Press-Fit Condylar Total Knee Arthroplasty Research Articles

Is there a difference in total knee arthroplasty risk of revision in highly crosslinked versus conventional polyethylene?

Highly crosslinked polyethylene (HXLPE) was introduced to reduce wear and associated osteolysis in total knee arthroplasty (TKA). However, there is limited clinical evidence that HXLPE is more effective than conventional polyethylene (CPE) in TKA. (1) Do primary TKAs with HXLPE tibial inserts have a lower risk of revision (all-cause, aseptic, and septic) than TKAs with CPE tibial inserts? (2) In NexGen TKA (Zimmer Inc, Warsaw, IN, USA) bearings, do HXLPE tibial inserts have a lower risk of revision (all-cause, aseptic, and septic) than CPE tibial inserts? (3) In Press-Fit Condylar TKA (PFC or PFC Sigma; DePuy Inc, Warsaw, IN, USA), do HXLPE tibial inserts have a lower risk of revision (all-cause, aseptic, and septic) than procedures performed with CPE tibial inserts? The Kaiser Permanente Total Joint Replacement Registry was used to identify primary TKAs (N = 77,084) performed during the study period (April 2001 to December 2011) with cobalt-chromium alloy on CPE (CoCr-CPE) and CoCr-HXLPE bearings. The registry has 95% voluntary participation and less than 9% were loss to followup during the 10-year study period. A total of 60,841 (79%) had CoCr-CPE bearings, 11,048 (14%) had CoCr-HXLPE bearings, and 5195 (7%) were unknown. Specific knee implant designs (NexGen, Zimmer and PFC-Sigma, DePuy Inc) were also evaluated. These implants represented 41% (31,793) and 49% (37,457), respectively, of the 77,084 TKAs of known implant types registered during that period; implant selection was at the discretion of the attending surgeon. Descriptive statistics and marginal Cox regression models with propensity score adjustments were applied to compare risk of revision for CoCr-CPE versus CoCr-HXLPE TKA bearings. At 5 years followup, cumulative incidence of revision for CoCr-CPE and CoCr-XLPE were 2.7% and 3.1%, respectively. Adjusted risks of all-cause (hazard ratio [HR], 1.05; 95% confidence interval [CI], 0.86-1.29; p = 0.620), aseptic (HR, 1.01; 95% CI, 0.77-1.32; p = 0.954), and septic revision (HR, 1.11; 95% CI, 0.81-1.51; p = 0.519) did not differ in patients with CoCr-XLPE bearings compared with CoCr-CPE. Within TKAs with NexGen components, the adjusted risks of all-cause (HR, 1.14; 95% CI, 0.86-1.51; p = 0.354), aseptic (HR, 1.14; 95% CI, 0.79-1.65; p = 0.493), and septic revision (HR, 1.14; 95% CI, 0.76-1.73; p = 518) were similar in patients with CoCr-XLPE compared with those with CoCr-CPE bearings. Finally, within the TKAs with PFC components, the adjusted risks of all-cause (HR, 0.80; 95% CI, 0.49-1.30; p = 0.369), aseptic (HR, 0.62; 95% CI, 0.62-1.14; p = 0.123), and septic revision (HR, 0.97; 95% CI, 0.51-1.85; p = 0.929) were also similar in patients with CoCr-XLPE compared with those with CoCr-CPE bearings. In this large study, we did not find differences in risk of revision for CoCr-HXLPE compared with CoCr-CPE bearings at 5 years followup. In selecting HXLPE in TKA, clinicians should consider the increased cost and lack of available evidence of performance for greater than 10 years followup. Future studies are necessary to evaluate longitudinal outcomes of CoCr-HXLPE versus conventional TKA bearings. Level III, therapeutic study.

How do knee implants perform past the second decade? Nineteen- to 25-year followup of the Press-fit Condylar design TKA.

