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

No changes in bone mineral density following total knee arthroplasty using an all-polyethylene tibial component

PURPOSE

Polyethylene particles produced from metal-backed tibial (MBT) implants are understood to contribute to bone loss and component loosening. This, along with advanced surgical techniques, improved materials and increasing costs, has renewed interest in all-polyethylene tibias (APTs). We investigated peri-APT bone mineral density (BMD) in patients, expecting to find no differences between two post-operative values.

METHODS

Patients over 65 years, with BMI ≤ 37.5 kg/m2 and no previous joint replacements were recruited to have computer-navigated total knee arthroplasty using an APT. The study cohort (n = 27) had mean age of 71.9 (SD 4.35) and BMI of 31.2 (SD 3.8). The BMD examinations were performed 6 weeks and 18 months post-operatively. Six regions of interest (ROI) were identified on anterior/posterior and lateral dual-energy X-ray absorptiometry scans. For each ROI, BMD relative differences (RDs) were determined between limbs and RDs at the two time points were compared.

RESULTS

No differences were found between the RDs for any ROI. No revisions or complications were reported. At 18 months post-operatively, 79.2% of the cohort were very satisfied or satisfied with the outcome of their surgery and Oxford Knee Scores improved significantly compared to pre-operatively (p < 0.001). Mean knee range of motion was 102° (SD 10.7°), and mean leg alignment was 2.0° valgus (1-6°valgus).

CONCLUSION

Results from BMD analysis suggest that implants were well fixated without compromising function. We believe that using APTs with computer navigation is a viable cheaper option to MBTs for patients who are less active, have lower BMI and good bone quality.

All-polyethylene tibia components have the same functional outcomes and survival, and are more cost-effective than metal-backed components in patients 70 years and older undergoing total knee arthroplasty : propensity match study with a minimum five-year follow-up

AIMS

The tibial component of total knee arthroplasty can either be an all-polyethylene (AP) implant or a metal-backed (MB) implant. This study aims to compare the five-year functional outcomes of AP tibial components to MB components in patients aged over 70 years. Secondary aims are to compare quality of life, implant survivorship, and cost-effectiveness.

METHODS

A group of 130 patients who had received an AP tibial component were matched for demographic factors of age, BMI, American Society of Anesthesiologists (ASA) grade, sex, and preoperative Knee Society Score (KSS) to create a comparison group of 130 patients who received a MB tibial component. Functional outcome was assessed prospectively by KSS, quality of life by 12-Item Short-Form Health Survey questionnaire (SF-12), and range of motion (ROM), and implant survivorships were compared. The SF six-dimension (6D) was used to calculate the incremental cost effectiveness ratio (ICER) for AP compared to MB tibial components using quality-adjusted life year methodology.

RESULTS

The AP group had a mean KSS-Knee of 83.4 (standard deviation (SD) 19.2) and the MB group a mean of 84.9 (SD 18.2; p = 0.631), while mean KSS-Function was 75.4 (SD 15.3) and 73.2 (SD 16.2 p = 0.472), respectively. The mental (44.3 vs 45.1; p = 0.464) and physical (44.8 vs 44.9; p = 0.893) dimensions of the SF-12 and ROM (97.9° vs 99.7°; p = 0.444) were not different between the groups. Implant survivorship at five years were 99.2% and 97.7% (p = 0.321). The AP group had a greater SF-6D gain of 0.145 compared to the MB group, with an associated cost saving of £406, which resulted in a negative ICER of -£406/0.145 = -£2,800. Therefore, the AP tibial component was dominant, being a more effective and less expensive intervention.

CONCLUSION

There were no differences in functional outcomes or survivorship at five years between AP and MB tibial components in patients aged 70 years and older, however the AP component was shown to be more cost-effective. In the UK, only 1.4% of all total knee arthroplasties use an AP component; even a modest increase in usage nationally could lead to significant financial savings.Cite this article: Bone Jt Open 2022;3(12):969-976.

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.