What are the causes of greater trochanteric pain syndrome?
Pain localizing to the lateral aspect of the hip is usually due to greater femoral trochantic bursitis or abductor tendon abnormalities, both often caused by repetitive hip flexion in middle-aged and elderly patients and indistinguishable clinically. MRI findings are more specific than clinical signs, and can differentiate between bursitis and tendon pathology.
Bursitis is manifested by increased T2-weighted fluid signal intensity in the trochanteric (subgluteus maximus) bursa paralleling the greater trochanter and interdigitating around the tendons. This fluid can be difficult to visualize on T1-weighted images. Abnormalities of the hip abductor tendons, which attach on the greater femoral trochanter (gluteus medius on the superoposterior facet, gluteus minimus on the anterior facet), include tendonopathy, manifested on MRI as increased signal intensity, and partial- and full-thickness tears, manifested as discontinuity of the tendon fibers.
Bursitis and tendinosis often coexist. Although patients with trochanteric pain syndrome always have peritrochanteric T2-weighted signal abnormalities, the converse is not usually true. Presence of increased peritrochanteric T2-weighted signal intensity, especially when of low grade and symmetric, can be seen in asymptomatic patients and does not imply pathology.
