Nutrition and degeneration of articular cartilage

Purpose

To determine the importance of synovial fluid (SF) or subchondral bone marrow (BM) as nutrition sources in cartilage degeneration.

Methods

Ninety-five-month-old male rabbits were randomly divided into 5 groups according to sources of nutrition: SFBM-both; BM-only; SF-only; None-SFBM; and Free plug (unrestricted). Nutrition to 4-mm-diameter cylindrical osteochondral plugs created on the trochlea of the distal femurs was obstructed by Polyvinyl Chloride (PVC) cap. Cartilage changes were assessed after 4, 8, and 12 weeks by histology, immunohistochemistry, and real-time PCR.

Results

Cartilage in the BM-only group suffered the greatest damage, followed by the None-SFBM and SF-only groups. Apoptosis was increased in the BM-only and None-SFBM groups compared with others. Cartilage was significantly thinner at all time points in the BM-only and None-SFBM groups when compared with SFBM-both and Free plug, whereas in the SF-only group, this difference occurred after 8 weeks. Compared with SFBM-both and Free plug, expression of collagen II and aggrecan mRNAs in all groups was decreased but MMP-3 increased, respectively.

Conclusion

Our data indicate that SF-derived nutrition is the dominant source of sustenance for adult cartilage structure and function. Cartilage damage is observed when the only nutrition source is the BM.     

MR imaging of articular cartilage

With the advent of new treatments for articular cartilage disorders, accurate noninvasive assessment of articular cartilage, particularly with MR imaging, has become important. Understanding the MR imaging features of articular cartilage has led to the development of two types of routinely available MR imaging techniques which have demonstrated clinical accuracy and interobserver reliability. Received: 25 January 2000 Revision requested: 21 March 2000 Revision received: 31 March 2000 Accepted: 3 April 2000     

Basic science of articular cartilage and osteoarthritis

Articular cartilage is a specialized tissue uniquely suited for load distribution with a low-friction articulating surface. Its compressive and tensile properties are determined by its matrix and fluid composition, and are maintained by chondrocytes in the homeostatic joint. Osteoarthritis (OA) is increasingly understood as a family of disorders in which the biomechanical properties of cartilage are altered and ultimately fail as the tissue is degraded by local proteases. Mechanically mediated and cytokine-mediated pathways of cartilage degeneration have been identified in the pathogenesis of OA. Further insight into the basic science of cartilage and OA is necessary to develop diagnostic and treatment strategies for this pervasive disease.     

Magnetic resonance imaging of articular cartilage and evaluation of cartilage disease

Clinical magnetic resonance imaging of articular cartilage is possible by using techniques that offer high contrast between articular cartilage and adjacent structures in reasonable examination times. The fat-suppressed, three-dimensional, spoiled gradient-echo sequence has been reported to be accurate and reliable, and the addition of this sequence to a routine examination does not significantly compromise patient throughput. Fast spin-echo imaging also shows promise in the clinical evaluation of articular cartilage, because the newer, stronger-gradient systems allow thinner slice acquisition with two-dimensional sequences. Together, these sequences allow the evaluation of intrachondral lesions and surface defects. Furthermore, quantitative measurements of cartilage volume for follow-up studies are possible with the use of the fat-suppressed, three-dimensional, spoiled gradient-echo sequence.     

关节软骨再生修复策略

关节软骨缺损主要由刨伤、骨坏死或剥脱性骨软骨炎等造成,由于软骨内没有血供及淋巴回流,受损后很难自我修复,严重将导致关节炎发生[1].1743年Hunter通过对关节软骨缺损的临床研究,曾经断言"软骨一旦损毁,不可修复"[2].一直以来,临床医师在不断探索有效的外科学软骨修复技术.笔者针对国内外关节软骨再生修复策略及存在问题进行综述.     

Basic science of articular cartilage repair

As the ability to understand the peculiarities of successful healing of articular cartilage defects moves forward, it becomes clear that this complex orthopaedic problem soon will be successfully addressed. A multidisciplinary approach, combining clinical experience, cogent biomaterial designs, new cell biologic processes, biomechanical assessment, and modern molecular biology, clearly is leading toward clinically acceptable, viable, and consistent articular cartilage regeneration.     

关节软骨CT增强:关节软骨黏多糖定量的实验研究

目的应用临床CT扫描调查使用关节软骨延迟对比增强CT定量诊断体外正常和退变的关节软骨聚集的黏多糖(glycosaminoglycan,GAG)的可能性。材料与方法本研究经机构及动物审查委员会豁免,无需知情同意书。取40个完整的猪髌骨分配到对照组(n=20)或胰岛素处理组(即GAG-耗尽组)(n=20)。每组的10个髌骨浸入阴离子型对比剂     

Magnetic resonance imaging of articular cartilage

Recent advances in treatments of the cartilage abnormalities require more information on the extent and shape of cartilage abnormalities and need for early detection of the lesions. In this article we review MR appearance of the cartilage correlated with histology, MR-related artifacts for cartilage imaging, conventional and dedicated MR techniques suitable for the cartilage, and their clinical utilization.     

