Cartilage and joints

good

1. SEMINAR ON CARTILAGE AND JOINTS STRUCTURE AND FUNCTIONS PRESENTER:DR. SIDDIQUE HUSSANUL RANNA PGT,ORTHOPAEDICS MODERATOR:DR.CHAO ROCHEK BURAGOHAIN ASST.PROF,ORTHOPAEDICS 10 TH JUNE 2015

2. INTRODUCTION CARTILAGE Is an avascular, stiff, load bearing form of connective tissue, consisting of extracellular fibers embedded in a water filled ground substances.

3. Peculiarities of cartilage Avascular and non nervous Receives nutrition by diffusion Posses some cartilage canals Canals help osteogenic cells and vessels to grow in ossific centers. Posses low metabolic rate than bone cells Most bones in intrauterine life are cartilage.

4. Peculiarities of cartilage cond.. Chondrocytes are isolated in separate lacunae Has capacity of appositional and interstitial growth Cartilaginous matrix has low antigenicity Homogenous transplantation is possible Repair of cartilage takes long time

5. Structure of cartilage Consists of Cells: * chondrocytes *cells appear in the lacunae or in cell nest Matrix *collagen fibers & elastin fibers Ground substance(gel like) *water, *proteoglycans&glycosamineglycans

6. Structure of ground substance Gel like substance rich in carbohydrate Consists mainly of water and dissolved salts meshwork of long proteoglycan molecules Proteoglycans consists of long polymers called GAGS(glycosaminoglycans)

7. Proteoglycans and GAGS Proteoglycans consists of long polymers called GAGS(glycosaminoglycans) GAGS are covalently bound with “core protein” Core protein may bear more than 100 GAGS sideways. Several PG molecules bound along huge Hyaluronate molecules to form aggregates.

8. Proteoglycans and GAGS,cont.. Weak inter molecular forces hold aggregates in 3D network with large water filled space between. GAGS posses acidic groups GAGS repel each other thus standing out stiffy from core protein. PG aggregates appear to be compressed and posses repulsion chains and subunits. PG may act as a minute spring, conferring elasticity.

9. Proteoglycans and GAGS,cont.. Some GAGS found in PG aggregans are condroitin-4 sulfate,condroitin-6 sulfate,dermatan sulfate and keratan sulfate. Link protein and chondronectin,are important for PG structure.

10. Proteoglycans and GAGS,cont..

11. Proteoglycans and GAGS,cont..

12. Structure of collagen fiber Too small and thin Characteristic cross banding and 3D structure Tropocollagen posses triple helices of polypeptide Tensile strength properties

13. Function of cartilage Supportive : soft tissue support Mechanical: response to friction,compression,shear and tensile loading Lubrication :lubricin plays major role in biolubrication and protection of joints. Viscoelastic function : proteoglycans, GAGS and elastic fiber Provides smooth gliding surface in joints Development and growth of bones

14. Types of cartilage mainly three types 1.Hyaline cartilage : most of the cartilage in body are hyaline cartilage Distribution: articular cartilage,costal,tracheobronchial,nose,and laryngeal cartilage(except epiglotis,cuniform,corniculate,apex of arytenoids) Matrix: hour glass like, Chondroitin sulfate predominance, Few collagen fiber

15. Types of cartilage cont.. 2.Elastic cartilage: Matrix : contains collagen fiber with large number elastic fiber which anastomose in all direction except around cartilage cells. Maintains shape of cartilage. Distribution :Pinna,eustachian,tubes,epiglottis,corniculate,cuniform,apex of arytenoids

16. Types of cartilage cont.. 3.Fibrocartilage: Matrix :abundent amount of collagen fiber, limited no. of cells and ground substance, collagen fiber arranged in bundles, cells present between bundles Distribution :intervertibral disc, interpubic disc, articular disc of TM, sternoclavicular and inferior radio-ulnar joints, menisci,

17. JOINTS Joints are the region of the skeleton where two or more bones meet and articulate. With the exception of the hyoid bone, every bone in the body is connected to or forms a joint. There are 230 joints in the body. Study of joint called ARTHOLOGY.

