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Classification of bones_and_joint_bmj


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Classification of bones_and_joint_bmj

  1. 1. MOB TCD Classification of Bones and Joints Professor Emeritus Moira O’Brien FRCPI, FFSEM, FFSEM(UK), FTCD Trinity College Dublin
  2. 2. MOB TCD Bone
  3. 3. MOB TCD Cortical Bone • Dense, hard bone found in cortex • Three quarters of skeletal tissue • High mineral content Carter & Hayes, 1976
  4. 4. MOB TCD Cortical Bone • Stiffer than cancellous • Withstands greater stress, less strain • Fractures when strain exceeds 2% Carter & Hayes, 1976
  5. 5. MOB TCD Cortical Bone • • • • Low surface area Porosity 5-30% Slow metabolic rate Develops in line of stress Einhorn,1996
  6. 6. MOB TCD Tibia • The shaft of the tibia is mainly compact bone • A central medullary cavity containing mainly fat • The ends are compact bone • With an inner core of cancellous bone • The periosteum is the vascular fibrous connective tissue investing bone
  7. 7. MOB TCD Trabecular or Cancellous Bone • Found inside cortical shell e.g. Vertebrae • Consists of horizontal and vertical plates • Spaces are filled with bone marrow • Large surface area • Porosity is between 30-90%
  8. 8. MOB TCD Trabecular or Cancellous Bone • Greater capacity to store energy • In vitro fractures at strains >75% • Metabolically more active • More sensitive to changes in endocrine hormones Carter & Hayes,1976; Einhorn, 1996
  9. 9. MOB TCD Cancellous Bone • Compressive strength is proportional to the square of the apparent density • Small changes in density • Large change in strength Dalen et al., 1976
  10. 10. MOB TCD Bone • Organic matrix • Type I collagen forms 90% of skeletal weight • Mineral hydroxyapatite ratio • Calcium 10 • Phosphate 6 • Carbonate 1
  11. 11. MOB TCD Bone Remodelling • Bone is a living tissue • Osteoclastic activity i.e. bone resorption takes only few days • Osteoblastic or bone formation takes several months
  12. 12. MOB TCD Bone Remodelling
  13. 13. MOB TCD Phases of Bone Remodelling Normal bone turnover Osteoporotic bone turnover osteocytes Quiescence bone Activation osteoclast Resorption Formation osteoblast osteoid new bone Quiescence D1202
  14. 14. A Healthy Skeleton depends on a Balanced RANK Ligand: OPG Ratio RANK Ligand NK RA nd iga L OPG Increases Bone Loss OPG RAN Liga K nd OPG Prevents Bone Loss 1 Hofbauer LC et al. JAMA 2004;292: 490–495; 2 Lacey DL et al. Cell 1998;93:165–176; 3 Boyle WJ et al. Nature 2003;423:337–342 MOB TCD
  15. 15. A Healthy Skeleton requires a Balance of Bone Resorption and Formation Activation Resorption: 10 days When bone turnover is increased, bone loss dominates Reversal Resting Formation: 3 months Adapted from Baron, R. General Principles of Bone Biology. In: Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism. Favus MJ (Ed.) 5th Edition. American Society for Bone and Mineral Research, Washington DC, 2003: 1–8 MOB TCD
  16. 16. MOB TCD Regulation of Osteoclastogenesis osteoblast Monoclonal antibody to RANKL AMG 162 RANKL M-CSF OPG RANK c-fms Osteoclast precursor differentiation Osteoclast
  17. 17. MOB TCD Bone Bones Require • Normal hormones • Adequate calories • Particular protein • Calcium • Vitamin D • Regular weight bearing • Exercise
  18. 18. MOB TCD Bone • The rate of turnover is determined by hormonal and local factors
  19. 19. Four Mechanisms of Bone Mass Regulation MOB TCD
  20. 20. MOB TCD Wolff’s Law • Changes in bone function lead to changes in bone • Bone is laid down where needed • Bone is resorbed where it is not needed Wolff, 1892
