Historic registry data for cementless total knee arthroplasty (TKA)

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The use of cemented versus cementless fixation in total knee arthroplasty (TKA) has been the subject of ongoing debate for over a decade [1, 2]. Early use of cementless TKA was met with mixed results, and although it gained wider acceptance about 10 years ago, evidence at the time still seemed to show that better outcomes were achievable with cemented fixation in TKA [2]. In 2012, Ranawat et al [2] concluded that cemented fixation in TKA was the gold standard, with superior and more durable fixation and better survivorship for mechanical failure compared with cementless fixation. In this series of articles, Gerard A Sheridan, from the Department of Orthopaedic Surgery, University of Galway, Galway, Ireland, Bassam Masri, from the Department of Orthopaedics, University of British Columbia, Vancouver, Canada, and David F Dalury, from the University of Maryland St Joseph Medical Center, Baltimore, Maryland, USA will take a closer look at TKA registry data from the last 10 years, appraise the mid-term outcomes of newer cementless designs and review the results of studies using radiostereometric analysis of cementless TKAs.

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Gerard A Sheridan

Department of Orthopaedic Surgery, University of Galway, Galway, Ireland

Cementless TKAs in the minority

 

Cemented TKAs dominated the landscape 10 years ago; yet, there was a relative paucity of long-term or comparative results looking at cemented, cementless, or hybrid TKAs coming from clinical studies. The national joint replacement registries thus form one of the best sources of outcomes data available from this period.

In North America, cemented fixation appeared to be the most common form of fixation, as shown by data from the 2014 Canadian Joint Replacement Registry (CJRR) Annual Report [3]. This revealed that 89.1% of TKAs performed from 2011 to 2012 were cemented TKAs, with 8.0% being hybrid and only 2.9% being cementless [3]. Similar figures were reported from the American Joint Replacement Registry (AJRR), such that in 2014 4.1% of TKAs were hybrid and 2.8% were cementless [4].

Europe showed a similar trend with cemented TKAs dominating the landscape. In 2014, the National Joint Registry (NJR) for England, Wales, and Northern Ireland reported that 93.2% of all primary TKAs were cemented, with 5.5% being cementless and 1.3% hybrid [5]. Analogous data was reported by the Swedish Knee Arthroplasty Register (SKAR) Annual Report 2014 [6]; here, a year-by-year graphical representation of the distribution of fixation methods showed that more than 90% of knee arthroplasties were performed using bone cement in 2013. Although the exact percentage of cementless knee arthroplasties was not reported, at the time it was noted that there was a slight increase in the use of cementless fixation starting roughly in 2009 [6]. However, in Sweden 60% of the uncemented cases were inserted at just one center and this thus made the results difficult to interpret [6].

The picture in Australia at the same time was somewhat different [7]. The 2014 Annual Report of the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) revealed that only just over half of primary TKAs used cemented fixation at 55.8% in 2013, followed by 25.3% being hybrid fixation, and the remaining cementless (18.9%) [7]. The use of cemented fixation actually increased from 44.8% in 2003, as the AOANJRR noted [7]. In contrast, the New Zealand Joint Registry Sixteen Year Report (January 1999–December 2014) reported a more similar picture to Europe and North America, whereby again cemented fixation dominated at 90.8% of TKAs followed by 5.2% hybrid and 4% cementless [8].

 

Underperformance of cementless TKAs in national registries

 

The historical data presented above show that the most common form of fixation was cemented, with cementless TKAs being in the minority. Cementless TKAs were also shown to have poor performance, with the data reported by these national registries supporting the use of cemented fixation in TKAs. Early studies, such as that from Barrack et al [1] from 2003 on primary cementless mobile-bearing TKAs, showed that there was a significantly higher revision rate for cementless mobile-bearing TKAs at the 2-year follow-up compared with their cemented counterparts (8% vs 0%, 6/73 vs 0/66; P <.05). Additionally, the results of one community registry showed that an increased revision risk was evident in younger patients under 55 years of age who underwent cementless TKA [9].

