Differential Diagnosis for Hip Pain with External Rotation

The patient's complaint of pain with external hip rotation can help narrow down the differential diagnosis. Here's a categorized list of potential diagnoses:

• Single most likely diagnosis
  • Trochanteric Bursitis: This condition is characterized by inflammation of the bursa over the greater trochanter, which can cause pain with external rotation of the hip. The pain is typically localized to the lateral aspect of the hip and can be exacerbated by activities that involve external rotation.
• Other Likely diagnoses
  • Gluteus Medius Tendinopathy: Similar to trochanteric bursitis, gluteus medius tendinopathy can cause pain with external rotation due to the involvement of the tendon that helps stabilize the hip during this movement.
  • Piriformis Syndrome: The piriformis muscle runs from the base of the spine to the thighbone, and its irritation or inflammation can cause pain in the hip, especially with external rotation, as the muscle can compress the sciatic nerve.
  • Hip Osteoarthritis: While osteoarthritis can cause a wide range of hip symptoms, pain with specific movements like external rotation can be a part of the clinical presentation, especially in advanced cases.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Septic Arthritis: Although less common, septic arthritis is a medical emergency that requires prompt diagnosis and treatment. It can present with pain on movement, including external rotation, and is associated with significant morbidity if not addressed promptly.
  • Avascular Necrosis (AVN) of the Femoral Head: AVN can cause hip pain that worsens with movement, including external rotation. Early diagnosis is crucial to prevent collapse of the femoral head and preserve hip function.
• Rare diagnoses
  • Slipped Capital Femoral Epiphysis (SCFE): More common in adolescents, SCFE can cause hip pain that is exacerbated by movement, including external rotation. It's a rare but significant condition that requires early intervention to prevent long-term damage.
  • Synovial Chondromatosis: A rare condition characterized by the growth of cartilage in the synovial membrane of the joint, which can cause pain, swelling, and decreased range of motion, including pain with external rotation.

Each of these diagnoses has a distinct set of characteristics and risk factors, and a thorough clinical evaluation, including history, physical examination, and potentially imaging studies, is necessary to determine the most likely cause of the patient's symptoms.