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Joint pathology. Normal anatomy. Joints provide movement and support . Classification: Solid (nonsynovial) also known as synarthroses ; lack a joint space allow minimal movement Cavitated (synovial): have a joint space allow for a wide range of motion. Synovial joint. Joint space.
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Normal anatomy • Joints provide movement and support. • Classification: • Solid (nonsynovial) • also known as synarthroses ; lack a joint space • allow minimal movement • Cavitated (synovial): • have a joint space • allow for a wide range of motion.
Joint space • Boundary formed by synovial membrane. • Lined by synoviocytes. • Synovial fluid (SF): • Pale yellow to clear, viscous • Rich in hyaluronic acid: acts as lubricant • provides nutrition for articular cartilage. • Arthrocentesis: needle aspiration of SF
Synovial fluid analysis • Routine studies of SF: • Gross appearance: normally pale yellow • WBC count and differential count : • normally <200 cells mm3, • neutrophils <25% of total count. • Culture & Gram stain :if infection is suspected • Crystal analysis
Crystal analysis • Monosodium urate (MSU) : found in gout • needle shaped (monoclinic) • Special polarization shows negative birefringence • Calcium pyrophosphate dehydrate (CPPD) crystals: found in pseudogout. • Monoclinic or triclinic (rhomboid) • Special polarization shows weakly positive birefringence
Monosodium urate crystal Negatively birefringent Calcium Pyrophosphate Positively birefringent crystal
Classification of joint diseases • Osteoarthritis • Neuropathic- Charcot’s joint • Rheumatoid arthritis • Gout • Pseudogout • SLE • Ankylosing spondylitis • Reiter’s disease • Psoriatic arthritis • Infections • Trauma
Osteoarthritis (OA) • Most common type of joint disease and joint disability in the US • A degenerative joint disease and is characterized by: • Progressive erosion of articular cartilage and • Associated reactive changes at the margin of the joints and in the subchondral bone. • Not primarily an inflammatory disease
More common in women than men Primarily targets weight bearing joints Hips, knees cervical and lumbosacral spine Other joints: Distal interphalangeal joint (DIP) and proximal interphalangeal joint (PIP) of the hands Osteoarthritis
Osteoarthritis con’t Causes: A combination of genetic and environmental factors. • Primary: as a result of aging phenomenon; • seen in older individuals • Secondary: develops as a result of a predisposing condition • seen in younger individuals • Trauma to joint • Obesity • Ochronosis - (alkaptonuria: accumulation of homogentisic acid) • Hemochromatosis
Osteoarthritis con’t Pathogenesis: • Exact etiology of OA osteoarthritis is unknown • Most important factor that predisposes to development of OA is • effect of abnormal load (mechanical trauma) on a weight bearing joint
Thinning of articular cartilage • Development of cracks
Formation of : • Loose body/joint mice • Subchondral cyst
Eburnation • Sclerosis • Narrowing of joint space • Loose body • Osteophyte
Osteoarthritis • Joint findings: • Erosions and clefts in articular cartilage • Clefts penetrate into underlying subchondral bone • Fragmentation of cartilage and subchondral bone result in formation of loose bodies • Bone rubs on bone polished ivory like appearance called eburnation • Subchondral bone cysts (visible on X rays) develop beneath the articular surface • Reactive bone formation at the margins of joints produce osteophytes (bony spurs).
Bouchard’s nodes (PIP) Heberden’s nodes (DIP)
Osteoarthritis Clinical findings: • Pain worse with activity • Morning stiffness : lasts less than half hour • Joint stiffness: with limitation of movement • Heberden’s nodes develop in the DIP joints and • Bouchard’s nodes in the PIP joints of the hand
Osteoarthritis • Lab studies: • No specific laboratory abnormality. • Synovial fluid analysis : normal • Diagnosis: xray findings • Presence of osteophyte at joint margins • Joint space narrowing • Subchondral bone cysts
Neuropathic arthropathy (Charcot’s joint) • It is a non-inflammatory joint disease • Secondary to a neurologic disease. • Joint destruction is due to insensitivity to pain • Causes: • Diabetes mellitus (Most common cause) (tarsometatarsal joint) • Syringomyelia (shoulder, elbow, wrist joints) • Tabes dorsalis (hip, knee and ankle joint)
Neuropathic arthropathy (Charcot’s joint) • Pathogenesis: • loss of proprioception and deep sensation leads to recurrent trauma • progressive destruction, and disorganization of the joint
Marked joint destructionis the hallmarks of a neuropathic joint
Rheumatoid arthritis (RA) • It is a chronic systemic, inflammatory disease • Genetics, enviromental factor and autoimmunity contributes to the etiology. • 30-50 years of age • Affects the peripheral joints in a symmetric manner producing proliferative synovitis that causes: • destruction of articular cartilage • ankylosis (fusion) of joint • joint deformity and disability
Rheumatoid arthritis (RA) Clinical features: • Symmetric bilateral involvement; warm, tender and swollen joints • Small joints of hands and feet • MCP and PIP joints (not DIP) • Other joints include: • Ankles, knees, wrists, and cervical spine • Note: involvement of joints causes: • Joint stiffness especially in the morning, which lasts more than an hour and improves with activity.
