Knee Replacements

knee replacementFor millions of patients, knee replacement surgery has helped to improve the overall quality of life. The first knee replacement surgery was performed in 1968. Since this time, the orthopedic surgery industry has gained a number of revolutionary products and procedures to enhance knee replacement surgery for both patients and doctors. The Agency for Healthcare Research and Quality estimates that more than 600,000 knee replacement surgeries are performed in the U.S. each year.

However, a number of patients have experienced more harm than benefit from knee replacement surgery. Several knee replacement manufacturers are currently facing lawsuits from patients who have experienced injury as a result of their knee replacements. The Zimmer Manufacturing Company has manufactured knee replacement products that have resulted in alleged severe side effects or complete knee replacement failure.

What Is Knee Replacement Surgery?

Knee replacement surgery is a procedure that resurfaces the bones and cartilage of the knee to restore mobility and comfort to patients with knee problems. Knee replacement surgery is recommended for patients who experience severe knee damage due to injury or arthritis.

Ideal patients have tried using medications and walking supports. However, patients who undergo knee replacement surgery often have severe knee problems that are not corrected using these means. Knee replacement surgery can help to relieve knee pain, correct leg deformities, and help patients resume normal daily activities.

Knee Replacement Process

During a typical knee replacement procedure, there are four basic steps.

  1. Preparing the bone. Before the replacement can begin, the orthopedic surgeon must remove the surfaces of the patient’s damaged tissue. The damaged cartilage at the ends of the patient’s tibia and femur are removed. Small amounts of underlying bone are also removed.
  2. Positioning the implants. In typical knee replacement surgery, metal components are implanted to replace the bone and cartilage that was removed during the preparation stage. This recreates the surface of the joint. In many cases, these metal parts are cemented, or “press-fit,” into the patient’s bone.
  3. Resurfacing the kneecap. The undersurface of the patient’s patella, or kneecap, is then cut and resurfaced using a plastic button. In some cases, the orthopedic surgeon will not resurface the patella. This depends on each patient’s specific details.
  4. Inserting a spacer. In order to create a smooth and comfortable gliding surface, the orthopedic surgeon will insert a medical-grade plastic spacer. This plastic spacer is inserted in between the implanted medical components.

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Knee Replacement Complications

Knee replacement patients have experienced a number of knee replacement complications. As a result, many knee replacement patients are forced to undergo revision surgery to correct problems with the device or problems created by the device. Knee replacement revision surgery can be costly and painful for patients. It can also be difficult for surgeons to perform, given the invasive nature of the implant.

Knee replacement complications can include:

  • Swelling at the implant site
  • Severe knee pain
  • Poor flexion and range of motion
  • Knee implant loosening
  • Complete knee implant failure

Zimmer Knee Replacement

One of Zimmer’s flagship products is the NexGen knee replacement system. This system was designed to increase the range of motion for the knee replacement patient. The current industry standard for knee replacements is 120 degrees of flexion, or the ability of the knee to bend. A healthy knee typically experiences 160 degrees of flexion. When Zimmer created the NexGen LPS-Flex knee replacement system, the company claimed that patients could receive up to 155 degrees of flexion.

Although there have not been any recalls for Zimmer knee replacement systems, several components have been recalled. In April 2010, Zimmer issued a notice in response to reported high failure rates of its NexGen MIS Tibial Component. In January 2012, one of Zimmer’s knee replacement components was recalled. This component was the Natural-Knee Durasul All-Poly Patella. The recall was a result of evidence showing increased risk of fracture with the component.

Show Sources
  1. "Class 2 Recall: NEXGEN COMPLETE KNEE SOLUTION MIS TIBIAL COMPONENTS, LOCKING SCREW AND STEM EXTENSIONS." U.S. Food and Drug Administration. U.S. Department of Health and Human Services, 13 Sept 2010. Web. 16 May 2013. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfRes/resCollection_2.cfm?ID=92118&CREATE_DT=2010-09-13
  2. Endres, Stefan, and Axel Wilke. "Early Experience With The NexGen CR-Flex Noble Knee Arthroplasty System: Results Of 2-Year Follow-Up." Orthopedic Reviews 2.1 (2010): 3-5. Academic Search Complete. Web. 16 May 2013.
  3. "PMA granted for Zimmer's NexGen LPS-Flex Mobile Knee." Medical Device Week 13 Dec. 2007. Academic OneFile. Web. 16 May 2013.