What causes enthesopathy along the greater trochanters of the right and left femur?

Causes of Enthesopathy Along the Greater Trochanters of the Femur

MRI is the gold standard imaging modality for diagnosing the specific cause of greater trochanteric enthesopathy, with significantly higher sensitivity (93%) and specificity (92%) compared to ultrasound for detecting gluteus medius/minimus tendon pathology. 1

Common Causes of Greater Trochanteric Enthesopathy

Mechanical/Activity-Related Causes

• Overuse injuries - Repetitive stress at tendon insertion sites, particularly in athletes
• Biomechanical factors - Altered gait, leg length discrepancy, or hip joint pathology
• Horseback riding - Long-term horseback riding can cause characteristic entheseal changes at the greater trochanter due to leg gripping and adductor muscle development 1
• Occupational stress - Repetitive activities requiring hip abduction/adduction

Inflammatory Causes

• Seronegative spondyloarthropathies - A hallmark feature of conditions like:
  • Ankylosing spondylitis
  • Psoriatic arthritis
  • Reactive arthritis
  • Enteropathic arthritis 2

Metabolic and Endocrine Causes

• Crystal deposition diseases - Gout, calcium pyrophosphate deposition
• Endocrine disorders - Diabetes, hypothyroidism
• Fluorosis
• Hyperparathyroidism

Medication-Induced Causes

• Retinoid therapy - Isotretinoin (Accutane) use has been associated with greater trochanteric enthesopathy, even with short-term use 3
• Fluoroquinolone antibiotics

Degenerative Causes

• Age-related degeneration - Common in older adults
• Early osteoarthrosis - Though not directly correlated with osteoarthritis severity 4

Diagnostic Approach

Initial Imaging

• Plain radiographs should be the first imaging test ordered for evaluation of hip pain 1, 5
  • May show calcification, ossification, or bone erosion at tendon insertion sites
  • Can identify hyperostosis, fragmentation, or crystal deposition 6

Advanced Imaging

• MRI without contrast is the preferred next step when radiographs are nondiagnostic 1, 5

  • Superior for evaluating peritrochanteric structures
  • Can detect gluteus medius/minimus tendinopathy, tears, or avulsions
  • Helps differentiate between various causes of enthesopathy

• Ultrasound with high-frequency transducers can be useful but has limitations 1, 5

  • More accessible and cost-effective than MRI
  • Good for detecting associated trochanteric bursitis
  • Less sensitive than MRI for detecting gluteus tendon pathology (79% vs. 93%) 1
  • May have difficulty differentiating between bursitis and tendinosis 5

Clinical Pearls and Pitfalls

Important Considerations

• Enthesopathy and enthesitis are not synonymous - enthesitis specifically refers to inflammatory pathology at insertion sites 7
• No single imaging finding is specific for inflammatory enthesitis, making diagnosis challenging 7
• Bursitis often coexists with and can mimic enthesopathy, requiring careful evaluation 2
• In patients with hip arthroplasty, adverse reactions to metal debris can be misinterpreted as trochanteric pathology 5

Common Diagnostic Pitfalls

• Failing to obtain MRI when radiographs are negative but symptoms persist
• Not considering medication history (especially retinoids) when evaluating enthesopathy
• Missing underlying systemic inflammatory conditions that may present with enthesopathy
• Confusing degenerative enthesopathy with inflammatory enthesitis

By systematically evaluating these potential causes through appropriate imaging and clinical correlation, the specific etiology of greater trochanteric enthesopathy can be determined, allowing for targeted treatment.