In an interdisciplinary project involving electronic engineers and clinicians, a telemetric system was developed to measure the bending load in a titanium internal femoral fixator. As this was a new device, the main question posed was: what clinically relevant information could be drawn from its application? As a first clinical investigation, 27 patients (24 men, three women) with a mean age of 38.4 years (19 to 66) with femoral nonunions were treated using the system. The mean duration of the nonunion was 15.4 months (5 to 69). The elasticity of the plate-callus system was measured telemetrically until union. Conventional radiographs and a CT scan at 12 weeks were performed routinely, and healing was staged according to the CT scans. All nonunions healed at a mean of 21.5 weeks (13 to 37). Well before any radiological signs of healing could be detected, a substantial decrease in elasticity was recorded. The relative elasticity decreased to 50% at a mean of 7.8 weeks (3.5 to 13) and to 10% at a mean of 19.3 weeks (4.5 to 37). At 12 weeks the mean relative elasticity was 28.1% (0% to 56%). The relative elasticity was significantly different between the different healing stages as determined by the CT scans.

Incorporating load measuring electronics into implants is a promising option for the assessment of bone healing. Future application might lead to a reduction in the need for exposure to ionising radiation to monitor fracture healing.

The precise localisation of osteoarthritic changes is crucial for selective surgical treatment. Single photon-emission CT-CT (SPECT-CT) combines both morphological and biological information. We hypothesised that SPECT-CT increased the intra- and interobserver reliability to localise increased uptake compared with traditional evaluation of CT and bone scanning together. We evaluated 20 consecutive patients with pain of uncertain origin in the foot and ankle by radiography and SPECT-CT, available as fused SPECT-CT, and by separate bone scanning and CT. Five observers assessed the presence or absence of arthritis. The images were blinded and randomly ordered. They were evaluated twice at an interval of six weeks. Kappa and multirater kappa values were calculated.

The mean intraobserver reliability for SPECT-CT was excellent (κ = 0.86; 95% CI 0.81 to 0.88) and significantly higher than that for CT and bone scanning together. SPECT-CT had significantly higher interobserver agreement, especially when evaluating the naviculocuneiform and tarsometatarsal joints.

SPECT-CT is useful in localising active arthritis especially in areas where the number and configuration of joints are complex.

The human cystein-rich protein 61 (hCYR61) belongs to an emerging family of genes which modulate growth and differentiation. Previously, hCYR61 was identified by us as a fast and transiently 1,25(OH)2-vitamin D3 responsive gene product in human osteoblasts by differential display PCR. Here, we further studied the role of the protein in human osteoblasts.

Using the human hFOB cell line hCYR61 mRNA was analysed by northern hybridisation. Protein levels were detected using western blotting. Intracellular localisation of the hCYR61 protein was determined using the expression as a fusion protein with green fluorescent protein. Immunohistology was performed in hFOB cells as well as primary human osteoblasts and human bone samples.

From northern analyses the hCYR61 mRNA was regulated by 1,25(OH)2-vitamin D3 as well as the growth factors TNFa, EGF, bFGF and IL1b 5-10-fold within 1 hour in the hFOB cell line. Here we show that the same factors markedly upregulated the hCYR61 protein within 24 to 48 hours in hFOB cells as has been analysed by western blotting. From cellular supernatants a highly upregulation of the hCYR61 protein by the growth factors was observed. A full length hCYR61 protein fused to the green fluorescent protein localised to the Golgi-apparatus. From immunohistology proliferating hFOB cells and primary osteoblasts express significant hCYR61 protein, whereas differentiated osteoblasts display a marked downregulation of hCYR61. In human bone high levels of hCYR61 were observed at the human growth plate as well as on surfaces of mineralised structures.

In summary, hCYR61 in human bone represents an immediate early regulated gene. The secreted protein plays a role as an extracellular matrix signaling protein which could play an important role in cell-cell communication within the bone microenvironment. The high expression level and regulation patterns observed in our studies suggest an important role in situations of bone repair and remodeling.