Monitoring of hardening and hygroscopic induced strains in a calcium phosphate bone cement using FBG sensor.

This study initially deals with the investigation of the induced strains during hardening stage of a self-setting calcium phosphate bone cement using fiber-Bragg grating (FBG) optical sensors. A complementary Scanning Electron Microscopy (SEM) investigation was also conducted at different time intervals of the hardening period and its findings were related to the FBG recordings. From the obtained results, it is demonstrated that the FBG response is affected by the microstructural changes taking place when the bone cement is immersed into the hardening liquid media. Subsequently, the FBG sensor was used to monitor the absorption process and hygroscopic response of the hardened and dried biocement when exposed to a liquid/humid environment. From the FBG-based calculated hygric strains as a function of moisture concentration, the coefficient of moisture expansion (CME) of the examined bone cement was obtained, exhibiting two distinct linear regions.

Gamma nail breakage: a report of four cases.

Gamma nails have been used extensively for the treatment of proximal femoral fractures. Nail breakage at the level of the aperture of the lag screw is rare. We report 4 such cases mainly associated with a large posteromedial cortex gap and nonunion. The need for adequate reduction to avoid such a complication is emphasised.

Vickers hardness studies of calcium oxalate monohydrate and brushite urinary stones.

PURPOSE: To measure the hardness of two types of urinary stones: calcium oxalate monohydrate (COM; CaC2O4 . H2O) and dicalcium phosphate dihydrate (brushite; CaHPO4 . 2H2O). MATERIALS AND METHODS: The composition of 28 calcium oxalate monohydrate and 22 brushite stones was characterized by infrared spectroscopy (FT-IR). Stone specimens were embedded in crystallographic resin, polished, and subjected to indentation tests using a Vickers tester. The hardness was calculated from measuring the diagonal lengths of the residual indentation on the specimen using the appropriate equation. RESULTS: The COM stones showed hardness values ranging from 15.3 to 64.2 HV with a mean of 35.8 +/- 13.3, while brushite stones ranged from 10.1 to 46.1 HV with a mean of 26.5 +/- 15.1. The results of ANOVA showed that there were significant differences (P < 0.05) between the two stone types. CONCLUSIONS: Calcium oxalate monohydrate stones exhibited greater hardness than brushite stones when assessed with Vickers studies.

Aging assessment by dynamic mechanical analysis of in vivo encrusted polymeric urinary stents.

PURPOSE: To investigate the viscoelastic properties of plastic pigtail stents after removal from patients using the method of dynamic mechanical analysis (DMA). MATERIALS AND METHODS: Dynamic mechanical analysis was performed in 12 polymeric pigtail stents left indwelling for various periods of time (0-120 days). The encrustations were characterized by infrared spectroscopy, and their morphology was observed using scanning electron microscopy. RESULTS: Softening and stiffening behavior was observed. Stiffening was found specifically in the stents with heavy mineral deposits. CONCLUSIONS: Material degradation becomes obvious after certain periods of time. The effect of stent degradation appeared in two forms: softening of the stent polymer, possibly through interaction with urine, and stiffening of the stent secondary to the formation of various insoluble mineral deposits covered by layers of organic matrix.

Mobilization of refractory chronic schizophrenics with haloperidol.

Adequate high doses of haloperidol have been administered to 24 chronic, refractory to standard antipsychotic treatment, schizophrenics (16 male, 8 female, mean age 32.9 years) to investigate the possibility of mobilizing and releasing these patients from the hospital. Treatment was started with 20 mg haloperidol and optimal doses were determined for each patient. The median daily optimal dose at the end of the trial was 100mg. All patients were followed up for 16 weeks. Evaluating criteria were the BPRS, the Discharge Readiness Questionnaire, a side-effect rating scale, a CGI scale and the number of patients able to leave the hospital. 3 patients were evaluated as able to leave the hospital. 87.4% of the patients were subjectively evaluated as improved. High doses of haloperidol did not correlate with a higher incidence of unwanted effects. On the contrary antiparkinson treatment was discontinued or decreased in 14 patients. It is concluded that nonresponsive chronic schizophrenics can profit from adequate high doses of haloperidol.