Editorial Comment: Selected Papers from the 9th International Congress of Arthroplasty Registries

Considering the overall favorable results in terms of implant survival, pain relief, and improved function following hip and knee replacement, is there still a need for arthroplasty registers? My answer is: unquestionably yes.

Ola Rolfson MD, PhD

Continued high-quality care and further improvements in joint replacement require continuous monitoring and outcome assessment using arthroplasty register data. The large sample sizes allow early detection of small but clinically important differences in implant survivorship [5], as well as insights into performance of different surgical methods and implant concepts (such as hooded vs. nonhooded liners [1]), and identification of high-risk patient subgroups [13]. It would take years longer to identify these kinds of differences in clinical trials, and because of daunting logistical challenges—the need for unrealistically large numbers and long surveillance periods—many or most of those trials probably would never be performed. Yes, registry research remains essential if we are to keep our patients safe.

Despite the pandemic, the International Society of Arthroplasty Registries (ISAR) has continued its mission of improving outcomes following joint replacement worldwide. To achieve progress, the work within ISAR is organized into subcommittees focusing on different areas of development. Currently, ISAR subcommittees cover benchmarking, patient-reported outcomes measures (PROMs), signal detection (that is, the rapid and early detection of underperforming implants and methods), education, and statistical methodology.

In the Proceedings of the 9^th International Congress of Arthroplasty Registries in this issue of Clinical Orthopaedics and Related Research®, we see a fine example from the PROMs working group, demonstrating how these subcommittees strive to reach development, harmonization, and conformity [2]. For many registries, PROMs have become an integral part of the multidimensional assessment of arthroplasty, but not all registries collect them, and they are not measured consistently across registries. The paper by Bohm et al. [2] identified differences but also some important points of consensus that I think will lead to cross-registry data pooling that can help us answer bigger questions even than can be addressed in the context of a single national registry.

The 9^th International Congress of Arthroplasty Registries, which was also the 1^st Annual Virtual Congress, was hosted by the Australian Orthopaedic Association National Joint Replacement Registry, on November 13^th-15^th 2020. The virtual format, of course, required a more condensed program. Nevertheless, this congress had a record-high attendance with more than 200 delegates. The congress covered developments within recurrent focus areas, in alignment with ISAR’s subcommittees, and showcased many of the benefits and necessity of arthroplasty register work.

For example, one study used the Norwegian Arthroplasty Register to identify design features associated with an increased risk of revision within an implant system that, overall, is known to perform well [11]. It’s inconceivable to me that insights like those offered by the authors of this paper, which require such vast numbers to make—over 50,000 patients, in this case—could ever be uncovered in the context of a clinical trial.

Compared to elective hip replacement, arthroplasty to treat hip fracture is associated with many more complications, and there is an urgent need to improve our care of patients with these injuries. While a considerable amount of work from European registries has suggested that cemented fixation will decrease the risk of revision and periprosthetic fracture [8, 10], cementless fixation remains normative in the United States. In this year’s ISAR Proceedings in CORR®, we have the first registry study from the United States of which I am aware that substantiated that same finding in a large population of patients having hip fracture surgery [7]. Local findings are important to help convince surgeons in different countries that registry findings apply to their patients.

Despite general progress within hip replacement over the last two decades, the risk for infection—the most devastating complication other than perioperative death—remains unchanged. New knowledge about the long-term consequences on patient-reported outcomes confirm the importance of further research on infection prevention and treatment. For example, one study in the proceedings identified potentially modifiable risk factors—such as surgical approach—for poorer function after treatment for periprosthetic joint infection [12]. I am pleased to see how register research on shoulder replacement has evolved over the last couple of years with an increasing number of abstract submissions each year at ISAR. Another paper in this proceedings [6] found no difference in short- to mid-term revision risk for anatomic and reversed shoulder replacements among patients with osteoarthritis.

Another topic covered in this year’s congress was the use of linkage to socioeconomic and health data sources to increase richness of information on patient demography, comorbidities, health care utilization, and health outcomes. Usage of prescription-based comorbidity data is a good way to augment arthroplasty register data. One study published this month evaluated more than half a million patients’ data in the Australian Orthopaedic Association National Joint Replacement Registry, and learned that a newer score—called the RxRisk-V score—was effective at anticipating which patients were at greatest risk for death after surgery, and that it can serve a complementary function to the American Society of Anesthesiologists (ASA) classification [9].

The consequences of the pandemic for patients waiting for joint replacement surgery have been dramatic [3, 4]. Before the society’s annual business meeting in May 2021, member registries were surveyed about the number of total hip and knee replacements registered in 2019 and 2020, respectively. We received responses from 21 of 40 registries. The overall decrease in number of total hip replacements was 22%, and for knee replacements it was 29%. Typically, most registries have reported a 2% to 3% yearly increase of procedures. Looking ahead, I suspect these trends will reverse as we emerge from the pandemic, but the effects on patients’ health have yet to be determined.

Speaking of looking ahead, on behalf of ISAR, I am happy to announce that the steering committee recently renewed the partnership agreement with CORR, so Clinical Orthopaedics and Related Research will remain ISAR’s official journal. We look forward for continued growth of this partnership and the publication of future proceedings here. The next meeting, the 10th International Congress of Arthroplasty Registries, will be hosted by the Danish Hip Arthroplasty Register on November 11^th-13^th 2021. Given the success of the previous virtual meeting and uncertainties regarding travel restrictions due to the pandemic, this meeting will also be virtual, the 2^nd Annual Virtual Congress. We certainly hope to convene in person again in May 2022, when the Irish Arthroplasty Register will organize our 11^th congress in Dublin, and in 2023, when the Canadian Joint Replacement Registry has taken on the responsibility to organize the meeting after that in Montreal.