The Wayne State University Physician Group said Friday that it plans to buy a building in Troy to house a new ambulatory-surgery center. The purchase launches the group's "suburban strategy," Robert Frank, dean of the Wayne State Medical School , said in a letter. Frank said the strategy will build the group's clinical business and, eventually, the bottom line of The Detroit Medical Center, the group's clinical partner. Frank acknowledged that the surgery center may make the DMC and other clinical affiliates "uneasy" but said the group had "taken special care to ensure that our strategies complement our partner's position rather than competing with it."