All-polyethylene tibial components are not inferior to metal-backed tibial components in long-term follow-up of knee arthroplasties

All-Polyethylene Tibias Equal to Metal-Backed Tibias in Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

We sought to conduct a systematic review of the literature and a meta-analysis of post-operative outcomes following TKA with an all-polyethylene tibial (APT) or a metal-backed tibial component (MBT). A systematic review of the literature was conducted to identify all studies comparing APT and MBT for TKA based upon rates of complications, revisions, reoperation, and patient-reported outcomes. Data was pooled and relative risk of each outcome measure at short (< 5 year), mid (5-10 year), and long (> 10 year) follow-up was calculated. Thirty-eight studies met criteria and were included for analysis, totaling 113,413 primary TKAs performed in 106,490 patients. Of these, 21,752 were performed with an APT and 91,661 with an MBT. APT had a statistically significant decrease in the relative risk of revisions, reoperations, total complications, septic complications, and aseptic complications at one-to-five-year follow-up. There was no statistically significant difference in the relative risk of these metrics between APT and MBT beyond 5 years. This study demonstrates that patients with APT components, compared to the MBT tibial components, had significantly lower rates of complications and revisions at 1-to-5-year follow-up, and no difference in these metrics beyond five years. Further prospective studies are warranted for better external validity of results found in this study.

All-polyethylene versus metal-backed tibial components in total knee arthroplasty: a meta-analysis of randomized controlled trials

OBJECTIVES

The design of tibial trays for total knee arthroplasty (TKA) has been a topic of research for several decades. Although all-polyethylene trays were developed to address issues such as osteolysis and to enhance the longevity of the prosthesis, as well as knee range of motion, metal-backed designs have remained the most commonly used type of prosthesis. This meta-analysis aimed to compare the clinical, radiological, and survival outcomes of both designs.

METHODS

Five databases were searched from inception until October 1, 2020, for randomized controlled trials (RCTs) that compared the outcomes of all-polyethylene and metal-backed tibial components in TKA. The outcomes of interest included range of motion, knee society score, stairs climbing scores, radiostereographic analysis, survivorship and complication. This review was conducted in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Risk of bias was assessed using the Newcastle-Ottawa tool.

RESULTS

A total of 14 RCTs with 1367 TKA were included with a mean age of - years and - years for all-polyethylene and metal-backed tibial components groups, respectively. All-polyethylene group demonstrated statistically significant differences in five-year survivorship (OR 0.27; 95% CI 0.10-0.75; p value 0.01) and stairs climbing score (OR - 2.07; 95% CI - 3.27-0.87; p value 0.0007) when compared to the metal-backed group. The metal-backed design was significantly more radiographically stable in anterior-posterior, varus-valgus, and internal-external rotations at the 2-year follow-up compared to all-polyethylene tibias (OR - 0.09; 95% CI - 0.16 to - 0.02; p value 0.02) as per the pooled radiostereographic analysis. However, ten-year survivorship (OR 0.92; 95% CI 0.53-1.60; p value 0.78), range of motion (OR - 0.57; 95% CI - 2.00-0.85, p value 0.43), knee society scores (OR 1.38; 95% CI - 0.47-3.23, p value 0.14), and complications (OR 0.83; 95% CI 0.5-1.39, p value 0.48) were comparable between both groups.

CONCLUSIONS

While this meta-analysis suggests that all-polyethylene tibial components in total knee arthroplasty may offer advantages over metal-backed components in terms of five-year survivorship, and stairs climbing score, this finding should be considered in the context of potential confounding factors. Nonetheless, based on the results, the all-polyethylene implant should be considered a viable choice for primary knee replacement.

LEVEL OF EVIDENCE

I.

Clinical outcomes and survival comparison between NexGen all-poly and its metal-backed equivalent in total knee arthroplasty

PURPOSE

This study aims to compare total knee replacement (TKA) with NexGen All-Poly (APT) and NexGen Metal-Backed (MBT) in terms of implant survivorship, reasons leading to implant failure and functional results of defined age categories.

