Early changes in the composition of rabbit articular cartilage following experimentally produced intra-articular fractures. A histological and thermoanalytical study.

Intra-articular fractures were produced in rabbit knee joints. The articular cartilage of the injured joints was processed histologically and analysed by a complex thermoanalytical method. It was demonstrated that intra-articular fractures in the early stages have essentially no irreversible damaging effects on the composition of articular cartilage of injured joints.     

MR T2 mapping成像评估止痛健骨方治疗膝骨性关节炎关节软骨损伤疗效的实验研究

目的探讨MR T2mapping成像评价止痛健骨方治疗骨性关节炎软骨损伤疗效的价值。方法采用木瓜蛋白酶关节腔注射法制作新西兰大白兔膝骨关节炎模型,根据治疗方法不同将48只新西兰大白兔随机分为正常对照组、模型对照组、盐酸氨基葡萄糖治疗组、止痛健骨方治疗组。各组治疗4周后行膝关节MR T2mapping成像并对关节软骨基质金属蛋白酶1(MMP-1)含量进行免疫组化分析。比较各组间关节软骨T2值及关节软骨MMP-1含量的差异,并分析不同干预方法、关节软骨MMP-1含量与关节软骨T2值的相关性。结果模型对照组关节软骨T2值高于其他3组(P均0.01),其他3组间关节软骨T2值差异无统计学意义。盐酸氨基葡萄糖治疗模型组、止痛健骨方治疗模型组间关节软骨MMP-1含量差异无统计学意义,但2组关节软骨的MMP-1含量低于模型对照组(P均0.05)、高于正常对照组(P均0.05)。关节软骨MMP-1含量与T2值间为非线性关系,随着前者的升高,后者先缓慢上升再快速上升(P0.05)。结论 MR T2mapping成像有助于评价止痛健骨方治疗模型兔骨关节炎软骨损伤的疗效,关节软骨MMP-1含量与T2值间可能为非线性关系。     

Magnetic resonance arthrography of the ankle.

Magnetic resonance (MR) arthrography is a useful technique in evaluating the articular structures of the ankle. With intra-articular administration of gadolinium-DTPA (Gd-DTPA), visualization and delineation of anatomic structures, that would not be depicted by other traditional imaging techniques, are achieved. It is a technique that proves to be advantageous as it does not require the use of ionizing radiation, nor iodinated contrast material as other conventional diagnostic modalities. MR arthrography also allows multiplanar imaging and provides excellent resolution.     

兔膝关节内骨折后关节面塑形能力的实验研究

目的观察兔膝关节内骨折后不同形式关节面不平整的塑形能力。方法在兔胫骨平台造成关节内骨折,骨折移位0.5、1.0、2.0 mm,形成关节面凹陷或台阶样结构。术后3个月取胫骨平台标本进行组织切片、HE染色,观察不同形式关节面不平整的塑形能力。结果兔胫骨平台凹陷性或台阶性不平整关节面移位0.5 mm时,通过凹侧软骨增生肥厚等塑形,可恢复关节面的平整。关节面移位1.0 mm及2.0 mm时,通过凹侧软骨增生肥厚及来自髓腔的增生修复组织,凹陷性不平整仍可恢复关节面的平整,但台阶性不平整难以通过关节面的重新塑形恢复关节面的平整。结论关节内骨折后形成关节面不平整,凹陷性骨折的再塑形能力可能优于台阶性骨折。     

Assessment of blood-induced cartilage damage in rabbit knees using scanning electron microscopy

PURPOSE: To investigate the harmful effects of a single episode of intra-articular bleeding on articular cartilage of rabbit knees using scanning electron microscopy. METHODS: Autologous blood was injected into the right knee joints of 18 New Zealand white rabbits. Surface and cellular damages were examined by the scanning electron microscope (n=9) and light microscope (n=34), respectively. The injected right knees were then compared with the corresponding control left knees at one, 3, and 6 weeks after the blood injection. RESULTS: The articular surface of the injected knees turned uniformly rough with multiple pits after one week. Maximal changes with elevations and depressions were observed at 3 weeks. These changes reversed at 6 weeks with the irregularities smoothing out. A similar pattern of transient cartilage damage was noted histologically. CONCLUSION: Both scanning electron microscopic and light microscopic findings suggest that a single episode of intra-articular bleeding leads to articular cartilage damage but this appears to be reversible. Our findings of transient damage to the articular cartilage suggest that there is no need for intra-articular evacuation and washout following an acute episode of haemarthrosis.     

