MSK

• Types of Arthritides

  • Osteoarthritis
  • Gout
  • Rheumatoid Arthritis
  • Ankylosing Spondylitis
  • Psoriatic Arthritis
  • Reactive Arthritis
• Osteoarthritis


  • Commonest joint disorder
  • Commonest cause of disability after middle age
  • Degeneration of articular cartilage
  • Pain
  • Stiffness
• Types of Osteoarthritis

  • Primary Osteoarthritis
  • Secondary Osteoarthritis
• Primary Osteoarthritis

  • No obvious predisposing cause
  • Runs in families
  • Type II collagen mutation
  • Susceptible joints are spine and large weight-bearing joints (knee, hip)
  • Interphalangeal joints may show osteophytic outgrowths (Heberden and Bouchard nodes)
• Secondary Osteoarthritis


  • Association with predisposing condition
  • Abnormal articular surface - post-traumatic
  • Increased stress on the joint - obesity, occupational, sports injuries, abnormal alignments
  • Previous inflammation - rheumatoid arthritis, sepsis
• Gout

  • Excessive uric acid
  • Hyperuricaemia
  • Deposition of urate crystals in articular cartilage
  • Big toe
  • Formation of tophi
• Rheumatoid Arthritis

  • Common
  • Systemic chronic inflammatory disease
  • Synovial membrane most affected
  • Insidious
  • Progressive
  • Remissions and exacerbations
  • Multiple joints symmetrical
  • Hands, knees and feet
  • Spine
• Connective Tissue Inflammation in RA


  • Rheumatoid nodules
  • Interstitial pneumonia
  • Necrotising arteritis
  • Interstitial myocarditis, polymyositis, neuritis, pericarditis, pleurisy
  • Juvenile RA, lymphadenopathy, splenomegaly
  • Long standing RA, amyloid disease
• Rheumatoid Factors


  • Anti-IgG antibodies
  • Formation of immune complexes
  • Joint inflammation
  • 85% RA patients "seropositive"
• Sero-Negative Arthritis

  • Ankylosing Spondylitis
  • Psoriatic Arthritis
  • Reactive Arthritis
• Ankylosing Spondylitis

  • Sacroiliac, costovertebral and vertebral joints
  • Osseous ankylosis
  • Limitation of movement
  • Aortitis
  • Uveitis
• Infections of the Joints

  • Acute infective arthritis
  • Tuberculous arthritis
  • Lyme disease
• Bone Cell Types

  • Osteoblasts
  • Osteocytes
  • Osteoclasts
  • Osteogenic cells
• Bone Remodelling Cycle

  1. Resorption: osteoclasts digest old bone

  2. Reversal: mononuclear cells appear on the bone surface

  3. Formation: osteoblasts lay down new bone until resorbed bone is completely replaced
• Osteolytic Lesions


  • Lesions with decreased bone mineral density caused by overactivation of bone resorption
  • Disseminated tumour cells stimulate osteolysis via enhanced osteoclast differentiation
  • Osteoclasts originate from hematopoietic precursor cells and have a primary role of bone resorption
  • Continued stimulation and loss of bone resorption regulation by osteoclast activation form the basis of an osteolytic lesion
• Osteoblastic Lesions


  • Lesions with increased bone formation characterized by increased areas of sclerosis within the skeleton
  • Metastatic lesions from prostate carcinomas are the most well known producer of osteoblastic lesions
  • Osteoblasts originate from mesenchymal progenitor cells and function by forming bone
  • Osteoblastic bone formation stages: proliferation, matrix maturation, mineralisation
  • Osteoblastic lesions originate from an alteration in bone remodelling with secretion of factors that affect the osteoblast/osteoclast relationship
• What are the main components of a synovial joint?

  Articular Cartilage

  Synovial Layer

  Fibrous Layer

  Joint cavity
• what is the role of articular cartilage in a synovial joint?

  Minimise friction

  Absorbing shock
• What is the role of the synovial layer in the synovial joint?

  Lubrication - makes synovial fluid
• What is the role of the fibrous layer in a synovial joint?


  Provide stability to the joint by holding the bones together
• What is the role of the joint cavity in a synovial joint?


  Provides a cushion between bones and tendons and/or muscles around a joint. Reduces friction
• Osteoarthritis Pathology

  • Thickened crunched-up bone with no covering cartilage
  • Osteophytes
  • Bone angulation
  • Inflamed synovium
  • Little remaining cartilage
  • Tight, thickened capsule
• Rheumatoid Arthritis Pathology

  • Destruction of cartilage
  • Inflamed joint capsule
  • Inflamed synovium
  • Decreased synovial fluid
• Risk factors for RA

  • Genetic risk
  • Susceptibility genes
  • Epigenetic modifications
  • Smoking
  • Microbiota
  • Females
  • Western diet
  • Ethnic Factors
• RA comorbidities

  • Stroke
  • Eye Problems
  • Lung Problems
  • Diabetes
  • Sleep Issues
  • Depression and anxiety
  • Heart disease
  • Vasculitis
  • Blood Disease
  • Osteoporosis
• Symptoms of seronegative RA 


  Pain, swelling, stiffness, and tenderness is a common feature noted in affected joints
• Where does ankylosing spondylitis affect?

  • Eyes
  • Shoulders
  • Gut (IBD)
  • Sacroiliac joint
  • Skin (psoriasis)
  • Knees
  • Heels
• Ankylosing Spondylitis 


  • Inflammatory back pain and other joints
  • Symptoms first strike before 45
  • More common in men
  • Can cause spinal joints to fuse together
  • Treated with NSAIDs and/or biologics
• What is the function of osteocytes?

  Maintain mineral concentration of matrix
• Where are osteocytes located?

  Entrapped in matrix of bone
• What is the function of osteoclasts?

  Bone resorption
• Where are osteoclasts located?

  Bone surfaces and at sites of old, injured, or unneeded bone
• What is the function of osteoblasts?

  Bone formation
• Where are osteoblasts located?

  Growing portion of bone, including periosteum and endosteum
• What is the function of osteogenic cells?

  Develop into osteoblasts
• Where are osteogenic cells located?

  Deep layers of the periosteum and the marrow