Bone mineral status in paraplegic patients who do or do not perform standing

Bone mineral density (BMD) was assessed by dual-photon X-ray absorptiometry at the lumbar spine (L3, L4), the proximal femur and the femoral shaft, and by single-photon absorptiometry at the forearm in 53 patients with complete traumatic paraplegia of at least 1 year's duration and in age- and sex-matched healthy controls. The patients did (n=38) or did not (n=15) regularly perform passive weightbearing standing with the aid of a standing device. Compared with the controls, the BMD of paraplegic patients was preserved in the lumbar spine and was markedly decreased in the proximal femur (33%) and the femoral shaft (25%). When considering all patients performing standing, they had a better-preserved BMD at the femoral shaft (p=0.009), but not at the proximal femur, than patients not performing standing. BMD at the lumbar spine (L3,L4) was marginally higher in the standing group (significant only for L3;p=0.040). A subgroup of patients performing standing with use of long leg braces had a significantly higher BMD at the proximal femur than patients using a standing frame or a standing wheelchair (p=0.030). The present results suggest that passive mechanical loading can have a beneficial effect on the preservation of bone mass in osteoporosis found in paraplegics.     

Absence of donor-type major histocompatibility complex class I antigen-bearing microglia in the rat central nervous system of radiation bone marrow chimeras

Localization of bone marrow-originated cells in the central nervous system (CNS) of the rat was investigated by using bone marrow chimeras. In order to do this, Lewis rats which carry major histocompatibility complex (MHC) class I antigens haplotype 1 (RT1.Al) were reconstituted with (Lew X PVG)F1 (RT1.Al/c) bone marrow cells after lethal irradiation. Transferred bone marrow cells were detected by immunohistochemical staining using a monoclonal antibody, OX27, specific for haplotype c of rat MHC class I antigens (RT1.Ac). The spleen and thymus of chimeric rats were fully reconstituted with transferred F1 cells 4 weeks after bone marrow transplantation. At this stage, mononuclear cells in the subarachnoid space of the CNS expressed OX27 antigen indicating that they were of bone marrow origin. A few OX27-positive blood cells were scattered in the CNS parenchyma 4-12 weeks after reconstitution. Ramified microglia, however, remained OX27-negative. Bone marrow-derived microglia were not observed throughout the period of examination until 24 weeks. In addition, experimental allergic encephalomyelitis (EAE) was induced in chimeric rats in order to augment the expression of MHC class I antigens on microglia. Even under this condition, no OX27-positive microglia were observed. Taken together, ramified microglia might be of neuroectodermal origin and there is little possibility that the microglia are derived from the bone marrow. However, if the ramified microglia are derived from blood cells, the microglia may be expected to have characteristic cell kinetics from the following points: (1) the precursor cells of the microglia may enter the CNS only at the perinatal stage; and (2) even under the condition in which lymphocytes and macrophages enter the CNS as observed in EAE, the precursor cells of the microglia are not supplied from the blood.     

X-linked hypophosphatemia: Normal renal function despite medullary nephrocalcinosis 25 years after transient vitamin D2-induced renal azotemia

Nephrocalcinosis (NC) detected by ultrasound is a recognized abnormality for some patients with X-linked hypophosphatemia (XLH) who received vitamin D₂ and inorganic phosphate therapy, but is commonly observed in XLH patients treated with 1,25-dihydroxyvitamin D₃ and inorganic phosphate supplementation. Nevertheless, long-term follow-up of kidney function in XLH patients with NC detected ultrasonographically has not been reported. We investigated two women with XLH, ages 31 (patient 1) and 39 (patient 2) years, each of whom had suffered at least one documented episode of vitamin D₂-induced hypercalcemia and renal azotemia during childhood. Patient 2 had also been treated with inorganic phosphate. No medications for XLH had been taken during adulthood. Renal ultrasonography at our institution demonstrated marked bilateral medullary NC in both women. No other explanation was found for their NC that apparently occurred several decades earlier from medical therapy for XLH. Detailed studies (including creatinine clearance, β₂-microglobulin excretion, and fasting urinary osmolality and acidification) revealed no impairment of kidney function in either patient. Our findings indicate that subradiographic medullary NC acquired during medical therapy for XLH may persist for decades, but with no adverse renal sequelae. Definitive (long-term) assessment of kidney function in the XLH population with NC, however, will be necessary to fully understand the risk of current medical treatment for this most common heritable form of rickets.     

