WordNet

tough elastic tissue; mostly converted to bone in adults (同)gristle
of or relating to cartilage
difficult to chew (同)gristly, rubbery

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軟骨[組織]
軟骨の

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/18 22:00:58」(JST)

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Cartilage /ˈkɑrtɨlɨdʒ/ is a flexible connective tissue in animals, including the joints between bones, the rib cage, the ear, the nose, the bronchial tubes and the intervertebral discs. It is not as hard and rigid as bone, but it is stiffer and less flexible than muscle.

Because of its rigidity, cartilage often serves the purpose of holding tubes open in an animal's body. Examples include the rings of the trachea, such as the cricoid cartilage and carina, the torus tubarius at the opening of the pharyngotympanic/auditory tube, the ala of the nostrils, and the auricle/pinna of the ear.

Cartilage is composed of specialized cells called chondrocytes that produce a large amount of collagenous extracellular matrix, abundant ground substance that is rich in proteoglycan and elastin fibers. Cartilage is classified in three types, elastic cartilage, hyaline cartilage and fibrocartilage, which differ in relative amounts of cartilage.^[1] Chondroblasts that get caught in the matrix are called chondrocytes.

Cartilage does not contain blood vessels (avascular) or nerves (aneural). The chondrocytes are supplied by diffusion. The compression of the articular cartilage or flexion of the elastic cartilage generates the pumping action, which assists the diffusion to the chondrocytes. Compared to other connective tissues, cartilage has a very slow turnover and does not easily repair.

Structure

Development

In embryogenesis, the skeletal system is derived from the mesoderm germ layer. Chondrification (also known as chondrogenesis) is the process by which cartilage is formed from condensed mesenchyme tissue, which differentiates into chondroblasts and begins secreting the molecules (aggrecan and collagen type II) that form the extracellular matrix.

Following the initial chondrification that occurs during embryogenesis, cartilage growth consists mostly of the maturing of immature cartilage to a more mature state. The division of cells within cartilage occurs very slowly, and thus growth in cartilage is usually not based on an increase in size or mass of the cartilage itself.^[2]

Composition

The articular cartilage function is dependent on the molecular composition of the extracellular matrix (ECM). The ECM consists mainly of proteoglycan and collagen. The main proteoglycan in cartilage is aggrecan, which, as its name suggests, forms large aggregates with hyaluronan. These aggregates are negatively charged and hold water in the tissue. The collagen, mostly collagen type II, constrains the proteoglycans. The ECM responds to tensile and compressive forces that are experienced by the cartilage.^[3] Cartilage growth thus refers to the matrix deposition, but can also refer to both the growth and remodeling of the extracellular matrix.

Function

Mechanical properties

The mechanical properties of articular cartilage in load bearing joints such as knee and hip have been studied extensively at macro, micro and nano-scales. These mechanical properties include the response of cartilage in frictional, compressive, shear and tensile loading. Cartilage is resilient and displays viscoelastic properties.^[4]

Frictional properties

Lubricin, a glycoprotein abundant in cartilage and synovial fluid, plays a major role in bio-lubrication and wear protection of cartilage.^[5]

Repair

Cartilage has limited repair capabilities: Because chondrocytes are bound in lacunae, they cannot migrate to damaged areas. Therefore, cartilage damage is difficult to heal. Also, because hyaline cartilage does not have a blood supply, the deposition of new matrix is slow. Damaged hyaline cartilage is usually replaced by fibrocartilage scar tissue. Over the last years, surgeons and scientists have elaborated a series of cartilage repair procedures that help to postpone the need for joint replacement.

Bioengineering techniques are being developed to generate new cartilage, using a cellular "scaffolding" material and cultured cells to grow artificial cartilage.^[6]

Clinical significance

Disease

Several diseases can affect cartilage. Chondrodystrophies are a group of diseases, characterized by the disturbance of growth and subsequent ossification of cartilage. Some common diseases that affect the cartilage are listed below.