METHODS

A single-centre, retrospective evaluation of 812 patients who underwent knee replacement with NexGen CR between 2005 and 2021, comparing a modern congruent APT component to a modular MBT equivalent component using a similar surgical technique at a notable mean follow-up duration. Implant survival, functional outcomes using the Knee Society Score and range of motion were evaluated and compared in different age categories.

RESULTS

Of the 812 NexGen CR TKAs performed at our institution, 410 (50.4%) used APT components and 402 (49.6%) MBT components. The survival rate of NexGen APT was 97.1% and that of NexGen MBT was 93.2% (p = 0.36). Removal of the implant occurred overall in 15 cases, for MBT in ten cases, and for APT in four cases. The FS was proved to be significantly higher when APT components were implanted in younger patients than for MBT (p = 0.005). A similar range of motion between the components was recorded (p = 0.1926).

CONCLUSION

Under defined conditions, we measured the clinical results of implants from a single manufacturer implanted in a single department using a similar surgical technique. Considering the limitations, we suggest that all-polyethylene tibial components are equal or even superior to metal-backed ones across the examined age categories.

Clinical Course of Pain and Function Following Total Knee Arthroplasty: A Systematic Review and Meta-Regression

BACKGROUND

Total knee arthroplasty (TKA) is widely considered a successful intervention for osteoarthritis and other degenerative knee diseases. This study addresses the need for a high-quality meta-analysis that outlines the clinical course of pain and function post-TKA.

METHODS

The review included prospective cohort studies assessing pain or function of patients undergoing primary TKA at baseline (preoperatively) and at least 2 additional time points including one at least 12 months postoperatively. Two reviewers independently screened references, extracted data, and assessed risk of bias using the Quality in Prognosis Studies tool. The time course of recovery of pain and function was modeled using fractional polynomial meta-regression.

RESULTS

In total, 191 studies with 59,667 patients were included, most with low risk of bias. The variance-weighted mean pain score (/100, 0 = no pain) was 64.0 (95% confidence interval [CI] 60.2-67.7) preoperatively, 24.1 (95% CI 20.3-27.9) at 3 months, 20.4 (95% CI 16.7-24.0) at 6 months, and 16.9 (95%CI 13.6-20.3) at 12 months, and remained low (10.1; 95% CI 4.8-15.4) at 10 years postoperatively. The variance-weighted mean function score (/100, 0 = worst function) was 47.1 (95% CI 45.7-48.4) preoperatively, 72.8 (95% CI 71.3-74.4) at 3 months, 76.3 (95% CI 74.7-77.8) at 6 months, and 78.1 (95%CI 76.4-79.7) at 12 months. Function scores were good (79.7; 95% CI 77.9-81.5) at 10 years postoperatively.

CONCLUSION

Patients undergoing primary TKA can expect a large and rapid but incomplete recovery of pain and function in the first postoperative year. At 10 years, the gains in pain scores may still remain while there is an improvement in function.

The Medium-Term Survival Analysis of an All-Polyethylene Tibia in a Single-Series Cohort of Over 1000 Knees

BACKGROUND

Total knee arthroplasty is a successful elective orthopedic procedure with an increasing number being undertaken. Original knee arthroplasties used an all-polyethylene tibia; however, with concerns over tibial loosening, the trend moved toward the metal-backed variety. Modern designs providing more conformity and changes in manufacturing of the polyethylene make it an equivalent but cheaper option.

METHODS

We analyzed the medium-term outcome in 1092 patients with an all-polyethylene tibial component in their total knee arthroplasty.

RESULTS

Twenty-six patients had further surgery on their knee for a variety of reasons. Assessing reoperation for any reason, the 7-year survival rate was 96.96% with an overall infection rate of 0.37%. Seven-year survival analysis using aseptic loosening as a criteria was 99.28%. Both the Short Form 12 physical score and Western Ontario and McMaster Universities Osteoarthritis Index score significantly improved and was sustained at 7 years. Body mass did not correlate to either outcomes or complications.

