High-Flex Knee Replacement Devices May Carry Risks

People in need of a knee replacement may want to proceed with caution if they are considering one type of procedure called high-flexion (hi-flex) knee replacement surgery. Recently, some studies have indicated that the risks of hi-flex knee replacement may outweigh the procedure’s benefits for most patients. Some devices used in high-flex knee surgery include <"http://www.yourlawyer.com/topics/overview/DePuy-High-Flex-Knee-Replacement-Lawsuit">DePuy’s Sigma CR150 High-flex Knee System and the Sigma RP-F Knee System, both of which are part of DePuy’s P.F.C. Sigma Revision Knee System line.

There is a high degree of dissatisfaction with standard knee replacements. Many patients who undergo traditional procedures complain that they are unable to squat on the floor or climb stairs easily following surgery. High-flex knee replacement is usually considered for highly active patients who wish to continue high level activities after their knee replacement. Devices like the Depuy high-flex knee replacements are designed for patients who require more knee motion for certain activities.

However, there are downsides to these procedures. For one thing, hi-flex knee replacement surgery requires that more bone at the back of the knee be removed so that the patient may bend the joint further farther. Also, high-flexion will not be achieved in patients whose mobility is very severely restricted before the surgery.

A study conducted between 2003 and 2004 involving one popular high-flex knee (not the Sigma CR150 High-flex Knee or Sigma RP-F Knee systems) that included 47 patients found that at the 32-month mark, 38% experienced aseptic loosening around the femoral components and 21% required a revision surgery due to progressing loosening and pain. The study also found that the higher the flexion achieved (125° compared to 136 °), the more likely patients were to experience loosening of the implant.

Another study compared high-flex prosthetics with normal prosthetics and actually revealed that for the average patient without any special demands, the additional knee flexion provided by the high-flex design made no significant difference in range of motion.

When loosening occurs with devices like the Sigma CR150 High-flex Knee or Sigma RP-F Knee systems, the complication could be attributed to surgical technique or problems with the product design or manufacture.

Some symptoms that indicate a possible failure of a high-flex knee implant include:

• Reduced functionality
• Difficulty walking or standing
• A loose feeling in your knee joint
• A popping sensation or clicking noise in the knee
• Persistent knee pain

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