Evaluation of vertebral volumetric vs. areal bone mineral density during growth

Bone mineral “density” (BMD) measured by dual-energy X-ray absorptiometry (DEXA) does not represent the volumetric density (grams per cubic centimeter), but rather the areal density (grams per square centimeter). This distinction is important during growth. The purpose of this study was to measure vertebral dimensions in cadavers of young pigtail macaques (Macaca nemestrina), and to derive equations to predict the volumetric bone density from noninvasive measurements. We measured the areal bone density by DEXA, vertebral volume by underwater weighing, mineral content by ashing, dimensions of lumbar vertebrae by calipers, and dimensions of vertebrae by radiography. Somatometric measurements of the female lumbar vertebral bodies showed that the shape changed during growth. The bone mineral content from the densitometer correlated significantly with the ash weight (r = 0.99, error 8.7%). The correlation coefficient between the volumetric bone mineral density and areal BMD measurement was significant (r = 0.68, p < 0.0001) with a 9.5% error; this improved significantly to 0.82 (7.2% error) when the BMD was divided by the vertebral depth from the radiograph. Areal BMD showed a strong correlation with age (r = 0.82, p < 0.0001), with an average increase of 7.4%/year. In contrast, volumetric mineral density showed a weak relationship with age (r = 0.43, p < 0.01), for an average increase of 1.5%/year. When studying bone mineral density during growth, the differences between volumetric and areal bone mineral density should be taken into consideration. (     

ZMW型环氧乙烷灭菌箱对骨移植材料灭菌效果的初步观察

目的 :观察ZMW型环氧乙烷灭菌箱对异体骨材料灭菌效果 ,旨在寻找一种安全、经济的灭菌方法。方法 :清洁条件下取骨 ,制成 0 .5cm× 0 .5cm× 2cm湿润骨材料和干燥骨材料 ,抽取样本 ,用ZMW型环氧乙烷灭菌箱 (15 0L)在不同温度及时间下消毒 ,以环氧乙烷指示胶带是否变色作为灭菌指标 ,样本在消毒前后分别作细菌培养。结果 :不同消毒条件下 ,每批样本均有细菌生长 ,干燥骨材料有菌率高于湿润的骨材料。结论 :ZMW型环氧乙烷灭菌箱不能使异体骨移植材料完全达到灭菌的要求 ,环氧乙烷指示胶带不能作为骨移植材料的灭菌指标 ,干燥可能使细菌的抗环氧乙烷能力增加 ,从而间接的影响了环氧乙烷的消毒效果。     

骨髓间充质干细胞的分离培养及生物学特性研究

目的：通过体外细胞的培养方法将骨髓间充质干细胞由骨髓血中分离出来并加以纯化，进一步在体外培养条件下研究其增殖及生长特征，从而为探讨后续利用组织工程学方法修复肌肉骨骼系统组织缺损的可能性提供实验基础。方法：从骨髓血中提取间充质干细胞，体外培养扩增，再以相差显微镜、电镜观察并绘制生长曲线。结果：（1）通过离体培养，可以使体内环境下低丰度的骨髓间充质干细胞实现数目扩增。（2）体外培养条件下骨髓间充质干细胞具有成纤维细胞的生长特性。（3）体外单层培养条件下贴壁生长的骨髓间充质干细胞会出现“返祖现象”。（4）骨髓间充质干细胞内细胞器与其生物活性变化相一致。结论：骨髓间充质干细胞体外培养成功为今后利用自体间充质干细胞通过组织工程学方法修复肌肉骨骼系统的组织缺损提供功能细胞奠定了基础。     

The difficult primary hip

Hip arthroplasty is a common orthopaedic procedure with proven long-term success and reliable results. A wide range of associated conditions may affect the outcome of the arthroplasty and the surgeon has to keep these in mind when planning the surgery. In this article, such situations are discussed and recommendations are drawn from the evidence available in literature.     

