BANGOR – Allan Smith, 8, walked quickly to the front of a federal courtroom on Harlow Street Tuesday afternoon. The child is the focus of a product liability lawsuit being played out this week at U.S. District Court.

Guided by his father, Wayne Smith, and Dr. John McGill, a local plastic surgeon who has taken over some of his medical care, the bespectacled child displayed scars on his right knee and upper right thigh, physical reminders of a gruesome injury he suffered in a 1999 lawn mower accident at his Prentiss Township home. The lawsuit claims Wal-Mart sold, and MTD produced, a “reasonably dangerous” riding lawn mower.

The child, represented by his parents, is suing Wal-Mart and MTD Products for negligence and breach of warranties in connection to the July 25, 1999, mishap. His father claims the gear-shifting mechanism malfunctioned and brakes did not work on a riding mower he had bought that afternoon at the Lincoln Wal-Mart store. The machine unexpectedly backed up, running over the boy’s foot. Then Allan’s kneecap got caught in the mower blade, severing it and damaging surrounding muscles, tendons and ligaments. He was 6 at the time.

The lawsuit began Monday with D. Brock Hornby, Maine’s chief U.S. District judge, presiding.

Tuesday’s testimony mixed the pathos of parents trying to save their son with drier technical testimony from MTD experts who denied their company made a faulty machine.

Allan underwent two surgeries to fix the injury and was hospitalized at Eastern Maine Medical Center for 16 days after being taken there by ambulance. He was anesthetized a total of five times.

Paralyzed with fright, the boy required the constant presence of his parents, who slept in his hospital room in the EMMC children’s unit, according to testimony. The boy would fall asleep at night only if his mother or father were holding his hand. To ease his discomfort, his parents often put their fingers between the bottom of his full-leg cast and his toes to lessen the chafing about which he complained.

The Smiths claim to have suffered emotional distress from seeing the accident happen. Through their attorney, Warren Silver of Bangor, they have submitted medical bills as evidence. Wayne Smith claims he lost three weeks’ salary after the accident though no total money claim has been mentioned to the eight-member jury so far.

Wal-Mart and MTD Products deny the negligence and breach-of-warranty allegations. Represented by Portland attorney Harold Friedman and Ohio attorney Rick Coyne, the defendants claim Allan Smith’s negligence caused the accident and that the negligence of his parents caused their emotional distress.

Recalling the accident caused Allan’s mother, Shelley Smith, 31, to break down on the stand Tuesday morning.

The woman said she stood at the head of her driveway off Route 170 and watched as her sons, Allan and 2-year-old Jordan, made their way toward their father who was riding up the driveway on the lawn mower. The boys were accompanied by Devon King, their 16-year-old uncle, who had Jordan on his shoulders. Allan led the way.

The mother said she saw her husband motion to the boys to stay away, that something was wrong. Then she saw Allan on the ground hollering “Daddy, Daddy.” Amid tears, Shelley Smith said she saw Devon King lift up the 500-pound lawn mower, then saw her husband start to run up the driveway with their injured son. In his panic, Wayne Smith fell on his elbows, then picked up his son again and continued to run toward help.

“I yelled at him to hang onto his [Allan’s] leg because pieces were all on the side,” Shelley Smith recalled.

Allan’s parents and Wayne’s father took the boy to a hospital in Lincoln. He was transferred to EMMC and was operated on in the early morning hours of July 26, 1999, according to court testimony.

Graphic slides narrated by an orthopedic surgeon Monday showed the boy’s kneecap flipped over on his leg. The kneecap had to be screwed into place.

Two weeks later a plastic surgeon, Dr. David Halpern, took some of the boy’s calf muscle and attached it to the kneecap area to fill in a hole. Halpern no longer practices in Maine but McGill, Halpern’s associate, took over the case and described Tuesday how skin had to be grafted from the boy’s upper right thigh, a site that later became infected. He once was put under anesthesia for 20 cortisone shots to the area.

On Tuesday afternoon, the defense started its case. Testimony detailed extensive safety checks given to MTD lawn mowers at the plant. Gunter Plemper, head of consumer product safety for MTD, attributed the machine’s malfunction to “misuse” and said it was “highly unlikely” the machine was put together incorrectly.

The company has factories in Mississippi, Ohio and Canada. The Smiths’ lawn mower, purchased for $799, was manufactured in June 1999 in Indianola, Miss.

Sue MacDonald of Winn, manager of the Lincoln Wal-Mart in 1999, denied attorney Silver’s contention that store employees were known to misuse lawn equipment before the items were sold.

The case is expected to go to the jury Wednesday.