Partial Knee Replacement Seemed Safer but Failed More Than Total Replacement

Total knee replacement patients had worse outcomes in the first month after surgery than those who had partial replacements

(RxWiki News) Total knee replacement surgery is one of the more common operations performed in hospitals today. It’s not the only option, however, for a bum knee- nor is it the safest.

A new study found that partial knee replacements were less likely than total knee replacements to be deadly. However, the study also revealed that partial knee replacements needed to be redone more often.

"Discuss the potential risks of knee replacement with your surgeon."

This study was led by Professor David Murray, MD, FRCS, of the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences at the University of Oxford.

The researchers looked at data from the National Joint Registry for England and Wales, the largest joint registry in the world. They used data from April 2003 until August 28, 2012, and identified 75,996 people who had total knee replacements and 25,334 people who had unicompartmental knee replacements, also known as partial knee replacements.

Total knee replacements are usually done for severe arthritis, and about half of people who have a total knee replacements are eligible for partial replacements.

In a partial replacement, one of the three major compartments of the knee is replaced. These compartments include the inside of the knee, the outside and the front, which is the part between the knee cap and the thighbone. A partial knee replacement is typically a simpler operation than a total replacement because only part of the knee is replaced with an implant.

Dr. Murray and colleagues found that although partial knee replacements required many more revisions (repeat surgeries to replace the implant) than total knee replacements, the partial replacements also were less likely to come with severe complications.

People who had a partial knee replacement were 40 percent more likely to have revision surgery in the first eight years after the surgery than people who had total knee replacement, the researchers found.

The authors of this study noted that partial knee replacement is "often offered to younger patients who, because of their higher activity levels, tend to have better functional outcomes, but increased failure rates."

People who had total knee replacement were four times more likely to die in the first month after surgery, and 15 percent more likely to die in the first eight years after surgery, than people who had partial knee replacement.

Dr. Murray and team also found that those who had total knee replacement were twice as likely to have a blood clot, heart attack or deep infection than someone who had a partial replacement. Total knee replacement patients also were three times more likely to experience a stroke.

People who had total knee replacements had more blood transfusions and tended to be in the hospital for longer after surgery compared to partial knee replacement patients.

Revision rates are usually the statistics that physicians consider most when determining the type of implant to perform, the researchers noted. However, these researchers found there were many pros and cons associated with each type of knee replacement.

The researchers cautioned that the risk of life-threatening complications is very low, overall, with knee replacement surgery. A study published in the 2010 issue of the Journal of Bone and Joint Surgery estimated that the risk of death following surgery was 0.1 percent.

"To put the risks in perspective, if 100 patients had a partial knee rather than a total knee replacement there would be one fewer death and three more re-operations in the first four years after surgery," Dr. Murray said in a press statement.

This study was published July 8 in The Lancet.

One of the study authors, Hemant Pandit admitted to being a speaker for Biomet, manufacturers of orthopaedic implants and Professor Murray receives royalties related to the Oxford UKR and is paid consultancy fees by the same company.The Nuffield Department at Oxford receives research funding from Biomet, Stryker, and Zimmer, all of whom are manufacturers of orthopaedic implants.

The study authors report that none of these companies were involved in the funding or conduct of this study.

Review Date: 
July 8, 2014