Historic registry data for cementless total knee arthroplasty (TKA)

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.

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].