No abstract

The purpose of this retrospective clinical study was to evaluate the factors that affect recompression of operated vertebrae after percutaneous balloon kyphoplasty (PKP) for osteoporotic vertebral compression fractures (VCFs) and assess their clinical importance. PKP has been used for VCFs with satisfactory results. Several studies about subsequent VCFs adjacent to cemented vertebrae have been reported after PKP. However, the presence and significance of recompression of operated vertebrae have not been adequately described. In total, 80 patients treated with PKP for single thoracolumbar VCFs were reviewed. The follow-up period was at least 1 year. Patients were divided into those without recompression (maintained group, n = 70) and those with recompression (recompressed group, n = 10). Plain roentgenography (preoperative, operative, and last), preoperative BMD, and preoperative MRI were checked. Age, gender, T-score in BMD, duration of symptom, compression rate (CR) of VCF, reduction rate, kyphotic angle (KA), reduction angle, intervertebral cleft (IVC), and non-PMMA-endplate-contact (NPEC) were evaluated. To evaluate the clinical results, we checked the VAS score at each follow-up period. All data were analyzed statistically. The CR for the recompressed group increased significantly after surgery and decreased at the last follow-up (p \ 0.05). The last CR was not significantly different from the preoperative CR. The KA showed the same pattern. The preoperative, postoperative, and last VAS scores were significantly different from one another in both groups (p \ 0.05). Between the groups, preoperative KA, postoperative KA, last KA, IVC, and NPEC were significantly different (p \ 0.05). In particular, last KA, IVC, and NPEC showed highly significant differences (p \ 0.001). In a correlation test for the evaluated factors, IVC (r = 0.557) and NPEC (r = 0.496) were the most significant. The presence of IVC and NPEC may play an important role in inducing recompression of treated vertebrae after PKP. Careful observation of patients with these conditions is necessary to prevent deterioration of their clinical course.

No abstract

Crystalline Mg-based alloys with a distinct reduction in hydrogen evolution were prepared through both electrochemical and microstructural engineering of the constituent phases. The addition of Zn to Mg-Ca alloy modified the corrosion potentials of two constituent phases (Mg + Mg2Ca), which prevented the formation of a galvanic circuit and achieved a comparable corrosion rate to high purity Mg. Furthermore, effective grain refinement induced by the extrusion allowed the achievement of much lower corrosion rate than high purity Mg. Animal studies confirmed the large reduction in hydrogen evolution and revealed good tissue compatibility with increased bone deposition around the newly developed Mg alloy implants. Thus, high strength Mg-Ca-Zn alloys with medically acceptable corrosion rate were developed and showed great potential for use in a new generation of biodegradable implants.