1. JOINTS

2. Joints Joints or articulations: sites where two or more bones meet
Gives our skeleton mobility and holds it together
Weakest parts of the skeleton:
Yet, their structure resists various forces, such as crushing or tearing, that threaten to force them out of alignment

3. Structural Classification
Focuses on the material binding the bones together and whether or not a joint cavity is present
In fibrous joints the bones are joined together by fibrous tissue and lack a joint cavity
In cartilaginous joints the bones are joined together by cartilage and they lack a joint cavity
In synovial joints, the articulating bones are separated by a fluid-containing joint cavity

4. Functional Classification
Is based on the amount of movement allowed at the joint:
Synarthroses are immovable joints
Amphiarthroses are slightly movable joints
Diarthroses are freely movable joints

5. Fibrous Joints Bones joined by fibrous tissue No joint cavity
Amount of movement allowed depends on the length of the connective tissue fibers uniting the bones
A few are slightly movable, most are immovable
Three types:
Sutures
Syndesmoses
Gomphoses

6. Fibrous Joints Sutures
Occur only between bones of the skull
Wavy articulating bone edges interlock, and the junction is completely filled by a minimal amount of very short connective tissue fibers that are continuous with the periosteum
During middle age, the fibrous tissue ossifies and the skull bones fuse into a single unit
At this stage, the sutures are more precisely called synostoses (bony junctions)
Because movement of the cranial bones would damage the brain, the immovable nature of sutures is a protective adaptation

7. FIBROUS JOINT

8. Fibrous Joints Syndesmoses
Bones are connected by a ligament (cord or band of fibrous tissue)
Connecting fibers vary in length: amount of movement allowed depends on the length of the connecting fibers

9. Fibrous Joints Syndesmoses
Slight to considerable movement is possible
Examples:
1. Ligament connecting the distal ends of the tibia and fibula is short, and this joint allows only slight movement
True movement is still prevented, so the joint is classed functionally as an immovable joint, or synarthrosis (amphiarthrosis)
2. Ligament (interosseous membrane) connecting the radius and ulna along their length are long enough to permit rotation of the radius around the ulna

10. FIBROUS JOINT

11. Fibrous Joints Syndesmoses

12. Fibrous Joints Gomphoses
Gompho: Greek for nail/bolt
Peg-in-socket fibrous joint
Refers to the way teeth are embedded in their sockets (as if hammered in)
Only example is the articulation of a tooth with its bony alveolar socket
Fibrous connection is the short periodontal ligament

13. Fibrous Joints Gomphoses

14. Cartilaginous Joints Articulating joints are united by cartilage
Lack joint cavity
Two types:
Synchondroses
Symphyses

15. Cartilaginous Joints Synchondroses
A bar or plate of hyaline cartilage unites the bones at a synchondrosis (junction of cartilage)
Virtually all synchondroses are synarthrotic (immovable)
Examples:
Epiphyseal plates connecting diaphysis and epiphysis regions in long bones of children
(a):Epiphyseal plates are temporary joints and eventually become synostoses (bony junctions)
(b):Immovable joint between the costal cartilage of the first rib and the manubrium of the sternum

16. Cartilaginous Joints Symphyses

17. Cartilaginous Joints Symphyses
Symphyses (growing together)
Articular surfaces of the bones are covered with articular (hyaline) cartilage, which in turn is fused to an intervening pad, or plate, of fibrocartilage
Since fibrocartilage is compressible and resilient, it acts as a shock absorber and permits a limited amount of movement at the joint
Amphiarthrotic joints (synarthrosis: immovable) designed for strength with flexiblity:
Examples:
Intervertebral joints
Pubic symphysis of the pelvis

18. Cartilaginous Joints Symphyses

19. Cartilaginous Joints Symphyses

20. Synovial Joints
Articulating bones are separated by a fluid-containing joint cavity
This arrangement permits substantial freedom of movement, and all synovial joints are freely movable diarthroses (freely movable)
All joints of the limbs—indeed, most joints of the body—fall into this class

21. SYNOVIAL JOINT

22. Synovial Joints General Structure
Contains five distinguishing features
1.Glassy-smooth articular (hyaline) cartilage covers the ends of the opposing articulating bones
Thin but spongy cushions absorb compression placed on the joint and thereby keep the bone ends from being crushed
2.The joint (synovial) cavity is a space that is filled with synovial fluid

