By Jon "DRJ" Najarian, co-founder of OptionMonster.

Surgical implant company Zimmer Holdings ( ZMH) is seeing significant options activity ahead of its earnings report before the opening bell Thursday.

Some 5,100 of the February 40 calls are trading with more than 86 percent on the offer, according to OptionMonster's tracking systems, which to us says accumulation. Zimmer stock, however, fell 5.6 percent in after-hours trading late yesterday to $39.66 after closing the regular session up on the day at $42.01.

At the same time Stryker> ( SYK - Get Report), a competitor of Zimmer in orthopedic implants, rose 4.75 percent in after-hours trading following a positive earnings report. Stryker options continued to be bullish leading up to the release, and the company expects sales to increase 6 percent to 9 percent in 2009.

Disclosures: Najarian has positions in Stryker.