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.     

Minimum twelve-year follow-up of fixed- vs mobile-bearing total knee arthroplasty: Double blinded randomized trial

BackgroundTotal knee arthroplasty (TKA) with fixed-bearing (FB) implants have demonstrated impressive functional results and survival rates. Meanwhile, rotating-platform (RP) constructs have biomechanically shown to reduce polyethylene wear, lower the risk of component loosening, and better replicate anatomic knee motion. There is growing question of the clinical impact these design changes have long-term.Questions/purposes: The aim of this double-blinded prospective randomized trial was to compare function and implant survival in patients who received either FB or RP press-fit condylar Sigma (PFC Sigma, DePuy, Warsaw, IN) total knee replacements at a minimum follow-up of twelve years.Patients and methodsPatient reported outcome measures used included the functional Knee Society Score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores, Medical Outcomes Short Form-36 (SF-36) score, and satisfaction assessment on a four-point Likert scale. The data was collected from times preoperative, two-years, and final encounter (mean 13.95 years). A total of 28 RP and 19 FB knees (58.8%) were analyzed at the final follow-up.ResultsAmong all patients, KSS and WOMAC scores statistically improved from pre-op to 2-year, while KSS statistically worsened from 2-year to final follow-up. The RP group averaged better follow-up scores in all assessments at the final follow-up with exception of overall satisfaction. There was no statistically significant difference in the functional Knee Society Score, Short Form-36, WOMAC scores, patient satisfaction or implant survival between the two groups at any measured period.ConclusionsThe use of a fixed-bearing or rotating-platform design does not convey significant superiority in terms of function or implant longevity at a minimum twelve years after total knee arthroplasty.Level of evidenceLevel I, Experimental study, randomized controlled trial (RCT).     

Bilateral total knee arthroplasty: One mobile-bearing and one fixed-bearing

We compared the early results of mobile-bearing knee prosthesis with fixed-bearing knee prosthesis in 16 patients who had one-stage, sequential, bilateral replacements. In each patient, a Low Contact Stress (LCS, Depuy) rotating-platform prosthesis was inserted in one side, and an Anatomic Modular Knee (AMK, Depuy) posterior-stabilised prosthesis was inserted in the other side. The same surgical routines were adopted for both sides in each patient. There were significant improvements in the Knee Society knee score and functional score, as well as the Oxford Knee score after both mobile-bearing and fixed-bearing knee replacements (p<0.001). However, we could not find any significant difference between the clinical results of the two prostheses. The authors early experience with the mobile-bearing total knee prosthesis was as favourable as the medium-term experience of the fixed-bearing total knee prosthesis in this prospective, match-pair study.     

Short-term differences in anterior knee pain and clinical outcomes between rotating and fixed platform posterior stabilized total knee arthroplasty with a new femoral component design

AIM To compare rotating versus fixed-bearing Press-Fit Condylar(PFC) Sigma posterior stabilized(PS) total knee arthroplasty(TKA) with the new "J curve"femoral design in terms of clinical outcomes and anterior knee pain.METHODS We retrospectively analyzed 39 patients who underwent primary total knee replacement surgery for knee osteoarthritis using the PFC Sigma PS TKA with either fixed(FP group, 20 cases) or rotating platform(RP group, 19 cases) treated between 2009 and 2013 by the same surgeon. The two groups were homogeneous for age, gender, weight, American Society of Anesthesiologists status, preoperative clinical and functional scores, and prosthetic alignment at two years after surgery. We analyzed clinical outcomes score at two years follow-up using Knee Society Score(KSS), Knee Injury and Osteoarthritis Outcome Score(KOOS),Knee Performance Score, Short Form(SF) 36, and anterior knee pain assessed by the Hospital for Special Surgery(HSS) patellar score.RESULTS No differences were found in KSS, Knee Performance Score, and SF-36 outcome scores. A statistically significant difference was found in the HSS Patella score objective(FP: 22.36; RP: 28.75; P 0.05), HSS Patella score total(FP: 73.68; RP:86.50; P 0.05), and KOOS symptoms(FP: 73.49; RP: 86.44; P 0.05).CONCLUSION Rotating platform in PFC Sigma PS TKA appears to reduce the short-term incidence of anterior knee pain compared to the fixed platform.     

