Sigma Total Knee Research Articles

Excellent Survival and Good Outcomes at 15 Years Using the Press-Fit Condylar Sigma Total Knee Arthroplasty

BackgroundWe report 15-year survival, clinical, and radiographic follow-up data for the Press-Fit Condylar Sigma total knee arthroplasty. MethodsBetween October 1998 and October 1999, 235 consecutive TKAs were performed in 203 patients. Patients were reviewed at a specialist nurse-led clinic before surgery and at 5, 8-10, and 15 years postoperatively. Clinical outcomes, including Knee Society Score, were recorded prospectively at each clinic visit, and radiographs were obtained. ResultsOf our initial cohort, 99 patients (118 knees) were alive at 15 years, and 31 patients (34 knees) were lost to follow-up. Thirteen knees (5.5%) were revised; 5 (2.1%) for infection, 7 (3%) for instability, and 1 (0.4%) for aseptic loosening. Cumulative survival with the end point of revision for any reason was 92.3% at 15 years and with revision for aseptic failure as the end point was 94.4%. The mean Knee Society Score knee score was 77.4 (33-99) at 15 years, compared with 31.7 (2-62) preoperatively. Of 71 surviving knees for which X-rays were available, 12 (16.9%) had radiolucent lines and 1 (1.4%) demonstrated clear radiographic evidence of loosening. ConclusionThe Press-Fit Condylar Sigma total knee arthroplasty represents a durable, effective option for patients undergoing knee arthroplasty, with excellent survival and good clinical and radiographic outcomes at 15 years.

Press fit condylar cobalt chrome sigma total knee arthroplasty: No difference to original design at five year point

BackgroundTotal knee arthroplasty (TKA) is an established procedure for relieving pain and improving function. The Press Fit Condylar Cobalt Chrome Sigma (PFCSCC) Total Knee System was introduced by Depuy, Johnson & Johnson in 2006, as an update of their existing PFC Sigma design intended to reduce backside wear. MethodsTo identify any significant early failures following the introduction of this knee system, we prospectively identified all patients undergoing TKA with the PFCSCC over a one-year period. Clinical and demographic patient data, American Knee Society scores, Oxford Knee scores, SF-12 scores and radiographic data were recorded pre-operatively and at three and five years post-operatively. Results233 patients underwent 249 primary TKA's with the PFCSCC. Seventeen patients (19 TKAs) died before the last review and 29 patients (30 knees) were lost to follow up. The mean age was 66.6 (range 34–80) with 47.6% male. Mean five year follow-up was 1836days (range 1530–2307). Five knees (2.2%) were revised for infection with three revised for pain. The 5-year survival rate was 96.6% and 98.6% for aseptic failure. American Knee Society Score (AKSS) was 32.6 (0–86.6) preoperatively and 80.7 (29–95) 5 years post-operatively P<0.001. OKS was 20.9 (7–38) preoperatively and 36.4 (10–48) at 5 years P<0.001. ConclusionWe report the first five year outcome of this design change, which demonstrates a good early survivorship when compared to the previous PFC Sigma design.

Ten-year results of the Press Fit Condylar Sigma total knee replacement

We report ten-year clinical and radiological follow-up data for the Sigma Press Fit Condylar total knee replacement system (Sigma PFC TKR). Between October 1998 and October 1999 a total of 235 consecutive PFC Sigma TKRs were carried out in 203 patients. Patients were seen at a specialist nurse-led clinic seven to ten days before admission and at six and 18 months, three, five and eight to ten years after surgery. Data were recorded prospectively at each clinic visit. Radiographs were obtained at the five- and eight- to ten-year follow-up appointments. Of the 203 patients, 147 (171 knees) were alive at ten years and 12 were lost to follow-up. A total of eight knees (3.4%) were revised, five for infection and three to change the polyethylene insert. The survival at ten years with an endpoint of revision for any reason was 95.9%, and with an endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society Score (AKSS) was 79 (10 to 99) at eight to ten years, compared with 31 (2 to 62) pre-operatively. Of 109 knee with radiographs reviewed, 47 knees had radiolucent lines but none showed evidence of loosening.

Does a mobile-bearing, high-flexion design increase knee flexion after total knee replacement?

