Hip Arthroplasty in Young Patients: Analysis of the New Zealand Joint Registry

Abstract

Purpose: The aim of this study was to look into the New Zealand Joint Registry (NZJR) data on total hip arthroplasty (THA) in paediatric and adolescent patients aged 20 and under. Specifically, indications for THA, trends in implants and outcome data. Methods: An analysis of all patients aged 20 and under, recorded in the NZJR from December 1999 until January 2021. Review of similar international reports and NZ adult data undertaken. Results: We identified 115 THA performed in patients aged 20 and under in the NZJR. Mean age at primary surgery is 17.9 years. Indications included avascular necrosis (24%), fracture (6%), tumour (3.5%), inflammatory conditions (16.4%), post-infective (6.1%), SUFE (8.7%) and various other disorders. A total of 9/115 THA were reported as being revised in the study period with a revision rate per 100 component years of 0.69. Bearing surface has trended towards ceramic heads. Cementless implants have been the most commonly utilized. The approach is almost exclusively posterior (79%). Head size has increased from formerly being 28 or less to now 32 and above. Conclusions: Rates of THA in this population remain very low, in keeping with international data. Indications are similar to those seen in other registry studies. Trends mimic those seen internationally and in adult cohorts with cementless implants and larger ceramic heads being favored. Revisions were recorded in 9/115 patients with polywear being the most common indication. Outcome measures were excellent with a mean Oxford hip score of 37.4 at 6 months post operatively.