Key Engineering Materials Vol. 587

Abstract: Benign lytic lesions represent a frequent pathology in our clinic. Regarding therapy, we approach these benign tumors through curettage and filling the defects with bone grafting or bone substitutes like hydroxyapatite crystals and tricalcium phosphate.We want to evaluate the efficiency of both bone grafts and bone substitutes regarding bone consolidation, osseointegration and time until absorption for tricalcium phosphate and hydroxyapatite crystals combination. We analyzed 14 patients treated in our clinic through curettage and defect filling during the last three years: 9 patients’ beneficiated from bone grafting and for the other 5 we used a hydroxyapatite and tricalcium phosphate combination from the same supplier. Diagnoses were bone cyst, non-ossifying fibroma and giant-cell tumor. Therapeutic method was linked with bone graft availability. Follow-up was 24 months through periodical x-ray controls in our clinic. Bone consolidation was satisfactory in all cases with no defect collapse. In conclusion, bone substitutes like combinations of hydroxyapatite crystals and tricalcium phosphate are a useful and safe method for surgical treatment of strictly benign lytic tumors.

Abstract: In this research, the purpose is to carry out the in vitro study of the plasticity hybrid complex. The main components of the material are tricalcium silicate (C₃S, Ca₃SiO₅) and collagen. In vitro studies, including cell toxicity test (MTT), flowcytometry detection and alkaline phosphatase test (ALP) were carried out to evaluate the biocompatibility of the materials and soaking mediums. Results showed that soaking mediums of different amounts of materials didn’t affect cell growth harmfully. Moreover, the soaking mediums would stimulate the osteoblast and trigger the biomineralization processes leading to higher secretion of ALP during cultivation.. The results in this research showed that the biocompatibility of our hybrid complex for future applications.

Abstract: In orthopedics are used a lot of specialized tools and reconstructive elements. Many of these are tools bounded by helical surfaces, significantly different from those used in similarly constructions with general character. There are analyzed, in a comparative way, two methods for profiling side mill tools for generation of specific threads used in the construction of the orthopaedic prosthetic screw. It is proposed an analytical method, based on the fundamental theorem of the surfaces enveloping versus a graphical method, developed in CATIA.

Abstract: The study presented in the current paper was designed to investigate periprosthetic bone remodeling associated with two cementless HA coated stem models, ABG-II (Stryker) and Corail (DePuy), randomly implanted in 40 active patients at Colentina Clinical Hospital,Romania. Anteroposterior with neutral rotation and Lequesne profile radiographs of both hips were taken and several data were recorded: acetabular angle, rotation center of the hip, rotation center height with respect to the greater trochanter tip, femoral cortical thickness, cortico-medullary index at three areas (lesser trochanter (LT), 8 and 12 mm distal to LT), and osteoporosis severity according to the Singh index. The presence of osteolytic lesions in the proximal femur was assessed according to the scale proposed by Goetz in the radiographs obtained at the end of the follow-up (1 to 5 years). The radiological results showed that all stems were stable, and no evolutive radiolucent lines have been observed. We also have noticed minimal remodelling changes in 7 hips (36.61%), with minor cancellous bone densification mainly in zones 2 and 6, without cortical hypertrophy or osteoporosis. A decreased bone density in zones 1 and 7, secondary to stress-shielding, has been evident in 5 hips. Stem subsidence has been similar to that reported in literature with other hydroxyapatite coated designs.