Clinical comparison of all-polyethylene and metal-backed tibial components in total knee arthroplasty

Based primarily on in vitro biomechanical studies, most total knee arthroplasty (TKA) manufacturers have abandoned the all-polyethylene tibial component (APT) in favor of the metal-backed tibial component (MBT). There is little clinical evidence to support this decision. A retrospective review of cemented TKA using the total condylar prosthesis was performed. One hundred eighteen patients with 131 TKAs were evaluated. Sixty-two of these knee prostheses had tibial components made entirely of polyethylene while 69 had the MBT. There were 13 cases of bilateral TKA in which the APT was used for one knee and the MBT for the other. All patients were examined by the authors for an average follow-up period of six years. Hospital for Special Surgery knee scores and a comprehensive roentgenographic evaluation were obtained. No significant difference was noted between the patients with APT and those with MBT, raising serious doubt on the need for the MBT in patients being treated with primary, cemented TKA.     

Long-term results of a total knee prosthesis utilising an all polyethylene tibial component

Introduction

The aim of this study was to assess the long-term performance of a cemented total knee replacement utilising an All Polyethylene Tibial (APT) component and in addition to perform an engineering analysis of any failures to help refine surgical technique.

Materials and methods

A total of 26 patients had a total knee replacement performed using a cemented Depuy Press Fit Condylar (PFC) APT component and a cruciate retaining femoral component. At final review all patients were assessed using The Knee Society Score together with radiographs. An engineering analysis simulated loading conditions of the implants that failed and these were compared with the performance of a modular metal-backed Tibial (MBT) component.

Results

A total of 20 patients were reviewed at mean time of 116 months following surgery. Knee Society Knee Scores and Function Scores in this cohort were 84/100 and 58/100, respectively. Two patients required revision for tibial component failure. Pre-operatively both had valgus deformities and in each case the tibial tray had been lateralised leaving a gap on the medial side where the APT component had no rigid support. The engineering analysis demonstrated that the volume of highly strained cancellous bone was greater in the APT design compared with the MBT design when a model with a 3 mm medial gap was loaded. The stiffer MBT base plate acted more rigidly and shielded the stress applied to the proximal tibial cancellous bone.

Conclusion

The APT component demonstrated satisfactory clinical and radiographic performance at long-term follow up. Appropriate cortical support of the APT component is important. The implant should be used with a degree of caution in patients with severe deformities and osteoporosis.     

Metal-Backed Versus All-Polyethylene Tibias in Megaprostheses of the Distal Femur

In megaprostheses, the tibial component is rarely a source of failure. The evolution of these implants has followed standard arthroplasty trends moving from majority use of all-polyethylene tibias (APT) to high volume use of metal-backed tibial (MBT) components. We report the results of 72 endoprostheses using either MBT (n = 42) or APT (n = 30) implanted between 1994 and 2006. Failures of the implant related to the tibial component were isolated, and 5-year survival of the tibial implant of the MBT cohort was 94%, and for the APT cohort, 87% (P = .39). The difference in tibial component failures between the 2 groups was not statistically significant (Pearson χ² = 0.1535, P = .6952). Revision rates for the entire implant and infection rates were not significantly different between the 2 groups.     

Primary TKA with a zirconia ceramic femoral component

This article presents the 2-year clinical results of primary total knee arthroplasty (TKA) performed with a zirconia ceramic femoral component. A posterior-stabilized TKA was performed for degenerative arthritis in 36 patients (39 knees). The components included a zirconia femoral component, a cobalt-chrome alloy tibial baseplate, and a polyethylene patella; all were implanted with bone cement. The ultra-high molecular-weight polyethylene-bearing insert had a deep-dish, ultra-congruent design. At the 2-year interval, mean Western Ontario and McMaster Universities (WOMAC) osteoarthritis indices improved from 41 to 86, and mean Knee Society Scores improved from 40 to 92. Revision to constrained implants was necessary in one patient for persistent knee instability after trauma. These early results are encouraging, but more data are needed to determine whether ceramics are a suitable alternative to metal countersurfaces in TKAs.     

