Structural phase formation and in vitro bioactivity evaluations of strontium phosphosilicate for orthopedic applications.
- 作者列表："Chetan","Vijayalakshmi U
:Structural features of apatites make them one of the most promising candidates for bone tissue regenerative applications. The unique structure and availability of mobile Metal ion as well as other components help interaction with biological fluids and can promote as well as stimulate bone regeneration with correct components. The present study focusses on Strontium phosphosilicate, an apatite analogue to Calcium phosphate-based HAP only loaded with better composition replacing Calcium with stimulatory Strontium and co-existent Silicate alongside phosphate both known to stimulate osteogenesis. Bulk particles were synthesized as powders with Acidic medium as well as the Basic medium of reaction mixture via Sol-Gel and Co-precipitation techniques respectively and phase formation was studied with respect to temperature further detailed by TGA-DSC studies. Secondary phases were also indexed based on which Acidic medium samples sintered at 800°C were comparatively better from the Basic medium on account of the presence of silicate phase forming agglomerated Strontium phosphosilicate. Hemolysis assay and MG-63 based cytotoxicity assay were carried out to study biocompatibility and antibacterial properties were also elucidated in Gram-positive and Gram-negative bacteria. Apatite seeding and bone mineralization studies were carried out with Simulated body fluid and characterized structurally and morphologically.
: Apatites 的结构特征使其成为骨组织再生应用最有前途的候选者之一。移动金属离子以及其他组件的独特结构和可用性有助于与生物流体相互作用，并且可以用正确的组件促进和刺激骨再生。本研究集中在磷硅酸盐锶，一种类似磷酸钙基 HAP 的磷灰石，仅负载更好的组合物，用刺激性锶代替钙，与磷酸盐共存的硅酸盐，已知两者均可刺激成骨。通过溶胶-凝胶和共沉淀技术分别在酸性介质和反应混合物的基本介质中合成了块状颗粒作为粉末，并进一步研究了相对于温度的相形成。TGA-DSC 研究。还根据在 800 ℃ 下烧结的酸性介质样品与基础介质相比较好，因为存在硅酸盐相，形成团聚的磷硅酸锶。采用溶血试验和 MG-63 细胞毒性试验研究革兰氏阳性菌和革兰氏阴性菌的生物相容性和抗菌性能。用模拟体液进行磷灰石种植和骨矿化研究，并进行结构和形态表征。
METHODS:Purpose To determine outcomes of transphyseal ACL reconstruction using a living parental hamstring tendon allograft in a consecutive series of 100 children. Methods One hundred consecutive juveniles undergoing ACL reconstruction with a living parental hamstring allograft were recruited prospectively and reviewed 2 years after ACL reconstruction with IKDC Knee Ligament Evaluation, and KT1000 instrumented laxity testing. Skeletally immature participants obtained annual radiographs until skeletal maturity, and long leg alignment radiographs at 2 years. Radiographic Posterior tibial slope was recorded. Results Of 100 juveniles, the median age was 14 years (range 8–16) and 68% male. At surgery, 30 juveniles were graded Tanner 1 or 2, 21 were Tanner 3 and 49 were Tanner 4 or 5. There were no cases of iatrogenic physeal injury or leg length discrepancy on long leg radiographs at 2 years, despite a median increase in height of 8 cm. Twelve patients had an ACL graft rupture and 9 had a contralateral ACL injury. Of those without further ACL injury, 82% returned to competitive sports, IKDC ligament evaluation was normal in 52% and nearly normal in 48%. The median side to side difference on manual maximum testing with the KT1000 was 2 mm (range − 1 to 5). A radiographic PTS of 12° or more was observed in 49%. Conclusions ACL reconstruction in the juvenile with living parental hamstring tendon allograft is a viable procedure associated with excellent clinical stability, patient-reported outcomes and return to sport over 2 years. Further ACL injury to the reconstructed and the contralateral knee remains a significant risk, with identical prevalence observed between the reconstructed and contralateral ACL between 12 and 24 months after surgery. Level of evidence III (Cohort Study).
METHODS:Purpose The purpose of the study was to investigate the biomechanics of walking and of the knee joint in the acute phase of ACL injury. Methods We examined 18 patients with acute ACL injuries and 20 healthy adults as controls. The biomechanics of the knee joint and of walking was assessed by 5 inertial sensors fixed with special cuffs to the lower back, the lower third of the thigh, and the lower third of the shank of the right and left legs. The movements and temporal characteristics were recorded while the subject was walking 10 m at a comfortable pace. Based on the results of examination, the patients were divided into two groups: with severe function impairment (6 patients) and with moderate function impairment (12 patients). Results It was found that in the first days post-trauma, not only the knee function was reduced, but the function of the entire lower limb as well. This led to a functional asymmetry. The kinematics of movements in the joints changed in accordance with slower walking. The walking became not only slower, but it was also associated with a decreased impact load in the weight acceptance phase. At later dates, the functional impairments were less pronounced. The total range of flexion motion did not exceed 20 degrees in the first group and 55 degrees in the second one. The injured joint developed functional immobilization within the first days post-injury. This was a guarding response by additional muscle strain to prevent unusual and limit physiological movements in the knee joint. The movements in the knee joint while walking were of small amplitude, rocking, and occurred only under load. The amplitude of the main flexion in the swing phase was reduced. Conclusion The stage of an ACL injury should be assessed not only based on the time post-trauma, but also taking account of the functional parameter—the knee range of flexion while walking. According to our findings, the only factor that had influenced the functional condition of the KJ was the duration of joint immobilization after trauma.
METHODS:Purpose Numerous techniques have been described for the tibial-sided graft preparation in anterior cruciate ligament (ACL) reconstruction. The use of less suture material for graft preparation is thought to improve ingrowth and to reduce the risk for infection. At the same time, the suture construct should be strong enough to resist the surgeon’s pull during tensioning of the transplant. Methods In total, 39 fresh-frozen procine deep flexor tendons were used and prepared as four-strand grafts. In the three-suture group ( n = 19), graft preparation was performed using three tibial-sided sutures, with each tendon end sutured separately. In the one-suture group ( n = 20), a modified graft preparation using only one tibial-sided suture was applied. Each sample underwent load-to-failure testing ( N _max) after cyclic pre-loading. To estimate intraoperative tension forces acting on the tibial-sided suture constructs, the maximal tension force of 26 volunteers on such a construct was measured using a load cell. Results The biomechanical testing of the two different suture constructs showed a significantly higher load-to-failure for the three-suture group (711 N ± 91 N) compared to the one-suture group (347 N ± 24 N) ( p = 0.0001). In both groups, the mode of failure was a tear of the suture in all samples. A failure of the suture–tendon interface was not observed in any case. The median maximal tension force on the construct applied by the 26 volunteers was 134 N (range 73–182 N). Conclusion The presented single-suture tendon graft preparation resisted to smaller failure loads than the conventional three-suture technique. However, no failures in the suture–tendon interface were seen and the failure loads observed were far beyond the tension forces that can be expected intraoperatively. Hence, the single-suture graft preparation technique may be a valuable alternative to the conventional technique.