  21. 21. MOB TCD Mechanical Strain • Osteogenesis is induced by dynamic not static strains • The optimal type of osteogenic activity should provide relatively high levels of strain Rubin & Lanyon, 1984
  22. 22. MOB TCD Bone • Tensile forces result in osteoclastic activity • On the convex side of an angulated bone • Compressive force results in osteoblastic activity on concave side
  23. 23. MOB TCD Bone Bones require • Normal hormones • Adequate calories • Particularly protein • Calcium • Vitamin D • Regular weight bearing exercise
  24. 24. MOB TCD Age Related Changes in Bone Mass1 Attainment of Peak Bone Mass Consolidation Age Related Bone Loss Menopause Men Fracture threshold Women 0 10 20 30 Age (years) 40 50 60 1. Compston JE. Clinical Endocrinology 1990;33:653-682 D1202
  25. 25. MOB TCD Peak Bone Mass • • • • Genetic Environmental factors Mechanical strain Hormones
  26. 26. MOB TCD Peak Bone Mass • Weight bearing activity during adolescence and early adulthood was a far more important predictor of peak bone mass than calcium intake Welten et al., 1994
  27. 27. MOB TCD Low Peak Bone Mass • Growing bone has a greater capacity to add new bone to skeleton than mature bone Forwood & Burr, 1993
  28. 28. MOB TCD Osteogenesis • Muscle action is main stimulus for bone formation • Mechanical force • Weight bearing Birge et al., 1968
  29. 29. MOB TCD Classification of Bones By Shape • Long • Short • Flat • Irregular • Sesamoid
  30. 30. MOB TCD Short Bones Short bones • Found only in the hand and foot • Vary in shape
  31. 31. MOB TCD Flat Bones and Irregular Bones Flat bones • Usually consist of two layers of compact bone • Cancellous bone lies in between • Found in the skull and sternum Irregular bones • Occur in the face and vertebrae
  32. 32. MOB TCD Sesamoid Bones Sesamoid bones • Develop in tendons where they cross bone • Or articular surfaces, patella • Sesamoids in relation to thumb and hallux
  33. 33. MOB TCD Long Bones Long bones • Have a cartilaginous ossification • Are found mainly in the limbs and consist of: • Shaft (the diaphysis), which is ossified from the primary center of ossification during intrauterine life • The cavity of the shaft, contains red marrow in the fetus, yellow fat in the adult
  34. 34. MOB TCD Bone Growth • Diaphysis: shaft ossified from primary center of ossification which appears 6-8th week of intrauterine life • Epiphysis: ossified from secondary center • Growth plate is cartilage • Injury of epiphysis affects growth
  35. 35. MOB TCD Epiphysis • Is ossified from a secondary center of ossification • These usually appear shortly after birth • Except for the lower end of the femur, which appears 9 months intrauterine life, just before birth • Epiphysis unite with the diaphysis (shaft) from puberty to early twenties depending on the bone involved
  36. 36. MOB TCD Metaphysis • The portion of the diaphysis beside the epiphysis is called the metaphysis • This is the region where osteomyelitis tends to occur in young people • The metaphyseal arteries are end arteries until ossification is completed i.e. the epiphyseal plate is ossified
  37. 37. MOB TCD Bones • Long bones grow in length from epiphyseal plates • Increase in width is from periosteum • Damage to the epiphyseal growth plate can lead to premature closing and retards normal growth • Anabolic steroids will also cause early closure
  38. 38. MOB TCD Epiphyses • • • • Traction epiphyses The tibial tuberosity Osgood-Schlatters Medial epicondyle of the humerus, in ‘little league elbow’ • Compression epiphysis • The distal end of the humerus
  39. 39. MOB TCD Musculoskeletal Problems • Younger athletes • Suffer many of the same injuries and illnesses as adults • Differences is the structure of growing bone Avulsed epiphysis
