Soft tissue hemangiopericytoma is a well-recognized entity considered to be an aggressive neoplasm with a high rate of recurrence and a propensity to metastasize. Immunohistochemical investigation was essential for the diagnosis of this tumor. Although hemangiopericytoma very rarely occurs in the spine, surgeons treating patients with this tumor should be aware of its metastatic potential.

It is important to appropriately differentiate dorsally sequestered disc herniation from other epidural mass lesions such as extradural tumor before operation and essential to perform early and sufficient surgical decompression of the spinal cord to prevent poor postoperative course in cases of acute onset and rapid progression of the paralysis caused by disc herniation.

We perfomed cementless total hip arthroplasty (THA) with block bone grafting for acetabular dysplasia in 24 hips since 1988 and reviewed radiographic findings for them. The average period of follow-up was 8.1 years (range 5.2 to 11.4 years). The average age at operation was 58.5 years (range 38 to 69). The types of radiographic fixation were classified according to the criteria of Engh et al as follows : optimum fixation in 17 hips, suboptimum fixation in 5 hips, and unstable fixation in 2 hips.Although the area of the cup covered by graft bone was less than 30%, 2 hips were unstable.These results suggest that not only cup coverage ratio but other factors may affect fixation.

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