50 patients out of a total of 88 who underwent treatment using a halo-fixateur between 1987 and 1997 were available for a follow-up interview reviewing local complications and quality of life. Marginal discomfort was observed in 54% of patients, moderate complaints/transitory pain in 30%, prolonged and severe discomfort and pain in 16%. 62% of patients took no analgetics, 22% infrequently, and 16% continuously throughout treatment. In pin-tract infection local treatment was successful in 6 patients, in 3 patients the screws needed to be relocated. Complaints of dysphagia due to extended forced lordosis of the cervical spine could be corrected by adjusting the position of the halo ring in 3 out of 8 patients. 3 patients developed pressure sores which could be managed without surgical intervention. Proper fixation and placement of the pin-tracts are crucial in the application of the halo fixateur if complications are to be avoided. Superficial infections must be treated locally. If the infection persists immediate pin relocation and systemic antibiotic therapy have to be initiated.

To evaluate the role of soluble mediators released after interaction of leukocytes with biomaterials on cells of the implant microenvironment, the surface expression of adhesion molecules (CD11b, CD62L, CD66b, ICAM-1) on freshly isolated whole blood leukocytes (WBL) was analyzed by flow cytometry after incubation in leukocyte/nickel-titanium shape-memory alloy (NiTi-SMA)-conditioned media. NiTi-SMA samples were either coated with calcium phosphate by dipping in oversaturated calcium phosphate solution (CaP-coating) or were non-coated. Peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) were isolated and seeded on both samples to generate respective conditioned media. In comparison with conditioned media obtained by non-coated NiTi-SMA, the expression of CD11b, CD66b, and ICAM-1 on WBL was upregulated by conditioned media obtained from CaP-coated samples. In contrast, the expression of CD62L on WBL was decreased after incubation in conditioned medium obtained from CaP-coated NiTi-samples compared to noncoated NiTi. These data demonstrate the possible influence of released mediators elicited by leukocyte-biomaterial interactions on cells of the implant microenvironment.

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