This 52-year-old former professional athlete presents with hip and groin pain. Labral tear was suspected. Would you buy a hot dog from this man (see coronal image 2)? What is your diagnosis? What do the pink, blue, and yellow arrows represent? To what do the red arrows point? To what do the green arrows point? I would not buy a hot dog from this man since the hot dog is filled with fluid and I like my hot dogs solid with meat in them. There are some components of more solid-looking tissue in this elongated elliptical “hot dog shaped” mass that is almost 10cm in length.
The diagnosis is iliopsoas bursitis. This is perhaps better appreciated on the axial T2* gradient-echo image (image 1) and also obvious on the coronal proton-density fat-suppression image 2 (green arrows).
The pink arrow (image 1) represents the femoral vein.
The blue arrow (image 1) represents the femoral artery.
The yellow arrow (image 1) represents the femoral nerve. Therefore, in aspirating this lesion (red arrows, image 1), make sure you do not hit the femoral nerve.
Finally, the green arrows represent synovial hypertrophy in the iliopsoas bursa. This lesion was successfully aspirated with pain relief; however, it returned rather quickly within several months.
You have been shown the final axial gradient-echo (image 3), in which a ridge on the iliopectineal eminence is highlighted with an arrow that is purple. Most cases of iliopsoas bursitis are related to altered biomechanics or altered anatomy of the anterior skeleton, and/or skeletal tendon and bursa relationship. This patient is set for reinjection using stem cells to prevent reoccurrence.
Snapping hip syndrome, which is one of the more common and important causes of a prominent iliopsoas bursitis may be divided into three categories: intraarticular, internal, (extra-articular) and external.
Intraarticular snapping hip may occur from bodies, broken osteophytes, cortical shear injuries, or ossific cartilaginous pieces. Synovial metaplasia or synovial chondromatosis is a less common contributor. Unstable tears of the labrum with infolding or flipping of the labrum in various positions can also produce a snapping sensation.
The next type of snapping hip or internal snapping hip syndrome involves abnormal motion of tendons. The iliopsoas tendon may snap as it passes over the iliopectineal eminence, which is highlighted in this patient with a purple arrow. This occurs during internal rotation, adduction and extension. Less commonly, the hip will snap over the anteroinferior iliac spine (AIIS). Ultrasound or cine loop imaging is the best way to document this, especially in conjunction with the audible and palpable snap.
More distally, a tendinous snap may also occur over the ridge of the lesser trochanter. The iliofemoral ligament may snap over the anterior aspect of the femoral head joint capsule.
External snapping hip impingement syndrome is seen more laterally where the iliotibial band, or less commonly the tendon of the gluteus maximus, may snap over the greater trochanter. These are also visible sonographically. Posteriorly, the long head of the biceps may snap on the ischial tuberosity.
Although not necessarily directly related to MRI, real-time sonography of the tendon with the patient lying supine and the leg flexed in external rotation, and then rotated forward from abduction to adduction, usually produces either snapping or an accelerated rotatory motion of the tendon as the patient lies supine on the table. This is done with the probe placed directly over the anterior rim of the acetabulum. This author has found dynamic sonography to be the most useful single test for this condition. Occasionally, a combination of anesthetic such as lidocaine, ropivacaine, and various steroid preparations may attenuate or delay surgical intervention.
The use of stem cells to obliterate a distended iliopsoas bursa in a patient with abnormal biomechanics is new and stay tuned for the follow up on this patient further down the road.
For more case review, check out MRI Online.