Selective closure of the dural defect based on cine-MRI will be useful for treating extradural arachnoid cysts.

We have studied damage to the tibial articular surface after replacement of the femoral surface in dogs. We inserted pairs of implants made of alumina, titanium and polyvinyl alcohol (PVA) hydrogel on titanium fibre mesh into the femoral condyles.The two hard materials caused marked pathological changes in the articular cartilage and menisci, but the hydrogel composite replacement caused minimal damage. The composite osteochondral device became rapidly attached to host bone by ingrowth into the supporting mesh.We discuss the clinical implications of the possible use of this material in articular resurfacing and joint replacement.J Bone Joint Surg [Br] 1997;79-B:1003-7. Received 17 January 1997 Accepted after revision 9 May 1997 Hemiarthroplasty using a metal prosthesis articulating with articular cartilage has been widely used for the hip, with associated pain, is a recognised late complication of hemiarthroplasty. 10,11Furthermore, the use of prosthetic replacements usually requires the removal of healthy cancellous bone which has an important shock-absorbing role.12 It is desirable therefore to develop new materials with mechanical properties which are more similar to those of normal articular cartilage.We have developed an artificial replacement for articular cartilage which preserves healthy subchondral cancellous bone. This substance is polyvinyl alcohol (PVA) hydrogel and we have improved its mechanical properties using a new synthetic process. [13][14][15] In previous studies we characterised the mechanical properties of this material in relation to its use as an artificial articular cartilage including its lubricating and shock-absorbing functions. A series of in vivo tests showed that it had good biocompatibility. 16 In addition, histological findings in synovial membranes and articular cartilage two months after the introduction of small particles (50 to 300 m) of PVA hydrogel and ultra-high-molecular-weight polyethylene (UHMWPE) into contralateral knees of the same rats showed that the PVA hydrogel particles caused much less inflammation. They were not resorbed because of their bioinert properties. 17A major problem, however, was the attachment of the material to the bone. To overcome this, we infiltrated PVA solution into the pores of one half of a block of titanium fibre mesh to obtain a composite material. The shear force between the PVA hydrogel and the titanium fibre mesh was approximately 2.2 MPa. 17Our aim in this study was to determine the changes which occurred in menisci and articular cartilage in contact with various implants. We implanted alumina, titanium and our composite 'osteochondral' device (COD) into the loadbearing regions of the femoral condyles of dogs and examined the time-dependent changes in the tibial articular cartilage. We also determined the ingrowth of new bone into the pores of the titanium fibre mesh and the remodelling of the bone around the implants. MATERIALS AND METHODSRectangular test pieces (10 ‫ן‬ 6 ‫ן‬ 5 mm) were manufactured from pure titanium fibre mesh wi...

No abstract

✓ Spinal fixation for destructive metastatic lesions at the lumbosacral junction is challenging because of the large and unique load-bearing characteristics present. In particular, caudal fixation is difficult in cases of sacral destruction because of insufficient S-1 pedicle screw anchorage. The authors describe their surgical technique for secure iliac screw placement and the clinical results obtained in five patients with metastatic spinal disease. All patients in this study underwent palliative operations with dual iliac screw fixation between April 1999 and October 2002, and the clinical and radiological findings were assessed. In all five patients, spinal metastases extended into the sacrum. The metastases were from renal cell carcinomas in two patients, lung cancer in two, and a paraganglioma in one patient. Postoperative follow-up periods ranged from 3 months to 6 years (mean 28.4 months). Preoperatively, four patients could not walk due to severe pain or neurological compromise. Postoperatively, all patients reported a reduction in pain and regained the ability to walk. Complications included one case of early wound infection. In the patients with long survival after the operation, there was one case of iliac screw loosening and one case of rod breakage. The dual iliac screw fixation technique provided sufficient immediate stability for destructive lumbosacral metastasis.

The profile of blood coagulation and fibrinolysis was studied in detail in eight patients with acute thrombotic thrombocytopenic purpura (TTP). In the majority of the patients, fibrinogen, factor XIII, antithrombin III, alpha 2-plasmin inhibitor, plasminogen, and alpha 2-macroglobulin were normal, whereas FDP, plasmin-alpha 2-plasmin inhibitor complex, and tissue-type plasminogen activator antigen were marginally or moderately elevated. Low fibronectin values were observed in four patients. Protein C and C4b-binding protein were nearly normal, whereas total protein S and free protein S were reduced in five and six patients, respectively. A positive correlation was found between total protein S and C4 and between free protein S and C3. von Willebrand factor antigen (vWf:Ag) and ristocetin cofactor (RCof) were either normal or elevated, but RCof/vWf:Ag ratio was decreased in seven patients. Crossed immunoelectrophoresis and sodium dodecyl sulfate (SDS)-agarose gel electrophoresis revealed that the large vWf multimers were either absent from or relatively decreased in all patients except one. In addition, one patient had unusually large vWf multimers, and a low-molecular-weight vWf fragment was apparently observed in three patients. These findings indicate that the intravascular generation of thrombin and plasmin was minimal in TTP and suggest that the alterations of the vWf molecule were caused not only by consumption through its participation in platelet thrombus formation but also by accelerated proteolysis. Low protein S values would be related to the immunological abnormalities underlying TTP.