MRI Does Not Improve Inter- or Intrarater Reliability for Hip Arthritis Grading Systems

Area of Science:

• Orthopedic Surgery
• Radiology
• Medical Imaging

Background:

• Magnetic resonance imaging (MRI) and radiographs are commonly used to evaluate preoperative osteoarthritis in patients undergoing hip preservation surgery.
• Assessing hip arthritis preoperatively is crucial for surgical planning and patient outcomes.

Purpose of the Study:

• To compare the inter- and intrarater reliability of magnetic resonance imaging (MRI) scans versus radiographs for diagnosing hip arthritis.
• To determine if MRI scans offer improved diagnostic accuracy over radiographs for specific osteoarthritis markers.

Main Methods:

• A cohort of 50 patients (mean age 42.8 years) underwent review of anteroposterior and cross-table lateral radiographs alongside coronal and sagittal T2-weighted MRI scans.
• Seven experienced hip preservation surgeons evaluated the imaging for joint space narrowing, subchondral cysts, osteophytes, sclerosis, Likert grade, and Tönnis grade.
• Inter- and intrarater reliabilities were calculated using the Fleiss method with 95% confidence intervals.

Main Results:

• Radiographs showed fair agreement for joint space narrowing, osteophytes, Likert grade, and Tönnis grade, and moderate agreement for subchondral cysts.
• MRI scans demonstrated poor to fair agreement for most osteoarthritis markers but substantial agreement for subchondral cysts.
• While intrarater reliability improved, no significant differences in interrater reliability were found between radiographs and MRI for key osteoarthritis indicators.

Conclusions:

• Both radiographs and MRI scans exhibit significant limitations and interrater variability in assessing common hip osteoarthritis markers.
• MRI scans provide high reliability for detecting subchondral cysts but do not improve the overall interobserver variability in grading hip arthritis.
• Neither imaging modality consistently outperforms the other in reliably grading hip osteoarthritis, highlighting the need for improved assessment methods.