Osteoarthritis: Osteoarthritis is a disease of the whole joint, however one of the most affected tissues is the articular cartilage. The cartilage covering bones (articular cartilage—a subset of hyaline cartilage) is thinned, eventually completely wearing away, resulting in a "bone against bone" within the joint, leading to reduced motion, and pain. Osteoarthritis affects the joints exposed to high stress and is therefore considered the result of "wear and tear" rather than a true disease. It is treated by arthroplasty, the replacement of the joint by a synthetic joint often made of a stainless steel alloy (cobalt chromoly) and ultra high molecular weight polyethylene (UHMWPE). Chondroitin sulfate or glucosamine sulfate supplements, have been claimed to reduce the symptoms of osteoarthritis but there is little good evidence to support this claim.^[7]
Traumatic rupture or detachment: The cartilage in the knee is frequently damaged, and can be partially repaired through knee cartilage replacement therapy. Often when athletes talk of damaged "cartilage" in their knee, they are referring to a damaged meniscus ( a fibrocartilage structure) and not the articular cartilage.
Achondroplasia: Reduced proliferation of chondrocytes in the epiphyseal plate of long bones during infancy and childhood, resulting in dwarfism.
Costochondritis: Inflammation of cartilage in the ribs, causing chest pain.
Spinal disc herniation : Asymmetrical compression of an intervertebral disc ruptures the sac-like disc, causing a herniation of its soft content. The hernia often compresses the adjacent nerves and causes back pain.
Relapsing polychondritis: a destruction, probably autoimmune, of cartilage, especially of the nose and ears, causing disfiguration. Death occurs by suffocation as the larynx loses its rigidity and collapses.

Tumors made up of cartilage tissue, either benign or malignant, can occur. They usually appear in bone, rarely in pre-existing cartilage. The benign tumors are called chondroma, the malignant ones chondrosarcoma. Tumors arising from other tissues may also produce a cartilage-like matrix, the best known being pleomorphic adenoma of the salivary glands.

The matrix of cartilage acts as a barrier, preventing the entry of lymphocytes or diffusion of immunoglobulins. This property allows for the transplantation of cartilage from one individual to another without fear of tissue rejection.

Imaging

Cartilage does not absorb x-rays under normal In vivo conditions, but a dye can be injected into the synovial membrane that will cause the x-rays to be absorbed by the dye. The resulting void on the radiographic film between the bone and meniscus represents the cartilage. For In vitro x-ray scans, the outer soft tissue is most likely removed, so the cartilage and air boundary are enough to contrast the presence of cartilage due to the refraction of the x-ray.^[8]

Histological image of hyaline cartilage stained with haematoxylin & eosin, under polarized light

Other animals

Cartilaginous fish

Cartilaginous fish (chondrichthyes) like sharks, rays and skates have a skeleton composed entirely of cartilage.

Invertebrate cartilage

Cartilage tissue can also be found among invertebrates such as horseshoe crabs, marine snails, and cephalopods.

Plants

Vascular plants, particularly seeds.^[9]

References

^ Pratt, Rebecca. "Supporting Tissue: Cartilage". AnatomyOne. Amirsys, Inc. Retrieved 26 October 2012.
^ Asanbaeva A, Masuda K, Thonar EJ, Klisch SM, Sah RL (2008). "Cartilage growth and remodeling: Modulation of balance between proteoglycan and collagen network in vitro with β-aminopropionitrile1". Osteoarthritis and Cartilage 16 (1): 1–11. doi:10.1016/j.joca.2007.05.019. PMID 17631390.
^ Asanbaeva A, Tam J, Schumacher BL, Klisch SM, Masuda K, Sah RL (2008). "Articular cartilage tensile integrity: Modulation by matrix depletion is maturation-dependent". Archives of Biochemistry and Biophysics 474 (1): 175–182. doi:10.1016/j.abb.2008.03.012. PMC 2440786. PMID 18394422.
^ Hayes WC, Mockros LF (1971). "Viscoelastic properties of human articular cartilage" (PDF). J Appl Physiol 31 (4): 562–8. PMID 5111002.
^ Rhee DK, Marcelino J, Baker M, Gong Y, Smits P, Lefebvre V, Jay GD, Stewart M, Wang H, Warman ML, Carpten JD (2005). "The secreted glycoprotein lubricin protects cartilage surfaces and inhibits synovial cell overgrowth". J Clin Investig 115: 622–31. doi:10.1172/JCI22263. PMC 548698. PMID 15719068.
^ International Cartilage Repair Society ICRS
^ "Supplements for osteoarthritis 'do not work'". BBC News. 16 September 2010.
^ About.com:osteoarthritis
^ University of Sydney: Eflora - Glossary

General references

Keller-Peck, C. (2008). Vertebrate Histology, ZOOL 400. Boise State University.