Factors influencing choice of implants in total hip arthroplasty and total knee arthroplasty: perspectives of surgeons and patients

To determine the factors influencing surgeons' choice of implants for total hip arthroplasty (THA) and total knee arthroplasty (TKA), 650 surveys were mailed to all active members of the American Association of Hip and Knee Surgeons practicing in the United States; 364 surveys (56%) were completed and returned. Analysis revealed that the average number of total hip and total knee replacements performed by the respondents in 1997 was 81 and 97; there was substantial regional variation. The average number of hip implant and knee implant brands used by these surgeons in 1997 was 2.4 and 1.8. Anticipated improvement in clinical results and cost of components were the most frequently listed reasons for changing brands. Surgeons were also queried about cost reduction programs at their particular institution. The most frequently listed strategies for cost reduction of implants included surgeon cost-awareness programs and volume discounting. More than half of the respondents (53.5%) anticipate manufacturers to decrease the cost of implants in the next 2 years. Most of the respondents (93.7%) currently have the ability to choose a particular implant. About half (46.7%) anticipate losing some or all control of this decision in the next 3 years. These respondents foresee their hospitals requiring the use of a discounted implant in the future. An additional survey was completed by 102 consecutive patients scheduled either for primary THA (64) or primary TKA (38) at our institution. When asked about implant selection, 93.1% responded that their orthopaedic surgeon should choose the prosthesis; 5.9% responded that their physician in consultation with the patient should choose the prosthesis. When asked what should be the primary determinant of implant choice, cost or quality, the overwhelming majority (97.1%) chose quality. A small percentage (2.9%) chose cost and quality. No patient chose cost alone. A large number of patients (84.8%) responded that they would pay additional costs if their insurance companies or health maintenance organizations refused to pay for a better but more expensive implant. Most patients realized how expensive components are, and 51% of the respondents correctly estimated the cost of an implant. Orthopaedic surgeons perceive that they are losing control of implant choice in THA and TKA. Cost of implants is one of the most significant factors influencing which implant is chosen. Patients (the true payors), however, overwhelmingly want their surgeons to choose the implant used at surgery, and they want quality, not cost, to be the primary determinant of this decision.     

Hybrid total knee arthroplasty

A prospective study of a hybrid total knee arthroplasty (TKA) with an uncemented femoral component and cemented tibial and patellar components was performed to combine the advantage of a press-fit femur while avoiding the problems in uncemented tibial and patellar implants. A total of 329 posterior cruciate-preserving TKA were studied at an average of 4.7 years after surgery: 84% of the knees had at most mild or occasional pain, 68% had good or excellent knee scores, and 62% could walk more than 1000 m. The function scores were 40% good or excellent in this collective, with an average age of 69.4 years at surgery. The component position and alignment were biomechanically correct. Radiolucent lines were observed regularly at the edges of the tibial and femoral components. There were no revisions for aseptic loosening. Hybrid TKA provides good results comparable to cemented TKA.     

2- to 9-year outcome of stemmed total knee arthroplasty: Similar failure rates in patients when used primary or as a revision

Background and purpose —

There is an increase in demand for primary and revision total knee joint procedures. We studied implant survival and functional outcome of patients operated with a constrained condylar knee (CCK) or a rotating hinge implant (RH) as a primary or a revision total knee arthoplasty (TKA).

Patients and methods —

We evaluated clinically and radiographically 65 surgical procedures with a mean follow-up time of 5 (2–9) years (40 CCK and 25 RH). There were 24 primary TKAs—due to instability—and 41 revision TKAs, mostly due to aseptic loosening. Mean age at the index operation was 68 (31–88) years.

Results —

Overall, there were 12 failures, including 8 reoperations due to deep infection. The overall 5-year survival rate with reoperation as the endpoint was 82% (95% CI: 72–99). Radiolucent lines on either the femoral or the tibial side were seen in 36 cases. When comparing the cases that were operated as a primary TKA or as a revision TKA, function, health-related quality of life, and survival were similar. However, after primary TKA the patients generally had less pain and a higher proportion of patients were very satisfied or satisfied.

