After knee replacement, therapy resistant, chronic synovitis is common and leads to effusion and pain. A cohort of 55 patients with 57 knee replacements and chronic synovitis underwent radiosynoviorthesis. In summary, 101 joints were treated using 182±9 MBq of 90Y-citrate. The number of radiosynoviorthesis ranged from 1 to 4 (53%, 21%, 23%, and 4%). Every patient received a 99mTc-MDP scintigraphy before and three months after every radiosynoviorthesis. Follow-up ranged from 5.7 to 86.7 months. For qualitative analysis, an four steps scoring was used (0 = no response or worsening, 1 = slight, 2 = good, 3 = excellent response). For quantification, the uptake was determined within the 99mTc-MDP scintigraphy soft tissue phase before and after therapy. At the end of long-term follow-up 27% of patients have an excellent, 24% good, 30% slight and 20% no response. The duration of response was 7.5±8.3 months (maximum 27 months). In repeated treatment, the effect after the first therapy was lesser than in patients who received a single treatment in total. However, three months after the last radiosynoviorthesis, patients with repeated treatment showed a similar effectiveness than single treated patients. At the end of long-term follow-up, patients with repeated radiosynoviorthesis had a higher effectiveness at similar duration response. In the 99mTc-MDP scan 65% of patients showed a reduction of uptake. When comparing subjective and objective response 78% of patients showed a concordance in both, symptoms and scintigraphy. Pilot histological analysis revealed that the synovitis is triggered by small plastic particles. Radiosynoviorthesis is effective in patients with knee replacement and chronic synovitis. It shows good subjective and objective response rates and long response duration. Repeated treatment leads to a stronger long-time response. The chronic synovitis is caused by plastic particles, which result from the abrasion of the polymeric inlay of endoprothesis

Summary Statement. One of the most challenging problems in osteogenic 3D-tissue engineering is, to quantify the amount of new hydroxylapatite deposition. . 18. F-NaF-Labeling is a new, high-sensitive method to proof and quantify the osteogenic potential of hMSCs in an in vitro 3D-model. Introduction. 18. F-labeled sodium fluorine was the first widely used agent for skeletal scintigraphy in the 1960s. . 18. F-NaF is rapidly exchanged for hydroxylgroups of the hydroxylapatite, covalently binding to the surface of new bone, which results in the formation of fluoroapatite. Three dimensional scaffolds are used to favor osteogenic differentiation of precursor cells. Cell-loaded scaffolds are investigated for their healing potential of critical size bone defects. Assessing the osteogenic potential of MSCs in 3D-in vitro cultures is of major interest in tissue engineering in order to maximise bone formation in vitro and in vivo. One of the most challenging problems is, to quantify directly the amount of new hydroxylapatite deposition without destroying the evaluated cell-loaded scaffold. Within this abstract, we present a novel, non-destructive, high-sensitive method to quantify the amount of local hydroxylapatite deposition in 3D-cultures using . 18. F-NaF. Material & Methods. hMSCs (n=5) were seeded in duplicates on highly porous collagen I/III scaffolds (circular, 8 × 2mm, 550.000 cells/scaffold). Osteogenic differentiation of the MSCs was established with DMEM low glucose + 10% FCS + 1% P/S + 10mM beta-glycerol phosphate + 173µM ascorbicacid-2-phosphate + 100nM dexamethasone. As control the same media without osteogenic supplements was used. Cultures were kept at 37°C and 5% CO. 2. , media was changed every 2 days. After 21 days 40 MBq . 18. F-NaF in 1ml 0,9%NaCl was added to each scaffold, placed in a 2ml tube. After 2 hours of incubation, scaffolds were washed in aqua dest. (3x). To measure the bound activity, two methods were used. First the scaffolds were placed in an activity-meter (dose-calibrator) to assess the amount of bound radioactive tracer in MBq. Then, all scaffolds were placed in a µ-PET-scanner also for quantification of the bound activity (Bq/ml) and for 3D-imaging. To quantify the absolute calcium content, the 8mm scaffolds were lysed and analyzed by inductively coupled plasma massspectrometry (ICP-MS). In advance a DNA-Pico-Green assay was performed and all results were normalised to the DNA-amount of each scaffold. Qualitative proof for the presence of hydroxylapatite was made by alizarin red staining as well as by scanning electron microscopy followed by energy dispersive X-ray-spectroscopy (SEM/EDX) of the histology sections (6µm) from the paraffin embedded duplicate scaffolds. Results. The . 18. F activity evaluated by µ-PET scan and the results from the activity meter showed a statistically significant tracer uptake in the osteogenic induced group when compared to controls; Mann-Whitney-U Test: p=0,008 (µ-PET), p=0,008 (activity-meter). Spearman-Correlation analysis showed a statistical significant high correlation for the two methods (correlation-coefficient 0,712; p = 0,019). Results from ICP-MS revealed significant amounts of calcium within the osteogenic group samples while within the control group was no calcium detection at all. The alizarin red stained slides also showed a positive stain for the osteogenic group, within the control group there was positive stain. SEM/EDX confirmed the presence of calcium and phosphorus for the osteogenic group. Conclusion. Measurement of . 18. F-NaF uptake is a high-sensitive method to proof and quantify the osteogenic potential of hMSCs in a collagen scaffold based three dimensional tissue engineering model

Objectives

This systematic review aimed to assess the in vivo and clinical effect of strontium (Sr)-enriched biomaterials in bone formation and/or remodelling.

There is no diagnostic, non-invasive method for the early detection of loosening after total hip arthroplasty. In a pilot study, we have analysed two serum markers of bone remodelling, procollagen I C-terminal extension peptide (PICP) and cross-linked N-terminal telopeptide (NTx), as well as the diagnostic performance of NTx for the assessment of osteolysis. We recruited 21 patients with loosening (group I), 18 with a well-fixed prosthesis (group II) and 17 at the time of primary arthroplasty for osteoarthritis (OA) (group III). Internal normal reference ranges were obtained from 30 healthy subjects (group IV).

The serum PICP level was found to be significantly lower in patients with OA and those with loosening, when compared with those with stable implants, while the NTx level was significantly increased only in the group with loosening, suggesting that collagen degradation depended on the altered bone turnover induced by the implant. This hypothesis was reinforced by the finding that the values in the pre-surgery patients and stable subjects were comparable with the reference range of younger healthy subjects.

A high specificity and positive predictive value for NTx provided good diagnostic evidence of agreement between the test and the clinical and radiological evaluations. The NTx level could be used to indicate stability of the implant. However, further prospective, larger studies are necessary.