Joint-preserving surgery with arthroscopic techniques of the hip follows detailed radiological assessment including plain radiography of the hips and magnetic resonance arthrography (MRI). The purpose of this study was to compare features on radiography and MRI of the hip before surgery and assess their prognostic value on the outcome after surgery.

Hip arthroscopy is indicated for the treatment of a variety of pathologies of the hip, in patients without osteoarthritis. The diagnosis in patients with pain at the hip is made after history taking, clinical examination and radiological evaluation with plain radiography in a standardized technique and a magnetic resonance arthrography of the hip. The main indications for hip arthroscopy include CAM-type femoroacetabular impingement (FAI) necessitating bony decompression and chondro-labral tears necessitating arthroscopic repair or debridement. The purpose of this radiological non-interventional outcome study was to assess features on plain radiography and MRI in favor of good outcome after hip arthroscopy.

This department performed 810 hip arthroscopies in the years of 2013 till 2021. All of those patients underwent standardized radiological evaluation with radiography and MRI. Radiographical parameters are assessed by a resident with experience in musculo-sceletal radiology, intra- and inter-observer reliability has been assessed for each parameter. All arthroscopies have been performed by two experience senior orthopedic surgeons. Ethical board approval has been obtained to follow-up on those patients. Follow-up includes the patient-reported outcome assessment using the iHOT12 score and the modified Harris hip score. The clinical end-point is the time till total hip arthroplasty (THA), a registry analysis of the Tyrolean Arthroplasty registry (TAR) has been performed. Statistical analysis is performed using ANOVA and Fishers T-Tests, the level of significance is .05.

Inclusion Criteria:

• Hip arthroscopy from 2013-2021 at this department.

Exclusion Criteria:

• Age below 18 years.

810 patients received hip arthroscopy at this institution. All of those patients received an magnetic resonance arthrography.