The registry data on revision rates appears to support the results of these earlier studies. For the CJRR and the AJRR, data on revision rates of cementless TKAs is not available. However, in Europe, in the UK the 2014 NJR report shows a 10-year revision rate of 4.49% for cementless TKA (both sexes), compared with 3.33% for cemented and 3.46% for hybrid TKAs [5]. The revision rate appeared to decrease with age: In younger patients < 55 years of age, the 10-year revision rate for cementless TKA was 10.53% in male and 8.72% in female patients, whereas a lower rate was reported in older patients aged 55–64 years of age, being 6.67% for male and 5.86% for female patients [5]. Sheridan explains, “we know that the functional demand from a TKA is lower with older patients. Many revision TKAs are carried out because the patient experiences a stiff knee that does not flex far enough to meet the demands of their activities of daily life. Younger patients have higher demands and thus the likelihood of younger patients having a revision to treat stiffness may be higher than in older patients. Furthermore, older patients have more comorbidities and tend to have more potential risks with undergoing surgery, which may deter the treating surgeon from operating on patients with more significant comorbidities. This could be one of the reasons why the revision rate reported was lower in older patients”. The report concluded that poor outcomes were seen with cementless or hybrid joints with posterior stabilized and fixed constraint, when compared with the unconstrained bearing type of implants, but that there was a lower chance of revision overall for cemented unconstrained implants compared with other combinations of constraint used in cemented TKA [5]. An increased risk of revision for uncemented implants was also shown in the Swedish registry data, where the risk for TKA with a cementless tibial component was 1.7 (1.4–1.9) times higher than for those cemented [6]. At the time, this was in agreement with the increased risk of revision being shown in registries from other countries [6].

In Australia, the AOANJRR from 2014 demonstrated a higher revision rate of 6.3% vs 5.3% for cementless vs cemented TKA, whereas hybrid TKA demonstrated a lower rate of 5.0% [7]. It was also noted that this higher rate of revision of cementless TKA was previously described [7]. For New Zealand, in the 2014 report the revision rate per 100 component years was 0.82 in cementless vs 0.47 in cemented TKA, and 0.52 in hybrid TKA [8]. Despite cementless TKA representing only 4% of primary TKA captured in the New Zealand registry, there was a significantly higher (P <.05) revision rate than for cemented or hybrid TKA [8].

 

Improvements start to be seen

 

Later studies started to show improvements in the outcomes of the cementless TKAs. In one study from 2016, good outcomes were demonstrated when computer-assisted surgery was used in conjunction with a cementless rotating mobile-bearing TKA [10]. Although no differences were detected in the clinical outcome or 10-year survivorship between the group of implants inserted using computer assistance and those inserted conventionally, when looking at secondary patellar resurfacing as an end point, this study detected higher survivorship with computer assistance [10]. A later systematic review from Van der List et al [11] on cohort studies and registries which reported outcomes of cementless TKAs revealed an annual revision rate for 0.46% per year for cementless TKAs and an extrapolated 10-year survivorship of 95.4% when using data from cohort studies. This systematic review was the first to include only recently published studies at the time (2005–2016) and thus provided an up-to-date overview of the outcomes of cementless TKAs [11].

Another systematic review by Franceschetti et al [12] from 2017 shows the start of a different picture: here, cementless TKAs were shown to be similar to cemented TKAs in terms of survival rates, and functional, radiological, and clinical outcomes. Furthermore, high survival rates were reported for both cementless and cemented TKAs, and no additional benefit was found with the use of cemented TKAs. Indeed, the authors concluded that cementless fixation be recommended as the first choice of fixation in patients younger than 60 years of age [12]. This was attributed to the fact that cementless fixation techniques lead to stable fixation as well as a lower operation time [12].

Despite the good outcomes reported by Franceschetti et al, registry data still seemed to report poorer results with cementless TKAs. Jorgensen et al [13] reviewed the data from the AOANJRR to assess factors associated with major aseptic revision of TKA. They found that cementless TKA had a higher rate of revision than cemented or hybrid TKA and that cementless fixation was a risk factor for higher rates of major aseptic revision [13]. Asokan et al [14] also noted that the NJR from the UK was still reporting higher revision rates in cementless TKAs. Nonetheless, clinical studies had started to report good outcomes with cementless implants [14]. One systematic review of randomized controlled trials of primary TKAs comparing cemented and cementless fixation outcomes revealed that there were no differences in revision rates or in knee function between the two fixation types at up to 16.6 years follow-up [15]. Further, Asokan et al [14] were able to show that the outcomes of more recent clinical studies on cementless TKA were “beginning to encourage surgeons back to this technique”. Cementless TKAs were shown to perform equally to cemented TKAs in terms of survivorship and functional outcomes, and indeed they were able to note emerging superior performance [14].

