What Can We Learn From 20-year Followup Studies of Hip Replacement?

Abstract

Background A patient who dies during the followup period of a study about total hip arthroplasty (THA) cannot subsequently undergo a revision. The presence of competing events (such as deaths, in a study on implant durability) violates an assumption of the commonly used Kaplan-Meier (KM) survivorship approach. In that setting, KM-based estimates of revision frequencies will be high relative to alternative approaches that account for competing events such as cumulative incidence methods. However, the degree to which this difference is clinically relevant, and the degree to which it affects different ages of patient cohorts, has been poorly characterized in orthopaedic clinical research. Questions/purposes The purpose of this study was to compare KM with cumulative incidence survivorship estimators to evaluate the degree to which the competing event of death influences the reporting of implant survivorship at long-term followup after THA in patients both younger than and older than 50 years of age. Methods We retrospectively reviewed 758 cemented THAs from a prospectively maintained single-surgeon registry, who were followed for a minimum of 20 years or until death. Revision rates were compared between those younger than or older than age 50 years using both KM and cumulative incidence methods. Patient survivorship was calculated using KM methods. A total of 21% (23 of 109) of the cohort who were younger than 50 years at the time of THA died during the 20-year followup period compared with 72% (467 of 649) who were older than 50 years at the time of surgery (p \ 0.001). Results In the cumulative incidence analysis, 19% of the younger than age 50 years cohort underwent a revision for aseptic causes within 20 years as compared with 5% in the older than age 50 years cohort (p \ 0.001). The KM method overestimated the risk of revision (23% versus 8.3%, p \ 0.001), which represents a 21% and 66% relative increase for the younger than/older than age 50 years groups, respectively. Conclusions The KM method overestimated the risk of revision compared with the cumulative incidence method, and the difference was particularly notable in the elderly cohort. Future long-term followup studies on elderly cohorts should report results using survivorship curves that take into account the competing risk of patient death. We

Overestimation of the risk of revision with Kaplan-Meier presenting the long-term outcome of total hip replacement in older patients

“…The relative difference between KM and CI estimations was increasing during follow-up, reaching up to 76.8% at 25 years. Thus, similarly to other reports, we found that the KM analysis overestimated significantly the risk of revision in comparison to the CI method (28-31). If this observation has an important clinical significance, remains to be examined.…”

“…It was then suggested that the CI approach provides more accurate results, especially in studies with long-term follow-up, including high number of deaths. This method provides more profound analysis into THR outcomes, allowing comparisons of survival results between different studies (29)(30)(31). These studies followed by a CORR's Editorial, by Wongworawat et al, suggesting the use of an alternative to KM analysis, when the frequency of competing event is greater than 10%-20% and the follow-up duration reach out 10 years (21).…”

Effect of surface mechanical attrition treatment on the microstructure of cobalt–chromium–molybdenum biomedical alloy

“…The wear of the prosthetic implants is an important problem in the field of orthopedics. Several research works have shown adverse effects caused by nanoparticles release induced by the wear of implants inside the patients' body (Charnley, 2012;Learmonth, Young, & Rorabeck, 2007;Martin et al, 2016). The cobaltchromium-molybdenum (CoCrMo) alloy is used in artificial hip and knee prosthesis due to its hardness and good corrosion resistance as well as its mechanical properties.…”

Impact of Various Factors on the Polyethylene Wear Rate in Total Hip Arthroplasty

“…В связи с постоянно увеличивающимся количеством операций у относительно молодых пациентов с большой предполагаемой продолжительностью жизни и, как правило, высоким уровнем двигательной активности, нарастает риск ревизий, выполняемых в значительно меньшие сроки [16,17,19]. границы молодого возраста для эндопротезирования ТБс, по данным разных авторов, колеблются от 50 до 65 лет, но подавляющее число исследований все же принимает в расчет именно 50 лет [5,17,[19][20][21][22][23][24]. Молодые пациенты обладают гораздо более высоким уровнем активности после операции, что ведет к ускоренному разрушению трущихся поверхностей, и многочисленные исследования демонстрируют взаимосвязь скорости изнашивания с развитием остеолиза, асептического расшатывания и частотой ревизий.…”

“…Молодые пациенты обладают гораздо более высоким уровнем активности после операции, что ведет к ускоренному разрушению трущихся поверхностей, и многочисленные исследования демонстрируют взаимосвязь скорости изнашивания с развитием остеолиза, асептического расшатывания и частотой ревизий. соответственно, показатели выживаемости имплантатов при тотальном эндопротезировании тазобедренного сустава у пациентов молодого возраста существенно хуже, чем в других возрастных группах [17,19,21,24,25].…”