Interpretation —

Although a high rate of severe complications was observed, most patients improved in function after surgery regardless of whether it was a primary or a revision TKA. We found narrow radiolucent lines—mainly on the tibial side—in nearly half of the cases, but none of the implants were loose radiographically. Overall patient satisfaction and health-related quality of life were high, and a minority had problems with persistent pain.There will be an increase in demand for primary and revision total knee joint arthroplasties over the coming decades (Kurtz et al. 2007, Hossain et al. 2010). The function of the soft-tissue envelope and possible bone deficiency guide implant choice. Revision implants are used in patients with severe valgus-varus instability and/or increased laxity in flexion gap (Hossain et al. 2010). There are constrained condylar prostheses (CCK) and linked rotating hinge (RH) designs. In the majority of cases, these designs are saved for revision surgery, but they may be used in primary TKA as well, especially if severe deformity or ligament instability is present (Petrou et al. 2004, Hossain et al. 2010).The main purpose of this retrospective study was to gain information on implant survival and functional outcome in 65 consecutive procedures using stabilizing TKAs with stemmed components (CCKs and RHs). Secondary outcome measures were complication rate, patient satisfaction, health-related quality of life, and radiographic results. We also wanted to determine whether there were any differences in patient outcome when these implants were used as a primary knee replacement or as a revision total knee replacement.     

Total knee arthroplasty using the total condylar III knee prosthesis

Twenty-seven total knee arthroplasties (TKAs) were performed in 24 patients using the total condylar III knee prosthesis (TCP III) and were evaluated clinically and radiographically with a mean follow-up period of 4 years. Eighteen were revision TKAs, and nine were primary knee arthroplasties. Evaluations were made using the Hospital for Special Surgery (HSS) knee scale as well as the Knee Society radiographic evaluation method. Clinical results for all knees were 11% (3 of 27) excellent, 70% (19 of 27) good, 15% (4 of 27) fair, and 4% (1 of 27) poor. The one poor rating resulted from an intraoperative vascular injury. The results showed no statistical difference between revision and primary TKA. After operation, pain relief, range of motion, walking, function, and activity level improved in both the primary and revision patients. Radiolucencies 2 mm or greater in width were found in 6 of the 27 tibial components, in none of the 27 femoral components, and in 1 of the 19 patellar components. Only two tibial implants showed progressive radiolucencies. No correlation was found between the radiographic position of the implants and the clinical results. The authors conclude that the TCP III is a satisfactory choice for TKA in selected knees in which there is significant instability and in which intramedullary fixation is required.     

Is a Titanium Implant for Total Knee Arthroplasty Better? A Randomized Controlled Study

BackgroundLighter weight and lower modulus are potential advantages of titanium (Ti) implants over cobalt chrome (CoCr) implants in total knee arthroplasty (TKA). This study was conducted to determine whether Ti implants in TKA resulted in better clinical outcomes and radiologic results.MethodsOne hundred and eight patients (216 knees) with knee arthritis warranting bilateral primary TKA were randomly allocated to undergo Ti rotating-platform TKA in one knee and CoCr rotating-platform TKA in the contralateral knee. The mean follow-up period was 5.3 years (range, 1-7 years). The weight of Ti implants was one-third lighter than that of CoCr implants (133.9 g vs 390.1 g, P < .01). Clinical outcomes were evaluated using clinical scores, patient preferences (lightness, comfort, naturalness, and satisfaction), gait analysis (kinetic and kinematic data), range of motion, and degree of pain. Radiologic results were evaluated based on the radiolucent line (RLL), degree of medial tibial bone loss, and loosening as seen on X-ray.ResultsNo significant differences were observed in clinical scores or patient preference. Regarding implant weight, approximately 70% of patients did not perceive the Ti implant as lighter. No significant differences were observed in gait analysis, range of motion, or degree of pain. The RLL was seen in 9% of the Ti implant group and 19% of the CoCr implant group.ConclusionThe lighter Ti implant did not show any clinical benefit over CoCr implants. The lightness of the Ti implant is not sufficient to matter or be noticeable. However, the Ti implant showed lower rate of RLL than the CoCr implant.Level of Evidencelevel I, randomized controlled trial.     