Nevertheless, in a series of articles by Mohammed et al [16–18] looking at the data from the NJR, results still seemed to favor the use of cemented TKAs. In one analysis comparing cemented and cementless TKAs, 10-year implant survival rates were above 95% for both fixation types, but cementless TKAs exhibited a slightly higher revision rate [16]. However, the rate of revision was lower for infection but higher for pain in the cementless TKA group [16]. A further publication compared the patient-reported outcome measures of the two fixation types, revealing better patient-reported outcomes for cemented TKAs compared to their cementless counterparts [17]. However, the authors noted that the differences were small and below the minimally clinically important difference and concluded that both types of fixation were acceptable [17]. In a later article from 2023, again using data from the NJR, Mohammed et al [18] looked at the risk of periprosthetic fracture between cemented and cementless TKAs. Here, it was shown that there were no significant differences in fracture rates between the two types of fixation, reported as 1.2% and 1.4% for cemented and cementless TKAs respectively at 10 years[18].

 

A changing landscape and improved outcomes

 

Changes in thinking about the use of cementless designs were starting to be reflected in some of the above-mentioned studies. Indeed, the most recent registry data from 2023 paint a slightly different picture to that of 2014. As Sheridan notes, “the shift towards using cementless TKAs is rather new, even though some surgeons have always used them. We know the early technology didn’t perform very well, but newer literature now shows excellent survivorship with the technological advancements that have occurred in recent times. There are, however, relatively few publications showing long-term follow-up on new implant types, thus we rely on the registries to provide data, as these are some of the biggest signal detectors”.

The 2023 report of the CJRR includes 10-year data on the cumulative percentage revision of cemented TKAs and 9-year data on cementless and hybrid primary TKAs [19]. At 10 years after primary replacement (Table 1), the cumulative percentage revision for cemented TKAs was 3.46% compared with 3.62% and 3.21% for cementless and hybrid TKAs respectively at 9 years after primary replacement [19]. The report concludes that for TKAs, regardless of the type of fixation used, there was no difference in revision risk [19]. In the US, the 2023 AJRR reported a substantial increase in the use of cementless TKAs, such that in 2022, 20.5% of all primary TKAs had cementless fixation (Figure 1); in contrast, the use of hybrid TKAs was low at 1.9%, having decreased from 4.1% in 2014 [4]. Indeed, the report shows that the use of cementless TKAs has rapidly increased from 2.8% in 2014 [4]. Furthermore, both cementless and hybrid TKAs were shown to be associated with decreased cumulative percent revision (Table 1) compared with cemented TKAs in men, both in younger and older age groups [4]. In contrast, in women aged 65 years and older, cemented fixation was associated with a significantly lower cumulative revision [4]. Despite this, there was no difference in revision risk for TKA regardless of the type of fixation used [4].

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Figure 1. This figure shows the percentage of total knee arthroplasties (TKAs) using cemented, cementless, or hybrid fixation from national joint replacement registry reports in 2023 [20]. The Canadian Joint Replacement Registry Annual Report from 2021–2022 did not present any data on this topic. Data from the American Joint Replacement Registry 2023 Annual Report provided only data for cementless and hybrid TKAs in 2022; the value for cemented is calculated based on these percentages. The data included here from the National Joint Registry uses information provided in Table 3.K3 in the report. The percentages are calculated based on the 1,354,653 TKAs excluding the unicondylar, patellofemoral, multicompartmental, and unconfirmed arthroplasties. For the 2023 Annual Report of the Australian Orthopaedic Association National Joint Replacement Registry, the percentages are for TKA procedures in 2022. For the Swedish Arthroplasty Register, percentages reported are for TKA procedures in 2021. No information was provided for the cemented TKAs. No information was provided for the hybrid or cemented TKAs in the New Zealand Joint Registry Twenty-four Year Report.