  40. 40. MOB TCD Lesions which affect Growth Plate Articular • Perthes: femoral • Kienbock: lunate • Kohler: navicular • Freiberg: 2nd metatarsal • Osteochondritis dissecans • Lateral aspect medial femoral condyle
  41. 41. MOB TCD Epiphyseal Injuries • • • • • • Shearing forces Avulsion forces Compression fractures Metaphyseal Growth plate Avulsion
  42. 42. Growth Plate Fractures Salter-Harris Classification • Type 1 and type 2 heal well • Type 3 and type 4 involve joint surface as well as growth plate • Type 5 compression of growth plate • Difficult to detect • Growth ceases MOB TCD
  43. 43. MOB TCD Blood Supply of Bone • Periosteal arteries enter bone at several points to supply the compact bone • Nutrient arteries supply spongy bone and bone marrow
  44. 44. MOB TCD Blood Supply of Bone • Periosteal arteries enter the bone at several points to supply the compact bone • Nutrient arteries supply the spongy bone and bone marrow • Epiphyseal arteries supply the epiphysis • Metaphyseal arteries supply the metaphysis
  45. 45. MOB TCD Blood Supply of Bone • Periosteal arteries occur particularly at the sites of attachments of muscles and tendons • If a group of muscles inserted into a bone is paralysed before puberty • That bone will be shorter than the equivalent bone on the other side • Due to reduced blood supply from the muscles involved • The lack of stimulus to bone from lack of muscle contractions • After puberty only muscle bulk is reduced
  46. 46. MOB TCD Blood Supply of Bone • Epiphyseal arteries supply the epiphysis • Metaphyseal arteries supply the metaphysis • These are end arteries until epiphysis unites with diaphysis
  47. 47. MOB TCD Avascular Necrosis • Bones that have a large surface area covered with articular cartilage tend to have a poorer blood supply • Avascular necrosis occurs if blood supply is cut off due to fracture • e.g. head of femur, due to fracture of neck of femur • Proximal portion of the scaphoid • Body of talus or dislocation e.g. lunate
  48. 48. MOB TCD Apophysis • • • • Tendon attachment to growth plate Traction injuries may occur Medial epicondylitis Limit numbers of pitches in baseball • Osgood-Schlatters lesion of tibial tuberosity • 12-16 year olds
  49. 49. MOB TCD Avulsion Fractures Medial epicondyle
  50. 50. MOB TCD Bones in Children • • • • More flexible More elastic Less brittle Growth plate is weakest link • Periosteum thicker
  51. 51. MOB TCD Bones in Children • Articular cartilage thicker • Junction between • Metaphysis and epiphysis vulnerable • Shearing forces • Tendon attachment to apophysis weak
  52. 52. MOB TCD Eating Disorders May result in • Delayed bone growth • Delayed menarche • Low peak bone mass • Osteopenia or osteoporosis • Increased musculo-skeletal problems
  53. 53. MOB TCD Articular Cartilage • The thickness of the cartilage depends on the stress to which it is normally subjected • Varies over the joint surface • Patella has the thickest articular cartilage
  54. 54. MOB TCD Articular Cartilage • Articular cartilage is avascular • Nourished by synovial fluid, from capillaries in the synovial membrane • When the articular surfaces are in contact Hollingshead, 1969
  55. 55. MOB TCD Musculoskeletal Injuries Extrinsic factors • Sport • Contact sports • Environment • Equipment • Protective • Overuse Intrinsic factors • Physical • Physiological • Psychological • Previous injury
  56. 56. MOB TCD Bone Pain • • • • Osteomyelitis Tumour (night pain) Osteochondritis Rheumatoid arthritis