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

PURPOSE: To evaluate the midterm results of 50 patients who underwent total knee replacement using Press Fit Condylar (PFC) Sigma system. METHODS: 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. RESULTS: 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. CONCLUSION: The PFC Sigma total knee arthroplasty system has demonstrated good midterm results at our institution.     

A comparison of fixed-bearing and mobile-bearing total knee arthroplasty at a minimum follow-up of 4.5 years

BACKGROUND: Durable long-term independent results with the Low Contact Stress rotating-platform (mobile-bearing) and the Insall Burstein-II (fixed-bearing) total knee prostheses have been reported, but no studies describing either the mid-term or long-term results and comparing the two prostheses are available, to our knowledge. METHODS: Thirty-two patients who had bilateral arthritis of the knee with similar deformity and preoperative range of motion on both sides and who agreed to have one knee replaced with a mobile-bearing total knee design and the other with a fixed-bearing design were prospectively evaluated. Comparative analysis of both designs was done at a mean follow-up period of six years, minimizing patient, surgeon, and observer-related bias. Clinical and radiographic outcome, survival, and complication rates were compared. RESULTS: Patients with osteoarthritis had better function scores and range of motion compared with patients with rheumatoid arthritis. However, with the numbers available, no benefit of mobile-bearing over fixed-bearing designs could be demonstrated with respect to Knee Society scores, range of flexion, subject preference, or patellofemoral complication rates. Radiographs showed no difference in prosthetic alignment. Two knees with a mobile-bearing prosthesis required a reoperation: one had an early revision because of bearing dislocation and another required conversion to an arthrodesis to treat a deep infection. CONCLUSIONS: We found no advantage of the mobile-bearing arthroplasty over the fixed-bearing arthroplasty with regard to the clinical results at mid-term follow-up. The risk of bearing subluxation and dislocation in knees with the mobile-bearing prosthesis is a cause for concern and may necessitate early revision. LEVEL OF EVIDENCE: Therapeutic Level II.     

后稳型旋转平台高屈曲假体与普通假体置换后的膝关节功能比较

目的 探讨后稳型旋转平台高屈曲假体膝关节置换的手术适应证及其在改善膝关节功能方面的优越性.方法 应用前瞻性随机对照研究方法,将2009年2月至2009年4月经门、急诊收治的膝关节骨关节炎患者75例94膝随机分为两组,一组接受后稳型旋转平台普通假体置换(PFC sigma RP假体),另一组接受后稳型旋转平台高屈曲假体置换(PFC sigma RPF假体).两组患者的一般情况及术前特种外科医院(the Hospital for Special Surgery,HSS)膝关节评分和膝关节活动范围差异均无统计学意义.根据患者入院顺序再次随机化,由3名术者抽签决定各自的手术对象.术后1、6、12及18个月复查HSS评分及膝关节活动范围,术后18个月对患者进行满意度问卷调查.所有患者术前、术后第3天、3、6、12和18个月拍摄术侧膝关节正、侧位和双下肢站立位全长X线片.结果 70例87膝完成最终随访,普通组33例46膝,高屈曲组34例41膝.术后18个月普通组HSS膝关节评分(92.4±5.0)分,高屈曲组(94.7±7.0)分,两组差异无统计学意义;普通组膝关节活动范围123.0°±15.3°,高屈曲组131.9°±14°,两组差异有统计学意义,高屈曲组大于普通组,但未达到样本量估计时所设定的20°.术后18个月,两组患者的手术满意率均为100%.结论 高屈曲假体与普通假体置换的近期疗效相似.高屈曲假体未显示出在膝关节屈曲活动范围方面的优势.

