A D.C. Superior Court judge ordered the city government yesterday to pay $950,000 for the lifelong care of an Oxon Hill boy who became totally disabled after a doctor at D.C. General Hospital failed to treat him properly for dehydration.

Judge Fred L. McIntyre, who heard evidence in the medical malpractice trial, ordered that most of the award -- considered one of the largest ever in the District -- be spent over the next 60 years for the 24-hour-a-day care of Robert L. McKnight Jr. Now 5 years old, the boy has no use of his arms or legs, cannot sit, talk or feed himself or control bowel or bladder functions.

At the two-day trial earlier this month, the city's lawyer, Assistant Corporation Counsel Martin L. Grossman, agreed not to contest liability in the case. Attorneys Jules Fink and Marden Dixon, who represented McKnight and his parents, agreed in turn to reduce the demand in their suit from $10 million to a maximum of $950,000.

Under the stipulations made in court, the city cannot appeal for a reduction of the judge's award.

According to testimony at the trial, the McKnights rushed their then 2-month-old son to the pediatric emergency room of D.C. General Hospital -- which is owned and operated by the District government -- late on the evening of March 19, 1975. They explained there that the infant was running a high fever and had not been eating or drinking well.

A doctor examined the baby and indicated on medical records that he was "well hydrated" and was not taking food or liquids because he had a sore throat. The doctor sent the child home after instructing the McKnights to give him an antibiotic and a medication for fever and to use a vaporizer.

A day later, the child was admitted to Children's Hospital with a temperature of 108 degrees. He had developed seizures and was in a state of severe dehydration.

"According to medical testimony at trial," McIntyre concluded in his opinion, "the child's condition leading to the severe brain damage could have been avoided had the child been admitted to District of Columbia General Hospital on March 19, 1975 and treated for dehydration."

Grossman said the city did not want to argue evidence in the case before a 12-member jury because "we felt we would be held liable." Grossman said both sides in the case agreed that a payment of $950,000 was reasonable.

McIntyre found in his opinion that although the boy may show some signs of improvement, "he will always remain profoundly retarded and be unable to function unassisted in society or to be gainfully employed."

The judge ordered that $534,000 of the award be used to pay for the child's care either in a commercial institution or in his family's home for the rest of his life -- estimated to be 60 years.

The judge awarded $60,000 to the child's parents, Robert Sr. and Theresa, to compensate them for caring for the boy over the last five years. He said that the parents "have suffered great anguish, distress and disruption of their lives" as a result of their son's injuries.

The Washington law firm of Katz and Fink, which began working on the case two years ago, was awarded $316,666.66 for legal fees. Half of the firm's fee, the standard one third of the total award, will be paid to attorney Dixon. Dixon, both a practicing physician and lawyer, was cocounsel in the case. The law firm may receive an additional $39,227.63 for other costs pending a hearing by McIntyre on the firm's expenses.

The McKnights, who have three other children and live in a two-bedroom garden apartment, said that no amount of money can substitute for the health and potentials in life that their son lost.

"It was not hard to see that my baby was sick," said Theresa McKnight, 27, who worked as a cleaning woman before her son became disabled. She now stays home caring for him. "I would put formula in his mouth, and it would just run back out.

"But the doctor took a quick look and said all the baby had wrong was a sore throat. I knew it was more than that," she said.

The next afternoon, McKnight said, the infant was staring at the walls like he was hypnotized.

"I didn't want to take Robert back to D.C. General," said Robert McKnight, 27, who drives a trash truck. "I didn't think the doctors there were treating my baby right. So we went to Children's Hospital. They immediately rushed the baby into treatment."

The McKnights said their child was in the hospital for six weeks. When he was brought home, another painful ordeal began for the McKnights.

Just as they did when Robert was two months old, the McKnights must still carry him in their arms, he must be spoon fed, and they must always be available to keep him from rolling off the bed or hurting himself in some other way.

"He can't sit up, he can't talk, he's cross-eyed, but he's alive," McKnight said. "We don't want to send him to an institution. We don't believe there's anyone else who'd be willing to care for him the way we do."

McKnight said he filed suit almost by accident. "I was feeling kind of helpless about my son one day when I was out buying a used car," he said. "I was telling the car dealer everything that had happened and he told me it sounded like I had good grounds for a suit."

The car dealer immediately called his personal attorney, who in turn contacted the law firm of Katz and Fink. Attorneys from the firm were put in touch with the McKnights.

Mrs. McKnight, who took the witness stand during the trial to describe her son's condition, told the judge that the child cannot help himself in any way.

"He doesn't speak, he only makes noises," she said. "He says, 'Ma, Ma, Ma,' but he doesn't know what he's saying."

The judge asked about the family's effort to get a babysitter.

"It's been hard to get a sitter for a child in that condition," Mrs. McKnight said. "We don't ask anymore."

The judge reached out and took the boy's limp arm. "Hey, Robert. How are you doing?" he asked.

The child, cuddled in his mother's arms, did not respond, but looked blankly beyond him at lighting fixtures recessed in the ceiling.

"Every time I look at him," Robert McKnight said, "I can't help but wonder what he would have been like . . ."