The effect of three different calcium phosphate implant coatings on bone deposition and coating resorption: a long-term histological study in sheep.

The present study investigated the hypothesis that hydroxyapatite (HA), tricalcium phosphate (TCP), and a HA-gel coated on endosseous titanium (Ti) implants by spark discharging (SD) and dip coating would achieve predictable osseointegration without evident bioresorption of the coatings on the long term. A costal sheep model was used for the implantation of the HA/SD, HA/TCP/SD, and HA-gel/SD specimens, which were retrieved 6 and 12 months following implantation. HA and Ti coatings on implants obtained by conventional plasma spraying (HA/PS, Ti/PS) were used as controls. Microscopy showed that osseointegration was achieved from all types of implants. No evidence for bioresorption of the HA/SD, HA/TCP/SD, and HA-gel/SD coatings was present but cohesive failure with disruption of the coating/implant interface was seen. A statistical analysis of the histomorphometrical data showed no time-dependent effect, however. HA/PS coatings achieved significantly higher bone-implant contact (BIC) percentages of the total implant surface (toBIC) than the other types of coatings (P=0.01). If the BIC percentages were traced separately for implant portions placed into cortical and cancellous bone (coBIC and caBIC, respectively), detailed analysis showed that the caBIC values of HA-gel/SD and HA/PS coatings were significantly higher than that of the other types of coatings (P=0.01). CaBIC values were highly correlated with toBIC values (P<0.001). The present study showed that the preparation techniques used produced thin, dense, and unresorbable coatings that achieved osseointegration. Compared with the control coatings, however, only HA-gel/SD coating can be recommended from the investigated preparation techniques for a future clinical use if a better coating cohesion is achieved.

HA/TCP compounding of a porous CaP biomaterial improves bone formation and scaffold degradation--a long-term histological study.

In the present study, two biphasic calcium phosphate biomaterials (BCP) with HA/TCP ratios of 50/50 and 30/70 were obtained from a pure HA biomaterial. The biomaterials which showed the same three-dimensional geometry were implanted into corticocancellous costal defects of sheep. In the specimens of all three biomaterials, abundant bone formation, mineral dissolution from the biomaterial scaffolds, and active cellular resorption of the scaffolds was present after 6 and 12 months. Backscattered electron microscopy showed bone invasion into the pores of the scaffolds and micromechanical interlocking at the bone/biomaterial interface without intervening soft tissue. The pattern of bone formation and scaffold resorption was different for cortical and cancellous bone. No time-based effect, however, was observed. Overall, the BCP biomaterials had formed significantly more bone than the HA biomaterial. Also, scaffold resorption, which was followed by a replacement with newly formed bone, was significantly higher in the BCP biomaterials. Although no significant differences were observed between both BCP biomaterials, the present study had confirmed the assumption that HA/TCP compounding was suitable to improve bone formation and scaffold resorption in the investigated biomaterials and at the same time maintain the osteoconductive properties of the scaffolds.

International experience with conversion from cyclosporine to tacrolimus for acute and chronic lung allograft rejection.

OBJECTIVE: A retrospective study involving 13 institutions was performed to assess the efficacy of conversion from cyclosporine (INN: ciclosporin) to tacrolimus. METHODS: Data from 244 patients were analyzed. Indications for conversion were recurrent-ongoing rejection (n = 110) and stage 1 to 3 bronchiolitis obliterans syndrome (n = 134). RESULTS: The incidence of acute rejection decreased significantly within 3 months after versus before the switch from cyclosporine to tacrolimus (P <.01). For patients with recurrent-ongoing rejection, the forced expiratory volume in 1 second decreased by 1.96% of predicted value per month (P =.08 vs zero slope) before and increased by 0.34% of predicted value per month (P =.32 vs zero slope) after conversion (P <.06). For patients with stage 1 to 3 bronchiolitis obliterans syndrome, a significant reduction of rejection episodes was observed (P <.01). In single transplant recipients a decrease of the forced expiratory volume in 1 second averaged 2.25% of predicted value per month (P <.01 vs zero slope) before and 0.29% of predicted value per month after conversion. Corresponding values for bilateral transplant recipients were 3.7% of predicted value per month (P <.01 vs zero slope) and 0.9% of predicted value per month (P = 0.04 vs zero slope), respectively. No significant difference in the incidence of infections within 3 months before and after conversion was observed. CONCLUSIONS: Conversion from cyclosporine to tacrolimus after lung transplantation is associated with reversal of recurrent-ongoing rejection. Conversion for bronchiolitis obliterans syndrome allows short-term stabilization of lung function in most patients.

