Stemmed Versus Nonstemmed Tibia in Primary Total Knee Arthroplasty: A Similar Pattern of Aseptic Tibial Loosening in Obese Patients with Moderate Varus. 5-Year Outcomes of a Randomized Controlled Trial

Causative factors for varus tibial baseplate subsidence in primary total knee arthroplasty: A retrospective analysis

Background

In this retrospective study, the focus was on identifying potential causative factors associated with varus subsidence of the tibial component in primary total knee arthroplasty (TKA). The research aimed to investigate the risk factors contributing to aseptic varus tibial baseplate subsidence (VTBS) leading to revision TKA procedures.

Patients and methods

A total of 120 patients with documented VTBS complications post-TKA were compared with a control group of 52 patients. Factors such as patient demographics, surgical data and comorbidities were included. The study also explored the Coronal Plane Alignment of the Knee (CPAK) classification pre- and post-operatively to understand its implications on varus subsidence.

Results

Significant differences noted in the VTBS group in variables including younger patient age (P=<0.001), increased BMI (P = 0.003), larger proportion of patients with tibial component oversize or undersizing (P=<0.001), less tibial stem extensions used (P < 0.001), higher CCI (P < 0.001) and a higher proportion of patients in CPAK group 2 (P = 0.044).

Conclusion

This investigation provides valuable insights into potential risk factors for VTBS, aiming to optimize patient outcomes and assist in preventing complications associated with TKA procedures.

Does the Addition of a Tibial Stem Extender in Total Knee Arthroplasty Decrease Risk of Aseptic Loosening in Patients with Obesity? An Analysis from the American Joint Replacement Registry

Mechanical loosening is a leading cause of failure of total knee arthroplasties (TKAs) for which obesity may be a risk factor. With rising rates of obesity and increasing incidence of TKA, the identification of factors to mitigate this cause of failure is necessary. The purpose of this study is to determine if the use of a tibial stem extender (TSE) decreases the risk of mechanical loosening in patients with obesity undergoing TKA. The American Joint Replacement Registry and linked Centers for Medicare & Medicaid Services claims database were utilized to identify a patient cohort with a body mass index (BMI) of 30 kg/m2 or greater and age 65 years or older who underwent primary elective TKA between 2012 and 2021. Patients were divided into cohorts based on obesity class and TSE utilization. The estimated association of TSE use, BMI categories, and covariates with the risk of revisions for mechanical loosening in both unadjusted and adjusted settings was determined. Hazard ratios and their 95% confidence intervals for the risk of mechanical loosening were calculated. A total of 258,775 TKA cases were identified. A total of 538 of 257,194 (0.21%) patients who did not receive a TSE and one patient out of 1,581 (0.06%) with a TSE were revised for mechanical loosening. In adjusted analysis, TSE use was not protective against mechanical loosening and BMI > 40 was not a significant risk factor. Use of a TSE was not found to be protective against mechanical loosening in patients with obesity; however, analysis was limited by the small number of outcome events in the cohort. Further analysis with a larger cohort of patients with TSE and a longer follow-up time is necessary to corroborate this finding.

Tibial stem extension versus standard configuration in primary cemented total knee arthroplasty: systematic review and meta-analysis

BACKGROUND

In order to increase the stability of tibial component in total knee arthroplasty (TKA), intramedullary stem extensions (SE) have been developed. The aim of this systematic review and meta-analysis is to address the critical knowledge gap on post-operative outcomes and complications rate comparison between tibial component with SE compared to the tibial component standard configuration (SC) in primary cemented TKA.

METHODS

We conducted a comprehensive search of online databases, including Pubmed, Embase, ISI Web of science, Cochrane Library, and Scopus, using the following MeSH terms, (total knee arthroplasty) OR (TKA) OR (total knee replacement) AND (Tibial stem) OR (stem extension) OR (long stem). We included clinical studies that compared the tibial SE with no tibial stem (standard configuration) in primary cemented TKA. The important exclusion criteria were studies on revision (secondary) TKA, un-cemented arthroplasty, high level constrained implants, TKA with tibial augment & tibial bone graft, TKA with femoral stems, studies on short tibial keel (shorter than SC), without any tibial keel, studies with less than 12 months of follow-up. Knee Society Score (KSS) functional and clinical scores were considered as clinical outcomes along with tibial loosening and implant survival rate. The retrieved studies were assessed for methodological quality using Cochrane Collaborations tool for assessing the risk of bias in randomized trials (ROB) and Cochrane Risk of Bias in Non-Randomized Studies-of Interventions (ROBINS-I) tools. Weighted mean difference (WMD) with 95% confidence interval (CI) was calculated using random-effects meta-analysis taking into account for heterogeneity.

