The FDA slapped its highest-risk classification on orthopedic titan Stryker’s (NYSE:SYK) ShapeMatch recall, warning that the devices may not have been manufactured properly.

The issue was picked up via post-market surveillance of product complaints, according to the federal watchdog agency.

The ShapeMatch cutting guides, designed to help orthopedic surgeons direct total knee replacement surgeries, "may not have been manufactured in accordance with surgeon preoperative planning parameters or may have been manufactured outside of the planning ranges specified in the 510(k) clearance," the FDA warned.

Stryker in November 2012 issued a warning to all U.S. ShapeMatch surgeons, asking them to stop using the devices. In January 2013 the company launched a recall, according to the notice.

The orthopedic device maker is coming off another recent warning stemming from an November 2012 inspection of a plant in Portage, Mich.

The Kalamazoo, Mich.-based medical device company said the letter, based on "quality system observations," flagged it for failing to tell the federal watchdog agency of a product recall and for marketing devices including its Neptune waste management system without 510(k) clearance from the FDA.