关节软骨MR成像进展

随着软骨序列的开发和应用，MRI对关节软骨的评价越来越重要。本文就关节软骨的MRI表现、关节软骨的MRI序列和扫描技术、关节软骨损伤以及修复术后MRI评价等方面进行了综述。     

Postmortem degradation of porcine articular cartilage

Postmortem decompositional changes to articular cartilage were analysed to help establish a new methodology in determining the postmortem interval. The cartilage was collected from porcine trotters buried in simulated shallow graves for different time periods. The trotters were dissected to expose the cartilage located at the metatarsal joint. Numerous macroscopic changes including a colour change, gradual degradation of cartilage and adjacent soft tissues and a loss of cartilage covering articular facets were observed. Further analysis was conducted using light microscopy (LM) and scanning electron microscopy (SEM) to assess microstructural changes. Both LM and SEM showed gradual morphological and structural changes to the tissue over time, along with loss of nuclear material. Tissue surface analysis with SEM highlighted orthorhombic shaped crystals that appear at approximately three weeks postmortem and persist until six weeks postmortem. Both microscopic and macroscopic characteristics followed a recognisable succession over the burial times observed. These results indicate that postmortem degradation of articular cartilage may be useful for estimating a presumptive postmortem interval.     

Magnetic resonance imaging of articular cartilage: trauma, degeneration, and repair

The assessment of articular cartilage using magnetic resonance imaging has seen considerable advances in recent years. Cartilage morphologic characteristics can now be evaluated with a high degree of accuracy and reproducibility using dedicated pulse sequences, which are becoming standard at many institutions. These techniques detect clinically unsuspected traumatic cartilage lesions, allowing the physician to study their natural history with longitudinal evaluation and also to assess disease status in degenerative osteoarthritis. Magnetic resonance imaging also provides a more objective assessment of cartilage repair to augment the information obtained from more subjective clinical outcome instruments. Newly developed methods that provide detail at an ultrastructural level offer an important addition to cartilage evaluation, particularly in the detection of early alterations in the extracellular matrix. These methods have created an undeniably important role for magnetic resonance imaging in the reproducible, noninvasive, and objective evaluation and monitoring of cartilage. An overview of the advances, current techniques, and impact of magnetic resonance imaging in the setting of trauma, degenerative arthritides, and surgical treatment for cartilage injury is presented.     

Current status of imaging of articular cartilage

 Various imaging methods have been applied to assessment of articular cartilage. These include standard radiography, arthrography, CT, CT arthrography, ultrasonography, and MR imaging. Radiography remains the initial musculoskeletal imaging method. However, it is insensitive to early stages of cartilage abnormalities. MR imaging has great potential in the assessment of articular cartilage, although high-quality scans are required because imaging signs of cartilage abnormalities may be subtle. The potential and limitations of various sequences and techniques are discussed, including MR arthrography. The role of the other imaging methods in assessment of articular cartilage appears to be limited.     

Temperature requirements for altering the morphology of osteoarthritic and nonarthritic articular cartilage: in vitro thermal alteration of articular cartilage

BACKGROUND: Radiofrequency and laser thermal chondroplasty procedures are performed to debride and smooth fibrillated, articular cartilage. HYPOTHESIS: Temperature requirements necessary to achieve morphological change will be lower in fibrillated arthritic cartilage as compared with nonarthritic articular cartilage. STUDY DESIGN: Controlled laboratory study. METHODS: A thermal cell-culture chamber was mounted on a stereoscopic microscope and coordinated with a custom temperature-control program. Nonarthritic and osteoarthritic articular cartilage specimens were sectioned into full-thickness slices. The articular sections were exposed to temperatures incrementally from 37 masculine C to 75 masculine C. Real-time, digital capture microscopy was used to visualize and analyze the morphological changes undergone by the articular cartilage specimens. RESULTS: Arthritic articular cartilage displayed morphological change at 56.5 +/- 1.7 masculine C. Loss of fibrillation was the initial morphological change visualized. Continued thermal exposure caused a shrinkage effect of the entire tissue section that was similar to the change seen in nonarthritic sections. Nonarthritic cartilage displayed morphological change at 60.9 +/- 1.9 masculine C. CONCLUSIONS: Consistent characteristic morphological changes were found at distinct temperatures in osteoarthritic and nonarthritic articular cartilage. CLINICAL RELEVANCE: This information begins to establish the thermal parameters required for morphological change of osteoarthritic articular cartilage.