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Medshape (Atlanta, GA) reports commercialization of the first FDA-cleared medical device made with shape memory polymers.

PlasticsToday Staff

March 22, 2013

3 Min Read
Shape memory polymers boost implant performance

Medshape (Atlanta, GA) reports commercialization of the first FDA-cleared medical device made with shape memory polymers.

Using Solvay's  Zeniva PEEK as a base material, MedShape developed a proprietary shape memory PEEK alloy called Altera which allows devices to enter the target surgical site in a compact geometry and then be triggered to deploy with minimal mechanical force into the optimal geometry for fixation.

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Suture anchor deploys wings. (Solvay)

The specific products are called the Morphix Suture Anchor for tendon and ligament repair and the ExoShape Soft Tissue Fastener for knee joint ACL reconstruction.

MedShape says it is the only company to have developed and introduced FDA-cleared devices manufactured from shape memory polymers based on PEEK (polyetheretherketone) and PMMA (polymethylmethacrylate) chemistries.

In 2011, MedShape was granted U.S. Patent No. 8,069,858 for its shape memory polymer based technology. Shape memory polymers are advanced materials that can "remember" more than one shape and transition easily between those shapes with minimal force and without loss of mechanical integrity.

Unlike traditional static implants, shape memory devices can adapt to changes in the site of implantation, such as local bone resorption, and can respond to implant loading to maintain secure fixation even under challenging conditions.

Use of shape memory materials in medical devices is not new. Examples include self-expanding cardiac stents, guide wires and orthopedic staples. Nickel-titanium (NiTi, Nitinol) is the most commonly used shape memory alloy and can recover strains up to 10 times more than traditional metals and alloys. According to Medshape, SMAs have the ability to change their shape up to 8% and still fully recover their original geometry.

The Medshape suture anchor is made of injection-molded Zeniva PEEK for biocompatibility, radiolucent properties, and high strength. It offers improved cyclic loading stability which means less chance of the surgical repair failing during the healing process. It deploys wings with a high bearing area into the cancellous bone beneath the cortical shelf for improved device fixation.

According to MedShape, active rehabilitation can cause anchor migration and loosening which may lead to clinical failure of the repair. Laboratory testing has shown that traditional anchor pullout can occur below 1,000 cycles at a load less than 50% of initial pullout strength.

The suture anchor is delivered pre-compressed in a low-profile geometry that inserts easily into the surgical site, utilizing a simple and reproducible tap-in technique. It is available in 2.5-, 3.5-, 4.5-, and 5.5-mm diameters and a range of suture and needle configurations.

The soft tissue fastener is designed for fixation of the soft tissue graft on the tibial side of the knee joint in ACL reconstructions. The ExoShape sheath is machined from 6-, 9-, and 13-mm Zeniva PEEK rod.

Medshape has also received FDA 510(k) Clearance of an ankle fusion device using shape memory alloy technology. Ankle fusion is performed to relieve pain in patients with severely degenerative ankle joints, to correct joint deformities or to revise failed total ankle replacements. The DynaNail's design utilizes shape memory alloy technology to actively adapt to changes, such as local bone resorption, in the arthrodesis (fusion) site.

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