Cross-cultural adaption of the Manniche questionnaire for German-speaking low back pain patients.

OBJECTIVE: To develop and validate a cross-cultural version of the Manniche Low Back Pain Rating Scale (MRS) for use in German-speaking low back pain patients. BACKGROUND: Clinical intervention research in back pain would be enormously facilitated if a small number of relevant, patient-centred questionnaires became internationally used. MRS seems to be particularly suitable for cross-cultural adaptation due to its coverage of multidimensional back pain-specific health domains. METHODS: MRS was translated and back-translated, pretested and reviewed by a committee. The German version was tested in 126 patients with low back pain from all countries of German-speaking Europe. Reliability (subsample n = 20), dimensionality and construct validity was assessed. Single-dimensionality, higher correlations of MRS with the physical scales compared with the mental scales of the MOS SF-36, a moderate to good correlation with the Roland Morris Questionnaire and a low correlation with the Finger Floor Distance were hypothesized. RESULTS: Spearman's Rho for test-retest reliability was 0.98 (p < 0.001); Cronbach's alpha 0.95. Factor analysis revealed only 1 factor with an Eigenvalue >1 [3.25]. MRS was strongly correlated with the Roland Morris Questionnaire (r = 0.91), and slightly correlated with the Finger Floor Distance (r = 0.23). Correlations of MRS with domains of the SF-36 "Physical Functioning", "Role Physical" and "Bodily Pain" were higher (r -0.66 to -0.72) than with "Role Emotional", "Mental Health" and "Social Functioning" (r -0.34 to -0.61). CONCLUSION: The German version of the MRS seems to be reliable, uni-dimensional and construct valid for the assessment of functional status in German-speaking low back pain patients.

Treatment of complex arteriosclerotic lesions with nitinol stents in the superficial femoral and popliteal arteries: a midterm follow-up.

PURPOSE: To evaluate the effectiveness of nitinol stents in patients with short, complex lesions in the superficial femoral and popliteal arteries and to assess midterm results. MATERIALS AND METHODS: Self-expandable nitinol stents were implanted in 54 extremities in 44 patients to treat complex stenoses (n = 32) and occlusions (n = 22) in the superficial femoral and popliteal arteries. Follow-up was performed for 5-51 months to evaluate early thrombosis and midterm patency rates. Midterm patency rates were compared between the following: stenoses and occlusions, proximal and distal locations, good and poor runoff, and diabetic patients and nondiabetic patients. All patients underwent clinical investigation and color Doppler sonography after 1 month and 6 months and at 6-month intervals thereafter. If restenosis or stent thrombosis was suspected, intraarterial digital subtraction angiography of the superficial and popliteal arteries was performed. RESULTS: Percutaneous stent implantation was successful in all patients. The mean duration of follow-up was 27 months (range, 5-51 months). No thrombotic occlusion occurred within the first 4 weeks after stent implantation. The primary 3-year patency rate was 76%, and the secondary patency rate was 87%. Three-year primary patency rates were 65% for diabetic patients and 82% for nondiabetic patients. CONCLUSION: In patients with short, complex stenoses and occlusions, implantation of nitinol stents may have a positive impact on midterm results.