What is the best radiographic view to diagnose hip osteoarthritis?

Best Radiographic View for Hip Osteoarthritis

An anteroposterior (AP) pelvis radiograph is the essential initial view for diagnosing hip osteoarthritis, and should be supplemented with a lateral view—either a frog-leg lateral or Lequesne's false profile view—to maximize detection of joint space narrowing, particularly in early disease. 1, 2

Initial Imaging Approach

• Plain radiographs remain the first-line imaging modality for suspected hip osteoarthritis, providing excellent screening for OA features including joint space narrowing, osteophytes, subchondral sclerosis, and cysts 3, 1, 2

• The standard radiographic series should include:

  • AP pelvis view (mandatory baseline view) 1, 4, 2
  • Lateral view of the symptomatic hip (frog-leg lateral or false profile) 1, 4

Why Multiple Views Matter

• The AP pelvis view alone misses significant joint space narrowing in early OA. In one study of 58 hips with incipient osteoarthritis, 22 hips (38%) showed no joint space narrowing on AP view, but 16 of these 22 hips (72.7%) demonstrated narrowing on the false profile view 5

• The false profile (faux profil) view detects anterosuperior joint space narrowing that is frequently missed on standard AP radiographs, making it particularly valuable in early or suspected OA when the AP view appears normal 5, 2

• The frog-leg lateral view provides alternative assessment of the joint space and femoral head morphology 1, 4

Optimal Radiographic Technique

• Weight-bearing views are critical for accurate assessment of joint space narrowing, as non-weight-bearing films can overestimate remaining cartilage 4

• For the AP pelvis view, the hip should be positioned with 15 degrees of internal rotation to optimize visualization 3

• The false profile view provides a true lateral projection of the femoral head and tangential view of the anterosuperior acetabulum, allowing measurement of both anterosuperior and posteroinferior joint space 5, 2

Diagnostic Criteria on Radiographs

• Joint space width less than 3 mm (or less than the contralateral hip) establishes radiographic hip OA 4

• Minimum joint space width less than 2.0 mm provides the most reproducible criterion for OA diagnosis, with excellent inter-observer agreement (kappa = 0.87) 6

• Additional features supporting OA diagnosis include osteophytes, subchondral sclerosis, and subchondral cysts 3, 4

When Imaging May Not Be Required

• In patients over age 40 with typical OA presentation (usage-related pain, brief morning stiffness <30 minutes, affecting one or few joints), clinical diagnosis without imaging is acceptable 3, 7

• However, imaging becomes necessary with atypical features: age <40, prolonged morning stiffness, rapid progression, or inflammatory signs 7

Advanced Imaging Considerations

• MRI is more sensitive than radiographs for detecting cartilage loss, bone marrow lesions, labral tears, and synovitis, but shows poor correlation with pain and functional impairment 2

• MRI without contrast or MR arthrography (rated 9/9 "usually appropriate") should be reserved for cases where radiographs are negative or equivocal but clinical suspicion remains high, or when intra-articular pathology beyond OA is suspected 1

Common Pitfalls to Avoid

• Do not obtain non-weight-bearing radiographs for OA assessment, as they significantly underestimate joint space narrowing 4

• Do not rely solely on the AP pelvis view in early or suspected OA—the addition of a lateral view (particularly false profile) detects 72.7% of cases missed on AP alone 5

• Avoid routine follow-up imaging in established OA unless there is unexpected rapid progression or change in clinical characteristics 3

• Remember that radiographic severity correlates poorly with symptoms—manage based on clinical presentation, not imaging findings alone 2