This prospective randomised controlled double-blind trial compared two types of PFC Sigma total knee replacement (TKR), differing in three design features aimed at improving flexion. The outcome of a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) was compared with that of a high-flexion rotating-platform posterior-stabilised design (RP-F) at one year after TKR. The study group of 77 patients with osteoarthritis of the knee comprised 37 men and 40 women, with a mean age of 69 years (44.9 to 84.9). The patients were randomly allocated either to the FB-S or the RP-F group and assessed pre-operatively and at one year post-operatively. The mean post-operative non-weight-bearing flexion was 107° (95% confidence interval (CI) 104° to 110°)) for the FB-S group and 113° (95% CI 109° to 117°) for the RP-F group, and this difference was statistically significant (p = 0.032). However, weight-bearing range of movement during both level walking and ascending a slope as measured during flexible electrogoniometry was a mean of 4° lower in the RP-F group than in the FB-S group, with 58° (95% CI 56° to 60°) versus 54° (95% CI 51° to 57°) for level walking (p = 0.019) and 56° (95% CI 54° to 58°) versus 52° (95% CI 48° to 56°) for ascending a slope (p = 0.044). Further, the mean post-operative pain score of the Western Ontario and McMaster Universities Osteoarthritis Index was significantly higher in the RP-F group (2.5 (95% CI 1.5 to 3.5) versus 4.2 (95% CI 2.9 to 5.5), p = 0.043). Although the RP-F group achieved higher non-weight-bearing knee flexion, patients in this group did not use this during activities of daily living and reported more pain one year after surgery.

Does hyperflex total knee design improve postoperative active flexion?

The rotating platform flexion (RPF) Sigma total knee prosthesis (DePuy; Warsaw, Indiana) was designed for maintaining the contact of the condyles with their corresponding tibial plateau throughout the high-flexion range. However, this requires an additional 3-mm bone cut of the posterior condyles. Compared to the conventional design, this modification is intended to improve the flexion range. This hypothesis was tested by studying the increase in flexion (flexion gain, range of motion [ROM], active flexion) of 59 consecutive patients who had received the hyperflex design implant (RPF), whose preoperative mobility values were retrospectively compared to these same values in another 59 consecutive matched patients who had received an implant with the conventional design of the same implant (rotating platform [RP]) between June 2005 and June 2006. Postoperative mobility was measured visually with a goniometer. Only osteoarthritic knees were eligible to be included. Knees with more than 20 degrees flexion contracture or less than 90 degrees flexion, and patients with a body mass index (BMI) greater than 30 were excluded. Both groups were comparable with regard to age, preoperative mobility values, and BMI. The sex ratio differed significantly, but preoperative mobility did not differ significantly in male and female patients in the RP and in the RPF groups. The difference in sex ratio did not appear to be a bias influencing preoperative mobility. Overall, the flexion gain was correlated to preoperative flexion (r=-0.75, p<0.001). The flexion gain in the RPF group was significantly greater than in the RP group (13+-20 versus 6+-13; p=0.02) as was the ROM gain (10+/-17 degrees versus 4+/-12 degrees; p=0.02). However, the one-year active mean flexions were not significantly different (118+/-14 degrees versus 116+/-6 degrees; p=0.47). In patients whose preoperative flexion was less than 120 degrees (18 and 27 RPF prostheses), the flexion and ROM gains were significantly greater in the RPF group (23+/-16 degrees versus 14+/-16 degrees; p=0.03 and 26+/-18 degrees versus 17+/-9 degrees; p=0.05), and the mean one-year active flexion was also greater in the RPF group (124+/-13 degrees versus 116+/-8 degrees, p=0.02). In patients with more than 120 degrees of preoperative flexion, the flexion and ROM gains and the final mean flexions in both groups were comparable. In particular, there were nine patients in the RP group and ten patients in the RPF group whose flexion decreased. Thus, the Sigma RPF prosthesis provided a significant additional flexion gain in patients with 90-120 degrees preoperative flexion, and less than 20 degrees flexion contracture. Patients with a preoperative flexion greater than 120 degrees were exposed to a decrease in flexion range whichever implant was used, RP or RPF. Level 3, therapeutic study.

Functional outcome of PFC Sigma fixed and rotating-platform total knee arthroplasty. A prospective randomised controlled trial

The aim of this study was to determine whether there is a difference in functional outcome between the PFC Sigma fixed-bearing and rotating-platform total knee replacement systems. One hundred twenty patients were randomised to receive either a fixed-bearing or rotating-platform PFC Sigma total knee replacement. Range of movement (ROM), Oxford knee score (OKS) and Knee Society score (KSS) were assessed independently before and one year after surgery. Weight-bearing X-rays were taken immediately and one year post surgery to determine the incidence of osteolysis and loosening. At a mean follow-up of 13.4 months there was no statistically significant difference in mean ROM, OKS and KSS between the two groups. There was no evidence of osteolysis or loosening in either of the groups and no revision for infection or implant failure. This study shows that there is no statistically significant difference in functional outcome between the two types of implants at short-term follow-up.

Press fit condylar Sigma total knee arthroplasty: 7–9 years results

Objective This study reports the first clinical and radiological results at 7–9 years for the DePuy Pressed Fit Condylar Sigma total knee arthroplasty (TKA).

