What type of ultrasound is recommended for examining a hip?

Ultrasound Examination of the Hip

For hip examination, a standard musculoskeletal ultrasound should be ordered, with specific focus on the anterior, lateral, and posterior aspects of the hip joint. 1

Appropriate Imaging Selection

When examining the hip, imaging selection should follow this algorithm:

1. Initial imaging: Plain radiographs (X-rays) of the pelvis and hip should always be the first test ordered for hip pain evaluation 1
2. Secondary imaging: When radiographs are negative, equivocal, or nondiagnostic:
   • For extra-articular soft tissue abnormalities (tendinitis, bursitis):
     • MRI hip without contrast (rating 9/9) or
     • Ultrasound hip (rating 7/9) 1, 2
   • For suspected labral tears or intra-articular pathology: MR arthrography (rating 9/9) 1, 2

Ultrasound Technique for Hip Examination

A standardized hip ultrasound examination should include:

Standard Scanning Planes

1. Anterior approach:

   • Anterior longitudinal scan parallel to the femoral neck (most valuable for detecting effusion, erosions, or osteophytes) 1
   • Anterior transverse scan (90° rotation from longitudinal) 1

2. Lateral approach:

   • Lateral longitudinal scan over the greater trochanter (for evaluating trochanteric bursitis) 1, 2

3. Posterior approach (when indicated):

   • Posterior longitudinal scan
   • Posterior transverse scan

Patient Positioning

• Supine position for anterior scans
• Lateral decubitus position for lateral scans
• Prone position for posterior scans

Ultrasound-Detectable Hip Pathologies

Hip ultrasound can effectively identify:

1. Joint effusion/synovial proliferation
2. Bursitis (trochanteric, iliopsoas, ischiogluteal)
3. Tendinopathy/tears (iliopsoas, gluteal, hamstring)
4. Cartilage lesions (limited assessment)
5. Bony surface irregularities (erosions, osteophytes)
6. Calcifications in tendons or bursae
7. Synovial cysts
8. Periarticular lesions 1, 2

Limitations of Hip Ultrasound

• Limited acoustic windows due to the hip's deep position
• Operator-dependent technique requiring significant experience
• Limited evaluation of deep intra-articular structures
• Decreased sensitivity in obese patients 2, 3
• Ultrasound alone is inadequate for comprehensive hip evaluation 2

Complementary Role with Other Imaging

• Ultrasound: Best for extra-articular soft tissue abnormalities, dynamic evaluation, and guided procedures 1, 4
• MRI: Superior for intra-articular pathology, bone marrow abnormalities, and deep soft tissue structures 1, 5
• CT: Better for bony detail and computer-navigated surgery planning 1

Ultrasound-Guided Procedures

Hip ultrasound is particularly valuable for:

• Joint aspirations
• Intra-articular injections
• Periarticular (bursa) injections
• Tendon procedures (fenestration, PRP injections)
• Perineural injections 1, 6

Common Pitfalls to Avoid

1. Inadequate examination: Failure to examine all relevant aspects (anterior, lateral, posterior)
2. Misinterpretation: Confusing normal anatomical structures with pathology
3. Technical errors: Improper transducer pressure, incorrect positioning
4. Overreliance: Using ultrasound alone for comprehensive hip evaluation instead of as a complementary tool
5. Inexperience: Hip ultrasound requires significant operator experience for accurate interpretation 2, 3

When ordering a hip ultrasound, specify the clinical question to ensure appropriate focus on the relevant anatomical structures and potential pathologies.