All-polyethylene and Metal-backed Tibial Components Are Equivalent With BMI of Less Than 37.5

Background  

Modular, metal-backed tibial (MBT) components are associated with locking mechanism dysfunction, breakage, backside wear, and osteolysis, which compromise survivorship. All-polyethylene tibial (APT) components eliminate problems associated with MBTs, but, historically, APT utilization has generally been limited to older, less active patients. However, it is unclear whether APT utilization can be expanded to a nonselected patient population.     

Survivorship comparison of all-polyethylene and metal-backed tibial components in cruciate-substituting total knee arthroplasty—Chinese experience

Considering its cost saving, the all-polyethylene tibial component is of potential interest in developing countries like China. But to our knowledge, a survivorship comparison of all-polyethylene and metal-backed tibial components in posterior cruciate ligament-substituting total knee arthroplasty (PS-TKA) has not been studied in China previously. Using survivorship analysis, we have studied the midterm outcome of 34 cemented PS-TKA using an all-polyethylene tibial component and of 34 cemented PS-TKA using a metal-backed tibial component which has an identical articular surface with all-polyethylene tibial components. All operations were performed by the same group of surgeons; 58 patients underwent a unilateral operation and five patients a bilateral operation. These patients had a mean follow-up of 5.9 years (range: 5–7 years); three patients were lost to follow-up and one was revised for infection. No significant difference between the two groups was reported regarding HSS scores, ROM, clinical and radiographic parameters measured and survival rates. Although the Asian lifestyle includes more squatting and bending of the knee, the results of this series of TKA using all-polyethylene tibial components in Chinese people are comparable to the satisfactory results of other reported all-polyethylene series whose patients are mainly Western people. Considering its cost saving and excellent clinical result, the all-polyethylene tibial component is of potential interest in developing countries.     

Implementation of a CT-based navigation system in two-stage reimplantation for infected total knee arthroplasty

Femorotibial alignment is an important factor affecting patient outcome after total knee arthroplasty (TKA). It was the aim of this study to report our first results using a CT-based navigation system in two-stage revision surgery for infected TKA. Two patients with chronic deep infection after primary TKA underwent two-stage revision arthroplasty with temporary articulating cement spacers followed by prosthesis re-implantation using a CT-based navigation system. Postoperative radiographs showed accurate alignment of the femoral and tibial components. CT-based navigation systems offer the opportunity for preoperative planning and accurate intra-operative navigation of cutting blocks. They can be considered of value for primary TKA but even more so for two-stage revision arthroplasty.     

The Use of Cementless Components Does Not Significantly Increase Procedural Costs in Total Knee Arthroplasty

BackgroundModern cementless total knee arthroplasty (TKA) designs have shown promising early clinical success; however, concerns exist regarding the higher cost of the cementless implants. The purpose of this study is to evaluate the total facility cost of cementless vs traditional cemented TKA along with the effect of cementless fixation on short-term outcomes.MethodsWe reviewed a consecutive series of patients between 2015 and 2017 who underwent either cementless or cemented primary TKA. Itemized facility costs were calculated for every procedure using a time-driven activity-based costing algorithm. Controlling for demographic variables and medical comorbidities, we performed a multivariate analysis to identify independent risk factors for facility costs following TKA. Short-term outcome metrics including complications, readmissions, and patient-reported outcomes were compared between groups.ResultsAmong the 2426 primary TKA patients in this study, 119 (4.91%) were performed using cementless implants. When compared to cemented TKA, cementless TKA patients had higher implant costs ($3047.80 vs $2808.73, P < .0001), but lower supply costs ($639.49 vs $815.57, P < .0001) and lower operating room personnel costs ($982.01 vs $1238.26, P < .0001). When controlling for confounding variables, cementless fixation did not have a significant effect on total facility cost or outcomes.ConclusionIn conclusion, the use of cementless TKA implants did not significantly increase total procedural costs when compared to traditional cemented TKA components at our institution. Our data suggest that the increased cost of a cementless implant is recouped through savings in cost of cement and supplies, as well as shorter operative times. The authors encourage investigators at other institutions to use the authors' methodology to evaluate (preferably in a prospective manner) whether the findings from this study can be corroborated.     

