PMC4353947_01
(A) Anteroposterior radiograph of the left hip at 3 weeks after the onset of pain. (B) In this radiograph obtained at 4 months after the onset of pain, it is apparent that joint-space narrowing of the superolateral portion of the femoral head had progressed rapidly.
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Anteroposterior radiographs showed that joint-space narrowing of the superolateral portion of the femoral head progressed rapidly for only 4 months (Fig. 1).
Magnetic resonance images obtained 4 months after the onset of hip pain show joint effusion and a pattern of bone-marrow edema from the upper portion of the femoral head to the intertrochanteric region, with diffuse low intensity on a T1-weighted image (A) and high intensity on the short tau inversion recovery (STIR) sequence (B). In addition, a small low-intensity band paralleling the articular surface in the femoral head is apparent on the T1-weighted image that indicates subchondral insufficiency fracture (white arrow).
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Boutry et al. and Sugano et al. described its key features: joint effusion and bone marrow with an edema-like pattern in the femoral head and neck or acetabulum or both. MRI findings of this case obtained at 4 months after the first office visit were consistent with those in the reports by Boutry et al. and Sugano et al. Besides, we observed a focal low-intensity band on T1-weighted images (Fig. 2).
Tomosynthesis (A) and multiplanar reconstruction of computed tomography (B) evaluation for subchondral fracture were performed. No obvious subchondral fracture was found in either image.
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However, neither tomosynthesis nor multiplanar reconstruction of computed tomography images showed any subchondral insufficiency fractures in any slices (Fig. 3).
(A) The labrum at the anterosuperior portion (arrowheads) was obviously inverted and widely covered the lunate surface of the acetabulum. The asterisk indicates the fossa acetabuli. ANT = anterior; POST = posterior. (B) Intraoperative photograph showing a defect of the acetabular cartilage just under the inverted labrum after resection of the labrum. (C) Intraoperative photograph showing an anterosuperior cartilage defect of the femoral head. (D) Photomicrograph obtained from the inverted labrum included lots of fragments of articular cartilage.
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During surgery, we found that the anterosuperior surface of the acetabular cartilage was covered extensively with the inverted labrum (Fig. 4A). However, a macroscopic defect and degeneration of the anterolateral portion of cartilage on the acetabulum and femoral head were obvious (Fig. 4B and C). The resected labrum included lots of fragments of articular cartilage (Fig. 4D).