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Midterm results with the PFC Sigma total knee arthroplasty system.

Our study shows excellent clinical results with the PFC Sigma total knee replacement after almost eight years follow-up.

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Johnson & Johnson DePuy offers the following knee systems:

Design concepts for high flexion in the new PFC Sigma RP-F knee are focusing on shortening radii of curvature, thickening of posterior femoral condyle, increasing of the height of the posterior-stabilized box and deepening the trochlea groove. More bone loss of femoral condyle in the new PFC Sigma RP-F knee is required for these design trends than in the LCS knee. These design changes result in a significant bone loss at revision surgery, excessive polyethylene wear, patellofemoral joint problem and knee instability. Once the posterior cruciate ligament is cut, options to prevent anteroposterior instability area limited to the use of a posterior stabilized design with a tibial post and femoral cam, or a dished polyethylene insert with a raised anterior lip. In a computational kinematic study, Morra et al. reported that in general, all of the designs that did not employ a tibial post and femoral cam mechanism developed tibiofemoral contact in the central or anterior portion of the tibial insert, thus decreasing the capacity to achieve deeper flexion. The incorporation of a central polyethylene tibial post and a horizontal femoral cam serve as a mechanical substitute for the posterior cruciate ligament, to induce femoral roll-back in knee flexion. However, some retrieval studies of posterior-stabilized knee arthroplasties obtained at the time of revision surgery have shown the occurrence of tibial post wear. Puloski et al. reported in qualitative and quantitative wear analysis that posterior stabilized implants may contribute to the production of additional wear debris and hence may influence the prevalence of negative outcomes such as osteolysis, aseptic loosening, and reactive synovitis. Mikulak et al. found that the vector sum of the tibiofemoral forces and the cam post forces is compression into the tibia. And rotational stresses can be transmitted to the modular interfaces and to the metal cement interfaces. Some described the cases of tibial post fracture. The failure mechanism of post fracture in that study was presumed to be caused by repetitive anterior impingement between the metal femoral cam and the polyethylene post.

Midterm results of cemented Press Fit Condylar Sigma total knee arthroplasty system.

In this radiostereometric analysis, we found that the micromotion of the PFC-Sigma prosthesis differs slightly from the original PFC design, an advantage of the PFC-Sigma prosthesis.

SIGMA® Total Knee System | DePuy Synthes Companies

In 1997, a modification of the femoral component was introduced, and the prosthesis was renamed PFC-Sigma.

High flexion of the knee after total knee arthroplasty is essential for a successful overall functional outcome. One problem of total knee arthroplasty in Asian people is that patients cannot flex the knee beyond 120° following the operation. Various factors that may influence the range of motion of the knee after a total knee arthroplasty have been postulated. There have been increasing complaints especially from Asian patients regarding the difficulties associated with carrying out their daily activities, whose life style involves sitting on the floor with their legs crossed or in the kneeling position. The high flexion posterior stabilized mobile bearing knee prosthesis has been introduced to enhance knee flexion. We evaluated the results of total knee arthroplasty using high flexion rotating platform mobile bearing knee system in Korean patients and compared the results of this new prosthesis total knee arthroplasty with those of total knee arthroplasty using standard rotating platform mobile bearing knee system in order to assess the clinical results including the maximal flexion angle after a follow-up of at least 2 years.

Fifty cases of total knee arthroplasty were performed with the PFC Sigma RP-F mobile bearing knee system and sixty-one cases were performed with the LCS mobile bearing total knee arthroplasty. The average duration of follow-up was 2.9 years.

P.F.C.® SIGMA® TC3 Knee System | DePuy Synthes …

Medium-term results with the Press Fit Condylar (PFC) Sigma knee prosthesis the Wrightington experience.