Total knee arthroplasty in patients 40 years and younger

Total knee arthroplasty (TKA) is a procedure with excellent clinical results in older patients with a primary diagnosis of osteoarthritis. Many younger patients undergo unicompartmental or high tibial osteotomy rather than TKA, but are not always good candidates for these joint-preserving procedures. The purpose of this study was to review the outcomes of patients 40 years of age and under who underwent TKA. We identified 33 patients (38 knees) who were 40 years of age or less at the time of surgery. These patients had a mean age of 36 years (range, 23 to 40 years), and were followed for a mean of 49 months (range, 16 to 101 months). The survival rate in the study cohort was 97%. For the young patient who is not a candidate for other types of joint preserving procedures, in the senior authors' experience total knee arthroplasties have performed well.     

Impact of cost reduction programs on short-term patient outcome and hospital cost of total knee arthroplasty

BACKGROUND: During the 1990s, cost reduction programs were developed to decrease the hospital cost of total knee arthroplasty. The purpose of this study was to evaluate the impact of hospital cost reduction programs for total knee arthroplasty on patient outcome at our hospital. METHODS: We evaluated 159 patients who had undergone unilateral primary total knee arthroplasty for the treatment of osteoarthritis at the Lahey Clinic. The results of fifty-six knee replacements performed in 1992 without a clinical pathway or a knee-implant standardization program (the control group) were compared with the results of 103 knee replacements performed in 1995 with a clinical pathway and a knee-implant standardization program (the study group). Before the operation, the two patient populations were similar in terms of age, pain score on a visual analog scale, and clinical knee scores; the groups were also similar with regard to the surgical approach and the time in the operating room. The minimum duration of follow-up was eight years for the control group and five years for the study group. RESULTS: All patients in both groups had excellent relief of pain and improvement in function. There were no differences in clinical outcome between the patient groups. The rate of patient satisfaction was 98% in the control group and 99% in the study group. Implementation of the clinical pathway was associated with a reduction in the average length of the stay in the hospital from 6.79 days in 1992 to 4.16 days in 1995. Implementation of the knee-implant standardization program was associated with increased use of all-polyethylene tibial components in 1995. Hospital cost adjusted for medical inflation was reduced 19% with the implementation of the clinical pathway and the knee-implant standardization program. CONCLUSIONS: The clinical pathway and the knee-implant standardization program reduced resource utilization and hospital cost for total knee arthroplasty without affecting short-term patient outcome in our hospital. Orthopaedic surgeons should carefully evaluate cost reduction programs, which may affect their patients, in order to maintain high-quality orthopaedic care and consistently successful patient outcomes.     

初次全膝置换自体骨移植修复胫骨平台骨缺损

[目的]探讨初次行全膝置换术中采用自体骨移植修复严重膝内翻胫骨内侧平台骨缺损的疗效.[方法]回顾性分析2006年2月-2019年3月收治的行初次膝关节表面置换术180例严重膝内翻患者的临床资料,其中86例胫骨截骨后仍存在内侧平台骨缺损、行自体骨移植修复.总结86例患者的临床与影像结果.[结果] 86例患者均顺利完成手术...     