23. SYNOVIAL JOINT

24. Synovial Joints General Structure
3.The two-layered articular capsule encloses the joint cavity
The external layer is a tough fibrous capsule, composed of dense irregular connective tissue, that is continuous with the periostea of the articulating bones
It strengthens the joint so that the bones are not pulled apart
The inner layer of the joint capsule is a synovial membrane composed of loose connective tissue
Besides lining the fibrous capsule internally, it covers all internal joint surfaces that are not hyaline cartilage

25. SYNOVIAL JOINT

26. Synovial Joints General Structure
4.Synovial (joint egg) fluid is a viscous egg-white consistency, slippery fluid that fills all free space within the joint cavity
Derived largely by filtration from blood flowing through the capillaries in the synovial membrane
Viscous egg-white consistency due to its content of hyaluronic acid secreted by cells in the synovial membrane, but thins, becoming less viscous, as it warms during joint activity

27. SYNOVIAL JOINT

28. Synovial Joints General Structure
4.Synovial fluid:
Also found within the articular cartilage providing a slippery weight-bearing film that reduces friction between the cartilages
Forced from the cartilage when a joint is compressed: weeping lubrication (lubricates the free surfaces of the cartilages and nourishes their cells)
Seeps back into the articular cartilages like water into a sponge, ready to be squeezed out again the next time the joint is put under pressure
Contains phagocytic cells that rid the joint cavity of microbes and cellular debris

29. SYNOVIAL JOINT

30. Synovial Joints General Structure
5.Reinforcing ligaments cross synovial joints to strengthen the joint
Capsular, or intrinsic ligaments: thickened parts of the fibrous capsule
Extracapsular ligaments: outside the capsule
Intracapsular ligaments: deep to the capsule
Since they are covered with synovial membrane, they do not actually lie within the joint cavity
Double jointed:
People whose joint capsules and ligaments are more stretchy and looser than average
They have the same number of joints

31. SYNOVIAL JOINT

32. Synovial Joints General Structure
Richly supplied with sensory nerve endings that monitor joints position and help maintain muscle tone
Richly supplied with blood vessels, most of which supply the synovial membrane
Other specific structures:
Hip, knee joints:
Fatty pads between the fibrous capsule and the synovial membrane or bone
Knee, jaw, sternum and clavicle, shoulder, distal radioulnar:
Wedge of fibrocartilage separating the articular surfaces
Called articular dics, or menisci
Extends inward from the articular capsule and partially or completely divides the synovial cavity in two
Improve the fit between articulating bone ends, making the joint more stable and maintaining wear and tear on the joint surfaces

33. KNEE JOINT

34. KNEE JOINT

35. Bursae and Tendon Sheaths
Not strictly part of the synovial joint, BUT often found closely associated with the joint
Bags of lubricant that reduce friction at synovial joints during joint activity
Bursae (purse): flattened fibrous sacs lined with synovial membrane and containing a thin film of synovial fluid
Common where ligaments, muscles, skin, tendons, or bones rub together
Example:
Bunion: enlarged bursa at the base of the big toe, swollen from rubbing of a tight or poorly fitting shoe

36. Bursae and Tendon Sheaths
Essentially an elongated bursa that wraps completely around a tendon subjected to friction
Like a bun around a hot dog

37. BURSAE

38. Factors Influencing the Stability of Synovial Joints
Because joints are constantly stretched and compressed, they must be stabilized so that they do not dislocate (come out of alignment)
Stability of a synovial joint depends chiefly on three factors:
1.The shapes of the articular surfaces of bones found at a synovial joint :
Determines the movements that occur at the joint
Play a minimal role in stabilizing the joint
Example: ball and deep socket of the hip joint provides the best example of a joint made extremely stable by the shape of its articular surfaces

39. Factors Influencing the Stability of Synovial Joints
2.Number and positioning of ligaments:
Ligament: band of regular fibrous tissue that connects bones
Capsules and ligaments of synovial joints unite the bones and prevent excessive or undesirable motion
As a rule: the more ligaments a joint has, the stronger it is
When other stabilizing factors are inadequate, undue tension is placed on the ligaments and they stretch
Stretched ligaments stay stretched (like taffy)
A ligament can stretch only about 6% of its length before it snaps
When ligaments are the major means of bracing a joint, the joint is not very stable