Abstract：

Objective To explore the indication and the functional advantages of the high-flexion posterior stabilized (PS) rotating-platform mobile-bearing (RP-MB) total knee system. Methods A prospective randomized, controlled trial was performed. Osteoarthritis was the indicators for total knee arthroplasty.From Feb. 2009 to Apr. 2009, 75 patients (94 knees) were randomly assigned to to receive either a highflexion PS, RP-MB total knee system(PFC sigma RPF) or a standard one (PFC sigma RP). There were no statistical difference in the baselines, the preoperative scores of the Hospital for Special Surgery (HSS) and the knee range of motion (ROM) of both groups. The functional status were assessed with Hospital for Special Surgery and the ROM of the knee at the postoperative 1, 6, 12, 18 months. The satisfaction rates were assessed at the postoperative 18 months. The radiographic measurements were t assessed at the postoperative 3days and 3, 6, 12, 18 months. Results A total of 70 participants (87 knees) completed the 18-month followup. At the time of the final follow-up, the average Hospital for Special Surgery knee score was 92.4±5.0points in the standard group and 94.7±7.0 points in the high-flex ion group. The difference was not statistically significant(P ＞0.05). The average maximal flexion was 131.9±14 degrees in the high-flexion group and 123.0±15.3 degrees in the standard group. There was a statistical difference. But it was not enough to confirm our hypothesis that the difference should be higher than 10 degrees. Moreover, the satisfaction rate were 100% in both groups, and no statistical significant difference was found. Conclusion No significant differences were found between standard and high-flexion posterior-stabilized rotating-platform mobile-bearing total knee prostheses in terms of clinical outcomes or range of motion.     

Greater satisfaction in older patients with a mobile-bearing compared with fixed-bearing total knee arthroplasty

A prospective, randomized, controlled, double-blind trial was performed to compare outcomes between 61 mobile- and 58 fixed-bearing primary TKAs in patients aged 70 years or older. At last follow-up, no difference was found for Knee Society score. The mobile-bearing group had greater knee flexion at 3 and 6 months, but this was similar at 2 years. The patient satisfaction was better in the mobile-bearing group than in fixed-bearing group, with respect to Knee Society functional score, Western Ontario MacMasters University score, Short-Form 12 score, and visual analog scale score. A multivariate analysis confirmed that the only independent factors predictive of postoperative quality of life were early postoperative flexion. We believe that better perception and satisfaction with mobile-bearing in older patients was due to the earlier regain of their knee flexion. Our results justify the use of mobile-bearing design in the older population.     

Clinical Outcome of Medial Pivot Compared With Press-Fit Condylar Sigma Cruciate-Retaining Mobile-Bearing Total Knee Arthroplasty

Background

The purpose of this study was to compare the long-term clinical results, radiographic results, range of knee motion, patient satisfaction, and the survival rate of Medial-Pivot posterior cruciate-substituting, knee prosthesis and a press-fit condylar (PFC) Sigma cruciate-retaining mobile-bearing knee prosthesis in the same patients.

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

The PFC Sigma total knee was introduced in 1997, incorporating a number of design changes. We report the mid-term results of a consecutive series of PFC Sigma knee arthroplasties performed between November 1997 and December 1998. Out of a total of 156 patients (166 knees), 5 patients (5 knees) were lost to follow-up and 6 patients (6 knees) died of unrelated causes. This left 145 patients (155 knees), 90 female and 55 male, with a mean age of 70 years (range, 53-88) and an average follow-up of 90 months (range, 84-96). Posterior cruciate retaining components were used in 136 knees (88%) and posterior-stabilized in 19 (12%). The patella was resurfaced in 74 (48%) knees. Follow-up was at 3, 6 and 12 months, then yearly. Preoperative American Knee Society and Oxford scores were compared with follow-up scores. The Knee Society radiological score was used for radiographic assessment. One knee (0.6%) was revised due to aseptic loosening. One knee (0.6%) had superficial wound infection, which settled with oral antibiotics. Two knees became deeply infected. Of these, one resolved following early debridement, the other developed chronic infection. Using revision for any reason as the end-point our cumulative success rate was 99.4%. The mean preoperative Knee score improved from 45 (30-65) to 84 (45-92), Functional score from 38 (25-55) to 73 (50-95) and Oxford score from 43 (33-52) to 17 (14-29). Radiographic review showed radiolucent lines in 54 (35%) tibial and 17 (11%) femoral components. The Radiological Knee Society score was less than 4 in all except one tibia where the score was 7. Our study shows excellent clinical results with the PFC Sigma total knee replacement after almost eight years follow-up.     

