The warning letter, dated September 19, does not restrict production or shipment of the hip devices, called Trilogy Acetabular Systems, or require withdrawal of any products from the market, Zimmer said in a regulatory filing.

The FDA said Zimmer failed to implement a testing mechanism to demonstrate the products met certain design specifications and had not validated the effects of manufacturing operations on products that incorporate metallic spikes.

The warning follows a June inspection of the company's Ponce plant. Zimmer said it temporarily suspended release of the affected products and has since completed the validation process for Trilogy products that do not incorporate metallic spikes.

The company expects to complete validation of Trilogy spiked products within the next few weeks.

(Reporting By Susan Kelly in Chicago; Editing by Carol Bishopric and Tim Dobbyn)

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