40. Factors Influencing the Stability of Synovial Joints
3.Muscle tone: low levels of contractile activity in relaxed muscles
Keeps the muscles healthy and ready to react to stimulation
For most joints, the muscle tendons that cross the joint are the most important stabilizing factor
Tendon: cord of dense fibrous tissue attaching muscle to bone
Kept taut at all times by the tone of their muscles
Extremely important in reinforcing the shoulder and knee joints and the arches of the foot

41. Movements Allowed by Synovial Joints
Every skeletal muscle of the body is attached to bone or other connective tissue structures at no fewer than two points
The muscle’s origin is attached to the immovable (or less movable) bone
The other end, the insertion, is attached to the movable bone
Body movement occurs when muscles contract across joints and their insertion moves toward their origin
Movements can be described in directional terms relative to the lines, or axes, around which the body part moves and the planes of space along which movement occurs, that is, along the transverse, frontal, or sagittal plane

42. Movements Allowed by Synovial Joints
Range of motion:
Nonaxial: slipping movements only
No axis around which movement can occur
Uniaxial:
Movement in one plane
Biaxial:
Movement in two planes
Multiaxial:
Movement in or around all three planes of space and axes

43. Movements Allowed by Synovial Joints
Three general types of movement:
1. Gliding
2. Angular
3. Rotation

44. Movements Allowed by Synovial Joints
In gliding movements:
Also known as translation
One flat, or nearly flat, bone surface glides or slips over another (back-and-forth or side-to-side) without appreciable angulation or rotation
Examples:
Intercarpal and intertarsal joints
Flat articular processes of the vertebrae

45. Synovial Movement Gliding

46. Movements Allowed by Synovial Joints
Angular movements:
Increase or decrease the angle between two bones
May occur in any plane of the body and include:
Flexion
Extension
Hyperextension
Abduction
Adduction
Circumduction

47. Movements Allowed by Synovial Joints
Angular Flexion:
Bending movement, usually along the sagittal plane
Decreases the angle of the joint and brings the articulating bones closer together
Examples:
(b): Bending the knee from a straight to an angled position
(b): Arm flexed at the shoulder when the arm is lifted in an anterior direction
(c): Bending the body trunk from a straight to an angled position
(d): Bending the head forward on the chest

48. Movements Allowed by Synovial Joints
Angular Flexion:
(b): Bending the knee from a straight to an angled position
(b): Arm flexed at the shoulder when the arm is lifted in an anterior direction

49. SYNOVIAL MOVEMENT

50. Movements Allowed by Synovial Joints
Angular Flexion:
(c): Bending the body trunk from a straight to an angled position
Lateral Flexion: lateral bending of the trunk away from the body midline in the frontal plane

51. Movements Allowed by Synovial Joints
Angular Flexion:
(d): Bending the head forward on the chest

52. SYNOVIAL MOVEMENT

53. Movements Allowed by Synovial Joints
Angular Extension:
Reverse of flexion and occurs at the same joints
Involves movement along the sagittal plane that increases the angle between the articulating bones
Examples:
Straightening a flexed elbow or knee
(c): straightening a flexed body trunk
(d): straightening a flexed neck

54. Movements Allowed by Synovial Joints
Angular Extension:
(c): straightening a flexed body trunk
Angular Hyperextension:
Bending backward beyond its straight (upright) position

55. SYNOVIAL MOVEMENT

56. Movements Allowed by Synovial Joints
Angular Extension:
(d): straightening a flexed neck
Angular Hyperextension:
Bending backward beyond its straight (upright) position

57. SYNOVIAL MOVEMENT

58. Movements Allowed by Synovial Joints
Up-and-down movements of the foot at the ankle joint are given more specific names
(e): Dorsiflexion:
Lifting the foot so that its superior surface approaches the shin
Decreases the angle between the top of the foot (dorsal surface) and the anterior surface of the tibia
Corresponds to wrist extension
(e): Plantar flexion:
Depressing the foot
Decreases the angle between the sole of the foot (plantar surface) and the posterior side of the tibia
Corresponds to wrist flexion

59. SYNOVIAL MOVEMENT

60. Movements Allowed by Synovial Joints
Angular Abduction (f):
Moving away
Movement of a limb (or fingers) away from the midline or median plane of the body (or of the hand), along the frontal plane
Examples:
Raising the arm laterally
Raising the thigh laterally
When the term is used to indicate the movement of the fingers or toes, it means spreading them apart
In this case midline is the longest digit (third finger or second toe)

