Cemented Femoral Fixation in Total Hip Arthroplasty Reduces the Risk of Periprosthetic Femur Fracture in Patients 65 Years and Older: An Analysis From the American Joint Replacement Registry.

BACKGROUND: Periprosthetic femur fracture (PPFx) is a devastating complication after total hip arthroplasty (THA). Despite concerns for increased PPFx, cementless fixation predominates in the United States. This study used the American Joint Replacement Registry to compare PPFx risk between cemented and cementless femoral fixation for THA. METHODS: An analysis of primary THA cases in patients aged 65 years and more was performed with the American Joint Replacement Registry data linked to Centers for Medicare and Medicaid Services data from 2012 to 2020. Analyses compared cemented to cementless femoral fixation. We identified 279,052 primary THAs, 266,040 (95.3%) with cementless and 13,012 (4.7%) with cemented femoral fixation. Cox proportional hazard regression analyses evaluated the association of fixation and PPFx risk, while adjusting for sex, age, and competing risk of mortality. Cumulative incidence function survival curves evaluated time to PPFx. RESULTS: Age ≥ 80 years (P < .0001) and women (P < .0001) were associated with PPFx. Compared to cemented stems, cementless stems had an elevated risk of PPFx (Hazards Ratio 7.70, 95% Confidence interval 3.2-18.6, P < .0001). The cumulative incidence function curves demonstrated an increased risk for PPFx across all time points for cementless stems, with equal magnitude of risk to 8 years.` CONCLUSION: Cementless femoral fixation in THA continues to predominate in the United States, with cementless femoral fixation demonstrating increased risk of PPFx in patients aged 65 years or more. Surgeons should consider greater use of cemented femoral fixation in this population to decrease the risk of PPFx.

The James A. Rand Young Investigator's Award: Increased Revision Risk With Mobile Bearings in Total Knee Arthroplasty: An Analysis of the American Joint Replacement Registry.

BACKGROUND: Mobile-bearing (MB) total knee arthroplasty (TKA) may reduce wear and improve patellar tracking but may increase revision risk due to tibial component design, balance complexity, and bearing dislocation. We utilized the American Joint Replacement Registry to examine risk of revision with MB compared to fixed-bearing (FB) designs. METHODS: An analysis of primary TKA in patients over 65 years was performed with American Joint Replacement Registry data linked to Centers for Medicare and Medicaid Services data from 2012 to 2019. Analyses compared MB to FB designs with a subanalysis of implants from a single company. We identified 485,024 TKAs, with 452,199 (93.2%) FB-TKAs and 32,825 (6.8%) MB-TKAs. Cox proportional hazards regression modeling was used for all-cause revision and revision for infection, adjusting for sex, age, and competing risk of mortality. Event-free survival curves evaluated time to all-cause revision and revision for infection. RESULTS: MB-TKAs were at an increased risk for all-cause revision: hazard ratio (HR) 1.36 ([95% confidence interval (CI) 1.24-1.49], P < .0001) but not revision for infection: HR 1.06 ([95% CI 0.90-1.25], P = .52). When comparing implants within a single company, MB-TKAs were at an increased risk of all-cause revision: HR 1.55 ([95% CI 1.38-1.73], P < .0001). Event-free survival curves demonstrated increased risk for all-cause revision for MB-TKA across all time points, with a greater magnitude of risk up to 8 years. CONCLUSION: Although survivorship of both designs was outstanding, MB-TKA designs demonstrated increased risk for all-cause revision. Additional investigation is needed to determine if this is related to patient selection factors, surgical technique, bearing, or implant design.

Effects of Hospital and Surgeon Volume on Patient Outcomes After Total Joint Arthroplasty: Reported From the American Joint Replacement Registry.

BACKGROUND: The purpose of this study was to evaluate outcomes and complications because it relates to surgeon and hospital volume for patients undergoing primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) using the American Joint Replacement Registry from 2012 to 2017. METHODS: A retrospective study was conducted on Medicare-eligible cases of primary elective THAs and TKAs reported to the American Joint Replacement Registry database and was linked with the available Centers of Medicaid and Medicare Services claims and the National Death Index data from 2012 to 2017. Surgeon and hospital volume were defined separately based on the median annual number of anatomic-specific total arthroplasty procedures performed on patients of any age per surgeon and per hospital. Values were aggregated into separate surgeon and hospital volume tertile groupings and combined to create pairwise comparison surgeon/hospital volume groupings for hip and knee. RESULTS: Adjusted multivariable logistic regression analysis found low surgeon/low hospital volume to have the greatest association with all-cause revisions after THA (odds ratio [OR], 1.63, 95% confidence interval [CI], 1.41-1.89, P < 0.0001) and TKA (OR, 1.72, 95% CI, 1.44-2.06, P < 0.0001), early revisions because of periprosthetic joint infection after THA (OR, 2.50, 95% CI, 1.53-3.15, P < 0.0001) and TKA (OR, 2.18, 95% CI, 1.64-2.89, P < 0.0001), risk of early THA instability and dislocation (OR, 2.47, 95% CI, 1.77-3.46, P < 0.0001), and 90-day mortality after THA (OR, 1.72, 95% CI, 1.27-2.35, P = 0.0005) and TKA (OR, 1.47, 95% CI, 1.15-1.86, P = 0.002). CONCLUSION: Our findings demonstrate considerably greater THA and TKA complications when performed at low-volume hospitals by low-volume surgeons. Given the data from previous literature including this study, a continued push through healthcare policies and healthcare systems is warranted to direct THA and TKA procedures to high-volume centers by high-volume surgeons because of the evident decrease in complications and considerable costs associated with all-cause revisions, periprosthetic joint infection, instability, and 90-day mortality. LEVEL OF EVIDENCE: III.