External links

Cartilage.org, International Cartilage Repair Society
KUMC.edu, Cartilage tutorial, University of Kansas Medical Center
Bartleby.com, text from Gray's anatomy
MadSci.org, I've heard 'Ears and nose do not ever stop growing.' Is this false?
CartilageHealth.com, Information on Articular Cartilage Injury Prevention, Repair and Rehabilitation
About.com, Osteoarthritis
Cartilage types
Different cartilages on TheFreeDictionary

UpToDate Contents

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1. 変形性関節症の病因 pathogenesis of osteoarthritis
2. 小児および思春期における良性骨腫瘍：概要 benign bone tumors in children and adolescents an overview
3. 骨格の正常な発達および骨形成ならびに骨吸収の調節 normal skeletal development and regulation of bone formation and resorption
4. 変形性関節症の危険因子および考えられる原因 risk factors for and possible causes of osteoarthritis
5. 膝および股関節の変形性関節症に対する外科治療の概要 overview of surgical therapy of knee and hip osteoarthritis

English Journal

Collagen catabolism through Coll2-1 and Coll2-1NO2 and myeloperoxidase activity in marathon runners.

Henrotin Y, Labasse A, Franck T, Bosseloir A, Bury T, Deberg M.SourceBone and Cartilage Research Unit, University of Liège, CHU Sart Tilman, Liège, Belgium.
SpringerPlus.Springerplus.2013 Dec;2(1):92. Epub 2013 Mar 8.
To determine the influence of marathon on the serum levels of two markers of cartilage degradation, Coll2-1 and its nitrated form, Coll2-1NO2, and of a marker of neutrophils activation, the myeloperoxidase (MPO). Coll2-1, Coll2-1NO2, total and active MPO were measured in 98 marathon runners without
PMID 23519606

Curcumin: a new paradigm and therapeutic opportunity for the treatment of osteoarthritis: curcumin for osteoarthritis management.

Henrotin Y, Priem F, Mobasheri A.SourceBone and Cartilage Research Unit, University of Liège, Institute of Pathology, Level +5, CHU Sart-Tilman, Liège, 4000 Belgium ; Physical Therapy and Rehabilitation Department, Vivalia, Princess Paola Hospital, Marche-en-Famenne, Belgium.
SpringerPlus.Springerplus.2013 Dec;2(1):56. Epub 2013 Feb 18.
The management of osteoarthritis represents a real challenge. This complex and multi-factorial disease evolves over decades and requires not only the alleviation of symptoms, i.e. pain and joint function but also the preservation of articular structure without side effects. Nutraceuticals are good c
PMID 23487030

A molecular ensemble in the rER for procollagen maturation.

Ishikawa Y, Bächinger HP.SourceResearch Department, Shriners Hospital for Children, 3101 SW Sam Jackson Park Road, Portland, OR 97239, USA; Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR 97239, USA. Electronic address: yxi@shcc.org.
Biochimica et biophysica acta.Biochim Biophys Acta.2013 Nov;1833(11):2479-91. doi: 10.1016/j.bbamcr.2013.04.008. Epub 2013 Apr 18.
Extracellular matrix (ECM) proteins create structural frameworks in tissues such as bone, skin, tendon and cartilage etc. These connective tissues play important roles in the development and homeostasis of organs. Collagen is the most abundant ECM protein and represents one third of all proteins in
PMID 23602968