At 14- to 17-year followup, we reported successful outcomes of the Press-fit Condylar total knee arthroplasty (TKA) system in 160 TKAs performed between 1986 and 1989. However, there are few published reports on TKA survivorship and patient function that include patients evaluated into the third decade after surgery. The study purpose was to determine (1) the survivorship of the implant; and (2) knee function in patients with this TKA system at a mean 20-year followup. We ascertained revision status of all living patients (42 of 160 knees) and all patients (22 knees) who died since the previous study. Among patients alive at the latest followup, Knee Society function scores were obtained and radiographs were evaluated. Kaplan-Meier survivorship analysis with 95% confidence intervals was performed with revision for any reason and aseptic loosening as endpoints. A competing risks analysis with 95% confidence intervals was also performed for revision for any reason as the endpoint. At the mean 20-year (range, 19-25 years) followup, all living patients retained their original implants from the index TKA, exclusive of three polyethylene exchanges. This study demonstrates an 87% Kaplan-Meier survivorship for revision for any reason (95% confidence interval [CI], 80%-92%) and a 98% Kaplan-Meier survivorship for revision for aseptic loosening (95% CI, 93%-99%). Competing risks survivorship was 79% (95% CI, 70%-85%) at 25 years for revision for any reason. Mean Knee Society function score was 46.9. Since the previous study, three revisions have been performed, all for polyethylene wear. The Press-fit Condylar implant system continues to be successful, maintaining longevity up to 25-year followup. This is one of the longest followup studies, reporting continued successes over 20 years, and should serve as a benchmark for current-generation implants. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Size measurement and flexion gap balancing in total knee arthroplasty—new benefits of the Attune™ system?

To the Editor, Although primary total knee arthroplasty (TKA) has been a procedure with high surgical success and various systems have revealed an outstanding long-term survival in recent decades [1], our patients still report knee pain or further problems in 20 % of cases [2, 3]. These cases are mostly caused by improper placement of the femoral shield or difficulties in balancing techniques [2, 3]. The Attune Total Knee Arthroplasty System (DePuy Synthes, Warsaw, IN) [4] was designed to address these cases by optimising guidance in femoral size measurement and flexion gap balancing using one single tool. The authors experienced benefits while measuring (1) flexion gap, (2) possible undercutting, and (3) cranio-caudal width of the femoral shield on the basis of the corresponding inlay in flexion in one surgical step. In addition, further narrow variants, minimising the medio-lateral width of the femoral shield, aid in more individual component placement as the system offers these options in four out of ten possible femoral sizes in contrast to one or no narrow variant (press fit condylar TKA or low-contact-stress TKA, DePuy Synthes, Warsaw, IN). After our initial experience as early users, we believe that the Attune TKA System offers an appropriate solution for the flexion gap balancing technique in individual total knee arthroplasty. However, the authors have initiated a prospective controlled outcome trial to conclusively testify this initial impression. With kind regards, Patrick Sadoghi, MD and Norbert Kastner, MD

Mid Term Results of Total Knee Arthroplasty (8 to 10 Years)

Purpose: We wanted to evaluate the mid-term (8 to 10 years) clinical and radiologic results of total knee arthroplasty. Materials and Methods: We evaluated 71 knees in 45 patients after they had undergone total knee arthroplasty between January 1996 and April 1998. All the procedures were performed by a single-surgeon using the PFC (Press Fit Condylar) system. The clinical and radiologic results were evaluated using the American Knee Society Scoring System and the American Knee Society Roentgenographic Evaluation and Scoring System. Survivorship analysis was performed using the Kaplan-Meier method with revision for any reason as the end point. Results: The average range of motion of the knee joint was () preoperatively and () at the last follow-up. The average knee and functional scores were improved from 46.2 and 42 preoperatively to 88.7 and 82.9, respectively, at the last follow-up. The tibiofemoral angle changed from varus preoperatively to valgus at the last follow-up. The total radiolucecy rate was 34% and the total radiolucency score was 1.9. Reimplantations were performed in 5 cases and the survival rate was 94.7% at 8 years. No differences was found in the survival rate according to PCL preservation. Conclusion: The mid-term results of PFC total knee arthroplasty were reliable and satisfactory because there was an increased range of motion, decreased pain, restoration of function and a relatively low complication rate.

