Trends in Utilization of Total Hip Arthroplasty for Femoral Neck Fractures in the United States

All patients admitted with a primary diagnosis of closed transcervical fracture of the femoral neck (ICD-9-CM 820.0x) were selected. This resulted in 1,674,160 fractures. All patients with fractures with a concurrent primary procedural code of ORIF (79.35), HA (81.52), or THA (81.51) were identified, resulting in a total sample size of 1,155,960 surgical fractures. Analysis of the fractures based on additional specificity,ie subcapital versus midcervical versus basicervical, was not carried out because >90% of femoral neck fractures in the database were coded as “unspecified” or “other” (ICD9 CM 820.00 and 820.09, respectively).

Comorbidity burden was quantified using Elixhauser coding algorithms as previously described.³¹ The Elixhauser comorbidity measure is a model consisting of 31 conditions and has recently been identified as a better predictor of mortality in patients undergoing orthopedic procedures when compared with the Charlson Comorbidity Index.³¹ Dichotomous variables for each Elixhauser comorbidity were created, and χ² tests were utilized to assess the association between each comorbidity and mortality. The weighted Elixhauser score for each statistically significant comorbidity was calculated as described by van Walraven and colleagues.³² The Elixhauser comorbidity score was then calculated for each patient by summing the individual weights of all comorbidities. Postoperative adverse events were determined using the complication-screening-package as previously described.³³

All adverse events were categorized into 3 categories, including general medical complications, mechanical complications, and surgical complications. All adverse events recorded in the NHDS database are events that occurred during a single hospitalization. Therefore, it does not take into account adverse events that occurred after discharge, and, for example, mortality refers to postoperative mortality that occurs prior to discharge. The study period comprised data captured from 1990 to 2007, and 3 groups were generated from this time period to better characterize patients throughout the large study time frame. Group 1 comprised patients who underwent surgical management of femoral neck fractures from 1990 to 1995, group 2 consisted of patients treated from 1996 to 2001, and group 3 included patients treated from 2002 to 2007.

Categorical data were analyzed using the χ² test, and continuous data were analyzed by the independent-samples t test and ANOVA. Multivariable binary logistic regression analyses were performed to assess the contributions of individual comorbidities to mortality, adverse events, and nonroutine discharge. Elixhauser comorbidities with a P value of < .10 in the bivariate analysis and presenting in at least 0.2% of the population were included in the logistic regression.³¹ Odds ratios and confidence intervals were calculated to assess the association between comorbidities and our dichotomous variables. A P value of < .001 defined statistical significance.³³ Statistical analysis was conducted using SPSS version 21 (IBM).

RESULTS

Patient Demographics
Our query demonstrated a total of 1,155,960 patients who underwent surgical fixation of femoral neck fractures (Table 1). The most commonly used treatment modality was HA (75%), followed by ORIF (18%) and later by THA (7%). The majority of patients were females in each treatment group. Patients’ age varied according to treatment group, with patients undergoing HA having a mean age of 81.0 ± 9.0 years, patients undergoing ORIF having a mean age of 75.0 ± 17.0 years, and those undergoing THA having a mean age of 79.0 ± 10.0 years (P < .001). The majority of patients were ≥80 years in all treatment groups, but the ORIF group had the greatest proportion of patients <65 years (P < .001). Among patients undergoing HA, 62.4% were ≥80 years, while the ORIF and HA groups consisted of 48.6% and 51.5% of patients in that same age group, respectively.

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