In-Hospital Outcomes of Hip Arthroplasty for Femoral Neck Fractures in Young Adult Patients: A Nationwide Study.

Introduction: Femoral neck fractures (FNFs) in young adults are relatively uncommon but pose significant clinical and surgical challenges. Hip arthroplasty is rarely used as a treatment option in this population but has seen rising use over the previous decade. This study seeks to compare hip arthroplasty outcomes among young adult patients in the United States admitted with FNF by evaluating hip hemiarthroplasty (HHA) and total hip arthroplasty (THA). Materials and Methods: Using the National Inpatient Sample (NIS) data, adult patients less than 50 years old who underwent HHA or THA from 2016 to 2020 were analyzed. Both groups' postoperative length of stay (pLOS), total hospital charges, and prosthesis-related complications (PRCs), including mechanical loosening (ML), prosthesis dislocation (PD), and periprosthetic fracture (PPF), were analyzed and compared. Results: Out of 174,776,205 hospitalizations between 2016 and 2020, 15,590 young adult patients had FNF, and 2970 patients (2.18%) underwent hip arthroplasty (1195 HHAs and 1775 THAs). After controlling for demographic, clinical and hospital characteristics, HHA was associated with a 22.4% longer pLOS compared to THA [rate ratio: 1.224, 95% CI: 1.183 to 1.266; p < 0.001]. Patients in the HHA group also had higher odds of PPF (aOR: 9.06, 95% CI: 4.21, 19.48; p < 0.001). Conversely, patients in the THA group had higher odds of PD (aOR: 6.00, 95% CI: 1.78, 20.24; p=0.004). There was no statistically significant difference in total hospital charges between the groups [cost ratio: 1.03, 95% CI: 0.995 to 1.075; p=0.092]. Conclusion: Among young adults with FNF undergoing hip arthroplasty, HHA is associated with a longer postoperative hospital stay and higher risk of PPF as a major early complication, while THA is associated with a higher risk of PD. Financial burden is comparable for both procedure groups. When hip arthroplasty is a preferred treatment for FNFs, individual patient factors are important considerations that should guide the choice of procedure.