  57. 57. MOB TCD Stress Fractures • • • • • • • • • Biomechanical causes Training errors Athletic triad Amenorrhea Eating disorders Osteoporosisor osteopenia X-ray many times negative MRI is extremely sensitive Stress fracture of the femoral neck is potentially serious and need often surgery
  58. 58. MOB TCD Joint • Junction between two bones • Function and movement depends • Size and shape of articular surfaces • Soft tissues surrounding the joint
  59. 59. MOB TCD Range of Joint Movement • • • • • • Shape of articulating surfaces Restraint due to ligaments and muscles crossing joint Pain, weakness, spasm or contracture of muscles Bulk of adjacent soft tissue Impingement of bony surfaces Scarring of skin due to injury or burns
  60. 60. MOB TCD Muscles • Muscle can only act on a joint, if it crosses the joint • Muscles that have a common action on the joint tend to have same nerve supply • Usually nerve of compartment gives an articular branch to joint • Exception, flexors of the elbow, where median, ulnar and radial all give branches
  61. 61. MOB TCD Classification of Joints • • • • Fibrous Cartilaginous Primary and secondary Synovial
  62. 62. MOB TCD Fibrous Joints • Fibrous union • Slight movement • Gomphosis i.e. tooth and its socket • Sutures • Syndesmosis
  63. 63. MOB TCD Fibrous (Suture) • Consists of dense fibrous connective tissue between the bones • Periosteum covering the opposing surfaces of the bones • Synostosis • Fusion of the bones across the sutural joints continues throughout life
  64. 64. MOB TCD Fibrous Syndesmosis • Interosseous membranes: radius and ulna, similar in lower limb and inferior tibio-fibular joint
  65. 65. MOB TCD Primary Cartilaginous • Cartilage continuous with bone • No movement • Rib and costal cartilage: costo-chondral joints • First costal cartilage and sternum • Diaphysis and epiphysis
  66. 66. MOB TCD Primary Cartilaginous • Epiphysis and diaphysis • Rib and costal cartilage • 1st costal cartilage and manubrium sternum • No movement
  67. 67. MOB TCD Primary Cartilaginous • Epiphysis and diaphysis
  68. 68. MOB TCD Secondary Cartilaginous • • • • • Hyaline cartilage Disc of fibro-cartilage Mid line joints Very little movement Intervertebral discs
  69. 69. MOB TCD Secondary Cartilaginous • Manubrium and body of sternum • Pubic symphysis
  70. 70. MOB TCD Synovial • Hyaline articular cartilage • Capsule • Synovial membrane lines capsule, non articular structures inside joint • Never lines articular cartilage • Discs or menisci are fibro cartilage
  71. 71. MOB TCD Types of Synovial Joints • • • • • • • • Shape of articular surface Plane Hinge Condylar Pivot Saddle Ellipsoid Ball and socket
  72. 72. Types of Synovial Joints Shape of Articular Surface • Plane: talo-calcaneal • Hinge: elbow, interphalangeal joints • Condylar: knee, metacarpophalangeal • Pivot: superior radio-ulnar, atlantoaxial • Saddle: trapezium-base first metacarpal • Ellipsoid: wrist • Ball and socket: hip, shoulder, talocalcaneo-navicular MOB TCD
  73. 73. MOB TCD Description of a Joint Classify • Shape of articular surfaces • Cartilage covering surface • Attachments of capsule • Ligaments, disc • Haversian pads of fats fill joint spaces • Synovial membrane • Movements • Relations • Blood and nerve supply • Clinical significance
  74. 74. MOB TCD Capsule • • • • Collagen Expanded tendon Sesamoid bone Thickened to form ligaments • Haversian pads of fats fill joint spaces
  75. 75. MOB TCD Plane Joint • Surface is flat • Only allows gliding movement • Non-axial e.g. facet joints of vertebrae • Talo-calcaneal joint Talo-calcaneal
  76. 76. MOB TCD Hinge Joint • Movement in one plane (uniaxial) e.g. elbow • Interphalangeal joints in hand and foot • Strong ligaments on sides, weaker anterior and posterior
