Case Report: Preoperative Planning of Revision Total Hip Arthroplasty with a 3D Printed Hemipelvis Model in Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is a chronic autoimmune arthritis lasting more than six weeks in a patient younger than 16. JIA presents as morning stiffness, pain and reduced mobility. The hip joint is affected in 20–50% of cases. Conservative treatment consists of immunomodulating drugs. However, the disease progresses to a need for total hip arthroplasty (THA) in most patients before 40, with a median age of 22.7 years. Hip implants are designed for adult bone sizes, as THA is predominantly performed in an elderly patient in the context of degenerative joint disease. As such, these implants are often too large for the smaller bony dimensions of children. Moreover, the young patient will likely need further revision arthroplasties later in life as components loosen or fail. Each consequent surgery requires meticulous preoperative planning and implant selection to augment the bony defects of previous ones. We present a 31-year-old male patient with JIA after bilateral THA with implant loosening after 15 years on the left side and after 16 years on the right side. He was scheduled for bilateral revision THA. After 3D reconstruction of the hips with computed tomography, we planned a revision THA on a real-sized 3D printed model of the patient’s left hemipelvis with an augment of the posterior acetabular wall. In our hands, 3D printing is a helpful tool for better planning the revision of THA in complex cases.