Anterior Inferior Acetabular Hip Paralabral Cyst

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Fig. 6. Rectus femoris avulsion in an athlete. (A) Coronal inversion recovery, and (B) axial T2, fat-suppressed images demonstrate avulsion of the origin of the biceps femoris from the left anterior inferior iliac spine. Note prominence of avulsed tendon (arrows) with surrounding soft-tissue edema and hemorrhage.

Fluid distending the iliopsoas bursa, resulting in symptoms, is a common clinical problem. There may be communication between hip joint and bursa, with bursal distension resulting from intracapsular hip pathologies. This potential communication is readily depicted on hip arthrography [28]. Fluid in the iliopsoas bursa may present at the level of the acetabular rim (Fig. 8) [29]. This may mimic a paralabral cyst secondary to a acetabular labral tear. In other cases, the

Iliopsoas Bursitis Rupture

Fig. 7. Water-skiing injury with hamstring avulsion. Axial T2, fat-suppressed (A) and coronal inversion recovery (B) scans reveal complete avulsion (Type III musculotendinous injury) of the conjoined tendons of the left proximal hamstring muscle group from the ischium. The tendons are retracted distally (arrows) with hematoma in the soft tissues and hemorrhage in the retracted muscles.

Fig. 7. Water-skiing injury with hamstring avulsion. Axial T2, fat-suppressed (A) and coronal inversion recovery (B) scans reveal complete avulsion (Type III musculotendinous injury) of the conjoined tendons of the left proximal hamstring muscle group from the ischium. The tendons are retracted distally (arrows) with hematoma in the soft tissues and hemorrhage in the retracted muscles.

Iliopsoas Bursa Aspiration Technique

Fig. 8. Iliopsoas bursitis. Axial proton-density-weighted image of the right hip demonstrates a mixed signal intensity, rounded, well-defined mass anterior to the right femoral head (arrow). This is at the expected location of an iliopsoas bursa. Note that the femoral vessels (curved arrow)are just medial to the bursa.

Fig. 8. Iliopsoas bursitis. Axial proton-density-weighted image of the right hip demonstrates a mixed signal intensity, rounded, well-defined mass anterior to the right femoral head (arrow). This is at the expected location of an iliopsoas bursa. Note that the femoral vessels (curved arrow)are just medial to the bursa.

bursal distension may extend proximally into the pelvis, in close apposition to the iliac wing and iliacus muscle. Iliopsoas bursitis, when symptomatic, may be readily aspirated and injected with corticosteroid under CT or ultrasound guidance (Fig. 9).

The trochanteric bursa is in close apposition to the greater trochanter. The relationship of the trochanteric bursa to the gluteus medius and gluteus minimus tendons has been well-documented [2,30]. Trochanteric bursitis and

Iliopsoas Bursa

Fig. 9. Former college football linebacker with chronic left groin pain. Iliopsoas bursa aspiration and injection. (A) Axial CTscan demonstrates distended iliopsoas bursa (arrow). (B) Needle is placed into the center of the bursa under CT guidance (arrow). The cyst fluid is then aspirated and bursa is injected with anesthetic and steroid combination.

Fig. 9. Former college football linebacker with chronic left groin pain. Iliopsoas bursa aspiration and injection. (A) Axial CTscan demonstrates distended iliopsoas bursa (arrow). (B) Needle is placed into the center of the bursa under CT guidance (arrow). The cyst fluid is then aspirated and bursa is injected with anesthetic and steroid combination.

gluteus insertional tendinopathy are closely related entities on the basis of intertwined anatomy and pathologies.

HIP JOINT CAPSULE AND LABRUM

The fibrocartilaginous acetabular labrum—how and why it is injured, and its role in acute and chronic hip pain—has been the subject of much recent investigation [31-33]. Our understanding of labral pathology at the hip is in its relative infancy, however, particularly when compared with the glenoid labrum. Recent attention has focused on anatomic predispositions to labral injury with FAI [5,6,33] and DDH [7,8]. MR arthography has provided the means for the preoperative diagnosis and localization of labral tears [9,34-37] as well as demonstrating findings associated with either FAI or DDH. Many patients are then treated using hip arthroscopy, a technique gaining more widespread acceptance [38].

A number of mechanisms may result in acetabular labral injury, including hyperrotation, hyperextension, hyperflexion, and hyperabduction [39]. Patients often present with mechanical symptoms such as clicking or locking [7]. Radiographic evaluation may be unrevealing, or may demonstrate findings suggestive of DDH or FAI, features that are detailed below. It should be emphasized that labral pathology is frequently targeted to the anterior portion of the labrum. Visualization of the underlying bony anterior acetabular rim on radiograph may be accomplished with the false-profile view (Fig. 10) [40].

MR arthrography is performed by initial injection of the hip with a dilute solution of gadolinium under fluoroscopic control. A total of 8 to 12 cc containing 3 cc of iodinated contrast (to confirm localization), followed by a 1:150 to 1:200 solution of diluted gadolinium in nonbacteriostatic saline is instilled. MR imaging should be performed within 30 minutes of the injection, before significant absorption of the injected fluid.

False Profile View
Fig. 10. False-profile radiograph. The patient is standing and the pelvis is rotated posteriorly. This gives an accurate assessment of the anterior acetabular coverage of the femoral head.

As detailed earlier, Tl-weighted, fat-suppressed scans are used for the assessment of labral tears. Fluid mixed with gadolinium demonstrates high signal intensity on Tl-weighted scans, whereas other fluid collections remain of low signal intensity. This allows excellent resolution of the labral tear, which is a bright cleft adjacent to or within normal ''black'' labrum, which also helps differentiate joint capsular contents from noncommunicating juxta-articular cysts. T2-weighted scans are used for evaluation of extracapsular collections and are useful for resolving intracapsular chondro-osseous bodies. A fat-suppressed, fluid-sensitive sequence (proton-density or T2) is necessary for visualization of bone marrow or muscle edema.

The hip is evaluated in four imaging planes: coronal, sagittal, axial, and oblique sagittal; the latter a plane roughly parallel to the long axis of the superior labrum (Fig. 11). The sagittal and oblique sagittal planes afford visualization of the anterior labrum. The coronal plane is useful for the superior labrum. Sagittal, oblique sagittal, or axial planes afford visualization of the posterior labrum. Given the normal rounded anatomy of the hip joint surfaces, articular cartilage should be carefully evaluated on all imaging planes.

In the authors' institutional experience with over 2000 hip MR arthrographies, we have found that most labral tears occur in the anterior (Fig. 12) or superior (lateral) quadrants. Some tears are specifically anterosuperior in location [41]; in general, posterior tears are far less common. Tears may manifest as labral detachment (Fig. 13) separating the base of the labrum from underlying bone, may be longitudinal or transverse within the labral substance, or may result in labral blunting. With labral degeneration, there is elevated signal intensity within the normally dark fibrocartilaginous labral substance (Fig. 14), similar in appearance to meniscal degeneration at the knee [36,41].

Paralabral cysts may develop adjacent to labral tears [42], probably via a oneway valve mechanism with preferential extrusion of fluid thorough a labral tear

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Responses

  • Jodi
    What is a anterior paralabral cyst in hip?
    8 years ago
  • paul
    How to treat a paralabral cyst on the hip?
    8 years ago

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