18. Classification of joints mainly of two types 1.Diarthroses or synovial joints : *skeletal elements are separated by a cavity *free movements are possible 2.Synarthroses or solid joints: *skeletal elements are held together by connective tissues or cartilage. *allowed restricted little or no movements

19. 1.Diarthroses or synovial joints : Characteristic feature: 1.articular cartilage 2.joint capsules-----formed by fibrous tissue 3.joint cavity------enclosed by fibrous capsule 4.synovial membrane 5.synovial fluid 6.accessory structure: meniscus,labrum,articular disc, fat pads,tendon,ligament,bursae.

20. 1.ARTICULAR CARTILAGE hyaline cartilage covering the bone surfaces Posses ECM enzymes: matrix metalloproteinase(MMPs) and TIMPs.

21. Functions of articular cartilages Extremely low coefficient of friction Shock absorption Distribution of joint loads Reduce contact stress

22. Injury and healing of articular cartilage Limited healing potential due to avascularity. Three types injury of articular cartilage: Type 1: microscopic damage to cells and ECM Type 2: chondral fracture or fissuring Type 3: deeper injury,penetration to subchondral bone

23. Microscopic structure of articular cartilage Four microscopic zones 1.Superficial or gliding zone: 10—20% 2.Middle or transitional zone : 40---60% 3.Deep or Radial zone: 30% 4. Calcified zone

24. MENISCUS Meniscus is an incomplete rim of white fibrous cartilage between articular cartilages. Distribution: knee joints, articular disc of sternoclavicular and acromioclavicular joints,triangularfibrocartilage, labra in hip&shoulder.

25. Meniscus cont.. functions Tibiofemoral load transmission. Shock absorption Lubrication Prevent synovial impingement Distribute synovial fluid Contribute to joint stability, gliding motion .

26. Composition of meniscus CELLS Primarily fibrochondrocyte Responsible for synthesis and maintenance of ECM ECM Water-70% Interlacing collagen fibers. 95% type 1 collagen Smaller amount type II,III,V,VI Elastin-0.06% Noncollagenous protein-8-13%

27. Ultra structure of meniscus Three collagen fiber layer. Which convert compressive loads to circumferential or hoop stress. Superficial layer: gliding movements Circumferential layer : resist stress during weight bearing Radial layer: between above two layer serve as “ties”.

28. Joint capsule two layers: Outer fibrous membrane Complete enclose joints Interrupted by synovial protrusion called bursae Bursae are routes for spread of infection into joints Form intrinsic ligaments.

29. Inner synovial membrane Lines fibrous capsules and covers articular cartilage, Intracapsular ligaments, bur -sae,tendon sheaths. Forms synovial villi Composed of two layers: 1.Intima or cellular layer 2.Subintimal or fibro – -vascular layer

30. Synovial fluid Plasma transudate from synovial capillaries. Modified by secretory activities of type B cells. Lack of fibrinogen Does not clot normally.

31. Laboratory Testing: Macroscopic Volume-0.2-4ml Color and Clarity-colorless and clear or transparent. Inclusions-rice bodies,ochronotic shards Viscosity-string test Clotting Mucin Clot

32. Laboratory Testing: Chemical Protein: 1-3 g/dl Glucose: no lower than 10mg/dl less than serum glucose Uric Acid: 6 to 8 mg/dl Lactic Acid: less than 25 mg/dl Rheumatoid Factor:50% RA +ve.

33. Laboratory Testing: Microscopic Cell Counts : Norma l values: RBCs = none WBCs = 0 – 150/ cumm . Differential: Norma l values: Neutrophils 7% Lymphocytes 24% Monocyte (Histocytes) 48% Macrophages 10% Synovial lining cells 4% Crystals : uric acid crystals,CPPD,cholester--ol,steroid induced, apatite crystals.

