A 41-year-old District man who contended that the amputation of part of his leg resulted from improper treatment at D.C. General Hospital for an ingrown toenail was awarded $850,000 yesterday by a D.C. Superior Court jury.

Jack Olender, attorney for William Smith, argued incisions made in Smith's toe by a podiatrist at the hospital in early October 1984 led to infection that brought on gangrene and the eventual amputation.

Olender argued that a circulatory problem in Smith's leg should have forestalled cutting in the toe without evaluation by a physician or surgeon.

Martin L. Grossman, an official in the D.C. corporation counsel's office, said the city will probably file a motion for a new trial. The podiatrist, who is retired, was not a defendant.

Olender said he introduced evidence to show that the podiatry clinic at the hospital was unsanitary at the time of the surgery and that Smith, a short-order cook at D.C. General at the time, was inadequately treated for infection on a return visit.

Olender said Smith was admitted shortly afterward to the Washington Hospital Center and his right leg was amputated above the knee.

Olender said in a telephone interview that Smith, who has been fitted with a prosthesis, lost his job at D.C. General because authorities were afraid he would slip and fall. He said Smith, once an avid basketball player, is now a Silver Spring apartment building security guard and works behind a desk.

Grossman said the city has a claim pending against the Washington Hospital Center in connection with the case. He declined to discuss details of the case, asserting that it remains in litigation.

In a telephone interview last night from Tampa, the podiatrist, Robert Cartwright, denied responsibility for what happened to Smith and said that Smith had apparently undergone home treatment before coming to the clinic. "The damage was done at home," Cartwright said. "He came there with the problem."