RESULTS

A total of 223,743 patients (223,766 knees) from 15 articles were included. The risk of tibial aseptic loosening is 54% lower on average in SE group in comparison with SC group (RR: 0.46; 95% CI: 0.29 to 0.74), which is more notable among obese class I patients (RR: 0.47; 95% CI: 0.28 to 0.78), but not significantly different among obese class II patients (RR: 0.58; 95% CI: 0.19 to 1.78). KSS functional and clinical score increased 3.85 score (95% CI: 1.52 to 6.18), and 1,24 scores (95% CI: - 0.22 to 2.70) among patients in SE group, respectively. The survival rate was 1.04 times greater in the SE group. There was no notable difference in terms of knee deformity (hip-knee-ankle angle) correction, all cause secondary procedure, and complications rate between the two groups.

CONCLUSION

The meta-analysis of post-operative functional scores and tibial loosening rate indicates a preference for tibial SE over the SC in primary cemented TKA. Some studies were rated as having a fair to critical risk of bias during the quality assessment. To strengthen the evidence and improve the applicability of our findings in clinical practice, future high-quality studies are required.

Current Evidence Does Not Support the Use of Tibial Stem Extension in Total Knee Arthroplasty of Obese Patients: A Systematic Review

BACKGROUND

Obesity rates have been increasing globally, leading to a higher incidence of knee osteoarthritis and a surge in primary and revision total knee arthroplasty (TKA). The debate continues on the impact of obesity on TKA success, particularly regarding the use of stemmed tibial components in obese patients. This systematic review aimed to compare the effectiveness of stemmed tibial components versus standard keeled tibial components in obese patients undergoing TKA.

METHODS

A systematic review was conducted using databases including PubMed, Embase, Scopus, and Web of Science from inception to December 2023. The eligibility criteria were Participants: Patients who have obesity undergoing TKA; Intervention: stemmed TKA; Comparator: standard keeled tibial TKA; Outcomes: aseptic loosening, patient-reported outcome measures (PROMs), and overall revision. Data extraction and quality assessment were performed using the Newcastle-Ottawa Scale for cohort studies and the Cochrane risk-of-bias tool for randomized trials.

RESULTS

The search yielded 470 studies, with 10 studies (42,533 knees) meeting the inclusion criteria. These studies included 3 randomized controlled trials and 7 retrospective cohorts. The primary outcomes measured were aseptic loosening and overall revision rates, while secondary outcomes included PROMs. Results indicated mixed findings, with some studies suggesting improved outcomes with stemmed components in cases of aseptic loosening and mechanical failure, while others showed no significant difference. The PROMs did not show a significant difference between groups post-TKA. The certainty of the evidence was graded as "very low" using the Grading of Recommendations, Assessment, Development, and Evaluations framework.

CONCLUSIONS

Current literature does not provide conclusive evidence to support the routine use of stemmed tibial components in TKA for obese patients. The decision to use stem extensions should not solely rely on the patient's obesity status. Further high-quality studies are needed to clarify the role of stemmed components in TKA for this patient population.

LEVEL OF EVIDENCE

III.

Systematic Review of Tibial Stems in Primary Total Knee Arthroplasty

Tibial stems are increasingly used in primary total knee arthroplasty (TKA) to enhance stability and reduce component load, particularly in complex cases involving obesity, severe deformity, bone loss, and inflammatory arthritis. However, limited literature exists on their indications, outcomes, and complications. This study systematically reviews the indications for tibial stems in primary TKA, the types of stems used, and their associated outcomes, including revision rates and complications. A systematic review, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was conducted using PubMed, Embase, and Cochrane databases up to January 2024. Studies comparing stemmed and non-stemmed tibial baseplates, as well as those not comparing with non-stemmed tibial baseplates, were included. Abstracts, commentaries, and case reports were excluded. Twenty-three studies, comprising 2,073 tibial stems (30-145 mm), met the inclusion criteria. The primary indication for tibial stems was in obese patients, with variable body mass index (BMI) thresholds. The use of tibial stems, particularly short cemented stems, demonstrated favorable outcomes in complex primary TKA, including reduced rates of aseptic loosening and improved functional scores. In cases of severe varus deformity and osteoarthritis with associated tibial stress or plateau fractures, tibial stems were effective in reducing complications and improving implant stability. Short cemented tibial stems benefit complex primary TKA, especially in obese patients and those with severe deformities, preserving bone stock, optimizing load transmission, and minimizing complications. Further research is needed to establish standardized guidelines for optimal tibial stem use in primary TKA.