Japanese Journal

iPS細胞研究最前線 : 疾患モデルから臓器再生まで(Vol.18)患者由来iPS細胞を用いた疾患モデル作製研究 : 骨軟骨疾患

戸口田淳也,池谷真
医学のあゆみ 252(12), 1245-1250, 2015-03-21
NAID 40020402296

軟骨移植による鼻形成術 (特集東洋人におけるRhinoplasty)

山下昌信
形成外科 58(3), 235-244, 2015-03
NAID 40020378237

関節軟骨の再生医療

亀井直輔,越智光夫
再生医療 : 日本再生医療学会雑誌 14(1), 9-17, 2015-02
NAID 40020397346

Related Pictures

★リンクテーブル★

リンク元	「100Cases 16」「軟骨」「cartilaginous」「軟骨組織」
拡張検索	「annular cartilage」

「100Cases 16」

Cartilage
	Light micrograph of hyaline cartilage showing chondrocytes and organelles, lacunae and extracellular matrix.
Identifiers
FMA	71500
	Anatomical terminology

　　[★]

☆case16　膝の痛み

■glossary

indigestion 消化障害、消化不良

■症例

80歳　男性

主訴：左膝の痛みと腫脹

現病歴：左膝の痛みを2日前から認めた。膝は発熱・腫脹しており、動かすと疼痛を生じる。時々胸焼けと消化不良が見られる。6ヶ月前のhealth checkで、高血圧(172/102mmHg)と血中クレアチニンが高い(正常高値)こと以外は正常といわれた。その4週間数回血圧を測定したが、高値が継続したため、2.5mg bendrofluamethizide(UK)/ベンドロフルメチアジド bendroflumethiazide(US)で治療を開始した。最近の血圧は138/84 mmHgであった。

喫煙歴：なし。

飲酒歴：一週間に平均4unit。

既往歴：股関節に中程度(mild)の変形性関節症

家族歴：特記なし

服薬歴：アセトアミノフェン(股関節の疼痛に対して)

身体所見 examination

　血圧 142/86mmHg。体温37.5℃。脈拍88/分。grade 2 hypertensive retinopathy(高血圧症性網膜症)。心血管系、呼吸器系に検査場異常なし。手にDIPにヘバーデン結節なし。

　左膝が発熱し腫脹している。関節内に液、patellar tap陽性。90℃以上膝関節を屈曲させると痛みを生じる。右の膝関節は正常に見える。

検査　 investigation

　生化学：白血球増多、ESR 上昇、尿素高値、グルコース高値

　単純X線：関節間隙やや狭小。それ以外に異常は認めない。

■problem list

　#1 左膝の痛み

　#2 胸焼け

　#3 消化不良

　#4 高血圧

　#5 クレアチニン正常高値

　#6 股関節の変形性リウマチ

　#7 高血圧性網膜症

■考え方

　・関節痛の鑑別診断を考える。

　・VINDICATEで考えてみてもよいでしょう。

　・関節痛の頻度としては　外傷＞慢性疾患(OAなど)＞膠原病＞脊椎疾患＞悪性腫瘍

■関節痛の鑑別疾患

DIF 282

V Vascular 血友病 hemophilia, 壊血病 scurvy, 無菌性骨壊死 aseptic bone necrosis (Osgood-Schlatter diseaseとか)

I Inflammatory 淋疾 gonorrhea, ライム病 lyme disease, 黄色ブドウ球菌 Staphylococcus, 連鎖球菌 Streptococcus, 結核 tuberculosis, 梅毒 syphilis, 風疹 rubella, 単純ヘルペス herpes simplex, HIV human immunodeficiency virus, サイトメガロウイルス cytomegalovirus

N Neoplastic disorders 骨原性肉腫 osteogenic sarcoma, 巨細胞腫 giant cell tumors

D Degenerative disorders degenerative joint disease or 変形性関節症 osteoarthritis

I Intoxication 痛風 gout (uric acid), 偽痛風 pseudogout (calcium pyrophosphate), ループス症候群 lupus syndrome of hydralazine (Apresoline) and procainamide, gout syndrome of diuretics

C Congenital and acquired malformations bring to mind the joint deformities of tabes dorsalis and syringomyelia and congenital dislocation of the hip. Alkaptonuria is also considered here.