53 yr old lady with chronic pain right hip region with no trauma, shows ill-defined ,irregular , edematous foci in the tendon insertion region of greater tuberosity, with possible fatty degeneration of muscle belly and no avulsion fracture. Gluteus minimus also shows similar features suggesting strain of glutei possibly responsible.
Teaching points by Dr MGK Murthy.
- Gluteus medius originates from outer surface of ilium and gluteal aponeurosis and inserts on to oblique ridge on the lateral surface of greater trochanter. A bursa separates the tendon from the surface of the trochanter, over which it glides for various functions. When the leg is straight it abducts , when the hip is flexed internally rotates, when the hip is extended externally rotates, all functions aided by minimus .
- Dysfunction of medius is best identified by positive Trendelenburg test. Common cause( up to 46% in some series) of chronic backache, buttock pain radiating to thigh
- Muscle strain versus tendinopathy versus partial or complete tears are a spectrum that needs to be analyzed on imaging. X- ray may play role in identifying the bony abnormalities including spurring and chips or calcifications. USG is helpful particularly in cases of bursal evaluation and as initial assessor of the dysfunction. MRI is the gold standard for evaluating both medius and minimus , with regards to size of belly, musculotendinous junction, tendinous insertion, marrow abnormality of trochanter, soft tissue abnormality, associated findings in hip joint .