This 20-year-old female presents with hip pain. You are getting two clues for the price of one. First, look at images 1 and 2. Hip pain is quite an amorphous symptom. It can come from the joint, the groin, the sacrum, the pubis, or even the spine. We all have a tendency to gravitate towards the joint.
Q1 – Why are we getting two clues for the price of one?
Q2 – Why does the patient have hip pain?
A1 – Because there are two iliopsoas tendons. In other words, the iliopsoas tendon has a bifid morphology (image 4, pink arrows).
A2 – Swelling is more conspicuous around the lateral of the two heads (images 4 and 5, blue arrows). Such swelling is an indirect sign of irritation of the tendon and its surrounding tissues. The iliopsoas tendon is a primary hip flexor and passes over the iliopectineal eminence of the pelvis. This bony prominence is labeled on image 6 (yellow arrow). As the tendons ride over this area, a snap or a click occurs, otherwise known as coxa saltans. Hip flexion and extension, raising and lowering of the whole leg or rotation, namely twisting of the hip, may exacerbate or reproduce symptoms. The peritendinitis, demonstrated with the blue arrows, is a secondary manifestation of this catching phenomenon on the iliopectineal eminence. In this case, the eminence itself is indeed edematous (high signal deep to the yellow arrow on image 6).
Q3 – Names like coxa saltans, or iliopsoas tendonitis perhaps, are given to this condition. Can you think of another name?
A3 – Dancer’s hip.
Some have actually broken down snapping hip tendon syndrome into extra- and intraarticular types.
- Lateral extraarticular type occurs when the iliotibial band, tensor fascia lata, or gluteus medius slide back and forth across the greater trochanter. This can lead to tearing, especially of the gluteus medius and particularly in large women. Concomitant bursitis is frequently present.
- The medial extraarticular type addresses the iliopsoas tendon catching on either the anteroinferior iliac spine, the lesser trochanter, or the iliopectineal eminence during hip extension especially. Peritendinitis and eventually bursitis results. Our patient has this type with peritendinitis.
- With tight constriction and irregular tracking over the anterior labrum, some patients with snapping hip tendon syndrome may develop intraarticular abnormalities involving the labrum and even signs and symptoms of hip impingement with effusion. In this author’s experience, ligamentum teres rupture is another cause of intraarticular snapping hip syndrome.
- The condition is more common in athletes and MR identifies the indirect, and sometimes direct, signs. However, the direct signs are best identified with dynamic ultrasound with hip motion.
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