61. SYNOVIAL MOVEMENT

62. Movements Allowed by Synovial Joints
Angular Adduction (f):
Moving toward
Opposite of abduction
Movement of a limb (or fingers) toward the midline of the body (or the hand)
In the case of digits, toward the midline of the hand or foot (In this case midline is the longest digit (third finger or second toe)

63. Movements Allowed by Synovial Joints
Circumduction (f):
Is moving a limb so that it describes a cone in the air
Distal end of the limb moves in a circle, while the point of the cone (shoulder or hip joint) is more or less stationary
Because circumduction consists of flexion, abduction, extension, and adduction performed in succession, it is the quickest way to exercise the many muscles that move the hip an shoulder ball-and–socket joints
Example:
Pitcher winding up to throw a ball

64. SYNOVIAL MOVEMENT

65. Movements Allowed by Synovial Joints
Rotation (g):
Is the turning of a bone along its own long axis
Only movement allowed between the first two cervical vertebrae and is common at the hip and shoulder joints
Examples:
Medial rotation of the thigh:
Femur’s anterior surface moves toward the median plane of the body
Lateral rotation of the thigh:
Femur’s anterior surface moves away from the median plane of the body

66. SYNOVIAL MOVEMENT

67. Special Movements
Certain movements do not fit into any of the categories previously listed

68. Special Movements
Supination and Pronation: refer to the movements of the radius around the ulna
(a): Supination (turning backward) is rotating the forearm laterally so that the palm faces anteriorly or superiorly
In the anatomical position, the hand is supinated and the radius and ulna are parallel
Example:
Lifting a cup of soup up to your mouth on your palm

69. Special Movements
(a): Pronation (turning forward) is rotating the arm medially so that the palm faces posteriorly or inferiorly
Moves the distal end of the radius across the ulna so that the two bones form an X
Forearm position when we are standing in a relaxed manner
Example:
Dribbling a basketball

70. BODY MOVEMENTS

71. Special Movements
(b):Inversion and Eversion are special movements of the foot
Inversion turns the sole of the foot so that it faces medially
Eversion turns the sole of the foot so that it faces laterally

72. BODY MOVEMENTS

73. Special Movements
(c):Protraction and Retraction: nonangular anterior and posterior movements in a transverse plane
Examples:
Protraction moves the mandible anteriorly, juts the jaw forward
Retraction returns the mandible to its original position

74. BODY MOVEMENTS

75. Special Movements (d):Elevation and Depression:
Elevation means lifting a body part superiorly
Example:
When you shrug your shoulders you are elevating the scapulae
Depression means to move an elevated body part inferiorly
During chewing, the mandible is alternately elevated and depressed

76. BODY MOVEMENTS

77. Special Movements
Opposition occurs when you touch your thumb to the tips of the other fingers on the same hand
Makes the human hand a fine tool for grasping and manipulating objects
The saddle joint between metacarpal 1 and the carpals allows this movement

78. BODY MOVEMENTS

79. Types of Synovial Joints
Although all synovial joints have structural features in common, they do not have a common structural features
Based on the shape of their articular surfaces, which in turn determine the movements allowed, synovial joints can be classified further into six major categories:
1. Plane
2. Hinge
3. Pivot
4. Condyloid
5. Saddle
6. Ball-and-socket

80. Types of Synovial Joints Plane (a)
Have flat articular surfaces and allow gliding and transitional movements
Does not involve rotation around any axis
Only example of nonaxial joints
Examples:
Intercarpal and intertarsal joints
Joints between vertebral articular processes

81. SYNOVIAL JOINTS

82. Types of Synovial Joints Hinge (b)
(b): Consist of a cylindrical projection on a bone that fits into a trough-shaped structure on another bone
Movement is along a single plane and resembles that of a mechanical hinge
Uniaxial hinge permits flexion and extension only
Examples:
Bending and straightening the elbow
Interphalangeal joints

83. SYNOVIAL JOINTS

84. Types of Synovial Joints Pivot (c)
Consist of a rounded structure that protrudes into a sleeve or ring composed of bone (and possibly ligaments) of another bone
Only movement allowed is uniaxial rotation of one bone around its own long axis
Examples:
Joint between the atlas and dens of the axis, which allows you to move your head from side to side to indicate “NO”
Proximal radioulnar joint
Head of the radius rotates within a ringlike ligament secured to the ulna

