PITTSBURGH -- Quarterback Tommy Maddox has no structural damage in his injured spine and was walking in his hospital room in Tennessee on Monday, but the Steelers weren't ready to say when he can play again.

"We're quite happy with his progress,'' team doctor Anthony Yates said at a news conference Monday morning.

Maddox was hurt on the final play of the third quarter of the Steelers' 31-23 loss at the Tennessee Titans and spent Sunday night in the hospital with a concussion.

He was expected to return to Pittsburgh on Monday night and be hospitalized in the University of Pittsburgh Medical Center for further tests. But all indications were that his injury is not career-threatening.

Maddox underwent X-rays, a CT scan and MRI exams Monday morning and no structural damage was detected, Yates said. Maddox was initially diagnosed with a spinal cord contusion -- a bruising and swelling that includes hemorrhaging -- but instead he has an interruption in the normal electrical activity in the spine.

For at least the next several weeks and perhaps longer, former starter Kordell Stewart, whom Maddox replaced during the third game of the season, will be the quarterback. The Steelers (5-4-1) are at home Sunday against Cincinnati (1-9).

At least 15 minutes passed Sunday at The Coliseum while Maddox was turned onto his back and strapped to a backboard after trainers cut off his face mask. Players for both teams knelt and prayed.

Maddox was unconscious for about five minutes but never stopped breathing.

Maddox was hurt while flipping the ball to Antwaan Randle El for a 2-yard gain. As Maddox fell forward, Titans linebacker Keith Bulluck put his forearm into Maddox's shoulder. Maddox's head rolled underneath him slightly as he hit the ground, and he did not move.

Maddox has enjoyed a storybook season, rising from third on the depth chart to replace and lead the Steelers to a 5-2-1 record in games in which he played.

Before this season, he hadn't started an NFL game in 10 years and spent three years out of football before reviving his career in the Arena League and, later, the XFL.