Particle size and morphology of UHMWPE wear debris in failed total knee arthroplasties--a comparison between mobile bearing and fixed bearing knees.

Osteolysis induced by ultrahigh molecular weight polyethylene wear debris has been recognized as the major cause of long-term failure in total joint arthroplasties. In a previous study, the prevalence of intraoperatively identified osteolysis during primary revision surgery was much higher in mobile bearing knee replacements (47%) than in fixed bearing knee replacements (13%). We postulated that mobile bearing knee implants tend to produce smaller sized particles. In our current study, we compared the particle size and morphology of polyethylene wear debris between failed mobile bearing and fixed bearing knees. Tissue specimens from interfacial and lytic regions were extracted during revision surgery of 10 mobile bearing knees (all of the low contact stress (LCS) design) and 17 fixed bearing knees (10 of the porous-coated anatomic (PCA) and 7 of the Miller/Galante design). Polyethylene particles were isolated from the tissue specimens and examined using both scanning electron microscopy and light-scattering analyses. The LCS mobile bearing knees produced smaller particulate debris (mean equivalent spherical diameter: 0.58 microm in LCS, 1.17 microm in PCA and 5.23 microm in M/G) and more granular debris (mean value: 93% in LCS, 77% in PCA and 15% in M/G).     

帕米磷酸钠和降钙素对人工关节磨损微粒引起单核细胞分泌溶骨性因子的影响

目的　探讨帕米磷酸钠和降钙素防治人工关节松动的可能性。方法　采集人体外周血 ,分离单核细胞 ,分组培养。实验分 4组 ,第 1组 :仅单核细胞 ,为对照组 ;第 2组 :单核细胞及微粒 ,为微粒组 ;第 3组 :单核细胞、微粒及帕米磷酸钠 (阿可达 ) ,为阿可达组 ;第 4组 :单核细胞、微粒及降钙素 (密钙息 ) ,为密钙息组。培养 48h后 ,检测细胞上清液中肿瘤坏死因子 (TNF) α、白细胞介素 (IL) 1和IL 6的含量。结果　微粒组的细胞上清液中溶骨性因子含量明显高于对照组 (P <0 .0 1) ;而阿可达组和密钙息组的溶骨性因子含量明显低于微粒组 (P <0 .0 1)。结论　阿可达和密钙息能有效地抑制微粒刺激单核巨噬细胞分泌溶骨性因子 ,从而间接抑制破骨细胞的活性。     

Multiple brown tumors in a patient with nutritional secondary hyperparathyroidism

Summary For years, brown tumors have been considered to be a characteristic of primary hyperparathyroidism. However, since 1963 several reports indicate the incidence of brown tumors in patients with renal secondary hyperparathyroidism to be 1.5%–1.7%. The appearance of multiple brown tumor lesions is rather uncommon in secondary hyperparathyroidism which is also true for malabsorption as its cause. We report on a 56-year-old man presenting with pain in the bones and multiple osteolyses. A bone biopsy specimen and the laboratory examinations were indicative of secondary hyperparathyroidism caused by malabsorption most likely due to Billroth's II/I gastric resection. Thus, the patient's osteolyses represent brown tumors which have been induced by nutritional secondary hyperparathyroidism.     

药物对微粒刺激单核细胞溶骨性因子分泌的影响

目的建立人工关节无菌性松动的体外模型，探讨药物防治人工关节松动的可能性。方法(1)体外模型：人体外周血单核细胞分别与骨水泥、聚乙烯和钛合金微粒混合培养，测定上清中溶骨性因子。(2)实验分组：采集志愿献血外周血，分离单核细胞。分骨水泥、聚乙烯和钛合金三组。每组再分4亚组，I亚组：单核细胞；H亚组：单核细胞十微粒；Ⅲ亚组：单核细胞十微粒十帕米膦酸钠；IV亚组：单核细胞十微粒十降钙素。培养48小时，检测上清TNF-α、IL-l和IL-6的含量。结果Ⅱ亚组上清中溶骨因子含量高于I、Ⅲ、IV(p＜0．01)；I、Ⅲ、IV组间差异无统计学意义(P＞0．05)。结论二磷酸盐类药物和降钙素能够抑制微粒对单核巨噬细胞的激活作用，并能直接抑制破骨细胞，因此有望成为防治人工关节无菌性松动的有效药物。     

