N3303 Musculoskeletal Disorders (1)

MUSCULOSKELETAL DISORDERS

• Categories of Disorders:

  • Trauma

  • Degenerative Disorders

  • Infection and Inflammatory Disorders

Musculoskeletal System - Bones

• Functions of Bones:

  1. Structural support

  2. Storage of minerals (calcium, phosphorus, magnesium)

  3. Production of blood cells (red bone marrow)

  4. Protection of major body organs and soft tissues

  5. Leverage for movement

• Types of Bone:

  • Cortical Bone: Dense, solid bone

  • Trabecular Bone: Also known as cancellous bone; less dense, porous structure; more susceptible to osteoporosis (common areas: femur, wrist, vertebrae)

Bone Development

• Osteoblasts: Bone-forming cells that initiate mineralization by secreting osteoid.

• Osteocytes: Mature osteoblasts that maintain metabolism; do not divide.

• Osteoclasts: Responsible for bone resorption and degradation.

• Bone Remodeling: Cycle involving osteoblasts and osteoclasts; important for maintaining skeletal mass.

  • Modeling: New bone growth via osteoblastic activity.

  • Remodeling: Maintenance through resorption by osteoclasts.

• Factors Influencing Bone Health:

  • Calcium (Ca+) availability

  • Parathyroid hormone (PTH)

  • Vitamin D

  • Calcitonin

  • Weight-bearing stress and hormonal influences (androgens, estrogens)

Calcium Physiology

• Calcium Absorption: Enhanced by Vitamin D; insufficient vitamin D leads to hypocalcemia, triggering PTH release, which stimulates osteoclasts to release bone calcium.

• Vitamin D Function: Requires kidney function and sunlight for activation.

Musculoskeletal System - Muscle, Tendons, and Ligaments

• Muscle Structure: Composed of myofibrils and sarcomeres; control of skeletal muscle is voluntary (somatic nervous system).

• Muscle Adaptations:

  • Hypertrophy: Increase in muscle size due to use/resistance

  • Atrophy: Decrease in muscle size due to disuse or impairment

• Connective Tissues:

  • Tendons: Attach muscle to bone

  • Ligaments: Connect bones to other bones; critical for joint support

Musculoskeletal Trauma

• Types of Injuries:

  • Fractures

  • Sprains and strains

• Sprains: Overstretching of ligaments; common in ankles

  • Symptoms: Pain, swelling, bruising, pain with movement

• Strains: Overstretching of tendons/muscles; common in lower back and hamstrings

  • Symptoms: Pain, limited range of motion, muscle spasms

Fractures

• Definition: Disruption of bone continuity; can be complete or incomplete.

• Types:

  • Open (Compound): Bone protrudes outside the body; higher risk of infection.

  • Closed (Complete): Bone fragments separate but remain beneath tissue

  • Incomplete: Bone fragments partially joined

  • Compression: Crushing of cancellous bone

  • Stress: From repetitive activity

• Treatment Goals:

  • Reduction (alignment)

  • Immobilization (casting, traction)

R-I-C-E Therapy for Acute Injuries

1. REST: Initial 24-48 hours

2. ICE: 20 minutes per hour for first 48 hours

3. COMPRESSION: Use of brace, splint, or wrap

4. ELEVATE: Raise injured area above heart level

Bone Healing Process

1. Fracture and Inflammatory Response: Bleeding and hematoma formation; lasts 48 hours to days.

2. Granulation Tissue Formation: Fibroblasts grow and vascular tissue develops.

3. Callus Formation: Callus created from osteoblasts and chondroblasts; mineralization occurs within 6 weeks.

4. Lamellar Bone Deposition: Strength buildup through ossification, occurring weeks after callus formation.

5. Remodeling: Continued bone remodeling by osteoclasts and osteoblasts to restore strength, completed within 3-6 months.

Complications of Musculoskeletal Trauma

1. Neurovascular injury: Damage to blood vessels can lead to significant issues.

2. Compartment Syndrome: Elevated tissue pressure in a closed space reduces blood flow.

3. Infection: Potential for local or systemic issues post-injury or surgery.

4. Venous Injury: Risks of DVT or pulmonary embolism.

5. Fat Embolism: Fat globules enter circulation post-fracture, especially in pelvic fractures.

Degenerative Disorders of the Musculoskeletal System

• Effects of Aging:

  • Prevalence of osteoclast activity over osteoblast activity leading to bone loss.

  • Nutrition, lifestyle, and hormonal imbalances also contribute.

Osteoporosis

• Definition: Low bone density and structural deterioration; higher risk of fractures.

• Pathophysiology: Activity imbalance leads to bone fragility.

• Risk Factors: Aging, hormonal changes, lack of physical activity, poor nutrition, prolonged corticosteroid use.

Osteoarthritis (OA)

• Definition: Progressive degeneration and inflammation of joints.

• Symptoms: Pain, stiffness, reduced range of motion, joint swelling.

• Risk Factors: Age, obesity, history of injuries, and joint loading.

Rheumatoid Arthritis

• Pathophysiology: Chronic autoimmune disease leading to joint inflammation and destruction.

• Symptoms: Symmetrical joint involvement, fatigue, morning stiffness, deformity development.

Infections and Inflammatory Disorders

Osteomyelitis

• Definition: Bone infection caused by microorganisms, typically bacteria.

• Types:

  • Hematogenous, Contiguous, Chronic

• Symptoms: Fever, pain, tenderness.

• Treatment: Long-term antibiotics and possibly surgical intervention.

Septic Arthritis

• Definition: Inflammation of joints due to bacterial infection.

• Symptoms: Pain, swelling, decreased range of motion.

• Immediate treatment is crucial to prevent joint destruction.

Gouty Arthritis (Gout)

• Definition: Recurrent inflammation due to elevated uric acid levels.

• Symptoms: Severe pain, especially in the big toe, joint swelling.

Psoriatic Arthritis (PsA)

• Link to psoriasis: Involves joint inflammation associated with skin disorder.

• Symptoms: Pain, swelling, fatigue.

Lyme Disease and Ankylosing Spondylitis

• Lyme Disease: Caused by tick bites; results in rashes and joint pain.

• Ankylosing Spondylitis: Chronic inflammation leading to rigidity and pain in the spine.