THE NBA PLAYOFFS : Celtic Guards Johnson and Ainge Injured, May Not Play Tonight

Back injuries suffered by Dennis Johnson and Danny Ainge could leave the Boston Celtics without their starting backcourt for tonight’s Game 6 of the National Basketball Assn. Eastern Conference championship series.

Neither player practiced Thursday, having experienced back pains after Wednesday night’s 102-96 overtime loss to the Detroit Pistons. Johnson, in fact, did not accompany the Celtics on their flight here, and will be examined in Boston by team physician Arnold Scheller this morning. Ainge made the trip. Johnson was slow getting up after Piston center Bill Laimbeer appeared to have pulled him to the floor while scoring a basket with 3:11 to play in the fourth quarter of Game 5. Johnson finished with 23 points and made a layup after his injury. Ainge went scoreless in 47 minutes.

Should one be unable to start, Jim Paxson will take his place. Should both sit out, Dirk Minniefield, who has played 6 minutes in the series, figures to be needed.