CONCLUSION

An all-polyethylene tibia in a total knee arthroplasty has good outcome data and high patient satisfaction with good survivorship in the medium term, coupled with potential cost-saving benefits.

Cemented all-poly tibia in resource constrained country, affordable and cost-effective care. Is it applicable at this era? Review article

Osteoarthritis of knee is a progressive disease requiring total knee replacement in advanced stage. TKR is being performed in high numbers in developing countries as well. It carries significant economic burden on health system including high cost of implants. Initially, tibial components were cemented all polyethylene monoblock constructs. Subsequent studies showed excellent long term follow up in terms of durability up to 20 years.Successive studies reported aseptic loosening as the cause of failure but such studies failed to address factors responsible for failure other than implant. Cemented metal-backed non-modular tibial components (MBT) are implants in current use. They provide modularity in terms of polyethylene thickness, stems wedges. A literature reported cost saving of $1.17 million, by operating 16,500 total joints using all poly-tibial tibial component rather than metal backed tibial component. studies have reported no significant difference in terms of survivorship, function and backside wear.

Methods

For this study only English written articles were included. Studies included case reports, case series, RCTs and systemic reviews related to all polyethylene tibial components. Articles reporting all levels of evidence – Level I to IV- were included as part of our research. PubMed, Google Scholar and Cochrane Reviews databases from 2000 to 2016 were searched for studies.

Results

Information was gathered and thoroughly studied from 30 articles with overall result in favor of the APTC implant.

Conclusion

All polyethylene tibial component (APTC) is an appealing and cost effective alternative, and is associated with the excellent survivorship and lower risk of revision. In light of the present-day economic evidence and long-term functional outcome, all-polyethylene should be in more use than metal backed especially in resource-constrained setting.

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Total Knee Arthroplasty revolutionized the management of end-stage arthritis of the knee.

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Tibial components were cemented all polyethylene monoblock with decreased bone resection.

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Cemented metal-backed non-modular tibial components (MBT) were subsequently introduced.

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Incremental cost can be a devastating problem for the patients at resource-constrained settings.

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In this era of competitive implant's industries, cost-effective options should be explored and adapted.

All-polyethylene tibial components in young patients have stable fixation; a comparison RSA study

BACKGROUND

All-polyethylene (AP) tibial components in patients aged greater than 60 years have stable tibial migration patterns and favorable survival rates when compared to identical Metal-backed (MB) designs. Tibial component migration in younger patients has not been reported. The aim of this study was to examine the migration characteristics of patients aged less than 60 years compared to a previous cohort of AP and MB tibial components of identical design in older patients.

METHODS

A prospective consecutive study examined tibial component migration in 21 patients aged less than 60 years undergoing a cemented total knee arthroplasty with an AP tibial component by radiostereometric analysis (RSA) to 24 months. Results were compared to the authors' previous series of 21 patients aged greater than 60 years that were randomized to either an AP or MB tibial component.

RESULTS

Both age groups of patients implanted with an AP component had stable migration patterns with no patient having greater than 0.2° rotation or 0.2 mm maximum total point motion. Five of 11 MB tibial components displayed continued migration between one and two years. Subsidence was similar in all groups, whilst maximum total point motion was greater for the MB cohort (0.34 mm, 0.33 mm, 0.61 mm; AP <60, AP >60, MB).

CONCLUSIONS

Young patients implanted with an AP tibial component had stable tibial migration patterns comparable to older patients with the same AP implant. Regardless of age, AP tibial components were at least as stable as MB tibial components.

LEVEL OF EVIDENCE

Level II, Prospective comparative study.

