Prosthetic choice in mitral valve replacement for severe chronic ischemic mitral regurgitation: Long-term follow-up

BackgroundProsthetic choice for mitral valve replacement is generally driven by patient age and patient and surgeon preference, and current guidelines do not discriminate between different etiologies of mitral valve disease. Our objective was to assess and compare short- and long-term outcomes after mitral valve replacement among patients with biological or mechanical prostheses in the setting of severe ischemic mitral regurgitation.MethodsBetween 2000 and 2016, 424 patients underwent mitral valve replacement for severe ischemic mitral regurgitation at our institution, using biological prosthesis in 188 (44%) and mechanical prosthesis in 236 (56%). A 1:1 propensity score match (n = 126 per group) and inverse probability of treatment weighting were used to compare groups. Short-term outcomes included in-hospital mortality and other cardiovascular adverse events. Long-term outcomes included survival and hospital readmission for cardiovascular causes, stroke, and major bleeding.ResultsIn-hospital mortality and early postoperative adverse events were similar between groups in the propensity score match and inverse probability of treatment weighting cohorts. Overall long-term survival was similar at 5 and 9 years, but mechanical prosthesis recipients were more frequently readmitted to hospital for cardiovascular causes, including stroke and non-neurological bleeding in propensity score matching and inverse probability of treatment weighting analyses (all P values < .004). Type of prosthesis did not independently influence all-cause mortality (hazard ratio, 1.01; 95% confidence interval, 0.71-1.43; P = .959), but placement of a mechanical prosthesis was associated with increased risk of readmission for cardiovascular events (hazard ratio, 1.65; 95% confidence interval, 1.17-2.32; P = .004) among matched patients.ConclusionsThe type of prosthesis has no influence on long-term survival among patients with severe ischemic mitral regurgitation undergoing mitral valve replacement. There may be an increased risk of neurologic events and serious bleeding associated with mechanical prostheses.     

个体化假体复合组织工程技术修复兔下颌骨缺损

目的研究快速成型（RP）技术辅助下制作的个体化假体复合珊瑚羟基磷灰石（CHA）、重组人骨形成蛋白2（rhBMP-2）修复兔下颌骨缺损的成骨效果。 方法以27只新西兰大白兔为实验对象，随机数字表法平均分成3组（每组9只），全部建立下颌骨连续性缺损模型，并在兔下颌骨缺损区分别植入个体化假体+自体骨（A组）、个体化假体+CHA（B组）、个体化假体+CHA+rhBMP-2（C组）。分别于术后4、12、24周3个时间点处死动物取材，进行大体标本观察，以及骨钙素（OC）、Ⅰ型胶原（COL-1）的免疫组化观察，分别比较各组修复骨缺损的能力，并对实验数据进行重复测量设计资料的单因素方差分析。 结果术后24周各组实验兔外形均对称，通过OC及COL-1的吸光度检测，骨缺损区均有大量新骨形成，A组（0.537 ± 0.010）、C组（0.530 ± 0.010）可见大量骨小梁及编织骨结构，缺损区的新骨OC、COL-1的免疫组化观察基本一致，差异无统计学意义（t = 0.007，P>0.05）；但A组强于B组（0.415 ± 0.009，t = 0.122，P<0.001）；C组也强于B组（t = 0.121，P<0.001），差异均有统计学意义。 结论在兔下颌骨缺损修复中，通过RP技术和组织工程技术相结合，CHA复合rhBMP-2后成骨能力明显增强，成骨效能肯定，为后期的临床应用提供可靠的实验基础。     

Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study

BACKGROUNDToday, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads.AIMTo compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits.METHODSThe study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet''s Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred.RESULTSThe breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly (P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM (P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 (P = 0.001).CONCLUSIONTANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration (P = 0.001) in healthy and in osteoporotic bone.     

鲑鱼降钙素对老年患者人工肱骨头置换术后影响的疗效观察

目的:观察抗骨质疏松药物对老年肱骨近端骨折患者行人工股骨头置换后的疗效影响。方法 :2012年11月至2016年6月肱骨近端骨折行人工肱骨头置换术患者38例,依据术后是否应用抗骨质疏松药物分为治疗组和对照组,治疗组19例,其中3部分骨折11例、4部分骨折8例,骨密度(0.58±0.14) g/cm~2;对照组19例,其中3部分骨折10例、4部分骨折9例,骨密度(0.58±0.11) g/cm~2。检测两组术前、术后4、8、12、24、48周假体周围骨密度(BMD),并行VAS疼痛评分,采用Neer评分系统评价肩关节功能。结果:术后患者切口均为甲级愈合,无并发症发生。35例患者获得1年随访。治疗组假体周围骨密度高于对照组,差异有统计学意义(P0.05);两组患者术后2、8周VAS评分差异无统计学意义(P0.05);治疗组Neer评分总分及功能评分优于对照组,差异有统计学意义(P0.05),疼痛及活动度评分两组比较,差异无统计学意义(P0.05)。依据Neer评分系统,治疗组优10例,良5例,可3例;对照组优3例,良9例,可5例;两组比较差异有统计学意义(P0.05)。结论:人工肱骨头置换结合抗骨质疏松药物治疗老年肱骨近端骨折可有效提高假体周围骨密度,恢复肩关节功能,早期临床效果满意。     

Fatigue resistance of yttria‐stabilized tetragonal zirconia polycrystal clasps for removable partial dentures

With the rapid development of computer‐aided design/computer‐aided manufacturing (CAD /CAM ) systems, the application of zirconia in removable partial dentures is expected to expand. Clasps composed of zirconia should improve esthetics without inducing the risk of metal allergy. The aim of this study was to examine the fatigue resistance of yttria‐stabilized tetragonal zirconia polycrystal (Y‐TZP) clasps for removable partial dentures. Yttria‐stabilized tetragonal zirconia polycrystal and cobalt‐chromium (Co‐Cr) alloy were prepared using CAD /CAM systems. Specimens were either of the semicircular type or of the flat type, with cross‐sectional areas of taper ratios of 0.50, 0.75, and 1.00. All specimens were tested using the cantilever test and the constant displacement fatigue test, and data were analyzed using ANOVA . During the cantilever test, the maximum displacement prior to fracture was greater than the required undercut, and the semicircular‐type specimen exhibited a higher fracture load than the flat type. None of the specimens displayed permanent deformation and showed almost the same degree of deformation after fatigue testing. A lower taper ratio was associated with lower average load values and greater displacement. Within the limitations of this study, it was possible to conclude that Y‐TZP provides the required undercut and adequate retentive force for removable partial denture clasps. Additionally, Y‐TZP and Co‐Cr alloy had almost the same degree of deformation even after the simulated lifespan of removable partial dentures.