Cemented TKAs still dominated within the United Kingdom: The NJR 2023 report documented that only 3.8% of all TKAs were cementless (Figure 1), whereas 95.5% were cemented and 0.8% hybrid [20]. However, in comparison to 2014 (4.49%), a much lower 10-year revision rate for cementless TKAs was reported at 3.89% [20]. At 10 years, the cumulative revision rate for cemented TKAs was 3.11% and for hybrid 3.46% (Table 1) [20]. The lowest revision rate was found for the monobloc polyethylene tibia (cemented) at 2.13% and the highest for preassembled/hinged/linked (cemented) TKAs [20]. Among the cementless TKAs, the lowest revision rate was noted for unconstrained mobile designs and the highest for the posterior-stabilized fixed designs [20]. For hybrid TKAs, unconstrained mobile designs had the lowest revision rate at 3.6% and the highest was again posterior-stabilized fixed designs [20]. Commenting on the revision rates in the NJR, Sheridan notes, “initial iterations of cementless prostheses faced challenges stemming from suboptimal geometry, ineffective osteoconductive surfaces, and insufficient properties to achieve early stable fixation. However, recent advancements in cementless technology have led to notable improvements, significantly decreasing stresses and micromotion before achieving osseointegration. Therefore, it will be very important in future reports for registries to specify between the results of older and newer generation cementless implants. If both generations are reported together, the results may understate the success of newer generation implants if both old and new generation implants are reported as a single revision rate. For this reason, it is important that dedicated studies exclusively assessing newer generation cementless implants are continually conducted and results are published to follow the outcomes of this technology into the future”.

The picture in Sweden based on the 2022 report of the Swedish Arthroplasty Register (SAR) shows that the use of cementless TKAs increased in Sweden from 2.4% in 2010 to 9.1% in 2021 (Figure 1), but cemented fixation remained the predominant method and hybrid TKAs were the least frequently used TKAs at 0.4% [21]. However, it should be noted that most cementless procedures are performed in two hospitals, with one reporting cementless fixation in 52% of TKAs and another in 27% [21]. The report also notes a significantly higher risk of revision found in cementless implants compared with cemented in the preceding 10-year period [21]. The SAR report went into further detail regarding TKAs carried out between 2010 and 2021 with a modern total knee replacement with a single-radius design for which both cemented and cementless versions exist [21]. For these implants, the cumulative revision rate at 10 years was 8% in cementless vs 3% in cemented single-radius design TKAs [21]. The cumulative revision rate for aseptic reason was 6% in cementless and lower at 2% in cemented single-radius design TKAs [21]. The analysis also showed that the demographic of patients with cementless single-radius design implants were, in comparison to those with cemented implants, mainly male, younger, had a somewhat lower Body Mass Index, and had a lower proportion of the American Society of Anaesthesiologists score (ASA) class ≥ III [21].

Similar to the above registries, in Australia, the recent 2023 AOANJRR observes that cemented fixation is the most used form of fixation (Figure 1), but in comparison to the other registries, there is a higher proportion of cementless and hybrid TKAs at 19.9% and 18.3% respectively [22]. The 10-year cumulative percent revision for both cemented and hybrid TKAs was 4.0% and 5.2% for cementless TKAs (Table 1). The AOANJRR 2023 report restricted the analysis to modern prostheses only [22].

When considering the last of the registry data discussed here, the data from the New Zealand Joint Registry (NZJR) 24-year report (January 1999–December 2022) is somewhat promising with regard to cementless TKAs [23]. The use of cementless TKAs continues to increase, making up 14% of all primary TKAs (Figure 1); however, the revision rate is significantly higher than for cemented or hybrid TKAs [23]. Nevertheless, the revision rate per 100 component years was 0.61 in cementless vs 0.45 in cemented TKAs (Table 1), which represents a large improvement in performance of cementless TKAs (0.82 vs 0.61, 2014 vs 2023) compared to cemented TKAs, for which the revision rate per 100 component years has remained stable [23].