  77. 77. MOB TCD Pivot Joint • Allows rotation around a single axis • Uni axial • Atlanto axial • Superior and inferior radioulnar joints
  78. 78. MOB TCD Saddle Joint • Saddle-shaped concavoconvex surfaces • Movement in two planes (biaxial) e.g. carpometacarpal of the thumb (trapezium and base of first metacarpal)
  79. 79. MOB TCD CondylarJoint • Two axes at right angles to each other • Movement in two planes (biaxial) • Meta-carpophalangeal • Sternoclavicular • Atlanto-occipital joints
  80. 80. MOB TCD Ball and Socket Joint • Allows movement in three axes • Multiaxial • Hip • Shoulder • Talocalcaneo-navicular joints
  81. 81. MOB TCD Synovial Joints • Discs of fibro cartilage or menisci in some joints • Blood supply at periphery • Increase the depth and mobility of the joint • Synovial folds in joints • Synovial membrane • Nerve endings also in fat • Infrapatellar fat pad • Facet joints of lumbar vertebrae • Elbow
  82. 82. MOB TCD Capsule • Consists of collagen (type I) • Thickened to form ligaments • Expanded quadriceps tendon • Sesamoid bone in quadriceps tendon • Synovial membrane lines the inner surface of the capsule and non articular structures inside capsule
  83. 83. MOB TCD Fibrocartilagenous Discs Lateral meniscus Infrapatellar fat pad
  84. 84. MOB TCD Haversian Pads of Fat • Fat pads are semi-liquid at body temperature • They fill the changing spaces that occur during movement • These pads help to reduce friction between moving tissues
  85. 85. MOB TCD Sensory Supply • Sensory nerves in fibrous capsule and ligaments and synovial membrane • Information about pain • The position of the joint (proprioception) • Poor proprioception predisposes to injury Isakov & Mizrahi, 1997
  86. 86. MOB TCD Synovial Joint • The epiphyses of many long bones are intracapsular • Injury to a joint, before the cessation of growth, may damage the epiphyseal cartilage • The articular surfaces are covered by hyaline or articular cartilage
  87. 87. MOB TCD Hyaline Cartilage • Hyaline cartilage is avascular • Nutrition is by diffusion from the synovial fluid • Must be in contact with the opposing articular surface
  88. 88. MOB TCD Open and Closed Kinetic Chain • Open kinetic chain • The distal segment is free in space • Raising the hand in the air • Closed kinetic chain • The distal segment is fixed
  89. 89. MOB TCD The Degrees of Freedom • Joints can also be classified by degrees of freedom • Reflects the axis of movement • If a joint has only one axis • It has only one degree of freedom
  90. 90. MOB TCD The Degrees of Freedom • Nonaxial: no axis of rotation • Uniaxial: move in one axis • Have one degree of freedom • Acromioclavicular 1 • Elbow 1, radioulnar 1 • Proximal and distal interphalangeal 1 • Biaxial: move in two axes • Have two degrees of freedom • Metacarpophalangeal 2 + • Wrist 2 + • Multiaxial: move in three axes • Have three degrees of freedom • Maximum any joint can possess • • • • Shoulder 3 Sternoclavicular 3 Hip 3 Talocalcaneonavicular 3
  91. 91. MOB TCD Close-Packed • • • • • • Stable position Surfaces fit together Ligaments taut Spiral twist Screw home articular surface Stable position
  92. 92. MOB TCD Least-Packed • Joint more likely to be injured in least-packed position • Capsule slackest • Joint held in this • Position when injured • Fluid in knee held in 20° flexion
  93. 93. MOB TCD Range of Joint Movement • • • • • • Shape of articulating surfaces Restraint due to ligaments and muscles crossing joint Pain, weakness, spasm or contracture of muscles Bulk of adjacent soft tissue Impingement of bony surfaces Scarring of skin due to injury or burns
  94. 94. “BMJ Publishing Group Limited (“BMJ Group”) 2012. All rights reserved.”