MILWAUKEE, AUG. 31 -- For the first time in weeks, the injury news was good for the Baltimore Orioles. The prognosis for first baseman David Segui improved considerably today, as tests on the rookie's injured right knee revealed only a severe bruise that will keep him sidelined two to three weeks.

It was originally feared that Segui might have suffered a broken kneecap in a collision with Memorial Stadium's metal tarpaulin holder as he chased a foul popup Wednesday. Initial X-rays were inconclusive; a CAT scan performed today showed no fracture but a bruise of the patellar tendon, which is attached to the kneecap.

General Manager Roland Hemond said Segui will have the knee immobilized a week to ten days, then begin rehabilitation and return to action shortly thereafter.

The Orioles' recent demise has been predicated partly upon a rash of debilitating injuries, and Frank Robinson greeted today's development with relative glee. "It's about time," said the manager, whose beleaguered club still has four players on the disabled list and two others -- Ron Kittle and Gregg Olson -- slowed by nagging injuries.

Hickey Comes Back

Major league rosters will expand to a maximum of 40 players Saturday, but the Orioles' only immediate additions will be pitcher Kevin Hickey and all-purpose man Jeff McKnight, both already familiar in Baltimore.

Baltimore officials promised their Class AAA affiliate, Rochester, they wouldn't order widespread callups until the Red Wings complete the International League playoffs. That could be as late as Sept. 19.

So Leo Gomez, Chris Hoiles, Mike Mussina and several other top prospects will remain at Rochester at least temporarily.

Left-handed reliever Hickey, who opened the season with the Orioles and was demoted 6 1/2 weeks ago, has allowed 15 earned runs but has struck out 28 strikeouts in 23 1/3 innings with the Red Wings.

McKnight played four positions in nine games during a 16-day stint with Baltimore that ended two weeks ago. For the season, he's hit .280 in 100 games at Rochester.

The others may be promoted later, though Robinson said Mussina -- the team's top pick in June's amateur draft -- is not likely to be among the crop of newcomers.

Hemond: Trades Unlikely

Hemond said the Orioles probably will not be involved in any trades in the near future. "I'm all talked out," he said.

"At this point, it would have to be somebody else calling us that we don't expect." Of course, he left a voice-mail message on his office telephone in Baltimore containing the number at which he can be reached here, just in case.

Schilling: Just a Temporary

Robinson said he will divide the closer duties among several pitchers in the absence of Olson, expected to miss at least a week with a sore right elbow. Robinson has pledged to let Olson pitch as soon as he declares himself fit to do so.

Reliever Curt Schilling had not allowed a run in 13 appearances (19 innings) entering tonight's game against the Brewers. Yet he's resisting any attempts to make him a permanent fixture in the bullpen, clinging steadfastly to a desire to be a starting pitcher again in 1991.

"This is a way to break in, get used to the hitters and the league," Schilling said. "For me, it's not a way to spend a career. I hope." . . .

The Orioles have lost seven consecutive series since taking two of three games from the Kansas City Royals Aug. 2-4. . . . Baltimore is on a pace to play 95 errorless games, which would break last year's club record of 93.