85. SYNOVIAL JOINTS

86. Types of Synovial Joints Condyloid (d)
Knuckle-like
Ellipsoidal joint
Consist of an oval articular surface of one bone that fits into a complementary depression in another bone
Both articular bones are oval
Biaxial joint that permits all angular movements (flexion, extension, abduction, adduction, and circumduction)
Examples:
Radiocarpal (wrist) joints
Metacarpophalangeal (knuckle) joints

87. SYNOVIAL JOINTS

88. Types of Synovial Joints Saddle (e)
Resemble condyloid joints, but they allow greater freedom of movement
Saddle joints consist of each articular surface bearing complementary concave and convex areas (shaped like a saddle)
Allow more freedom of movement than condyloid joints
Examples:
Carpometacarpal joints of the thumbs
Movements allowed by these joints are clearly demonstrated by twiddling your thumbs

89. SYNOVIAL JOINTS

90. Types of Synovial Joints Ball-and-Socket (f)
Consist of a spherical or hemispherical head structure that articulates with a cuplike socket structure
They are the most freely moving joints
Allow multiaxial movements
Universal movement is allowed (in all axes and planes, including rotation)
Examples:
Shoulder
Hip

91. SYNOVIAL JOINTS

92. Knee Joint
Knee joint is the largest and most common complex joint in the body
It allows extension, flexion, and some rotation
Despite its single joint cavity, the knee consists of three joints in one:
An intermediate:
One between the patella and the lower end of the femur (femoropatellar joint)
Lateral and medial joints (collectively known as the tibiofermoral joint) between the femoral condyles above and the C-shaped menisci, or semilunar cartilages, of the tibia below
Besides deepening the shallow tibial articular surfaces, the menisci help prevent side-to-side rocking of the femur on the tibia and absorb shock transmitted to the knee joint

93. KNEE JOINT

94. KNEE JOINT

95. Knee Joint Anterior View
Many different types of ligaments stabilize and strengthen the capsule of the knee joint
The patellar ligament and retinacula are actually continuations of the tendon of the bulky quadriceps muscles of the anterior thigh
Physicians tap the patellar ligament to test the knee-jerk reflex

96. KNEE JOINT

97. KNEE JOINT

98. Knee Joint Lateral View
The synovial cavity of the knee joint has a complicated shape, with several extensions that lead into “blind alleys”
At least a dozen bursae are associated with this joint
The subcutaneous perpatellar bursa is often injured when the knee is bumped

99. KNEE JOINT Lateral View

100. Knee Joint
All three types of joint ligaments stabilize and strengthen the capsule of the knee joint
The capsular and extracapsular ligaments all act to prevent hyperextension of the knee and are stretched taut when the knee is extended

101. Knee Joint Anterior View
Extracapsular fibular and tibial collateral ligaments:
Prevent lateral or medial rotation when knee is extended

102. KNEE JOINT

103. Knee Joint Posterior View
Oblique popliteal ligament:
Is actually part of the tendon of the semimembranous muscle that fuses with the capsule and strengthens the posterior aspect of the knee joint

104. KNEE JOINT

105. Knee Joint Posterior View
Arcuate popliteal ligament:
Arcs superiorly from the head of the fibula and reinforces the joint capsule posteriorly

106. KNEE JOINT

107. Knee Joint
Intracapsular ligaments are called cruciate ligaments because they cross each other, forming an X in the notch between the femoral condyles
Help prevent anterior-posterior displacement of the articular surfaces and secure the articulating bones when we stand

108. KNEE JOINT

109. HOMEOSTATIC IMBALANCE
Of all body joints, the knees are most susceptible to sports injuries because of their high reliance on nonarticular factors for stability and the fact that they carry the body’s weight
The knee can absorb a vertical force equal to nearly seven times body weight
However, it is very vulnerable to horizontal blows, such as those that occur during blocking and tackling in football

110. HOMEOSTATIC IMBALANCE Anterior View of Medial Knee Injury
When thinking of common knee injuries, remember the 3 C’s:
1. Collateral ligaments:
Most dangerous are lateral blows to the extended knee
These forces tear the tibial collateral ligament and the medial meniscus attached to it, as well as the anterior cruciate ligament