Osteolysis around total knee arthroplasty: A review of pathogenetic mechanisms

Aseptic loosening and other wear-related complications are some of the most frequent late reasons for revision of total knee arthroplasty (TKA). Periprosthetic osteolysis (PPOL) pre-dates aseptic loosening in many cases, indicating the clinical significance of this pathogenic mechanism. A variety of implant-, surgery- and host-related factors have been delineated to explain the development of PPOL. These factors influence the development of PPOL because of changes in mechanical stresses within the vicinity of the prosthetic device, excessive wear of the polyethylene liner, and joint fluid pressure and flow acting on the peri-implant bone. The process of aseptic loosening is initially governed by factors such as implant/limb alignment, device fixation quality and muscle coordination/strength. Later, large numbers of wear particles detached from TKA trigger and perpetuate particle disease, as highlighted by progressive growth of inflammatory/granulomatous tissue around the joint cavity. An increased accumulation of osteoclasts at the bone–implant interface, impairment of osteoblast function, mechanical stresses and increased production of joint fluid contribute to bone resorption and subsequent loosening of the implant. In addition, hypersensitivity and adverse reactions to metal debris may contribute to aseptic TKA failure, but should be determined more precisely. Patient activity level appears to be the most important factor when the long-term development of PPOL is considered. Surgical technique, implant design and material factors are the most important preventative factors, because they influence both the generation of wear debris and excessive mechanical stresses. New generations of bearing surfaces and designs for TKA should carefully address these important issues in extensive preclinical studies. Currently, there is little evidence that PPOL can be prevented by pharmacological intervention.     

Treatment of spinal epidural compression due to hematological malignancies: a single institution’s retrospective experience

Purpose

To analyze the neurological and mechanical outcomes in 44 consecutive patients treated for a hematological malignancy with epidural localization to assess the place of surgery in the treatment of this pathology.

Methods

Clinical records, CT and MRI scans of 44 patients with epidural localizations of multiple myeloma or lymphoma treated between 1990 and 2005 were analyzed retrospectively. Neurological status, epiduritis and osteolysis volumes, vertebral collapse, and spinal canal compromise were assessed. The neurological outcome was graded according to Frankel and the mechanical outcome was evaluated on the rate of vertebral collapse.

Results

Surgery was performed in 11 patients (25 %) for neurological (n = 9) or mechanical (n = 2) reasons. In five cases, a concomitant biopsy was performed because the etiology of the epiduritis was unknown. Fifteen patients (34.1 %) presented with a neurological deficit secondary to an acute vertebral collapse (n = 4), an epiduritis (n = 7), or both (n = 4). Whatever the treatment (surgical or not), a complete recovery (Frankel E) occurred in 14/15 (93.3 %) after a mean delay of 12 weeks (range 2–24 weeks). During the follow-up, seven collapses occurred. We estimated that a threshold of 30 % of osteolysis was associated with a significant risk of vertebral collapse (P = 0.005).

Conclusions

Hematological malignancies with epidural localization must be treated first medically, even in patients with neurological symptoms. Surgery should be considered only in the cases of acute vertebral collapse, medical treatment failure, or to prevent acute collapse in patients with vertebral osteolysis of more than 30 %.     

