PMC6909268_01
A unicameral bone cyst of the ilium. (a: top) Plain radiographs show an expansive osteolytic lesion in the ilium when the patient was 13 years old. (a: bottom) CT shows an expansive thinned cortex and osseous septa. (b: top) beta-TCP was implanted after cortical fenestration. (b: bottom) When the patient was 15 years old, 23 months after the first operation, a recurrent osteolytic area was obvious. (c: top, coronal; bottom, axial) The recurrent lesion contained fluid with high signal intensity in T2-weighted images, with septa characterized by low signal intensity.
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The osteolytic lesion extended to a region adjacent to the hip joint (Figure 1(a)). The content of the lesion was homogeneous with a low CT image intensity, suggesting that the content was fluid, but not blood (Figure 1(a)). Then beta-tricalcium phosphate (TCP) was implanted into the cavity (Figure 1(b)). When the patient was 15 years old, 2 years after the initial surgery, the osteolysis had expanded (Figure 1(b)). Septa were characterized by low signal intensity on both T2- and T1-weighted images (Figure 1(c)).
Reoperation for a recurrent unicameral bone cyst of the ilium. (a: top) When the patient was 15 years old, a second operation was performed to implant beta-TCP after fenestration of the cortex. (a: bottom) When the patient was 17 years old, 24 months after the operation, an osteolytic region at the acetabular area was obvious. MRI shows fluid in the ilium as having (b: top) high signal intensity in T2-weighted and (c: bottom) low signal intensity in T1-weighted images. (c: top) To decompress the cyst, the cortex was fenestrated, beta-TCP was implanted, and u-HA/PLLA composite screws were placed. (c: bottom) Bone consolidation is seen 24 months after the third operation, without recurrence of the osteolytic region.
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Because recurrence was diagnosed, a second operation was performed to fenestrate the same portion of the iliac crest as previously fenestrated, and beta-TCP was implanted into the recurrent cavity (Figures 2(a)). However, when the patient was 17 years old, about 24 months after the second operation, an osteolytic region in the acetabular area was obvious on a plain radiograph and MRI (Figures 2(a) and (b)). In addition, 3 u-HA/PLLA composite screws were placed (Figures 2(c)).