An analysis of rotating-platform total knee replacements

Rotating-platform, mobile-bearing total knee replacements have been developed to improve knee kinematics, lower contact stresses on the polyethylene tibial component, minimize constraint, and allow implant self-alignment. The purpose of the current study was to examine some of these parameters. Gait studies during normal gait showed that the stance phase was associated with knee flexion between 8 degrees and 15 degrees. Contact area studies have shown two types of rotating-platform total knee replacements, namely gait congruous (congruous only during the stance phase of gait) and totally congruous (congruous up to 90 degrees knee flexion) implants. Knee simulator studies have shown increased gravimetric wear with rotating-platform total knee replacements compared with their fixed-bearing counterparts. Rotate-only implants had less gravimetric wear than rotate and translate rotating-platform total knee replacements. Clinical studies show similar outcomes (knee scores, range of motion, and complications) when rotating-platform and fixed-bearing total knee replacements are compared. Although attractive, the benefits of rotating-platform total knee replacements still need to be proven.     

Fixed-bearing versus high-flexion RP total knee arthroplasty (TKA): midterm results of a randomized controlled trial

Background

We compared the midterm results after total knee arthroplasty (TKA) using PFC Sigma RP-F mobile model with PFC Sigma PS fixed model.

Materials and methods

In this randomized controlled trial, we analyzed 50 knees that underwent TKA with PFC Sigma RP-F and 60 knees with PFC Sigma PS fixed model. The follow-up period ranged from 76 to 104 months.

Results

The knee score, function score, and radiographic evaluation were significantly not different between the two groups at final follow-up. No revisions, subluxations, dislocations, or infections were seen. Also, no radiographic evidence of component loosening, osteolysis, or malalignment was observed in any knee. The results for both groups show good patient satisfaction.

Conclusions

The midterm clinical and radiographic results of the two prostheses did not show significant differences between the two groups.

Level of evidence

Level of evidence is level II.

     

Early clinical results of a high-flexion, posterior-stabilized, mobile-bearing total knee arthroplasty: a US investigational device exemption trial

Between May 2001 and June 2004, 388 total knee arthroplasty cases were enrolled in a prospective, randomized, multicenter investigational device exemption trial. Patients received either the investigational high-flexion mobile-bearing knee or a fixed-bearing control. At 2 to 4 years of follow-up, results in 293 patients with degenerative joint disease were compared using Knee Society Assessment and Function scores, radiographic results, complications analysis, and survival estimates. The mobile-bearing and fixed-bearing groups demonstrated similar, significant improvement over preoperative assessments in Knee Scores, maximum flexion, and range of motion. One mobile-bearing arthroplasty required revision. Radiographic results were unremarkable, and implant-related complications were rare in both groups. At this early follow-up, the investigational high-flexion mobile-bearing knee and its fixed-bearing counterpart demonstrated comparable, effective performance.     

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.     

Clinical and Radiographic Results of Attune and PFC Sigma Knee Designs at 2-Year Follow-Up: A Prospective Matched-Pair Analysis

Background

Anterior knee pain (AKP) and/or crepitation are important causes of dissatisfaction after total knee arthroplasty (TKA). Aim of this prospective, matched-pair study was to compare 2 different designs of patellofemoral (ie, trochlear groove) TKA. The Attune knee has an anatomic trochlear groove with a medialized dome patellar component vs the PFC Sigma with a single radius trochlear groove with a domed shaped patella.

A comparative analysis between fixed bearing total knee arthroplasty (PFC Sigma) and rotating platform total knee arthroplasty (PFC-RP) with minimum 3-year follow-up

Background

Since the introduction of mobile bearing total knee designs nearly 30?years back, many studies have been done to evaluate its long-term result. Comparison with fixed bearing designs has been done in the past, but the studies were confounded by variables such as disease, surgeon, bone quality, pain tolerance, etc. We attempt to eliminate these variables in this study.

Methods

A total of 50 patients who had bilateral arthritis of the knee with similar deformity and pre-operative range of motion on both sides agreed to have one knee replaced with mobile bearing total knee design (PFC-RP) and the other with a fixed bearing design (PFC Sigma) were prospectively evaluated. Comparative analysis of both the designs was done at a mean follow-up of 40?months, minimizing patient, surgeon and observer related bias. Clinical and radiographic outcome, survival and complication rates were compared.

Results

At a mean follow-up of 40?months (range 36–47?months), no benefit of mobile bearing (PFC-RP) over fixed bearing design (PFC Sigma) could be demonstrated with respect to Knee Society scores, pain scores, range of flexion, subject preference or patello-femoral complication rates. Radiographs showed no difference in prosthetic alignment. No patient required a revision surgery till last follow-up.

