Use of Total Hip Arthroplasty in Patients Under 21 Years Old: A US Population Analysis.

Background: The purpose of this study is to evaluate trends in the use of total hip arthroplasty (THA) in the United States in patients under 21 years of age. Specifically, we examined the frequency of THA in this patient population over the past 2 decades, the epidemiologic characteristics of patients under 21 who underwent THA, and the characteristics of the hospitals where these procedures were performed.
Methods: We retrospectively reviewed the Kids' Inpatient Database, an inpatient US national weighted sample of hospital admissions in patients under 21 from approximately 4200 hospitals in 46 states. We queried the database using Current Procedural Terminology codes for elective and non-elective primary THA for the years 2000-2016. We utilized the International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes to determine primary diagnoses.
Results: The weighted total number of THAs performed in patients under 21 in the Kids' Inpatient Database increased from 347 in 2000 to 551 in 2016. The most common diagnoses were osteonecrosis, osteoarthritis, and inflammatory arthritis. The frequency of THA for osteonecrosis increased from 24% in 2000 to 38% in 2016, while the frequency of THA for inflammatory arthritis decreased from 27% in 2000 to 4% in 2016.
Conclusion: The number of THAs in patients under 21 in the United States has increased over the past 2 decades and these procedures are increasingly performed in urban teaching hospitals. The decrease in THA for inflammatory arthritis in this population likely reflects improvements in medical management during the study period.
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