111. KNEE INJURY

112. HOMEOSTATIC IMBALANCE
2. Cruciate ligaments: Anterior Cruciate Ligament (ACL)
Most ACL injuries occur when a runner changes direction quickly, twisting a hyperextended knee
A torn ACL heals poorly, so repair usually requires a ligament graft using connective tissue taken from one of the larger ligaments (e.g., patellar, Achilles, or semitendinosus)

113. Shoulder (Glenohumeral ) Joint
Stability has been sacrificed to provide the most freely moving joint in the body
Is a ball-and-socket joint:
Large hemispherical head of the humerus fits in the small, shallow glenoid cavity of the scapula (like a golf ball setting on a tee)

114. Shoulder (Glenohumeral ) Joint
The ligaments that help to reinforce the shoulder joint are the coracohumeral ligament and the three glenohumeral ligaments

115. SHOULDER JOINT

116. SHOULDER JOINT

117. Shoulder (Glenohumeral ) Joint
The tendons that cross the shoulder joint provide the most stabilizing effect on the joint:
These tendons and associated muscles (subscapularis, supraspinatus, infraspinatus, and teres minor) make up the rotator cuff
This cuff encircles the shoulder joint and blends with the articular capsule

118. SHOULDER MUSCLES

119. SHOULDER MUSCLES

120. SHOULDER JOINT

121. SHOULDER JOINT

122. SHOULDER JOINT

123. Shoulder (Glenohumeral ) Joint
The rotator cuff can be severely stretched when the arm is vigorously circumducted (movement of a body part so that it outlines a cone in space)
This is a common injury of baseball pitchers
Dislocation:
Because the shoulder’s reinforcements are weakest anteriorly and inferiorly, the humerus tends to dislocate in the forward and downward direction

124. Hip (Coxal) Joint
The hip joint is a ball-and-socket joint that provides a good range of motion:
Not nearly as wide as the shoulder’s range of motion
Movements occur in all possible planes but are limited by the joint’s strong ligaments and its deep sockets
The hip joint is formed by the articulation of the spherical head of the femur with the deeply cupped acetabulum of the hip bone
The depth of the acetabulum is enhanced by a circular rim of fibrocartilage called the acetabular labrum

125. HIP JOINT

126. Hip (Coxal) Joint (c): anterior view (b): posterior view
Several strong ligaments reinforce the capsule of the hip joint
These ligaments are arranged in such a way that they “screw” the femur head into the acetabulum when a person stands up straight, thereby providing more stability
The muscle tendons that cross the joint contribute to the stability and strength of the joint, BUT the majority of the stability of the hip joint is due to the deep socket of the acetabulum and the ligaments

127. HIP JOINT

128. Elbow Joint
The elbow joint provides a stable and smoothly operating hinge joint that ONLY allows flexion and extension
Within the joint, both the radius and ulna articulate with the condyles of the humerus but it is the close gripping of the trochlea by the ulna’s trochlear notch that forms the “hinge” and stabilizes this joint
(b): lateral view

129. ELBOW JOINT

130. Elbow Joint
The ligaments involved in providing stability to the elbow joint are the annular ligament, the ulnar collateral ligament, and the radial collateral ligament
Tendons of several arm muscles, the biceps and the triceps, also provide additional stability by crossing the elbow joint
The radius is a passive “onlooker” in the angular elbow movements
However, its head rotates within the angular ligament during supination and pronation of the forearm

131. ELBOW JOINT

132. Common Joint Injuries Sprains
The ligaments reinforcing a joint are stretched or torn
Partially torn ligaments will repair themselves, but they heal slowly because ligaments are so poorly vascularized
Tend to be painful and immobilizing
Completely ruptured ligaments require prompt surgical repair because inflammation in the joint will break down the neighboring tissues and turn the injured ligament to “mush”
Surgery requires sewing hundreds of fibrous strands (NOT EASY)
Examples:
Lumbar region of the spine, the ankle, and the knee are common sprain sites

133. Common Joint Injuries Cartilage:
Although most cartilage injuries involve tearing of the knee menisci, overuse damage to the articular cartilages of other joints is becoming increasingly common in competitive young athletes
Is avascular and it rarely can obtain sufficient nourishment to repair itself; thus, it usually stays torn:
Because cartilage fragments (called loose bodies) can interfere with joint function by causing the joint to lock or bind, most sports physicians recommend that the central (nonvascular) part of a damaged cartilage be removed

