What are the most common damages to the structures of the hip that require a Magnetic Resonance Imaging (MRI)?

Most Common Hip Structures Requiring MRI Evaluation

Radiographically occult fractures of the proximal femur and pelvis are the most common hip injuries requiring MRI evaluation, with MRI demonstrating nearly 100% sensitivity for detecting these potentially life-threatening injuries when radiographs are negative but clinical suspicion remains high. 1

Fractures Requiring MRI

• Radiographically occult proximal femoral fractures are a critical indication for MRI, with multiple studies showing near 100% sensitivity for fracture detection in patients with negative radiographs but persistent clinical suspicion 1
• Pelvic fractures are frequently detected on MRI in patients with hip pain and negative radiographs, with studies showing that 38% of patients with acute hip pain and negative radiographs had fractures of the pelvis 1
• Intertrochanteric fractures with extension that are not visible on radiographs are commonly detected with MRI, which can accurately depict fracture morphology and guide treatment decisions 1
• Subchondral fractures are well-visualized on MRI and may not be apparent on conventional radiographs 2

Soft Tissue Injuries Requiring MRI

• Acetabular labral tears are best evaluated with MRI, particularly MR arthrography which is considered the gold standard with a rating of 9/9 (usually appropriate) according to ACR Appropriateness Criteria 3
• Piriformis syndrome and other soft tissue injuries around the hip require MRI due to its superior soft tissue contrast and ability to detect muscle and nerve abnormalities 4
• Hamstring strains with persistent symptoms despite appropriate rest and conservative measures warrant MRI evaluation to assess the extent of injury 5
• Tendinopathies and tendon tears around the hip joint are well-evaluated with MRI, which can precisely delineate the sources of hip pain by evaluating the soft tissues and ligamentous structures 6

Bone and Cartilage Pathologies Requiring MRI

• Avascular necrosis (AVN) of the femoral head is one of the most frequent indications for hip MRI, allowing early detection before radiographic changes occur 2, 7
• Femoroacetabular impingement (FAI) with associated labral and cartilage damage requires MRI for comprehensive evaluation prior to surgical intervention 7
• Developmental dysplasia of the hip (DDH) benefits from MRI assessment of both bony and soft tissue abnormalities 7
• Cartilage lesions, particularly those associated with labral tears, require MRI evaluation to determine the extent of damage and guide treatment decisions 3, 6

Technical Considerations for Hip MRI

• Coronal STIR sequence alone has demonstrated 99% sensitivity for fracture detection, with increased confidence and specificity when combined with coronal T1 sequence 1
• Three-dimensional (3D) MRI acquisitions allow for isotropic multiplanar reconstructions that improve visualization of small labral tears and other hip lesions with better correlation to arthroscopy 8, 7
• Standard MRI without arthrography has limitations in fully evaluating labral pathology (rated 6/9 - may be appropriate), while MR arthrography is superior (rated 9/9 - usually appropriate) 3
• High-resolution 3T MRI may improve visualization of the acetabular labrum and associated pathology, potentially eliminating the need for arthrography in some cases 3

Clinical Pitfalls and Caveats

• Relying solely on radiographs when clinical suspicion for fracture remains high can lead to missed diagnoses, as MRI has demonstrated nearly 100% sensitivity for detecting radiographically occult fractures 1
• Seemingly isolated fractures of the greater trochanter on radiographs frequently have intertrochanteric extension when evaluated with MRI, which can significantly alter treatment decisions 1
• Standard MRI without arthrography may miss small labral tears, making MR arthrography the preferred technique for comprehensive labral evaluation 3
• Distant metal hardware (such as in other extremities) should not significantly affect imaging of the hip and should not be a contraindication to obtaining necessary MRI studies 4