Temporal Trends of Revision Etiologies in Total Knee Arthroplasty at a Single High-Volume Institution: An Epidemiological Analysis

Body Mass Index and Revision Total Knee Arthroplasty: Does Cause for Revision Vary by Underweight or Obese Status?

BACKGROUND

Body mass index (BMI) impacts risk for revision total knee arthroplasty (rTKA), but the relationship between BMI and cause for revision remains unclear. We hypothesized that patients in different BMI classes would have disparate risk for causes of rTKA.

METHODS

There were 171,856 patients who underwent rTKA from 2006 to 2020 from a national database. Patients were classified as underweight (BMI < 19), normal-weight, overweight/obese (BMI 25 to 39.9), or morbidly obese (BMI > 40). Multivariable logistic regressions adjusted for age, sex, race/ethnicity, socioeconomic status, payer status, hospital geographic setting, and comorbidities were used to examine the effect of BMI on risk for different rTKA causes.

RESULTS

Compared to normal-weight controls, underweight patients were 62% less likely to undergo revision due to aseptic loosening, 40% less likely due to mechanical complications, 187% more likely due to periprosthetic fracture, 135% more likely due to periprosthetic joint infection (PJI). Overweight/obese patients were 25% more likely to undergo revision due to aseptic loosening, 9% more likely due to mechanical complications, 17% less likely due to periprosthetic fracture, and 24% less likely due to PJI. Morbidly obese patients were 20% more likely to undergo revision due to aseptic loosening, 5% more likely due to mechanical complications, and 6% less likely due to PJI.

CONCLUSION

Mechanical reasons were more likely to be the cause of rTKA in overweight/obese and morbidly obese patients, compared to underweight patients, for whom revision was more likely to be infection or fracture related. Increased awareness of these differences may promote patient-specific management to reduce complications.

LEVEL OF EVIDENCE

III.

Patients Who Have Limited English Proficiency Have Decreased Utilization of Revision Surgeries After Hip and Knee Arthroplasty

BACKGROUND

While racial and ethnic disparities are well documented in access to total joint arthroplasty (TJA), little is known about the association between having limited English proficiency (LEP) and postoperative care access. This study seeks to correlate LEP status with rates of revision surgery after hip and knee arthroplasty.

METHODS

This was a retrospective cohort study of patients aged ≥ 18 years who underwent either total hip or total knee arthroplasty between January 2013 and December 2021 at a single academic medical center. The predictor variable was English proficiency status, where LEP was defined as having a primary language that was not English. Multivariable regressions controlling for potential demographic and clinical confounders were used to calculate adjusted odds ratios of undergoing revision surgery within 1 and 2 years after primary arthroplasty for patients who have LEP, compared to English proficient patients.

RESULTS

A total of 7,985 hip and knee arthroplasty surgeries were included in the analysis. There were 577 (7.2%) patients who were classified as having LEP. Patients who have LEP were less likely to undergo revision surgeries within 1 year (1.4% versus 3.2%, P = .01) and 2 years (1.7% versus 3.9%, P = .006) of primary TJA. Patients who have LEP had adjusted odds ratios of 0.45 (confidence interval: 0.22-0.92, P = .03) and 0.44 (confidence interval: 0.23-0.85, P = .01) of receiving revision surgery within 1 and 2 years, respectively.

CONCLUSION

Patients who have LEP, compared to English proficient patients, were less likely to undergo revision surgeries at the same institution up to 2 years after hip and knee arthroplasty. These findings suggest that patients who have LEP may face barriers in accessing postoperative care.

The Epidemiology of Revision Total Knee Arthroplasty

With an expected increase in total knee arthroplasty (TKA) procedures, revision TKA (rTKA) procedures continue to be a burden on the United States health care system. The evolution of surgical techniques and prosthetic designs has, however, provided a paradigm shift in the etiology of failure mechanisms of TKA. This review can shed light on the current reasons for revision, which may lead to insights on how to improve outcomes and lower future revision risks. We will primarily focus on the epidemiology of rTKA in the present time, but we will also review this in the context of various time periods to see how the field has evolved. We will review rTKAs: 1) prior to 1997; 2) between 1997 and 2000; 3) between 2000 and 2012; and 3) in the modern era since 2012. We will further subdivide each of the sections into reasons for early (first 2 years after index procedure) versus late revisions (greater than 2 years after index procedure). In doing so, it was determined that prior to 1997, the most prevalent causes of failure were infection, patella failure, polyethylene wear, and aseptic loosening. After a major shift of failure mechanisms was described by Sharkey et al, polyethylene wear and aseptic loosening became the leading causes for revision. However, with the improved manufacturing technology and implant design, polyethylene wear was replaced with aseptic loosening and infection as the leading causes of failure between 2000 and 2012. Since that time, in the modern era of TKA, mechanical loosening and infection have taken over the most prevalent causes for failure. Hopefully, with continued developments in component design and surgical techniques, as well as increased focus on infection reduction methods, the amount of rTKA procedures will decline.