Modular Metal-Backed Tibial Components Provide Minimal Mid-Term Survivorship Benefits Despite Increased Cost and Frequency of Use: A Retrospective Review of the American Joint Replacement Registry Database.

BACKGROUND: Previous studies have demonstrated equivalent survivorship of modular metal-backed tibial (MBT) and all-polyethylene tibial (APT) components. The purpose of this study is to compare the utilization and outcomes of APT and MBT components in a large US database. METHODS: The American Joint Replacement Registry was queried to identify all patients undergoing primary total knee arthroplasty (TKA) during the study period from 2012 to 2019. These patients were divided into cohorts based on tibial component (APT or MBT). Cohort demographics including gender, hospital size, hospital teaching status, region, age, and Charlson Comorbidity Index were reported with descriptive statistics. Overall reoperation rates and revisions for infection, aseptic loosening, periprosthetic fracture, manipulation under anesthesia, and revision for other reasons were identified using International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes and compared across APT and MBT cohorts. Kaplan-Meir survival analysis was performed based on reason for reoperation for APT and MBT. RESULTS: During the study period, 703,007 TKAs were reported with 97.8% utilizing MBT and 2.2% utilizing APT components. Despite the introduction of alternative payment models during the study period, the utilization of APT decreased from 5.8% in 2012 to 1.7% in 2019. The survival of APT and MBT TKAs were similar across the study period: 98.1% vs 98.6% at 8 years. The rate of reoperation for all-causes was higher for APT compared to MBT (1.36% vs 1.00%; odds ratio 1.52). CONCLUSION: Despite their paucity of use and lower cost APT remained within a 0.4% margin of survivorship when compared to MBT implants for up to 8 years. LEVEL OF EVIDENCE: Level III, retrospective.

Cementless Fixation Is Associated With Increased Risk of Early and All-Time Revision After Hemiarthroplasty But Not After THA for Femoral Neck Fracture: Results From the American Joint Replacement Registry.

BACKGROUND: Despite ample evidence supporting cemented femoral fixation for both hemiarthroplasty and THA for surgical treatment of displaced femoral neck fractures, cementless fixation is the preferred fixation method in the United States. To our knowledge, no nationally representative registry from the United States has compared revision rates by fixation for this surgical treatment. QUESTION/PURPOSE: After controlling for relevant confounding variables, is femoral fixation method (cemented or cementless) in hemiarthroplasty or THA for femoral neck fracture associated with a greater risk of (1) all-cause revision or (2) revision for periprosthetic fracture? METHODS: Patients with Medicare insurance who had femoral neck fractures treated with hemiarthroplasty or THA reported in the American Joint Replacement Registry database from 2012 to 2017 and Centers for Medicare and Medicaid Services claims data from 2012 to 2017 were analyzed in this retrospective, large-database study. Of the 37,201 hemiarthroplasties, 42% (15,748) used cemented fixation and 58% (21,453) used cementless fixation. Of the 7732 THAs, 20% (1511) used cemented stem fixation and 80% (6221) used cementless stem fixation. For both the hemiarthroplasty and THA cohorts, most patients were women and had cementless femoral fixation. Early revision was defined as a procedure that occurred less than 90 days from the index procedure. All patients submitted to the registry were included in the analysis. Patient follow-up was limited to the study period. No patients were lost to follow-up. Due to inherent limitations with the registry, we did not compare medical complications, including deaths attributed directly to cemented fixation. A logistic regression model including the index arthroplasty, age, gender, stem fixation method, hospital size, hospital teaching affiliation, and Charlson comorbidity index score was used to determine associations between the index procedure and revision rates. RESULTS: For the hemiarthroplasty cohort, risk factors for any revision were cementless stem fixation (odds ratio 1.42 [95% confidence interval 1.20 to 1.68]; p < 0.001), younger age (OR 0.96 [95% CI 0.95 to 0.97]; p < 0.001), and higher Charlson comorbidity index (OR 1.06 [95% CI 1.02 to 1.11]; p = 0.004). Risk factors for early revision were cementless stem fixation (OR 1.77 [95% CI 1.43 to 2.20]; p < 0.001), younger age (OR 0.98 [95% CI 0.97 to 0.99]; p < 0.001), and higher Charlson comorbidity index (OR 1.09 [95% CI 1.04 to 1.15]; p < 0.001). Risk factors for revision due to periprosthetic fracture were cementless fixation (OR 6.19 [95% CI 3.08 to 12.42]; p < 0.001) and higher Charlson comorbidity index (OR 1.16 [95% CI 1.06 to 1.28]; p = 0.002). Risk factors for early revision due to periprosthetic fracture were cementless fixation (OR 7.38 [95% CI 3.17 to 17.17]; p < 0.001), major teaching hospital (OR 2.10 [95% CI 1.08 to 4.10]; p = 0.03), and higher Charlson comorbidity index (OR 1.20 [95% CI 1.09 to 1.33]; p < 0.001). For the THA cohort, there were no associations. CONCLUSION: These data suggest that cemented fixation should be the preferred technique for most patients with displaced femoral neck fractures treated with hemiarthroplasty. The fact that stem fixation method did not affect revision rates for those patients with displaced femoral neck fractures treated with THA may be due to current practice patterns in the United States. LEVEL OF EVIDENCE: Level III, therapeutic study.