Otis Armstrong, NFL rushing champion 1974, with 1,407 yards his second year out of Purdue -- and as recently as Oct. 13 versus the Redskins and Oct. 26 versus the Giants a 100-yard gamer -- evidently has played his last down.

The Denver Bronco back, sidelined with a concussion and neck sprain early in the Houston game Nov. 2, has been discovered to have a congenital condition described by the team physician: "The bony canal is too small for the spinal cord. There is a risk of paralysis of the arms and legs if he damages the cord. As far as our medical position is concerned, Otis Armstrong should not play football again" . . .

Close hockey watchers shivered when Detroit recalled Dennis Polonich this week, and pronto, we see why: Ray Bourque, Boston Bruin defenseman coming off NHL rookie-of-year laurels, out three weeks; jaw broken by a Polonich punch in the mean Red Wing's first game, first period . . . In New York, Bruin forward Peter McNab -- son of Cap GM Max -- is off the misdemeanor charge hook, prosecutors citing conflicting evidence about the Dec. 23, 1979 fight involving Boston players and Ranger fans.

While the soccer Dips scramble for buyers, Minnesota's Kicks have found some in Notts County (English league) honcho Ralph Sweet and two realtors from Dublin, Ireland, undiscouraged by the NASL team's financial losses despite 26,000 customers a game. And a group of California businessmen affiliated with Campus Crusade for Christ's Athletes in Action are dickering to buy NASL's Houston Hurricane and move them to Memphis, which lost its Rogues to Calgary. . .

Bill McPeak, Redskin coach when Bobby Mitchell came abroad for 1962, will speak at Mitchell's induction into the Washington Touchdown Club Hall of Fame Friday night. So will E. B. Williams and Irv Cross . . . h