Knee Implant Failure Risks Increased By Bone Loss, Obesity, Unusual Bone Shape: Study

Researchers from the OrthoCarolina Hip & Knee Center have identified several patient factors, which may contribute to the risk of knee implant failure following joint replacement surgery. 

In a study published in January edition of The Journal of Arthroplasty, researchers indicate that obesity, abnormal bone shapes, and bone loss all play a role factoring into catastrophic knee implant failures and the need for revision surgery.

The research looked at data on 1,106 total knee arthroplasty (TKA) revision surgeries performed from 2004 to 2017, focusing on radiographic analysis of 27 cases that were performed at their institution.

According to their findings, 26 out of the 27 patients had preoperative bone deformities. The average body mass index of those patients was 38, which is considered severely obese, and 25 out of the 27 had radiographic medial tibial bone loss prior to the implant collapsing.

Researchers noted that as the average body mass index (BMI) in the U.S. has risen, so has the BMI of patients undergoing primary total knee arthroplasty. They noted that multiple studies have found that obesity increases the rate of knee implant complications. Previous studies have also pointed to increasing rates of mechanical failure of knee implants.

“Obesity has been demonstrated to double the risk of aseptic tibial loosening in primary TKA,” the researchers noted. “It appears that increased tibial stress is a primary factor for this mode of failure.”

The findings suggested that larger patients may require additional tibial fixation, and that it may surgeons should consider using selective criteria for increased tibial implant fixation to avoid problems. They recommended surgeons use three combined criteria: preoperative varus deformity in patients with a BMI of 35 or higher who require tibial components that are smaller than 50% of implant sizes.

The findings come amid a growing number of knee replacement lawsuits filed in recent months over problems associated with several different types of systems widely used in recent years, which have been linked to high rates of implant failure, resulting in the need for knee revision surgery; including DePuy Attune Knee lawsuits,Exactech Optetrak Knee lawsuits, and Arthrex iBalance knee lawsuits. Many of the problems with these implants have been linked to tibial loosening and tibial baseplate failures.