by the National Institutes of Health (NIH) to elucidate the underlying mechanisms of wrist movement.

“Traditional wrist surgeries often constrain the wrist to move in one plane at a time,” said Wolfe. “Because of this, patients need to learn new ways to move their forearm and arm to compensate for the change. In so doing, they may further stress other joints; conversely, those with impaired neighbouring joints may not be able to return to some activities, like playing tennis or golf.”

Standard wrist replacements have also sustained a high failure rate because of the increased loads on the implant–bone interface due to these motion constraints, which leads to loosening and mechanical failure.

Surgery with Wolfe’s novel implant, called a wrist hemiarthroplasty, replaces the proximal carpal row of bones at the base on the hand, those usually affected in patients with wrist arthritis. The implant utilises modular components in various sizes to match a patient’s individual anatomy and more closely mimic normal wrist motion.

The researchers believe the improved motion will enable patients to resume sports and other activities that they enjoy. They also believe the implant will be more durable than traditional wrist replacements, which only last five to 10 years. The modular nature of the device will also allow the partial wrist replacement to be more easily converted to a novel ‘midcarpal’ total wrist replacement if needed, according to Wolfe.

The KinematX™ midcarpal modular wrist hemiarthroplasty has been licensed to Extremity Medical, a privately funded company in New Jersey that specialises in unique devices for the hand and foot. The company will be responsible for the manufacture and distribution of the new implant.

Source: Hospital for Special Surgery