August was a profitable month for several Stryker Corp. insiders.

Ronda Stryker, a longtime director of the Kalamazoo, Mich.-based device giant, continued her selling spree throughout the month, putting 630,000 shares into the market for a $21.5 million gain. The grand-daughter of company founder Homer Stryker began cashing out in May and has now unloaded over 1.9 million shares from a revocable trust, generating nearly $69 million in proceeds.

Attempts to reach Stryker through her husband’s investment advisory company were not successful. Stryker officials also did not return calls seeking comment about the sales.

Donald Engelman, another member on the Stryker board, also did some profit-taking during August, selling 14,136 shares late last week to make $584,241 in gross proceeds.

Engelman is a professor of molecular biophysics and biochemistry at Yale University and joined the Stryker board in 1989.

Not everyone was a seller last month. Board newcomer Datar Srikant spent $40,997 on 1,000 Stryker shares over two days last week. Srikant is senior associate dean and research director at the graduate business school at Harvard University and was appointed to the Stryker board July 29.

And Harris Corp. CEO Howard Lance, elected to the board in April, doubled his Stryker holdings with a 3,000-share purchase Aug. 10.