Inhibitory effects of erythromycin on wear debris-induced VEGF/Flt-1 gene production and osteolysis

Objectives  A highly vascularized and inflammatory periprosthetic tissue augments the progress of aseptic loosening, a major clinical problem after total joint replacement. The purpose of this study is to investigate the effect of erythromycin (EM) on ultra high molecular weight polyethylene (UHMWPE) particle-induced VEGF/VEGF receptor 1 (Flt-1) gene production and inflammatory osteolysis in a mouse model. Methods  UHMWPE particles were introduced into established air pouches on BALB/c mice, followed by implantation of calvaria bone from syngeneic littermates. EM treatment started 2 weeks after bone implantation (5 mg/kg day, i.p. injection). Mice without drug treatment as well as mice injected with saline alone were included. Pouch tissues were harvested 2 weeks after bone implantation. Expression of VEGF, Flt-1, RANKL, IL-1, TNF and CD68 was measured by immunostain and RT-PCR, and implanted bone resorption was analyzed by micro-CT (μCT). Results  Exposure to UHMWPE induced pouch tissue inflammation, increase of VEGF/Flt-1 proteins, and increased bone resorption. EM treatment significantly improved UHMWPE particle-induced tissue inflammation, reduced VEGF/Flt-1 protein expression, and diminished the number of TRAP⁺ cells, as well as the implanted bone resorption. Conclusion  This study demonstrated that EM inhibited VEGF and Flt-1 gene expression. The molecular mechanism of EM action on VEGF/Flt-1 signaling-mediated osteoclastogenesis warrants further investigation.     

全身多骨及皮肤受侵的Gorham-Stout综合征1例报告并文献复习

目的：提高对Gorham-Stout综合征的认识。方法报告1例下颌骨、肋骨、双手（足）多骨及皮肤受侵的Gorham-Stout综合征患者,结合文献对其临床特征进行探讨。结果DR片示右侧下颌支、多根肋骨、双手（足）多发中远节指（趾）骨质吸收溶解,残端呈“削笔尖”状,溶骨区无骨膜反应;CT结合二维及三维重建直观地显示了骨质破坏的范围、周围软组织萎缩;MRI见残留的右侧下颌小头周围少许长T1、T2异常信号渗出影环绕。肋骨及胸膜穿刺活检病理见成骨细胞明显减少,而血管和纤维组织增生。结论Gorham-Stout综合征是一种以大块骨质溶解为特征的罕见病,影像学及病理结合临床有助于发现该病。     

大颗粒聚乙烯对人工关节假体周围组织影响的实验研究

目的　制作松动人工关节的动物模型 ,了解大颗粒聚乙烯对实验动物人工关节假体周围骨组织的影响 ,并初步探讨其作用机制。　方法　选用健康新西兰白兔 2 0只 ,雌雄各半 ,体重 2 .3～ 2 .7kg。从两侧膝关节向股骨置入钴 -铬 -钼棒 ,分别于术后 2、4、6、8及 10周向一侧膝关节腔内注射聚乙烯微粒 (直径 10 0 μm)悬液 1.5 ml(实验侧 ) ,向另一侧膝关节腔内注射生理盐水 1.5 ml(对照侧 )。术后第 10周摄双下肢 X线片 ,了解假体周围是否有骨溶解和假体松动。术后第 12周处死动物。取 13只兔检查聚乙烯颗粒在关节囊分布情况 ,假体有否松动 ,周围有无新骨及界膜形成 ;取5只兔双侧股骨、膝关节囊作组织学检查 (实验过程中有 2只动物死亡 )。　结果　 1肉眼观察 :实验侧有 4侧金属假体被新生骨组织覆盖 ,9侧被纤维膜覆盖 ;对照侧有 11侧金属假体被新生骨组织覆盖 ,2侧被纤维膜覆盖 ,差异有统计学意义(P<0 .0 5 )。2 X线片观察 :假体位于股骨髓腔远端 ,其周围未见明显新生骨组织和骨溶解征像。3组织学观察 :实验侧关节囊见大量异物颗粒被成纤维细胞和多核巨细胞包绕 ,假体近端髓腔周围见成纤维细胞和纤维组织或新生骨组织形成 ,未见异物颗粒和多核巨细胞 ,靠近关节面部分见异物颗粒被成纤维细胞和多核巨细胞包绕