Many knee replacement surgeries are unwarranted, researchers say.

Nearly one-third of knee replacement surgeries in the U.S. may be classified as “inappropriate,” Virginia researchers found in a new study.

Daniel L. Riddle, Ph.D., PT, and colleagues from the Virginia Commonwealth University conducted the study using data from 205 people who had undergone total knee arthroplasty surgeries. 

The researchers used an appropriateness classification system developed by ESCOBAR to classify each surgery as “appropriate,” “inconclusive,” or “inappropriate.” They also used pain, physical function, knee motion, laxity, age and radiographic measurements. The average age of a person in the data set was 67 years; 60% were women. 

Results showed that about 44% of the surgeries were appropriate, about 22% were inconclusive and about 34% were inappropriate. Based on previous evidence and research, the hypothesized prevalence rate for inappropriate classifications was 20%.

Riddle attributes the 14% jump to the outdated classification system and the need for postoperative studies, he told McKnight’s. He cautions considering these factors before reading into the statistic. 

Riddle said he hopes this study makes “a good procedure even better by trying to make a developed general consensus” among U.S. practitioners, healthcare providers and researchers.

Results appeared June 30 in Arthritis and Rheumatology.