Clinical characteristics etiologies outcomes and complications of total knee arthroplasty in patients aged 18 to 54 years a nationwide inpatient sample analysis

Abstract

Total knee arthroplasty (TKA) is increasingly being performed in younger adults, although most published data have focused on older populations. This study aimed to describe the clinical characteristics, etiologies, and inpatient outcomes of TKA in patients aged 18–54 years using a large national database. We performed a retrospective descriptive analysis of TKA hospitalizations in patients aged 18–54 years using the Nationwide Inpatient Sample (2016–2019). Patients were identified using ICD-10 procedural codes. Age groups were compared with respect to etiologies, demographics, comorbidities, in-hospital complications, length of stay, and total hospital charges. Statistical analyses were based on weighted frequencies, chi-square tests, and t tests. Primary osteoarthritis was the most common indication across all age groups. Patients aged 18-34.9 years had the highest proportion of Medicaid coverage and the highest proportion of post-traumatic and inflammatory etiologies. In unadjusted analyses, this youngest group also had the longest mean hospital stay and the highest mean total hospital charges, as well as higher rates of blood loss anemia and blood transfusion. In-hospital mortality was rare and did not differ significantly across age groups. In this nationwide inpatient descriptive analysis, younger adults undergoing TKA demonstrated distinct etiologic, demographic, and comorbidity profiles, with unadjusted differences in in-hospital complications and healthcare utilization across age groups. These findings should be interpreted cautiously because the study was limited to inpatient outcomes and did not include multivariable adjustment or longitudinal follow-up.