Fixation of a hydroxyapatite-tricalcium phosphate-coated cementless knee prosthesis. Clinical and radiographic evaluation seven years after surgery

Miller-Galante II total knee arthroplasty (MG II TKA) was performed on 32 knees in 30 patients. On both the femoral and tibial components, the fibre-metal area was plasma-sprayed with hydroxyapatite-tricalcium phosphate (HA-TCP). The clinical and radiographic outcome was evaluated. A mean preoperative knee score of 26.0 +/- 18.6 (SD) increased to 97.5 +/- 3.5 and a mean pre-operative functional score of 21.7 +/- 15.0 (SD) increased to 83.4 +/- 12.4 at follow-up of seven years. Clear zones were common around the components at one month post-operatively but had completely disappeared after six months. An autopsy of a patient who underwent MG II TKA with HA-TCP two years previously, showed osteogenesis in all parts of the fibre-metal, and bone tissue comprised 77.7% of the interface. This coated prosthesis has good early fixation which is maintained at seven years with good clinical and radiographic outcomes.     

Conversion Total Knee Arthroplasty Needs Its Own Diagnosis-Related Group Code

BackgroundConversion from a prior knee procedure has been demonstrated to require greater operative times and resources, but still lacks a separate procedural or facility code from primary total knee arthroplasty (TKA). The purpose of this study is to determine differences in facility costs between patients who underwent primary TKA and those who underwent conversion TKA.MethodsWe retrospectively reviewed a consecutive series of patients undergoing primary TKA at 2 hospitals from 2015 to 2017, comparing itemized facility costs between primary and conversion TKA patients. A multivariate regression analysis was performed to identify independent risk factors for increased facility costs, the need for additional implants, length of stay, and discharge disposition.ResultsOf 2447 TKA procedures, 678 (27.7%) underwent conversion TKA, which was associated with greater implant costs ($3931.47 vs $2864.67, P = .0120) and total facility costs in a multivariate regression ($94.30 increase, P = .0316). When controlling for confounding variables, patients with a prior ligament reconstruction ($402 increase, P = .0002) and prior open reduction and internal fixation ($847 increase, P = .0020) had higher costs and were more likely to require stemmed implants (P < .05). There was an increase in TKA implant cost by $538 in patients with implants from a prior procedure (P < .0001).ConclusionConversion TKA is associated with greater implant and inpatient facility costs than primary TKA, particularly those who had a history of an open knee procedure. A separate diagnosis-related group should be created for conversion TKA given the increased cost and complexity of these procedures compared to primary TKA.     

Mid-term results of total knee arthroplasty after high tibial osteotomy

Background The outcome of total knee arthroplasty (TKA) after high tibial osteotomy (HTO) is still controversial. In order to determine if osteotomy has any effect on this outcome we performed a medium-term review of a cohort of patients with knee osteoarthritis. Materials and methods Thirty-two patients (38 knees), who were treated with a HTO before the TKA during the last 8 years, were compared with a matched group who underwent primary TKA. The knees were evaluated preoperatively and postoperatively according to the scoring systems of the Knee Society and Hospital for Special Surgery (HSS). The anteroposterior tibiofemoral alignment, the Insall–Salvati patellar position ratio, range-of-motion and the location of the lateral joint line, were also recorded. The patients were reviewed with a mean follow-up of 4.5 years after TKA. Results The preoperative and postoperative knee scores had no statistically significant differences between the two groups. So was the case with the intraoperative releases, blood loss, thromboembolic or neurologic complications and infection rates in either group. Access to perform the arthroplasty was reportedly more difficult and took an average of 25 min longer. A significant difference (p < 0.05) was detected in terms of impingement of the tibial stem on the lateral tibial cortex, patellar subluxation and patella baja between the two groups but this did not have any influence on the outcome of the prosthesis. Knee alignment and stability so as range of motion (ROM) measurements were also found with no statistical significance. Conclusion Although we did manage to detect statistically significant differences mainly in radiographic results between the two groups, this situation did not appear to influence the clinical outcome of the patients, however. The fact that most of the patients had good or excellent results at an average follow-up of 4.5 years suggests that HTO does not have a significant negative effect on later TKA.