Unicompartmental compared with total knee replacement for patients with multimorbidities: a cohort study using propensity score stratification and inverse probability weighting

Effect of intra-articular corticosteroid injections for knee osteoarthritis on the rates of subsequent knee replacement and post-operative outcomes: a national cohort study of England

BACKGROUND

Intra-articular corticosteroid injection (IACI) is an established treatment option for uncontrolled pain in osteoarthritis. There is a lack of longer-term follow-up in most studies of the effects of IACI, meaning there is scarcity of data on the impact of IACI on the subsequent need for joint replacement. Our aim was to assess the effect of IACI for knee osteoarthritis on the subsequent incidence of knee replacement surgery and on associated post-operative outcomes.

METHODS

We conducted a cohort study of knee osteoarthritis patients registered in the Clinical Practice Research Datalink (CPRD) GOLD database with an incident diagnosis between 2005 and 2019. Exposure was single or repeated IACI use, analysed separately. The primary outcome was knee replacement during 1-year and 5-year follow-ups. Secondary outcomes included post-operative patient-reported outcome measures and adverse events. Primary analyses used general practitioner practice preference for IACI as an instrumental variable given this methodology can account for strong and unmeasured confounding. Secondary analyses used propensity score matching, accounting for measured covariates only.

RESULTS

During 1-year follow-up, 1628/33,357 (4.9%) knee osteoarthritis patients underwent knee replacement, for which single IACI was associated with lower risk, which persisted to 5-year follow-up (incidence rate ratio: 0.52 [0.36, 0.77]). Conversely, in secondary propensity score analyses no association was found between IACI use and knee replacement rate at 1-year follow-up, and an estimated increased rate of knee replacement at 5-year follow-up. Use of IACI pre-joint replacement was not associated with any adverse post-operative outcomes, for example, 1-year complication rates (per 100 person-years) following knee replacement were 4.6 (3.8, 5.8), 4.0 (2.7, 6.0) and 5.0 (3.1, 8.1) among patients with no, single and repeat pre-joint replacement IACI use, respectively.

CONCLUSIONS

Findings from our main analysis suggest that short-term pain reduction following IACI for knee osteoarthritis may translate to lower rates of knee replacement over 5 years follow-up, although contradictory associations were observed in secondary analyses which likely reflected residual confounding by indication. Reassuringly, IACI use before knee replacement was not associated with post-operative adverse outcomes.

Cardinality matching versus propensity score matching for addressing cluster-level residual confounding in implantable medical device and surgical epidemiology: a parametric and plasmode simulation study

BACKGROUND

Rapid innovation and new regulations lead to an increased need for post-marketing surveillance of implantable devices. However, complex multi-level confounding related not only to patient-level but also to surgeon or hospital covariates hampers observational studies of risks and benefits. We conducted parametric and plasmode simulations to compare the performance of cardinality matching (CM) vs propensity score matching (PSM) to reduce confounding bias in the presence of cluster-level confounding.

METHODS

Two Monte Carlo simulation studies were carried out: 1) Parametric simulations (1,000 iterations) with patients nested in clusters (ratio 10:1, 50:1, 100:1, 200:1, 500:1) and sample size n = 10,000 were conducted with patient and cluster level confounders; 2) Plasmode simulations generated from a cohort of 9981 patients admitted for pancreatectomy between 2015 to 2019 from a US hospital database. CM with 0.1 standardised mean different constraint threshold (SMD) for confounders and PSM were used to balance the confounders for within-cluster and cross-cluster matching. Treatment effects were then estimated using logistic regression as the outcome model on the obtained matched sample.

RESULTS

CM yielded higher sample retention but more bias than PSM for cross-cluster matching in most scenarios. For instance, with ratio of 100:1, sample retention and relative bias were 97.1% and 26.5% for CM, compared to 82.5% and 12.2% for PSM. The results for plasmode simulation were similar.

CONCLUSIONS

CM offered better sample retention but higher bias in most scenarios compared to PSM. More research is needed to guide the use of CM particularly in constraint setting for confounders for medical device and surgical epidemiology.

[Evolving indications for partial knee replacement : New aspects]

BACKGROUND

Partial knee replacement has proven to be an effective therapy for advanced unicompartmental arthrosis of the knee. Despite continuous advancements in implants and surgical techniques over the past decades, the global preference for total knee arthroplasty still persists for historical reasons.

OBJECTIVES

This report aims to illuminate advantages and disadvantages of partial knee replacement considering long-term results, the evolution of indication criteria over recent decades and new aspects in patient selection with potential improvements through emerging technologies.

MATERIAL AND METHODS

The analysis involves the examination of long-term results from clinical studies and registry data, highlighting the risk factors for potential failures and their influence on the development of indication criteria.

RESULTS

Present-day long-term results demonstrate excellent prosthetic survival, aligning with outcomes from total knee arthroplasty. New perspectives for expanding indication criteria are discussed, including the possible application of partial knee replacement in cases of severe varus deformity > 15°, anterior cruciate ligament insufficiency, young active patients, anterior knee pain, and/or patellofemoral arthritis, as well as mild radiographic arthritis with degenerative medial meniscus root tear and meniscal extrusion.

DISCUSSION

Indication criteria have consistently expanded in recent years, taking into account modern insights, and the application of advanced technologies can enhance precision and minimize surgical errors. Furthermore, this report emphasizes that revision rates are not the sole criterion for success and underscores the necessity for a comprehensive examination of clinical results.