Our randomised controlled trial of 120 patients who underwent unilateral knee replacement for osteoarthritis showed no statistically significant difference in functional outcome and survivorship between the mobile-bearing and rotating-platform in the PFC Sigma total knee replacement at a mean of 13.4 months. However, in our trial the PCL was retained in all cases, all implants were cemented and the patella was not resurfaced. Results of this combination have not been previously reported.

In the last few years a number of studies have been published comparing the results of a fixed and mobile bearing total knee arthroplasty using a similar design of prosthesis, i.e. the PFC Sigma total knee replacement system [–]. All of these studies, however, differ with regards to PCL status, implantation techniques (cemented or hybrid) and resurfacing of the patella (Table ).

From the radiostereometric, radiographic, and clinical data, we conclude that the PFC-Sigma knee prosthesis can be used with confidence.
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  • The SIGMA ® Knee System ..

    Midterm Results with the PFC Sigma Total Knee Arthroplasty System ..

  • The cemented PFC Sigma prosthesis was used exclusively in all cases.

    Photograph of the PFC Sigma rotating-platform prosthesis

  • PFC Sigma Knee System components, sizes 2.5, 7, and 8; 3

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with PFC Sigma knee prosthesis ..

The range of motion after total knee arthroplasty rarely exceeded 120°. In a prospective, observational multicenter study of 684 patients, Miner et al. reported that there was no significant difference in satisfaction and perceived quality of life in patients who obtained greater than 95 of flexion after total knee arthroplasty than those who exhibited less than 95 of flexion at 12 months' follow-up. Meneghini et al. reported that there is no statistically significant benefit in overall knee function in terms of the mean Knee Society and function scores for those patients who attained high flexion greater than 125 and those who attained normal flexion after total knee arthroplasty. However, in the Asian life style, hyperflexion of the knee is necessary for daily living. In order to sit on the floor with crossed legs, the flexion of the knee joint should be more than 120° and more than 135° of flexion are required to sit down in kneeling position. To enhance knee flexion, several new designs were introduced. Among them, the new PFC Sigma RP-F knee is designed to provide range of motion of 155° without increasing contact stresses in the polyethylene by providing a third articulating surface and simultaneously allowing for proper patellar tracking. In the current series, mean postoperative range of flexion at last follow-up did not differ significantly between the two groups. The final follow-up mean maximum flexion angle was 125.6 in the LCS RP group and 127.0 in the PFC Sigma RP-F group ( = 0.620).

The DePuy Sigma TC3 Revision incorporates ..

Mobile bearing total knee arthroplasty designs offer the theoretical advantage of increased implant conformity and contact area while minimizing stresses transmitted to the fixation interface. The dual articulation is also designed to reduce polyethylene wear and to subsequently decrease the rate of revision total knee arthroplasty. This uncoupled motion through the tibial tray polyethylene bearing articulation theoretically minimizes the transfer of torsional stresses to the fixation interface that is present with fixed bearing total knee arthroplasty prosthetic designs. Many studies have been conducted on comparison of the fixed-bearing and mobile bearing total knee arthroplasty. However, there is a paucity of information in the literature regarding comparison of rotating platform and high flexion rotating platform total knee arthroplasty. So, we compared the results of PFC Sigma RP-F total knee arthroplasty with those of total knee arthroplasty using LCS mobile bearing knee system in order to assess the clinical results including the maximal flexion angle after a follow-up of at least 2 years.

DePuy® Rotating Platform Revision Knee Replacement.

The preoperative knee scores did not differ significantly (). There were no statistically significant differences between groups in the Knee Society Score (KSS), function, and the HSS scores postoperatively. In the LCS RP group, the mean postoperative final follow-up KSS knee score was 93.72 points, KSS functional score 77.29 points, and HSS score was 90.19 points. In the PFC Sigma RP-F group, the mean postoperative final follow-up KSS knee score was 93.54 points, KSS functional score 77.60 points, and HSS score was 89.86 points. The postoperative pain scores, according to both knee-scoring systems, did not differ significantly between the groups ( = 0.446 and = 0.118, respectively) ().

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