Evaluating the rotational alignment of the femoral component in PFC Sigma total knee arthroplasty

Evaluating the rotational alignment of the femoral component in PFC Sigma total knee arthroplasty

Midterm Results with the PFC Sigma Total Knee Arthroplasty System

We prospectively studied 207 consecutive patients (284 knees) undergoing total knee arthroplasty (June 1996 to December 1997) with a cemented tricompartmental Sigma PFC (DePuy Orthopaedics, Warsaw, Ind) total knee arthroplasty via a standard procedure (median follow-up, 87 months). Cruciate-retaining (272 knees, 96%) and cruciate-substituting (12, 4%) implants were used. There was one revision secondary to a ligament disruption after a fall. No implants were radiographically loose or at risk for loosening. Radiolucencies (none >2 mm or progressive) were shown on anteroposterior (7% of medial tibias) and lateral (17% of posterior femora) radiographs. Knee Society pain scores improved significantly (preoperative median, 20 points; postoperative median, 50 points [ P < .001]). The PFC Sigma Knee system has excellent midterm durability.

Five-year results of the Sigma total knee arthroplasty

The DePuy Sigma total knee arthroplasty (TKA) was introduced in 1997 as a modification of the Press Fit Condylar Knee (PFC) TKA and has been used extensively in the United Kingdom and worldwide. It is the most commonly used TKA in England and Wales, where it accounts for 36% of all primary TKA. The PFC was well established, with reported 10-year survival rates of 93–97%, but this study reports the first 5-year clinical and radiographic follow-up data for the Sigma TKA. Over a 10-month period, 212 Sigma TKAs were performed in 180 patients. Patients were seen at a specialist nurse-led clinic 7 to 10 days before admission and at 6 months, 18 months, 3 years and 5 years after surgery. Data were recorded prospectively at each visit. Radiographs were obtained at the 5-year follow-up appointment. Of 212 knees, 178 (151 patients) were alive at 5 years. Three were lost to follow up. Six knees (3.0%) were revised, five for infection and one underwent change of polyethylene insert at 4.9 years. Five-year survival with an endpoint of revision for any reason was 97.0%; with an endpoint of revision for aseptic failure it was 99.5%. The median American Knee Society knee rating score was 93 out of 100 at 5 years compared with 25 out of 100 at admission. Of 147 radiographs, none showed radiographic loosening of either component. Seventeen (11.6%) showed radiolucent lines. Twenty-eight (19.0%) had alignment outside the range of 7 ± 3° valgus. These results suggest that the Sigma TKA gives acceptable clinical results after 5 years. Further follow-up studies are required to see if this performance is maintained in the long term.

Midterm Results of Cemented Press Fit Condylar Sigma Total Knee Arthroplasty System

To evaluate the midterm results of 50 patients who underwent total knee replacement using Press Fit Condylar (PFC) Sigma system. We retrospectively reviewed 87 consecutive cases (50 patients with 37 bilateral cases) of PFC Sigma total knee replacement performed between January 1998 and December 1999. Patients were evaluated clinically and radiographically by an independent observer. The American Knee Society Score, Oxford Knee Score, and Knee Society radiographic assessment were used to rate knee function and to determine the satisfaction level of each patient. The mean age of the patients at the time of operation was 65 years (range, 41-85 years). The mean follow-up period was 5.4 years (range, 4.5-6.4 years). 44 patients (79 knees) were available for follow-up, 3 patients (3 knees) were lost to follow-up, and 3 patients (5 knees) died of unrelated causes. At the final follow-up, the mean Oxford Knee Score was 22. Using the American Knee Society Score, 88% of the knees were rated excellent, 4% good, 2% fair, and 6% poor. Five knees required revision surgery, the indications being infection in 4 knees and aseptic loosening in one knee. The survival rate of the implants was 94% at 6 years. The PFC Sigma total knee arthroplasty system has demonstrated good midterm results at our institution.

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Comparison of the PFC sigma fixed-bearing and rotating-platform total knee arthroplasty in the same patient: short-term results

This study compares the fixed-bearing PFC Sigma Total Knee Arthroplasty to the recently introduced rotating-platform version of the same design in 26 patients. At an average follow-up time of 46 months for the fixed-bearing side and 16 months for the rotating-platform side, no significant differences were found in terms of knee preference, knee pain, range of motion, overall satisfaction, or Knee Society scores (KSSs). No revisions, subluxations, dislocations, or infections were seen. Also no radiographic evidence of component loosening, osteolysis, or malalignment was found in any knee. The results of cementing the PFC Sigma rotating-platform, posterior-stabilized total knee show excellent patient satisfaction at 1 year and comparable clinical and radiographic results to the fixed-bearing version.