Editorial Comment on the Article by A.N. Tsed et al. “Total Knee Arthroplasty in Hemodialysis Patients: Routine or Complex Surgery?”

Severe comorbidities, like chronic kidney disease, strongly associated with higher risk of complications after total knee arthroplasty. Therefore hemodialysis patients need specific pre-operative as well as peri-operative management, including proper analgesic, antibacterial and thromboembolic pharmacological prophylaxis. Nevertheless the technical issues that surgeon has to solve in achieving proper leg alignment, knee stability and range of motion does not differ from other complex knee primary cases when revision implants and instruments are essential part of surgical requisite.

Short term outcomes following robotic arm-assisted lateral unicompartmental knee arthroplasty

Introduction

Robotic-arm assisted medial unicompartmental knee arthroplasty (RA-UKA) is associated with improved accuracy of implant positioning and excellent early functional outcomes. However, there is paucity of evidence regarding outcomes following RA-UKA for isolated lateral compartment osteoarthritis. The purpose of this study was to assess the short-term clinical and patient reported outcomes of lateral compartment UKA, utilising robotic-arm assistance.

Methods

This was a retrospective study of prospectively collected data of 21 consecutive patients who underwent lateral RA-UKA. The study included 9 (42.9%) males and 12 (57.1%) females with a mean age of 63.4 ± 9.2 years. The Oxford Knee Score (OKS) was measured pre-operatively and at 1-year post-operatively, while range of motion (ROM) and complications were also recorded.

Results

There was significant improvement of OKS at 1 year's follow up compared with the baseline score (21.8 ± 5.6 vs. 45.2 ± 2.8 respectively; p < 0.001). There was also an improvement in pre-operative ROM when compared to ROM at 1 year's follow up (123.5° ± 8° vs. 131.5° ± 6.3° respectively; p < 0.001). None of the study patients underwent revision surgery within 1 year's follow-up.

Conclusion

In our study, lateral RA-UKA resulted in significant improvements in clinical and patient reported outcomes with low complications rates. Further long-term comparative studies are needed to assess the utility of lateral RA-UKA vs. conventional UKA.

Reporting of Observational Studies Explicitly Aiming to Emulate Randomized Trials: A Systematic Review

Importance

Observational (nonexperimental) studies that aim to emulate a randomized trial (ie, the target trial) are increasingly informing medical and policy decision-making, but it is unclear how these studies are reported in the literature. Consistent reporting is essential for quality appraisal, evidence synthesis, and translation of evidence to policy and practice.

Objective

To assess the reporting of observational studies that explicitly aimed to emulate a target trial.

Evidence Review

We searched Medline, Embase, PsycINFO, and Web of Science for observational studies published between March 2012 and October 2022 that explicitly aimed to emulate a target trial of a health or medical intervention. Two reviewers double-screened and -extracted data on study characteristics, key predefined components of the target trial protocol and its emulation (eligibility criteria, treatment strategies, treatment assignment, outcome[s], follow-up, causal contrast[s], and analysis plan), and other items related to the target trial emulation.

Findings

A total of 200 studies that explicitly aimed to emulate a target trial were included. These studies included 26 subfields of medicine, and 168 (84%) were published from January 2020 to October 2022. The aim to emulate a target trial was explicit in 70 study titles (35%). Forty-three studies (22%) reported use of a published reporting guideline (eg, Strengthening the Reporting of Observational Studies in Epidemiology). Eighty-five studies (43%) did not describe all key items of how the target trial was emulated and 113 (57%) did not describe the protocol of the target trial and its emulation.

Conclusion and Relevance

In this systematic review of 200 studies that explicitly aimed to emulate a target trial, reporting of how the target trial was emulated was inconsistent. A reporting guideline for studies explicitly aiming to emulate a target trial may improve the reporting of the target trial protocols and other aspects of these emulation attempts.

Random effects modelling versus logistic regression for the inclusion of cluster-level covariates in propensity score estimation: A Monte Carlo simulation and registry cohort analysis

Purpose: Surgeon and hospital-related features, such as volume, can be associated with treatment choices and outcomes. Accounting for these covariates with propensity score (PS) analysis can be challenging due to the clustered nature of the data. We studied six different PS estimation strategies for clustered data using random effects modelling (REM) compared with logistic regression. Methods: Monte Carlo simulations were used to generate variable cluster-level confounding intensity [odds ratio (OR) = 1.01-2.5] and cluster size (20-1,000 patients per cluster). The following PS estimation strategies were compared: i) logistic regression omitting cluster-level confounders; ii) logistic regression including cluster-level confounders; iii) the same as ii) but including cross-level interactions; iv), v), and vi), similar to i), ii), and iii), respectively, but using REM instead of logistic regression. The same strategies were tested in a trial emulation of partial versus total knee replacement (TKR) surgery, where observational versus trial-based estimates were compared as a proxy for bias. Performance metrics included bias and mean square error (MSE). Results: In most simulated scenarios, logistic regression, including cluster-level confounders, led to the lowest bias and MSE, for example, with 50 clusters × 200 individuals and confounding intensity OR = 1.5, a relative bias of 10%, and MSE of 0.003 for (i) compared to 32% and 0.010 for (iv). The results from the trial emulation also gave similar trends. Conclusion: Logistic regression, including patient and surgeon-/hospital-level confounders, appears to be the preferred strategy for PS estimation.