In vivo MR imaging tracking of magnetic iron oxide nanoparticle labeled, engineered, autologous bone marrow mesenchymal stem cells following intra-articular injection

ObjectiveTo track superparamagnetic iron oxide nanoparticle (SPIO)-labeled, bone-derived mesenchymal stem cells (MSCs) by in vivo magnetic resonance imaging (MRI) with a 1.5 T-system following injection of engineered autologous MSCs into the knee joint cavity in rabbit articular cartilage defect models.MethodsRabbit MSCs were labeled with SPIO and a transfection agent. Cell viability, proliferation and differentiation capacity were assessed in vitro using appropriate functional assays. Cells underwent GRE T2*-weighted MRI in vitro. The autologous MSCs seeded in chitosan and glycerophosphate (C-GP) gel were injected into the knee joint cavity of rabbit models for cartilage defects. All rabbits underwent GRE T2*-weighted MRI 1, 4, 8 and 12 weeks post-injection. MR imaging findings were compared histologically.ResultsNanoparticles were stained with Prussian blue and observed by transmission electron microscopy inside the cells. Cell viability, proliferation, and differentiation were comparable between labeled and non-labeled cells. After intra-articular injection of labeled autologous MSCs, marked hypointense signal void areas representing the injected MSCs can be observed for at least 12 weeks on GRE T2*-weighted images. At 12 weeks post-injection, labeled MSCs migrated into the synovial fluid at the suprapatellar bursa, the popliteal space site and subchondral bone of the femur but no MSCs were detected in the defect. Histochemical staining confirmed the presence of Prussian blue-positive cells and BrdU-positive cells.ConclusionsMRI would be an efficient noninvasive technique to visually track SPIO-labeled seed cells in vivo; the engineered autologous MSCs do not actively participate in the repair of articular cartilage defects following intra-articular injection.     

Intra-articular hyaluronate in experimental rabbit osteoarthritis can prevent changes in cartilage proteoglycan content

OBJECTIVE: The purpose of this study was to determine the effects of intra-articular injections of high molecular weight (2000 kDa) sodium hyaluronate (HA) on the progression of articular cartilage degeneration in a rabbit partial medial meniscectomy model of osteoarthritis. DESIGN: Six experimental groups included normal, sham operated, and operated and injected animals, the latter injected once-weekly (for two weeks or twelve weeks, beginning four weeks after surgery) with either 1% (w/v) HA or phosphate buffered saline (PBS). Following assessment of gross morphology, serial adjacent blocks of full-depth articular cartilage were prepared from the tibial condyle for analysis of total water, hydroxyproline, DNA and proteoglycan (uronic acid) content, as well as the ratio of galactosamine to glucosamine. Samples were sub-divided into inner (medial) and outer (lateral) regions. RESULTS: No morphological differences were recognized between joints injected with PBS and those receiving HA. When analysed biochemically, there were no significant differences in hydration, hydroxyproline or DNA content between the experimental groups. In contrast, HA injection did affect changes in proteoglycan content. Expressed per tissue dry weight, uronic acid content in the operated group injected with PBS for two weeks was lower than normal (P<0.02), a result not seen in the corresponding HA injected group. After 12 weeks of PBS injections, uronic acid content (per dry weight) was higher than normal (P<0.01), an effect again not observed in the corresponding HA injected group. Results for the galactosamine: glucosamine ratio showed a reduction after 12 weeks of injections, but no differences between PBS and HA injected groups. CONCLUSIONS: Once-weekly, intra-articular injection of high molecular weight HA can prevent changes in proteoglycan content in tibial condylar articular cartilage, compared to PBS injected controls, in the rabbit partial meniscectomy model of osteoarthritis.     