Rotational acetabular osteotomy for acetabular dysplasia of the hip with a giant acetabular bone cyst: a case report

In acetabular dysplasia of the hip joint accompanied by a giant acetabular bone cyst, rotational acetabular osteotomy may cause serious complications, such as bone necrosis after surgery or fracture of the fragile acetabulum during the operation. In a patient with this condition, we performed a two-stage operation: first, autogenous bone grafting supplemented with hydroxyapatite filling, then rotational acetabular osteotomy (after new bone formation had been assured). Radiographs and CT scans showed favorable fusion of the grafted bone. Some 18 months after the second operation, arthrograms showed no inflow of contrast medium from the articular cavity into the bone cyst region, although this had been observed before treatment. Thus, an effective remodeling of bony congruency was indicated in the mobile acetabulum 5 years after the second operation. This two-stage operation appears to be useful for correcting acetabular dysplasia accompanied by a giant bone cyst and to carry a reduced risk of serious complications, such as deterioration of the articular surface of the acetabulum or necrosis of the translocated acetabulum.     

藻酸钙凝胶-成骨细胞-骨粉构建工程化骨修复兔颅骨缺损的实验研究

目的探讨藻酸钙凝胶、成骨细胞、骨粉复合构建的可塑形组织工程骨修补兔颅骨缺损后的形态学变化和成骨效果.方法28只日本大耳白兔,随机分为A(n=20)、B(n=8)两组,手术在兔颅顶骨矢状缝两侧分别各建立一个直径1cm的圆形全层缺损,用两种方法藻酸钙凝胶、成骨细胞、骨粉和藻酸钙凝胶、骨粉分别构建组成可塑形的组织工程骨复合材料,分别填补修复A组兔颅骨左右两侧的缺损,B组为空白对照组,通过大体、组织学、X线观察材料的形态变化、成骨情况,并对X线片和组织学切片进行评分.结果材料植入后,局部未见红肿、积液、渗出等异常反应.①藻酸钙凝胶-成骨细胞-骨粉组修补后12周颅骨缺损基本被硬性组织所修复,镜下见修复材料大多被骨组织替代,骨粉基本被吸收,有块状凝胶残留其中,组织学评分为(5.50±1.00).X线片见兔颅骨缺损处有高密度骨痂影存在,布满整个缺损区,X线片评分为(3.25±0.95).②藻酸钙凝胶-骨粉组修补后12周部分颅骨缺损被硬性组织所修复,镜下见修复材料部分转变成骨组织,骨粉基本被吸收,有凝胶残留其中,组织学评分为(3.25±1.50).X线片见兔颅骨缺损处有高密度骨痂影存在,主要分布在缺损区的边缘部位,X线片评分(2.25±0.25).③空白对照组骨缺损主要被膜样纤维组织修复,在紧邻骨缺损边缘处有硬性组织形成,镜下见修复组织边缘有骨组织存在,中央大部为膜状致密纤维组织,组织学评分为(1.50±0.50),X线片仅见靠近骨缺损边缘的部位存在致密骨痂影,X线片评分为(1.00±0.57).结论藻酸钙凝胶、成骨细胞、骨粉构建的可塑形组织工程骨可根据颅骨缺损的形态进行塑形填补,在体内有良好的成骨能力,可达到对兔颅骨缺损的骨性修复,但部分藻酸盐凝胶吸收缓慢,手术后12周仍不能满意吸收.