Zimmer manufactures a number of personalized orthopedic products that specialize in joint replacement technology. Products like the Zimmer NexGen LPS-Flex knee replacement system were designed to provide innovation in knee replacement devices. Marketing for the Zimmer NexGen LPS-Flex device claimed that patients would have greater mobility than with other knee replacement implants.
However, this superior design caused complications for a number of patients. In 2010, Zimmer recalled several lots of the NexGen LPS-Flex Gender Femoral Component due to manufacturing flaws. As a result, several lawsuits have been filed against Zimmer by patients who experienced side effects such as persistent pain and device loosening.
Zimmer NexGen LPS-Flex Design
The Zimmer NexGen LPS-Flex knee replacement system was designed to give patients a greater range of motion. The industry standard for knee replacement devices is roughly 120 degrees of flexion. Flexion is the ability to bend the knee. The Zimmer NexGen LPS-Flex boasted 155 degrees of flexion for patients. By marketing the Zimmer NexGen LPS-Flex this way, Zimmer made promises of superior performance.
When the knee bends, three main components are required. The femur, or thighbone, extends from an individual’s pelvis to the knee. During movement, the femur rolls and slides atop the tibia. The tibia is the bone extending from the individual’s knee to the ankle. The patella, or kneecap, slides over the femur during movement.
The Zimmer NexGen LPS-Flex was designed to provide better contact among the patient’s femur and tibia. This would provide greater flexion and comfort when the knee is heavily bent. In order to accomplish this, the Zimmer NexGen LPS-Flex system featured an extended roundness on the artificial femur component. Additionally, the Zimmer NexGen LPS-Flex uses a deep cut-out that allows greater clearance for the patellar tendon. The patella component may then properly cover the patient’s femur during knee bending.
NexGen LPS-Flex Component Recall
In December 2010, the company issued a voluntary recall for certain lots of the Zimmer NexGen LPS-Flex Gender Femoral Component. This component was created specifically for females who need total knee replacement surgery. The recall affected components that were distributed all over the world. According to the FDA, distribution countries included Germany, France, Spain, Bulgaria, and several other countries.
Prior to the recall, Zimmer sent out an “Urgent Device Correction and Removal” notice to distributors, sales associates, surgeons, and risk managers. Those who still had inventory were instructed to return them. Surgeons were not asked to take action, but were advised to take notice for future reference.
This Zimmer NexGen LPS-Flex component recall took place due to issues with the device’s cam. The cam is a special bar in the femoral component. In a standard knee device, an internal post located in the cushion of the tibial component is made to fit into the cam. However, the recalled femoral components exhibited a nonconforming cam radius within the device. These nonconforming geometry issues jeopardized the integrity of the knee replacement devices. To avoid widespread complications, Zimmer recalled the components from these specific lots.
Zimmer NexGen LPS-Flex Complications
Many patients experienced premature loosening of their Zimmer NexGen LPS-Flex knee replacement. In 2007, a published study observed 47 patients who received a Zimmer NexGen LPS-Flex knee replacement. Of the 47 patients, 27 experienced device loosening within three years of having the initial knee replacement procedure. Fifteen patients required a revision surgery before two years of the initial knee replacement procedure. The study confirmed that high-flexion and weight-bearing activities tended to contribute to loosening of the Zimmer NexGen LPS-Flex knee replacements.
Studies also show that patients who received a Zimmer NexGen LPS-Flex knee replacement experienced fractures around the implant. One patient in a 2010 study exhibited failure of the knee’s muscle group known as the extensor mechanism. Two patients from the same study experienced instability in the knee.