THE INFLUENCE OF FEMORAL FIXATION ON MORTALITY AND REVISION FOLLOWING ELECTIVE AND NON-ELECTIVE HIP ARTHROPLASTY IN PATIENTS > 65 YEARS OF AGE. A MATCHED COHORT ANALYSIS FROM THE AMERICAN JOINT REPLACEMENT REGISTRY (AJRR)

Introduction

In the United States, cementless femoral fixation remains the dominant mode of fixation for femoral neck fractures, despite strong worldwide registry data that supports cemented fixation. The reason for this discrepancy remains unknown, controversial and often difficult to compare due to multiple variables. The purpose of this study was to evaluate a matched cohort of patients undergoing arthroplasty for femoral neck fractures and assess outcomes of revisions, periprosthetic fractures and mortality.

Methods

This is an exact matched cohort study. Cemented fixation cases were exact matched to cementless fixation cases in a 1:1 fashion based on age, sex and Charlson Comorbidity Index (CCI). Outcome variables included: revision for periprosthetic fracture; all cause revision and mortality at any time point; all cause revision and mortality within 1-year and within 90-days. The primary independent variable was femoral fixation (cemented, cementless) and covariates included race (black, white, other), ethnicity (hispanic, non-hispanic), teaching status (minor, major, nonteaching) and bedsize (1–99, 100–399, >=400). Chi-square tests and multivariable logistic regression models were used for statistical analysis.

Results

A total of 64,283 femoral neck fractures were evaluated. 17,138 cementless femoral stems were matched exactly to cemented femoral stems based on age, gender and Charleston comorbidity index (CCI). In the multivariate logistic regression analysis, compared to cementless femoral fixation, cemented fixation was associated with a 20% reduction in overall revision (OR 0.796, 0.675–0.939), a 30% reduction in revision at 1 year (OR: 0.709, 0.589–0.854) and a 86% reduction in revision for periprosthetic fracture (OR: 0.144, 0.07–0.294). However, cemented stem fixation was associated with a 23% (OR: 1.33, 1.134–1.338) and 16% (OR: 1.232, 1.134–1.338) increase in mortality at 90 days and 1 year post op respectively.

Conclusions

In this exact matched cohort study, risk of early revision and revision for PPFx was dramatically reduced at all time points with the use of cemented stem fixation for elective THA and FNF.

However, the increased risk of 90d and 1 year mortality following cemented stem fixation in the elective population warrants further investigation.