Patients suffering from NexGen knee failure problems are filing Zimmer NexGen knee lawsuit claims to help compensate for outstanding medical bills and the pain and suffering associated with having additional surgeries. Surgical cement has been used to implant knee replacements for more than fifty years. Over that time, it has proven to be an effective method of fixation. Cementless (often called “press-fit”) implantation is a more recent development. It has been used increasingly over the past twenty years. The Zimmer knee recall issued by the FDA in September 2010 addressed the tibial plate, a component designed to be fixated with or without bone cement. We’ll describe the key issues concerning both methods of implantation below.
Fixating The Prosthesis With Surgical Cement
Bone cement was originally used in total knee arthroplasty as a substitute for ligaments (i.e. bands of connective tissue). The knee joint relies on four ligaments to keep the bones in place: the anterior and posterior cruciate ligaments, and the lateral and medial collateral ligaments. During knee arthroplasty, one or more of these ligaments may need to be removed. Bone cement is used to hold the implant in place.
The cement is applied between the surfaces of the tibia and femur, and the tibial and femoral components (respectively). Even though the bones need to be shaped prior to receiving the prosthesis, the cement is forgiving of irregularities on both surfaces. Once applied, the material hardens quickly. It can support the patient’s weight on the same day of the procedure.
One of the issues with cemented fixation is that the cement may begin to break apart due to load and wear. Small pieces may separate from the implant, contaminating nearby tissue.
Another potential problem is that the tibial component may sink into the top of the tibia. This occurs because the hard, bony surface of the tibia is removed prior to implantation of the tibial piece. Underneath the hard bone lies softer bone. Over time, the weight placed on the knee can cause the tibial plate to sink into it. Because the load is often distributed unevenly, this can lead to loosening of the prosthesis.
To clarify, this problem can occur with cemented and cementless knee replacements. In the former case, the cement acts as a mild buffer.
Implanting The Zimmer Knee Replacement Without Cement
Cementless fixation of the tibial and femoral components is less common than cemented fixation. The method requires the patient to have healthy bone stock, which is often an obstacle for older recipients. The implant is designed with a porous, textured contact surface. The tibia and femur grow into this surface, fusing with it.
This form of implantation is as stable as using cement. Once the patient’s bone has grown into the prosthesis, it can be expected to hold the tibial and femoral components in place. Data show that a knee replacement that has been implanted without cement will usually last as long as one implanted with it.
One of the drawbacks of cementless implantation is that the bone may become less stable as the result of debris that flakes off from the prosthesis. This debris is generated by friction. Whenever the patient moves her knee, the cobalt-chromium components rub against the polyethylene spacer that sits atop of the tibial plate. This generates particulate matter, which can cause inflammation in the joint, and eventually harm the bone.
While this problem can also occur with cemented fixation, it has a greater impact here. Debris, along with the body’s immune system, can create a situation that compromises the bony ingrowth that holds the prosthesis in place. If this occurs, the implant will loosen. This is one of the complications that prompted the FDA’s Zimmer knee recall of the tibial plate in 2010.
Zimmer NexGen Knee Lawsuit
The issues that plague the recalled tibial component of the NexGen knee replacement are believed to also affect the femoral component. This is the reason many experienced orthopedic surgeons have urged the manufacturer to announce a broader Zimmer knee recall. If you are experiencing knee pain, joint loosening, or other serious NexGen knee failure side effects, you may be able to file a claim for compensation. Contact a Zimmer lawsuit knee attorney to learn more about your options. We are currently filing individual lawsuits on behalf of patients and there is not national Zimmer class action lawsuit covering all cases.