Conclusions

Our study demonstrated no advantage of the mobile-bearing arthroplasty over fixed bearing arthroplasty with regard to clinical results at short-term follow-up. However, longer follow-up is necessary to confirm whether these results are sustained.     

Cemented rotating-platform total knee replacement. a concise follow-up, at a minimum of fifteen years, of a previous report

ABSTRACT: We previously evaluated 119 consecutive total knee arthroplasties that were performed in eighty-six patients with use of the cemented LCS (low contact stress) rotating-platform system with an all-polyethylene patellar component. The average age of the patients at the time of surgery was seventy years (range, thirty-seven to eighty-eight years). The purpose of this study was to report the updated results at a minimum follow-up of fifteen years. Thirty-seven patients (fifty-three knees) were living, and no patient was lost to follow-up. No knee was revised because of loosening, osteolysis, or wear. Three knees required a reoperation (two for periprosthetic fractures and one for infection). No component was revised as a part of the reoperations. Osteolysis was present in three knees. No knee had radiographic signs of component loosening, and there were no dislocated bearings. The average range of motion was from 1 degrees of extension to 105 degrees of flexion. The average clinical and functional Knee Society scores were 43 and 49, respectively, at the preoperative evaluation and 85 and 58 at the time of the final follow-up. We concluded that the cemented LCS rotating-platform knee performed well, with durable clinical and radiographic results at a minimum follow-up of fifteen years.     

Central Implantation of the Femoral Component Relative to the Tibial Insert Improves Clinical Outcomes in Fixed-Bearing Unicompartmental Knee Arthroplasty

BackgroundThe direct relationship between clinical outcomes and femoral component positioning relative to a tibial insert remains unknown. We determined whether the femoral component position relative to the tibial insert could affect clinical outcomes after fixed-bearing unicompartmental knee arthroplasty (UKA).MethodsThe femoral component position relative to the tibial insert of 66 patients with anteromedial osteoarthritis and osteonecrosis of the knee who underwent fixed-bearing UKA was assessed at 2 weeks postoperatively. We classified patients according to the contact point of the femoral component with the tibial component: group M (medial), 18 knees; group C (central), 30 knees; and group L (lateral), 18 knees. Patient-derived clinical scores using the 2011 Knee Society Score were also assessed preoperatively and at 2 years postoperatively and compared among the 3 groups using the analysis of variance.ResultsThe average 2-year postoperative “symptom” and “patient satisfaction” scores based on the 2011 Knee Society Score were significantly higher in group C than in group M or group L.ConclusionCentral implantation of the femoral component relative to the tibial insert plays an important role in decreasing pain and could result in better patient satisfaction after fixed-bearing UKA at 2 years postoperatively. Surgeons should set the femoral component at the center relative to the tibial insert for better patient satisfaction and higher active knee flexion after fixed-bearing UKA.     

10-year evaluation of the cementless low-contact- stress rotating-platform total knee arthroplasty

We present the clinical and radiographic outcomes of the cementless low-contact-stress (LCS) rotating-platform total knee arthroplasty. Overall, 423 prostheses were implanted in 393 consecutive patients (30 patients had bilateral total knee replacement) for primary varus gonarthrosis (381 patients) and rheumatoid arthritis (12 patients). There were 81 men and 312 women with a mean age of 73 years (range, 58-85 years). Patella replacement was not performed in any case. Clinical and radiographic evaluation was performed using the Knee Society Score (KSS) and the Knee Society Assessment Form, respectively. The mean follow-up was 10 years (range, 5-15 years). Three patients were lost to follow-up. Survival of the prostheses was 98% at 10 years; three prostheses required revision for deep infection, bearing dislocation, and periprosthetic fracture. The mean KSS improved significantly, from 42 and 44 points preoperatively to 90 and 79 points, respectively, at the latest evaluation (P < 0.001); results were excellent in 278 cases, good in 106, fair in 27, and poor in nine. Radiolucent lines were observed in 80 cases; revision arthroplasty was not performed in any of these cases. Complications included deep infection in one patient, bearing dislocation in one, skin necrosis in four, and a supracondylar fracture in one. The cementless LCS rotating-platform total knee arthroplasty is associated with excellent mid- and long-term results for patients with osteoarthritis and rheumatoid arthritis of the knee.