Concurrent Assessment of Cartilage Morphology and Bone Microarchitecture in the Human Knee Using Contrast-Enhanced HR-pQCT Imaging

Osteoarthritis (OA) is a prevalent articular disease characterized by whole joint degradation, including articular cartilage and bone. Presently, no single imaging modality is well suited to concurrently capture these changes. Recent ex vivo animal studies have demonstrated the efficacy of utilizing contrast agents in conjunction with micro-CT as a means of evaluating cartilage and bone alterations concurrently, though no work as of yet has been performed in large animal models or humans. This study sought to develop and validate a novel joint imaging technique, contrast enhanced high resolution peripheral quantitative computed tomography (CEHR-pQCT), to concurrently assess bone microarchitecture and cartilage morphology in the whole human knee. Fresh frozen cadaveric knees were harvested (n?=?10) and scanned using magnetic resonance imaging (MRI), HR-pQCT without contrast, and HR- pQCT following intra-articular injection of nonionic contrast media. Cartilage morphology and bone microarchitecture were evaluated in weight bearing regions of interest in both the tibia and femur. Joints were then disarticulated, and the articular cartilage thickness measured by needle probe. Measures of cartilage morphology, thickness and volume, were found to be significantly less when measured by CEHR- pQCT compared to magnetic resonance imaging in all regions. Compared to needle probing, cartilage thickness measured by CEHR-pQCT was less in the lateral tibia and greater in the medial tibia. Bone microarchitecture was found to be significantly different when measured with CEHR-pQCT compared to HR-pQCT, where cortical bone mineral density (BMD) was depressed, and trabecular bone mineral density was greater. This study demonstrates that CEHR-pQCT can be used to concurrently measure cartilage morphology and bone microarchitecture; however, systematic errors impact both measures. This is the first study using contrast media in combination with HR-pQCT in whole joints. Additionally, all imaging parameters, as well as the contrast media, were selected to be directly transferable to in vivo studies, laying the foundation to perform in vivo scanning of knee cartilage and bone.     

Tissue toxicity of antiseptic solutions. A study of rabbit articular and periarticular tissues

The gross, histologic, and biochemical effects of four commercially available antiseptic solutions on rabbit knee articular and periarticular connective tissues were investigated. Rabbit knee joints were injected with 2.0 cc of either Betadine prep solution, Betadine scrub solution, pHisohex or 3% hexachlorophene. The opposite knees were injected with sterile saline. All animals were injected three times at 48-hour intervals and sacrificed 10 days after the last injection. The solutions containing detergents, Betadine scrub, and pHisohex caused severe gross and histologic damage to articular cartilage, synovia, and muscle. The hexachlorophene loss solution caused moderate histologic damage, but caused articular cartilage ground substance. Betadine prep solution caused only minimal gross and histologic damage, without any biochemical evidence of articular cartilage damage. If antiseptic solutions are to be used in irrigating or packing joint injuries, the use of Betadine prep is recommended.     

In vivo contrast-enhanced micro MR-imaging of experimental osteoarthritis in the rabbit knee joint at 7.1T1

OBJECTIVE: In this longitudinal MR study the early stages of joint pathology in two surgically-induced rabbit models of osteoarthritis (OA) were monitored by in vivo contrast-enhanced MRI at 7.1T. Qualitative and quantitative MR data were compared with macroscopic and microscopic findings. METHOD: Scanning of mature, male New Zealand White rabbits (N=12) was performed before surgery, and at 2, 4, and 8 weeks after unilateral transection of the anterior cruciate ligament (ACLT), medial meniscectomy (ME), or sham operation. MR-images were simultaneously obtained of both knee joints after intravenous injection of Magnevist. We implemented a 2D T1-weighted (T1w) coronal, fat-saturated gradientecho protocol (68 x 138 microm2, slice thickness 1 mm). Additionally, consecutive 3D gradientecho images were obtained from two sham-operated and two rabbits of the ME group (234 x 273 x 234 microm(3)). ACLT animals were sacrificed at 2 weeks (N=1), and 8 weeks (N=3), ME animals were sacrificed at 4 weeks (N=2), and 8 weeks (N=4), and sham-operated animals were sacrificed at 2 weeks (N=1) and 8 weeks (N=1), respectively. RESULTS: Both OA models reflected important characteristics of the clinical picture of OA. With MR we were able to monitor time dependently the decline of synovial effusion and the formation of osteophytes. Morphologic MR examination showed a moderate to high accuracy for detecting synovial effusion (75%), meniscus (86%) and cruciate ligament (91%) lesions, and osteophytes (88%) as assessed by macroscopic examination. False-negative MR findings for gross macroscopic changes were due to the relative high slice thickness in 2D scans and the fact that the slices only covered the main weightbearing area of the femorotibial joint. Contour abnormalities of articular cartilage were not reliably detected. Quantitative analysis revealed a statistically significant increase of cartilage signal intensity in medial tibial cartilage (48+/-9% ACLT, and 29+/-9% ME in 2D datasets) as compared to contralateral control knees in two-week scans. Signal enhancement persisted or increased at later dates. CONCLUSION: With high-resolution contrast-enhanced MRI at 7.1T the time course of gross pathologic changes in rabbit knees with surgically induced OA can be monitored. Still insufficient spatial resolution and image contrast of the applied 2D protocols limit the sensitivity and prohibit detection of articular cartilage contour abnormalities. However, signal alterations in the cartilage layer indicate alterations of tissue composition at a very early stage of OA development. When used with 3D protocols, contrast-enhanced MRI offers a promising tool for qualitative and quantitative in vivo monitoring of OA in rabbit models.     

