HISTOLOGICAL FEATURES OF PSEUDOTUMOR AFTER SMALL HEAD DIAMETER METAL-ON-METAL TOTAL HIP ARTHROPLASTY

The pathologic aspects of periprosthetic tissues in failed second-generation metal-on-metal (MoM) resurfacing hip arthroplasties have been widely described in terms of necrosis and inflammation. To our knowledge little data are reported on the association of this lesion with the use of small head diameter (less than 32 mm). In this study we present a small series of pseudo-tumor in small head metal-on-metal total hip arthroplasty focusing our attention on the histologic aspects of the harvested pathologic tissue. The histological examination of our cases showed a presence of lymphocytic infiltrate suggesting a delayed hypersensitivity reaction to metal of type IV (ALVAL) but different to each other in terms of the prevalence of the cellular component. If macrophages are predominant, the pathogenetic mechanism seems to be the reaction against metallic particle. On the other hand, if granulocytes are predominant, it is possible to consider a hypersensitivity reaction. Our observation suggests that the evidence of Pseudotumor in case of small-head metal-on-metal arthroplasty should be considered with the same properties of big-head and therefore these patients should be followed scrupulously.

The use of a preformed spacer in two-stage revision of infected hip arthroplasties

Two-stage revision with the use of an antibiotic-loaded cement spacer has spread widely as a successful treatment for THA infection. Between 1999 and 2008, 28 patients with infected THA were treated with two-stage implant revision using a preformed spacer. The spacer was left in situ for 5.5 months (range 1-13 months), and the patients were allowed to walk with partial weight bearing. At a mean follow-up of 53 months (range 18-106 months), recurrence of infection was observed in only one patient. Complications were observed in five patients: three spacer dislocations, one distal femoral fracture occurred during stem removal, and one femoral artery pseudo-aneurysm. The mean HHS increased from 43 points (range 13-77) to 82 points (range 35-96). Though small prospective studies are reported in literature, good eradication rate and good functional outcomes encourage for the use of an antibiotic-loaded cement spacer. The industrial production ensures procedure standardization, well-defined physical and chemical properties to the device and eliminates time necessary to intraoperatory manufacturing.

Etiology of portal vein thrombosis in adults. A prospective evaluation of primary myeloproliferative disorders

In a prospective study of 33 adults with portal vein thrombosis unrelated to a liver tumor, we have assessed the prevalence of primary myeloproliferative disorders using conventional criteria and cultures of bone marrow progenitor cells. A primary myeloproliferative disorder was documented in 14 patients investigated at the time of recognition of portal vein thrombosis. Among these 14 patients, the main clue to the presence of the myeloproliferative disorder was (a) the observation of suggestive abnormalities of peripheral blood cell counts in 4 patients; (b) characteristic findings at bone marrow biopsy or determination of total red cell volume in 3 patients; and (c) formation of "spontaneous" erythroid colonies in cultures of bone marrow progenitor cells in erythropoietin-poor medium in 7 patients. In 2 other patients, agnogenic myeloid metaplasia with myelosclerosis of apparently recent onset developed 5 yr after recognition of portal vein thrombosis. In conclusion, primary myeloproliferative disorders--in a full-blown or latent form, or at an early stage--are a major cause of portal vein thrombosis.