Comprehensive evaluation of risk factors for aseptic loosening in cemented total knee arthroplasty: A systematic review and meta-analysis

Purpose

Aseptic loosening is the most common cause for revisions after total knee arthroplasty (TKA). Despite many studies exploring various risk factors associated with aseptic loosening, findings often present inconsistencies. To address this, we conducted a thorough review of the literature to identify and analyse these risk factors in cemented TKA. Additionally, we performed a meta-analysis to reconcile the divergent conclusions observed across studies.

Methods

We searched PubMed, Web of Science and Embase from 1996 up to 2024 and evaluated the quality of the included literature. Seventy-four studies were included to assess the association of BMI, diabetes, high physical activity (HPA), osteoporosis, rheumatoid arthritis (RA), cement material and implant design. Twenty-nine studies were used to calculate relative risk and CIs (using the random effects theory) and study heterogeneity for six different risk factors (BMI, diabetes, HPA level, cement material, polyethylene and implant design).

Results

Patients with diabetes are eight times more likely to experience aseptic loosening compared to those without diabetes (RR = 9.18, 95% CI: 1.80-46.77, p < 0.01). The use of tibial stem extension or highly crosslinked polyethylene can help reduce the incidence of aseptic loosening. However, we did not identify BMI, HPA, osteoporosis, RA, the use of high-viscosity cement and the utilization of mobile-bearing designs as risk factors for aseptic loosening post-cemented TKA.

Conclusions

Patients with diabetes undergoing TKA should be counselled regarding their potential increased risk of aseptic loosening. The use of tibial stem extensions and HXLPE can mitigate the incidence of aseptic loosening in cemented TKA. However, given a limited number of studies were included in the meta-analysis, we believe that higher-level studies are necessary to clearly identify other risk factors.

Level of Evidence

Level III.

Does the use of tibial stem extensions reduce the risk of aseptic loosening in obese patients undergoing primary total knee arthroplasty: A systematic review and meta-analysis

BACKGROUND

This study aimed to compare the risk of revision for aseptic loosening in obese (body mass index >30 kg/m2) patients with stemmed (ST) versus non-stemmed (NST) tibial implants in primary total knee arthroplasty (TKA).

METHODS

A systematic review and meta-analysis were conducted following PRISMA and MOOSE guidelines. Studies reporting a direct comparison between ST and NST tibial implants in obese patients were included. The primary outcome of interest was revision for aseptic loosening. Outcomes were analysed using meta-analysis of relative risk. Risk of bias assessment was performed using the Newcastle-Ottawa Scale for observational studies and the RoB-2 Cochrane tool for randomised studies.

RESULTS

Seven studies met the selection criteria, consisting of four cohort studies and three randomised controlled trials. Mean follow up time for the eligible cohort was 62.6 months. Meta-analysis demonstrated a statistically significant reduction in the risk of aseptic revision in the ST group compared with the NST group (risk ratio 0.25, 95% confidence interval 0.07 to 0.92). After removal of all zero-event studies, the results remained in favour of the ST group (risk ratio 0.15, 95% confidence interval 0.03 to 0.64).

CONCLUSIONS

This study found that obese patients undergoing TKA with stemmed tibial implants may have a lower risk of aseptic revision compared with those with non-stemmed tibial implants. However, due to the lack of high-quality literature available, our study is unable to draw a definitive conclusion on this matter. We suggest that this topic should be re-evaluated using higher-quality study methods, particularly national joint registries studies and randomised controlled trials.

Comparison of bilateral cementless total knee arthroplasty results between patients in different BMI groups

INTRODUCTION

The aim of this study was to compare the results of cementless bilateral total knee arthroplasty (TKA) between individuals in different obesity groups.

MATERIALS AND METHODS

This was a retrospective cohort study. Patients with a body mass index (BMI) greater than 25 who underwent bilateral TKA for gonarthrosis between 2014 and 2020 and completed a minimum follow-up of 24 months were included. Age, sex, height, weight, BMI, operation time, length of stay, patient satisfaction, knee scores and complications were compared. Patients with missing data, who were followed for less than 24 months or had postoperative fractures around the knee were excluded.

RESULTS

There was a significant difference between the groups in terms of operation time (Class III > overweight > Class II > Class I p < 0.001). There was a significant difference in complications between the groups (Class III > Class I > Class II > overweight p = 0.010). According to our pairwise comparison, complications were more common in the class III group than in the overweight group. Knee score (KS) and function score (FS) increased significantly after surgery in all groups (p < 0.001), with no difference in FS (p = 0.448). Knee score changes were greater in the overweight and class I groups (p < 0.001). There was a significant interaction between both KS and FS and person satisfaction (p < 0.001).

CONCLUSION

Cementless TKA improved KS and FS in all obesity groups, yielded high patient satisfaction. Although the incidence of complications was higher in the morbidly obese patients than in the overweight patients, the difference was not significant. Patients with morbid obesity should be informed about related risks before planning cementless TKA.