Magnetic resonance imaging of hyaline cartilage regeneration in neocartilage graft implantation

BACKGROUND: The purpose of this study was to investigate the regenerative potential of hyaline cartilage in a neocartilage graft implant with the aid of MR cartilage imaging using a rabbit model. METHODS: Surgical osteochondral defects were created in the femoral condyles of 30 mature New Zealand rabbits. The findings of neocartilage in autologous cartilage grafts packed into osteochondral defects were compared with control group of no implant to the osteochondral defect. The outcome of the implantations was correlated with histologic and MR cartilage imaging findings over a 3-month interval. RESULTS: Neocartilage grafts packed into osteochondral defects showed regeneration of hyaline cartilage at the outer layer of the implant using MR cartilage imaging. Fibrosis of fibrocartilage developed at the outer layer of the autologous cartilage graft together with an inflammatory reaction within the osteochondral defect. CONCLUSION: This animal study provides evidence of the regenerative ability of hyaline cartilage in neocartilage transplants to repair articular cartilage.     

The use of intra-articular Na-hyaluronate as a potential chondroprotective device in experimentally induced acute articular cartilage injury and repair in rabbits.

OBJECTIVE: This study examined if viscosupplementation from intra-articular administration of a commercially available form of hyaluronan (HA) could promote the restoration of proteoglycan (PG) depletion induced by chymopapain and then if the repair could be maintained once HA treatment was discontinued. METHODS: Animals received cartilage injury with intra-articular chymopapain (2.0 mg) followed by weekly treatment with intra-articular HA. HA treated animals were compared to injured animals with no treatment, contralateral untreated joints and joints from normal controls. The effect of intra-articular HA alone on articular cartilage was also examined. RESULTS: Serum keratan sulfate levels confirmed degradation of the cartilage PGs in the chymopapain-injected knees. Intra-articular chymopapain resulted in marked loss of PGs. There were no significant differences among the control groups (untreated control, HA/800 treatment only). HA treatment did not affect the loss of PGs caused by chymopapain after 42 days. However, in animals receiving chymopapain injury followed by weekly HA treatment for 42 days and then 42 days of free cage activity without HA, cartilage PG contents were significantly increased. Intra-articular HA alone had no effect on the articular cartilage. CONCLUSION: The results in the present study suggest a potential protective effect of HA on chymopapain-induced acute articular cartilage injury in rabbits that, in time, permits damaged cartilage to resynthesize matrix PGs after the HA treatment is discontinued.     

Proteoglycan and collagen sensitive MRI evaluation of normal and degenerated articular cartilage.