Survivorship Analysis at 15 Years of Cemented Press-Fit Condylar Total Knee Arthroplasty

We performed a survival analysis on 354 cemented primary press-fit condylar total knee arthroplasties in 277 patients with prospective follow-up (mean, 8.8 years; range, 0.3-16.9 years). The number of patients alive reaching 15 years at follow-up for survival analysis was 15. The cumulative survival rate at 15 years was 81.7% (95% confidence interval, 72.1%-88.5%), using revision for all causes as our end point. Indications for revision in our patient group were aseptic loosening 4.5%, infection 2.3%, and exchange of polyethylene insert 1.1%. Our results indicate that the cemented press-fit condylar total knee arthroplasty has a good long-term survival, at 15 years, based on revision as the end point.

THE MARK COVENTRY AWARD: Sterilization and Wear-related Failure in First- and Second-generation Press-fit Condylar Total Knee Arthroplasty

We compared the incidence of wear-related failures between two large cohorts of patients undergoing total knee arthroplasty implanted with identical modular tibial trays and polyethylene inserts sterilized by different methods. A total of 1183 second-generation press-fit condylar prostheses having inserts packaged and sterilized in an oxygen-free environment were assessed at a minimum 5-year followup (mean, 7.0 years). Wear-related failure was defined as (1) osteolysis greater than 100 mm2 or (2) revision of the implant resulting from osteolysis, polyethylene wear, chronic synovitis, and/or effusion. Wear-related survivorship was calculated using Kaplan-Meier survival analysis. Results were compared with our previously published study of 1287 first-generation press-fit condylar modular knees having inserts sterilized by gamma irradiation in air at 5-year minimum followup (mean, 7.8 years). The wear-related failure rate for the second-generation design was 1.1% and 10-year survivorship was 97.0% compared with 8.3% failure and 87.7% 10-year survival for the first-generation design. For second-generation components, patient age was the only variable correlated with wear-related failure. For first-generation components sterilized in air, several variables were correlated to wear-related failure with shelf age of the polyethylene insert being the most important factor. These data emphasize the dramatic effect improvements in polyethylene manufacturing, specifically sterilization methods, can have on implant survivorship. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Press-Fit Condylar Design Total Knee Arthroplasty

The Press-Fit Condylar total knee arthroplasty implant design has been used by many orthopaedic surgeons over the last twenty years. The design has survived with relatively minor modifications and remains a popular implant system today. The present study represents the fourteen to seventeen-year results for our patients who were described in our previous report on the eight to ten-year results. The senior author performed 160 consecutive total knee arthroplasties with use of the Press-Fit Condylar cruciate-retaining device in 134 patients between 1986 and 1989. The mean age of the patients at the time of the index procedure was 70.5 years. Follow-up data were available for sixty-three of sixty-four surviving knees. Surviving patients were followed for a mean of 15.8 years. The knees were evaluated on the basis of Knee Society function and clinical scores, radiographs, and survivorship analysis. The mean Knee Society function score was 65, and the mean clinical score was 89. The overall survival rate of the knee was 91.5% with revision for any reason as the end point and 97.2% with aseptic loosening as the end point. The rate of revision of the tibial insert because of wear-related aseptic loosening was 2.5%. We found no relationship between revision and the shelf life or method of sterilization of the polyethylene insert. Radiolucent lines were present in 62% (twenty-one) of thirty-four knees; all radiolucent lines were nonprogressive. None of the implants were loose according to the criteria of the Knee Society. This long-term analysis indicates that the Press-Fit Condylar total knee implant is a successful implant system with excellent longevity.

