PIERRE - An Aberdeen woman whose legs were amputated because of complications following knee-replacement surgery must get a new trial in her malpractice lawsuit against two doctors, the South Dakota Supreme Court ruled Thursday.

The high court said Adeline Papke is entitled to a new trial because the jury in her first trial was given an improper instruction that probably influenced its decision to rule against her.

The judge's instructions to the jury said a doctor is not necessarily negligent because the doctor errs in judgment or because the doctor's efforts prove unsuccessful. That instruction also said a doctor is negligent if the error in judgment or lack of successful treatment is due to a failure to perform duties defined in other instructions.

The Supreme Court said language on "error in judgment" should not be used in jury instructions for ordinary medical malpractice cases in South Dakota because it does not explain the applicable standard of care at issue in those lawsuits.

"By using the term 'error in judgment,' a jury could reasonably find a physician not liable in instances where the physician discloses that in hindsight, yes, he or she made a mistake, but that it was only an error in judgment," Justice John K. Konenkamp wrote for the court.

Papke's right to a fair trial also was violated when she was not given sufficient notice about testimony given by an expert witness for the doctors, the high court said.

The ruling gives Papke another trial in her lawsuit against Dr. Thomas Harbert, Dr. Mark Harlow and their clinic, Aberdeen Orthopedics & Sports Medicine.

Papke, who was 70 at the time, fell when her left knee gave out while she was watering flowers in her yard in September 2002, according to court documents.

After she was taken to a hospital emergency room, Harbert was called to evaluate her.

Harbert and Harlow performed surgery to replace both of Papke's knees in October 2002, but her knees dislocated while she was recovering, according to court documents. The doctors put casts on both of her legs, and she developed sores on her feet.

Another doctor diagnosed Papke with circulation problems. Her condition worsened and both legs were eventually amputated above the knee

Papke sued Harbert and Harlow, alleging that her medical treatment fell below the appropriate standard of care.

During the trial in January 2006, a lawyer for the doctors said Harbert made a treatment judgment that turned out to be wrong, but that did not amount to negligence.

The Supreme Court noted that courts in other states have adopted different approaches on whether jury instructions in such cases can include language on a doctor's "error of judgment."

That language should not be used in ordinary medical malpractice cases in South Dakota, the high court said.