Outcomes After Revision Total Knee Arthroplasty from a Specific, Now-recalled Implant System

Effects of elevated body mass index on the success of total knee and total hip arthroplasty: a comprehensive overview

INTRODUCTION

The average body mass index (BMI) in the United States has tripled over the last five decades despite concerted population-based efforts for weight management. Elevated BMI and, in particular, obesity are risk factors for osteoarthritis. This trend has led to increased demands for total knee (TKA) and total hip arthroplasty (THA), necessitating an in-depth understanding of how elevated BMI impacts TKA and THA.

AREAS COVERED

This paper reviews the literature investigating the effects of elevated BMI, primarily obesity, on TKA and THA, focusing on preoperative, intraoperative, and postoperative considerations. It describes the associated risks, economic implications, and ethical considerations of patients with high BMIs undergoing TKA or THA. To ensure all relevant literature was included, Ovid Medline and Google Scholar databases were searched for the following terms, 'body mass index,' 'obesity,' 'knee,' 'hip,' and 'arthroplasty' for articles published from January 2019 through July 2024.

EXPERT OPINION

Despite the challenges of high BMI in TKA and THA, a deeper understanding of obesity as a chronic illness, coupled with advances in surgical techniques, can improve patient outcomes. A multidisciplinary approach and further research will optimize the care of patients with elevated BMIs undergoing total joint arthroplasty (TJA).

Femoral Component Debonding Frequently Missed on Advanced Imaging Prior to Revision of a Recalled Total Knee Arthroplasty

BACKGROUND

Identification of femoral component debonding in the work-up of painful total knee arthroplasty (TKA) often poses a diagnostic challenge. The purpose of this study was to compare the sensitivity and specificity of radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) for identifying femoral component loosening with debonding at the time of revision of a primary TKA with a recalled polyethylene insert.

METHODS

Using an institutional database, we identified all cases of revision TKA performed for this specific implant recall following a primary TKA between 2014 and 2022. Patients who had a preoperative radiograph, CT, and MRI were included (n = 77). Sensitivity, specificity, and positive and negative likelihood ratio (LR) for predicting loosening were compared among the imaging modalities, using the intraoperative evidence of implant loosening as the gold standard.

RESULTS

At the time of revision surgery, the femoral component was noted to have aseptic loosening with debonding in 46 of the 77 (60%) of the TKAs. There were no significant differences in demographics in the cohort with femoral debonding compared to those with well-fixed implants. The CT demonstrated a sensitivity of 28% and a specificity of 97%, while the MRI demonstrated a sensitivity of 37% and a specificity of 94% for detecting femoral loosening due to debonding. Both CT and MRI demonstrated poor negative LRs for femoral loosening (LR 0.7).

CONCLUSIONS

In this series of revision TKAs for a specific recalled component, neither CT nor MRI accurately diagnosed femoral component debonding. For patients who have this implant, it is imperative to interrogate the implant-cement interface intraoperatively and prepare for full revision surgery as well as marked bone loss secondary to osteolysis.

Mechanical complications after total knee arthroplasty

INTRODUCTION

With the increasing demand for total knee arthroplasty (TKA) and the burden of revision TKA on the healthcare system, as well as the quality of life implications for patients, it is extremely important for surgeons to be able to anticipate and prevent TKA mechanical complications. Surgeons must be familiar with the different causes and mechanisms of TKA complications so that they can properly treat patients with failed TKAs and better avoid these complications.

AREAS COVERED

This review addresses TKA mechanical complications and provides context for the topic. A detailed review of surgical factors, implant factors, and patient factors that contribute to mechanical complications after TKA is provided. All of the literature cited in this review was gathered from the PubMed online database using different keywords based on the section of the manuscript.

EXPERT OPINION

As surgeons and engineers solve certain issues in TKA, new challenges will inevitably arise. We must continue to push forward and innovate from both a surgical technique and implant design perspective.