Survival analysis of cemented Press-Fit Condylar total knee arthroplasty

We performed a survival analysis on 354 cemented primary Press-Fit Condylar (PFC) total knee arthroplasties (TKA) in 277 patients with prospective follow-up (mean, 6 years; range, 2-11.7 years). No patient was lost to follow-up. Using revision for all causes as the endpoint, the cumulative survival rate at 10 years was 95.5% (95% confidence interval, 90.1%-98.1%). The 10-year clinical outcome available on 41 patients was good, with significant improvement in pain and mobility assessments using the Nottingham data collection system. Our results indicate that the cemented PFC TKA has good long-term survival based on revision as the endpoint. Revision for implant failure is rare and brings to question modifications to this prosthesis.

The Press-Fit Condylar total knee system: 8- to 10- year results with a posterior cruciate-retaining design

A total of 108 consecutive Press-Fit Condylar total knee arthroplasties were performed in 94 patients. All patients had implantation with a cemented posterior cruciate-retaining design, which included resurfacing of the patella. Mean age at surgery was 70 years (range, 35-87 years). Patients were followed for a mean of 9 years (range, 8-10 years) with follow-up for all surviving patients. The average postoperative functional knee score was 96 points. Nonprogressive radiolucent lines were present in 59%. One patellar component was radiographically loose. Five knees underwent revision procedures, none for aseptic loosening. Survivorship was 93.4% at 9 years with revision for any reason as the endpoint and 98.7% with aseptic loosening as the endpoint. This knee arthroplasty shows excellent results at 8 to 10 years with no patients lost to follow-up.

Failure of a cemented all-polyethylene patellar component of a press-fit condylar total knee arthroplasty

A 65-year-old woman had a posterior cruciate-retaining cemented Press-Fit Condylar (PFC; Johnson & Johnson Professional, Inc., Raynham, MA) knee replacement with resurfacing of the patella using a cemented all-polyethylene, 3-peg component. Five years postoperatively, the patient developed anterior knee pain. The patella tracked normally, but radiographs showed a shift of the patellar component. At revision, there was shear failure of all 3 fixation pegs and loosening of the component. Revision with a cemented Press-Fit Condylar Sigma patellar 3-peg component (Johnson & Johnson Professional, Inc., Raynham, MA) was performed.

Press-fit condylar total knee arthroplasty: 5- to 9-year follow-up evaluation

Between November 1984 and December 1987, 378 consecutive Press-Fit Condylar (PFC, Johnson & Johnson Professional, Raynham, MA) total knee arthroplasties were performed in 290 patients. The average age at surgery was 67 years (range, 22–91 years). The average follow-up period was 6.5 years (range, 5–9 years). Scoring was carried out according to the Knee Society scoring system. The average preoperative knee score was 28, and the average postoperative knee score was 88. The average preoperative functional knee score was 49, and the average postoperative functional knee score was 72. Ninety-five percent of the patients had no pain on level walking and were satisfied with their functional result. The average postoperative knee flexion was 110°. No implant showed any evidence of radiographic loosening. There were 17 complications, all requiring reoperation. Complications included excessive wear of a metal-backed patella in 8 knees. If complications resulting from the earlier use of a metal-backed patella are eliminated, the overall complication rate is 2.9%, which is comparable to or lower than the rates for other total knee systems with similar follow-up periods.

Two-to Four-Year Results of Posterior Cruciate-Sparing Condylar Total Knee Arthroplasty With an Uncemented Femoral Component

One hundred fourteen hybrid Press-Fit Condylar total knee arthroplasties (TKAs) were reviewed an average of 2.8 years after surgery to determine if this method of implantation provided satisfactory results compared with conventional cemented TKAs. Ninety-three percent of the knees had good or excellent results, and 94% of the knees had at most only mild or occasional pain. One knee with a metal-backed patella was revised for mechanical failure of the patellar button. Roentgenographic analysis of the femoral component interface showed that 30% of knees had a radiolucent line in at least one zone. However, none of the lines was wider than 1 mm, and none was about the central stem. There were no signs of loosening about any of the components. It was concluded that hybrid TKA provides a good and predictable result that is comparable to cemented TKA.