Quantitative magnetic resonance imaging (MRI) techniques have earlier been developed to characterize the structure and composition of articular cartilage. Particularly, Gd-DTPA(2-)-enhanced T1 imaging is sensitive to cartilage proteoglycan content, while T2 relaxation time mapping is indicative of the integrity and arrangement of the collagen network. However, the ability of these techniques to detect early osteoarthrotic changes in cartilage has not been demonstrated. In this study, normal and spontaneously degenerated bovine patellar cartilage samples (n=32) were investigated in vitro using the aforementioned techniques. For reference, mechanical, histological and biochemical properties of the adjacent tissue were determined, and a grading system, the cartilage quality index (CQI), was used to score the structural and functional integrity of each sample. As cartilage degeneration progressed, a statistically significant increase in the superficial T2 (r=0.494, p<0.05) and a decrease in superficial and bulk T1 in the presence of Gd-DTPA(2-) (r=-0.681 and -0.688 (p<0.05), respectively) were observed. Gd-DTPA(2-)-enhanced T1 imaging served as the best predictor of tissue integrity and accounted for about 50% of the variation in CQI. The present results reveal that changes in the quantitative MRI parameters studied are indicative of structural and compositional alterations as well as the mechanical impairment of spontaneously degenerated articular cartilage.     

成纤维细胞生长因子对兔关节软骨损伤的修复作用

目的：观察成纤维细胞生长因子对兔关节软骨组织损伤的修复作用。方法：于６例兔股骨外侧髁最高点膝关节面处钻孔,在术中及术后将ＦＧＦ注射入钻孔的膝关节腔,每只动物对侧作自身对照,注射生理盐水或不予处理。１月后作大体及病理组织学观察。结果：实验组关节面钻孔部位５例已封闭,较平整光滑;而对照组４例关节面未完全封闭,粗糙,凹凸不平;２例已封闭,但不平整。光镜下实验组关节软骨钻孔部位有明显的软骨性修复。结论：成纤维细胞生长因子能促进兔关节软骨损伤的修复     

Application of microscopic MR for evaluation of cartilage repair]

Magnetic resonance imaging is gold standard for noninvasive evaluation of articular cartilage damage and has been also used for monitoring cartilage repair. The aim of this study was to find correlation between histological microscopy and microscopic MR in evaluation of the repair of osteochondral defects in articular cartilage. Study was based animal model (rabbit). The cartilage repair process was evaluated histology and micro MR. Most of the defects were filled with fibrocartilage and fibrous tissue formed. Both methods were equally efficient to show repair tissue thickness, subchondral bone reconstruction and disintegration. Result of observation by both histological and MR microscopy and showed good correlation. Micro MR is promising evaluation tool for cartilage repair monitoring. Results of micro MR correlate well with standard microscopy.     

Magnetic resonance imaging of articular cartilage of the knee

Recently developed magnetic resonance (MR) imaging techniques allow accurate detection of moderate- and high-grade articular cartilage defects. There has been increased interest in MR imaging of articular cartilage in part because it is useful in identifying patients who may benefit from new articular cartilage replacement therapies, including chondrocyte transplantation, improved techniques for osteochondral transplantation, chondroprotective agents, and cartilage growth stimulation factors. The modality also has the potential to play an important role in the follow-up of patients during and after treatment. Detection of articular cartilage defects is beneficial for patients undergoing arthroscopy for other injuries, such as meniscal tears, because the presence of articular cartilage injury worsens prognosis and may modify therapy options.     

多光谱小动物活体成像技术在骨性关节炎模型评价中的应用

目的：利用多光谱小动物活体成像技术动态观察和评价大鼠骨性关节炎模型的应用价值。方法：取3月龄SD雄性大鼠15只（180±20）g,利用碘乙酸关节腔注射法建立骨性关节炎模型：左膝关节腔注射碘乙酸50μl建立OA模型组,右膝关节腔注射等量无菌生理盐水做为正常对照。分别于建模2、4周时进行X-ray活体成像观察,测算骨密度。4周后处死大鼠,取双侧关节进行组织病理学观察,X线和组织病理学参考Kellgren-Lawrence和Collins进行分级。结果：OA模型造模成功,活体成像观察发现与对照组相比,模型组出现关节面不平整、骨赘形成、关节变形、软骨缺损等典型骨性关节炎表型,并伴有股骨远端骨密度下降明显（P〈0.01）,胫骨近端骨密度下降不明显（P〉0.05）,病理学结果一致;2周后模型组膝关节接近Collins 1级、Kellgren-Lawrence 2级,4周后模型组膝关节接近Collins 4级、Kellgren-Lawrence 3级;对照组关节面平整,关节间隙正常,软骨未见明显缺损,Collins及KellgrenLawrence 0级,股骨远段及胫骨近端骨密度正常。结论：多光谱小动物成像技术可用于骨性关节炎模型的影像学活体动态观察及骨密度检测,对骨性关节炎模型评价和相关研究具有重要意义。     

