Snapping Hip Syndrome is a clinical condition characterized by an audible or palpable “snap” or “click” that occurs during hip movement, specifically during flexion and extension. While often a painless annoyance, it can lead to secondary bursitis and significant functional limitation in athletes and dancers. For the board-certified physician, the key is localizing the snap to one of three specific anatomical categories.

1. Classification and Pathophysiology

External Snapping Hip (Most Common)

• Mechanism: The posterior border of the Iliotibial (IT) Band or the anterior fibers of the Gluteus Maximus snap over the Greater Trochanter.
• Clinical Presentation: The snap is felt laterally. It is often visible to the naked eye as a “jump” of the soft tissue over the bone.
• Trigger: Occurs when moving the hip from flexion to extension.

Internal Snapping Hip

• Mechanism: The Iliopsoas Tendon snaps over a bony prominence, most commonly the Iliopectineal Eminence or the Lesser Trochanter. It can also involve the tendon snapping over the femoral head.
• Clinical Presentation: The snap is felt deep in the groin.
• Trigger: Occurs when the hip is moved from a “frog-leg” position (flexion, abduction, external rotation) into extension, adduction, and internal rotation.

Intra-articular Snapping Hip

• Mechanism: Caused by internal joint pathology such as Acetabular Labral Tears, Ligamentum Teres Tears, or Loose Bodies (e.g., synovial chondromatosis).
• Clinical Presentation: Usually a sharp, painful “click” rather than a “snap,” often accompanied by a sensation of the hip “giving way.”

---

2. High-Yield Physical Exam Maneuvers

• For External Snapping (Ober’s Test): Assessing for IT band tightness. To reproduce the snap, have the patient move their hip from flexion to extension while palpating the greater trochanter.
• For Internal Snapping (Log Roll & Extension): Place the hip in a flexed, externally rotated position and passively bring it into extension. You will often feel or hear the iliopsoas “pop” as it crosses the bony eminence.
• For Intra-articular (FADIR & McCarthy): Flexion, Adduction, and Internal Rotation (FADIR) is highly sensitive for labral pathology.

---

3. Diagnostic Imaging: The Role of Dynamic Ultrasound

While X-rays are usually normal (except for ruling out loose bodies), Dynamic Musculoskeletal Ultrasound is the diagnostic gold standard for coxa saltans.

• Technique: The sonographer places the transducer over the suspected area (lateral for IT band, anterior for Iliopsoas) and asks the patient to perform the movement that triggers the snap.
• Findings: The clinician can visualize the tendon “snapping” or “flipping” over the bone in real-time. This is often more diagnostic than a static MRI.

---

4. Management

• Conservative (First-Line): Most cases of external and internal snapping respond to a dedicated physical therapy program.
  • Stretching: Focus on the IT band and Iliopsoas.
  • Strengthening: Addressing gluteal weakness to improve pelvic stability and reduce the compensatory “over-firing” of the iliopsoas.
• Interventional:
  • Bursal Injections: Ultrasound-guided corticosteroid injections into the trochanteric bursa (for external) or the iliopsoas bursa (for internal) can reduce pain associated with the friction.
• Surgical (Rare): Reserved for cases that fail 6–12 months of conservative care.
  • IT Band Release: “Z-plasty” lengthening of the IT band.
  • Iliopsoas Tenotomy: Partial release or lengthening of the iliopsoas tendon at the lesser trochanter.

---

5. High-Yield Board “Fast Facts”

• External: IT band over Greater Trochanter; lateral pain.
• Internal: Iliopsoas over Iliopectineal Eminence; groin pain.
• Intra-articular: Labral tear or loose bodies; sharp click/locking.
• Dynamic Ultrasound: The preferred imaging modality to confirm the diagnosis.
• The “Pop”: Internal snapping occurs as the hip moves from flexion to extension.