34. Laboratory Testing: Microbiology Infectious organisms Bacteria Fungi Mycobacteria Viruses Route of entry Bloodstream Penetrating wounds Osteomyelitis rupture Arthroscopy intra-articular steroid injections prosthetic joint surgery

35. TYPES OF SYNOVIAL JOINT Uniaxial joints: Hinge joints Pivot joints Bicondylar joints Biaxial joints: Ellipsoid or condyloid joints Saddle joints: Triaxial or multiaxial joints : Plane or gliding joints Ball and socket joints

36. Uniaxial joints : Hinge joints : allows extension and retraction.e.g. Humero- ulnar, IP joints Pivot joints : Osseous pivot rotates in an osteoligamentous ring,e.g.superior radio ulnar joint,atlanto axial joints.

37. Uniaxial joints: Bicondylar joints Predominantly uniaxial May posses very little rotation about a axis orthogonal to the first. Two convex condyles articulate with concave or flat surface. Example: knee joints, TM joints

38. Biaxial joints: Ellipsoid or condyloid joints: Oval convex surface apposed to an elliptical concavity e.g. radio-carpal and MP joints in wrist . Saddle joints: Opposing surface are reciprocally concavo-convex. Flexion- Extension, Abduction-Adduction, May combined as circumduction.

39. Triaxial or multiaxial joints Plane or gliding joints : Gliding movements only Forms apposition of plane surfaces . E.g. some interCP, inter MT,sterno-clavicular, AC joints. Ball and socket joints : Globular head into a cup like cavity Moves around more than 3 axis which have a common center.e.g hip &shoulder joints.

40. SYNARTHROSES OR SOLID JOINTS FIBROUS JOINTS: skeletal elements are held together by connective tissues Immovable joints Three subtypes 1.Sutur 2.Gomphosis 3.Syndesmosis CARTILAGINOUS OR AMPHIARTHROSIS: Bones are held together by cartilages Allows restricted little movements Two subtypes: 1.Primary or synchondrosis 2.Secondary or Symphysis

41. FIBROUS JOINTS 1. Sutures or synostoses : are found between bones of the skull . In fetal skulls the sutures are wide to allow slight movement during birth. They later become rigid (synarthrodial). 2. Syndesmosis: are join directly by ligaments or aponeurotic. e.g. inferior tibio-fibular, posterior part of sacroiliac joints. moveable(amphiarthrodial), but not to such degree as synovial joints.

42. FIBROUS JOINTS.cont.. 3. Gomphosis : is a joint between the root of a tooth and the sockets in the maxilla or mandible . Two components remain in contact by collagen fiber of periodontium.

43. CARTILAGENOUS JOINTS: Primary cartilaginous or synchondrosis joints : Bones are connected by hyaline cartilage or fibrocartilage. sometimes occurring between ossification centers. This cartilage may ossify with age. These joints usually allow no movement, or minimal movement in the case of the manubriosternal and first manubriocostal joints.

44. CARTILAGENOUS JOINTS.cont.. Secondary cartilaginous joints or Symphysis: Connect the two bones by fibrocartilage. E.g. Symphysis pubis,vertibral bodies connected by Intervertibral disc.

45. Movements and Mechanisms of Joints :- 1- Gliding movements. 2- Angular movements. 3- Rotation movements. 4- Circumduction movement.

46. 1-  Gliding movement   It is simple movement that occurs in plane joint. In this movement one articular surface will glides over the other.

47. 2- Angular movement : increase or decrease of an angle between the articular bones. A- Flexion & extension : These movements occur around transverse axis. B- Abduction & adduction: Occur around antero-posterior axis.

48. 3-  Rotation movements : It is the movement in which the bone rotates around . Axis inside the bone itself e.g. rotation of humerus. 2. Axis outside the bone e.g. rotation of radius around ulna in pronation & supination 3. Axis in another bone e.g. rotation of atlas around axis e.g. rotation of head.

49. 4-  Circumduction   It is a rotatory movement of a limb around a imaginary cone. e.g. in circumduction of upper limb the apex of the imaginary cone lies in axilla and hand rotates around the base of the cone

50. Factors Affecting Stability of joints   1- Shape & fitting of surfaces. 2- Thickness & elasticity of capsule. 3- Ligaments. 4- Surrounding muscles.

51. Factors Affecting Rang of Movements   1- Tension of ligaments and capsule. 2- Contraction of antagonistic muscles. 3- Contact of soft tissue. 4- Shape of articulating bones.

52. THANK YOU ALL