Detection of articular defects using magnetic resonance imaging: an experimental study

This study evaluates magnetic resonance imaging (MRI) in the detection of surgically created articular defects in bovine knees. A total of 26 articular defects was created in 2 fresh cadaveric cows' knees. The defects created include chondromalacic grade 2 defects, chondral and osteochondral defects from 3 to 15 mm in diameter. The knee joints were repaired in a normal saline bath to exclude air in the joint prior to MR scanning. T1 weighted spin echo (SE) images and 3D gradient echo (FISP 40 degrees 3D) images were obtained. The T1 weighted SE imaging technique detected 15 defects (57.7%) compared with FISP 3D imaging technique detection of 17 defects (65.4%). The two techniques combined enable 21 of 26 defects (80.8%) to be detected. The imaging techniques used in this study were not able to detect chondromalacic defects less than 10 mm in diameter, nor chondral defects less than 5 mm in diameter. However, small osteochondral defects of 3 mm in diameter are detectable provided the depth of the defect is not less than 10 mm. The FISP 3D imaging technique alone is more sensitive in detecting chondral defects. Both imaging techniques have similarly high sensitivities in detecting osteochondral defects. The imaging time for combined T1 weighted SE and FISP 3D sequence is short (16.5 mm) and this combined technique may be useful for MR scanning of knee joints suspected to have articular defects.     

Diffraction-enhanced X-ray imaging of articular cartilage

OBJECTIVE: To introduce a novel X-ray technology, diffraction-enhanced X-ray imaging (DEI), in its early stages of development, for the imaging of articular cartilage. DESIGN: Disarticulated and/or intact human knee and talocrural joints displaying both undegenerated and degenerated articular cartilage were imaged with DEI. A series of three silicon crystals were used to produce a highly collimated monochromatic X-ray beam to achieve scatter-rejection at the microradian level. The third crystal (analyser) was set at different angles resulting in images displaying different characteristics. Once the diffraction enhanced (DE) images were obtained, they were compared to gross and histological examination. RESULTS: Articular cartilage in both disarticulated and intact joints could be visualized through DEI. For each specimen, DE images were reflective of their gross and histological appearance. For each different angle of the analyser crystal, there was a slight difference in appearance in the specimen image, with certain characteristics changing in their contrast intensity as the analyser angle changed. CONCLUSIONS: DEI is capable of imaging articular cartilage in disarticulated, as well as in intact joints. Gross cartilage defects, even at early stages of development, can be visualized due to a combination of high spatial resolution and detection of X-ray refraction, extinction and absorption patterns. Furthermore, DE images displaying contrast heterogeneities indicative of cartilage degeneration correspond to the degeneration detected by gross and histological examination.     

T2 Mapping of Articular Cartilage of Glenohumeral Joint with Routine MRI Correlation—Initial Experience

The evaluation of articular cartilage currently relies primarily on the identification of morphological alterations of the articular cartilage. Unlike anatomic imaging, T2 mapping is sensitive to changes in the chemical composition and structure of the cartilage. Clinical evaluation of T2 mapping of the glenohumeral joint has not been previously reported. The objectives of this study were to evaluate the feasibility of magnetic resonance T2 mapping of the glenohumeral joint in routine clinical imaging, to assess the normal T2 mapping appearance of the glenohumeral joint, and to compare the findings on T2 maps to conventional MR pulse sequences. Magnetic resonance imaging (MRI) examinations of 27 shoulders were performed in a routine clinical setting. All studies included acquisition of T2 mapping using a dedicated software. The T2 maps were analyzed along with the routine MR exam and correlation of cartilage appearance on T2 map and on conventional MR sequences. T2 imaging maps were obtained successfully in all patients. T2 maps and routine MRI correlated in cases of normal cartilage and prolonged T2 values and cartilage defects. In four cases, increased T2 relaxation times in the cartilage and cartilage defects were more apparent on T2 maps. Acquisition of T2 maps at the time of routine MRI scanning is feasible and not time-consuming.