134. Common Joint Injuries Cartilage: Arthroscopic surgery:
A small instrument bearing a tiny lens and fiber-optic light source, enables the surgeon to view the joint interior
Repair ligament
Remove cartilage fragments
Removal of part of a meniscus
Removal of part of a meniscus does not severely impair joint mobility, but the joint is definitely less stable
Minimizes tissue damage and scarring

135. JOINT INJURY

136. Common Joint Injuries Dislocation: luxation
Occurs when bones are forced out of alignment
Usually accompanied by sprains, inflammation, and joint immobilization
Like fractures, dislocations must be reduced (bone ends must be returned to their proper positions)
Examples:
Jaw
Shoulder
Fingers
Thumb
Subluxation: partial dislocation of a joint

137. Inflammatory and Degenerative Conditions
Bursitis:
Inflammation of the bursa
Is usually caused by a blow or friction
Severe cases are treated by injecting anti-inflammatory drugs into the bursa
If excessive fluid accumulates, removing some fluid by needle aspiration may relieve the pressure
Examples:
Falling on one’s knee may result in a painful bursitis of the prepatellar bursa (housemaid’s knee / water on the knee)
Prolonged leaning on one’s elbow may damage the bursa close to the olecranon process (student’s elbow / olecranon bursitis)

138. Inflammatory and Degenerative Conditions
Tendonitis:
Is inflammation of the tendon sheaths, and is usually caused by overuse
Symptoms: pain and swelling
Treatment: rest, ice, anti-inflammatory drugs

139. Inflammatory and Degenerative Conditions
Arthritis:
Describes many inflammatory or degenerative diseases (over 100) that damage the joints
Resulting in pain, stiffness, and swelling of the joint
Acute forms:
Usually result from bacterial invasion and are treated with antibiotics
Synovial membrane thickens and fluid production decreases, causing increased friction and pain
Chronic (long-term) forms: osteoarthritis, rheumatoid arthritis, and gouty arthritis

140. Inflammatory and Degenerative Conditions
Osteoarthritis (OA):
Most common chronic arthritis
Often called “wear-and-tear” arthritis
Probably related to aging
But a genetic basis
Slow and irreversible
It is the result of breakdown of articular cartilage (by enzymes: but in healthy people replaced) and subsequent thickening of bone tissue, which may restrict joint movement
Cartilage softened, roughened, pitted, and eroded
Treatment:
Aspirin, acetaminophen, magnetic therapy (assumed to stimulate the growth and repair of articular cartilage), glucosamine (nutritional supplement: decrease pain and inflammation, preserve articular cartilage)
Examples: cervical and lumbar spines, fingers, knuckles, knees, hips

141. Inflammatory and Degenerative Conditions
Rheumatoid arthritis:
Chronic inflammatory disorder that is an autoimmune disease
Disorder in which the body’s immune system attacks its own tissues
Microorganisms that bear chemicals similar to some naturally present in the joints
BOTH are attacked by the immune system
Any age
Examples:
Many joints, particularly the small joints of the fingers, wrists, ankles, and feet
Afflicted at the same time and bilaterally (right and left sides)
Treatment: anti-inflammatory and immunosuppressant drugs

142. ARTHRITIS

143. Inflammatory and Degenerative Conditions
Gouty Arthritis: gout
Uric acid, a normal waste product of nucleic acid metabolism, is ordinarily excreted in urine without any problems
However, when blood levels of uric acid rise excessively (due to its excessive production or slow excretion), it may be deposited as needle-shaped urate crystals in the soft tissues of joints
Inflammatory response follows
Genetic factors are definitely implicated
Untreated:
Articular bone ends fuse and immobilizes the joints
Treatment:
Anti-inflammatory drugs
Avoid alcohol: promotes uric acid overproduction
Avoid foods high in purine-containing nucleic acids (liver, kidneys, sardines)

144. ARTIFICIAL JOINT

145. DEVELOPMENTAL ASPECTS OF JOINTS
Joints develop at the same time as bones, resembling adult form by eight weeks gestation
At late middle age and beyond, ligaments and tendons shorten and weaken, intervertebral discs become more likely to herniate, and there is onset of osteoarthritis