Osteolysis Complicating Total Knee Arthroplasty

Osteolysis is a process mounted by the host immune system that relies on several variables, including patient-related factors, type of insert material, modes of wear, and implant design. Imaging techniques such as radiography, computed tomography (CT) scans, magnetic resonance imaging (MRI), and tomosynthesis aid in diagnosing osteolysis. Surgical options for the treatment of osteolysis include the insertion of bone grafts, bone cement, and prosthetic augmentation. Although no approved pharmacological therapies for the specific treatment of osteolysis exist, the use of bisphosphonates and statins decreases the risk of osteolysis.

All-polyethylene versus metal-backed tibial component in total knee arthroplasty

PURPOSE

The aim of this systematic review was to evaluate the clinical outcomes, rate of revisions and complications of all-polyethylene tibial and metal-backed tibial components in patients treated with knee arthroplasty for primary or secondary osteoarthritis.

METHODS

A systematic review of the literature according to the PRISMA guidelines was performed. A comprehensive search of PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases using various combinations of the keywords such as "knee", "arthroplasty", "metal-backed", and "all-polyethylene", since inception of databases to 2016, was performed.

RESULTS

Thirty-two articles, describing patients with all-polyethylene tibial or metal-backed tibial components in the setting of osteoarthritis, were included. A total of 68,202 knees in 58,942 patients were included, with an average age at surgery of 69.3 years, ranging from a mean age of 57.9-82 years. The mean KSS was 82.4 and 81.3 (n.s.), the mean KSS(F) was 73.6 and 74.9 (p = 0.04), the mean ROM was 104.5 and 104.6 (n.s.), and the mean HSS was 87 and 86, each, respectively, for the metal-backed tibial components group and all-polyethylene tibial components group. The overall rate of revisions was 1.90 %. The rate of revision in the metal-backed tibial components group was 1.85 %, whilst the rate of revision in the all-polyethylene tibial components group was 2.02 % (p < 0.00001).

CONCLUSION

Metal-backed tibial and all-polyethylene tibial components did not show any significant difference in most of the included outcome scores, but statistical differences were found in terms of complications and revision rate. These items have a negative impact on the cost-effectiveness of all-polyethylene tibial components. Even if all-polyethylene tibial components show similar clinical outcome score, equivalent range of knee motion, and long-term survival compared to metal-backed tibial components, complications and revision rate seem to lead the surgeon to prefer the last ones. The clinical relevance of this study is that metal-backed tibial components should be preferred in TKA surgery because complications are higher using all-polyethylene tibial components. On the other hand, the quality of evidence, according to GRADE system, is low underling the necessity of more randomised study to clarify these items.

LEVEL OF EVIDENCE

III.

Midterm results after unicompartmental knee replacement with all-polyethylene tibial component: a single surgeon experience

PURPOSE

The aim of this study was to determine the survival rate, the causes of failure, and the functional outcomes of an all-polyethylene tibial unicompartmental knee prosthesis.

METHODS

One hundred (100) nonselected, consecutive patients indicated for unicompartmental knee replacement for isolated medial knee compartment osteoarthritis by a single surgeon at a single institution from 2000 to 2004 were included in this study. Data was collected retrospectively at final follow-up from the hospital electronic database, including progress notes, demographic information, Hospital for Special Surgery (HSS) Knee Score, details on the surgical procedure, reoperations/revisions, and mortality. A survival analysis was performed to estimate the probability of survival over time.

RESULTS

The survival probability of the all-polyethylene UKA implant was 95.4 % after a mean follow-up of 8 years, which is comparable to reports from studies using metal-backed modular designs for UKA. The causes of failure were progression of arthritis in adjacent compartments (2 %) and loosening of the tibial component (2 %). The mean preoperative HSS knee score improved from 36.6 ± 14.3 to 76.6 ± 21.6 at latest follow-up (p < 0.0001).

CONCLUSIONS

In summary, an all-polyethylene tibial component has equivalent survivorship to modular designs. Implant selection does not seem to have great influence on the outcome, but rather the success depends on appropriate indications and surgical technique.