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Table 1. Ten-year revision rate for cemented, cementless, and hybrid total knee arthroplasties (TKAs). Only national registries which provide this data in their annual report have been included. *The Canadian Joint Replacement Registry is from 2021–2022. †No information provided in the 2014 report, and only 9-year revision rates provided in the 2021–2022 report. ‡Revision rate per 100 component years is provided. Rate per 100 component years is equivalent to yearly revision rate expressed as a percentage and is derived by dividing the number of prostheses revised by observed component years multiplied by 100. Shown is revision vs arthroplasty fixation. In the 2023 report, follow-up was up to 22 years since operation. §Cumulative percent revision of primary TKA with primary diagnosis of osteoarthritis, excluding two cementless femoral prostheses with oxidized zirconium surface. ║Cumulative percent revision of minimally stabilized primary TKA with primary diagnosis of osteoarthritis, excluding cementless femoral prostheses with oxidized zirconium surface and restricted to modern prostheses.

The increase in use of cementless or hybrid fixation techniques in TKA seen between the 2014 report and the 2022 or 2023 reports is similar to that found in the results of a systematic comparative analysis of using worldwide knee arthroplasty registries looking at a similar time period (2010–2022) [24]. Leitner et al [24] found a clear increase in the use of such techniques noting that this replicated “the actual trend, that cementless TKA is the subject of renewed interest”.

 

Conclusion

The increased use of cementless or hybrid fixation in TKA is also reflected in the clinical setting; for example, Sheridan performs cementless primary total knee arthroplasty in almost all patients regardless of sex or age. Once good cortical rim fit is achieved in the tibia and there is precise implant size matching between the tibial component and the cut bone surface, the issue of tibial subsidence is negligible. The only caveat to the universal use of cementless tibial components is in the case of severe bone porosity or very poor bone quality which is usually best identified intraoperatively. In those cases, it may be more appropriate to insert a cemented tibial component. Regarding the femoral component, given the congruity between the femoral bone cut surfaces and the cementless femoral component, femoral subsidence does not pose a significant risk and so essentially all femoral components may be cementless.

Sheridan remarked, “when we look back at the registry data from 2014, the 10-year revision rates are encompassing those older prosthesis designs with poorer outcomes. We can see, when comparing those rates with the most recent registry data, that there are real improvements. The recent data is capturing the newer designs and, in some cases, the analyses are even restricted to only include modern designs. What we need to see is how this is reflected in clinical trials”.

In conclusion, there is a notable signal being detected in the international registry reports. New generation cementless TKA is performing well and in some cases even outperforming cemented TKA. With the advent of improved cementless TKA design, one can expect to see an increase in the usage of these implants among knee surgeons in the future and they may possibly even replace cemented TKA as the gold standard. In order for this to occur, unequivocal results from dedicated well-designed studies will need to demonstrate excellent results with newer generation cementless TKA designs.

The second article in this series takes a closer look at the clinical studies using modern designs and will shed light on the clinical outcomes in what is becoming a popular choice for modern-day knee arthroplasty surgeons.

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Part 2 | Mid-term outcomes of modern cementless total knee arthroplasty and patient selection in 2024
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Part 3 | Radiostereometric analysis of newer cementless total knee arthroplasty designs
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AO Recon resources

Contributing experts

This series of articles was created with the support of the following specialists (in alphabetical order):
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David F Dalury

University of Maryland St Joseph Medical Center, Baltimore, Maryland, USA

Member AO Recon Education Forum

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Bassam Masri

Department of Orthopaedics, University of British Columbia, Vancouver, Canada

Chairperson AO Recon Education Forum and Member AO Recon Steering Board

 

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Gerard A Sheridan

Department of Orthopaedic Surgery, University of Galway, Galway, Ireland

This article was written by Lyndsey Kostadinov, AO Innovation Translation Center, Clinical Science, Switzerland.

References

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  2. Ranawat CS, Meftah M, Windsor EN, et al. Cementless fixation in total knee arthroplasty: down the boulevard of broken dreams - affirms. J Bone Joint Surg Br. 2012;94(11 Suppl A):82–84.
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  18. Mohammad HR, Judge A, Murray DW. A Comparison of the Periprosthetic Fracture Rate of Cemented and Cementless Total Knee Arthroplasties: An Analysis of Data From the National Joint Registry. J Arthroplasty. 2023.
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