Rheumatoid arthritis Extra-articular manifestations: • Rheumatoid nodules • Vasculitis • Pulmonary: pleural effusion; interstitial fibrosis • Baker’s cyst increased articular pressure leads to outpouching of the synovium • Carpal tunnel syndrome median nerve entrapment • Hematologic: anemia of chronic disease; Felty’s syndrome( AI neutropenia/splenomegaly)
Rheumatoid arthritis • Baker’s cyst (synovial cysts): • It is usually found in the in the posterior aspect of the knee • It may be confused with popliteal artery aneurysm
Interstitial lung fibrosis
Rheumatoid arthritis Lab findings con’t • Blood work: • Elevated ESR • Positive rheumatoid factor (80%) • Anticyclic -citrullinated peptide CCP(most specific marker) • Synovial Fluid: • WBC: 3,000 – 50,000 • Mostly PMNs (neutrophils) • X-ray: • Soft-tissue swelling • Erosions at articular surface • Narrow joint space (destruction of articular cartilage) • Fusion of joints (ankylosis) • Joint deformity
Juvenile Rheumatoid arthritis (JRA) • Definition: JRA is characterized by a chronic synovial inflammation of unknown cause • It usually occurs in young girls < 16 years of age • RF is usually absent seronegative • Still’s disease • Polyarticular JRA • Pauciartucular JRA
Still’s disease: Commonly presents as an “infectious disease” with fever, rash,generalized lymphadenopathy neutrophilic leukocytosis and polyarthritis Polyarticular JRA: Clinically disabling arthritis affecting many joints Other features include: low-grade fever growth retardation, adenopathy cervical spine involvement Juvenile Rheumatoid arthritis (JRA)
Juvenile Rheumatoid arthritis (JRA) • Pauciarticular JRA: • Arthritis is present in a few joints • Inflammation of the anterior uveal tract uveitis • May lead to visual loss and blindness
Gout • Gout is a disorder of uric acid metabolism characterized by: • Hyperuricemia • Recurrent attacks of joint inflammation (gouty arthritis) and tissue deposition of uric acid crystals • It can lead to joint destruction if untreated • Gender: males> females
Gout • Causes: • Primary gout (Idiopathic)is due to: • Under-excretion of uric acid in urine- most common • Overproduction of uric acid- less common
Gout Causes : • Secondary gout: due to a secondary disorder. • the cause of hyperuricemia is known but gout is NOT the main or dominant clinical disorder. • Common causes include: • ↑nucleic acid turnover: leukemia, lymphoma • Drugs: diuretics, aspirin, ethanol • Chronic Renal failure • Lead intoxication(Saturnine Gout)
Gout Acute arthritis: clinical features • The initial attack • It commonly involves 1stmetatarsophalangeal joint (big toe) inflammation of this 1st MTP joint is called podagra • The involved joint is red, hot and exquisitely tender
Gout Chronic gout: It develops in uncontrolled or poorly controlled gout • It is characterized by presence of tophi • Tophi: deposits of MSU crystals in soft tissues: Pathognomonic lesion of gout found in the helix of the ear, fingers, toes • M/E: granulomatous reaction with foreign body type of giant cells surrounding amorphous MSU crystals
Gout Complications: • Arthritis: • Asymmetric polyarthritis with • erosion of cartilage and subchondral bone due to crystal deposition • Renal Disease – gouty nephropathy • chronic medullary interstitial nephritis • Urolithiasis (renal stones) • Acute Renal failure – MSU deposition in collecting tubules
Gout • Synovial fluid: • Demonstration of MSU crystals in synovial fluid is diagnostic • Intracellular, needle-shaped, negatively birefringent crystals • CBC: Absolute neutrophilicleukocytosis • Serum uric acid levels: • Hyperuricemia is usually but not always present. • Only 5-20% patients with hyperuricemia develop gout • 10% patients with gout have normal uric acid levels
Pseudogout ( chondrocalcinosis) • It is associated with deposition of CPPD crystals in joints i.e knee • It is a disease of the elderly • Pathogenesis: • Normal aging process biochemical change in cartilage ↑ level of pyrophosphate pyrophosphate combines with Ca++ crystals deposited in the articular cartilage • Release of CPDD crystals in the joint causes inflammatory reaction
Pseudogout • Clinical findings • Asymptomatic (chondrocalcinosis) • Acute attack (pseudogout): • Oligoarthritis resembling gout • Chronic form: • Polyarthritis resembling RA
Pseudogout • Clinical findings con’t • Synovial fluid analysis: • Blue staining rhomboid crystals. • Positive birefringence • Xray - calcification of articular cartilage
Seronegativespondyloarthropathies • A group of related disorders. • Develop in genetically predisposed individuals • when they come in contact with certain environmental factors ( triggering agents) • Characteristics include: • Lack Rheumatoid factor (RF negative) • Individuals HLA-B27 positive • Male dominant • Involve sacroiliac joint ( sacroilitis) with or without peripheral arthritis
Seronegativespondyloarthropathies • Types of spondyloarthropathy: • Ankylosing spondylitis (AS) • Reiter’s syndrome • Arthritis associated with • ulcerative colitis • shigellosis • psoriasis