Musculoskeletal Disorder Overview

Learning Objectives

• Understand and discuss the etiology, diagnosis, and treatment strategies of the following musculoskeletal disorders:
  • Bone Disorders
  • Osteoporosis
  • Fractures
  • Joint Disorders
  • Gout
  • Rheumatoid Arthritis
  • Osteoarthritis

The Musculoskeletal System

• Composed of:
  • Bones (the skeleton)
  • Muscles
  • Cartilage
  • Tendons
  • Ligaments
  • Joints
• Function:
  • Supports the body
  • Allows motion
  • Protects vital organs

Cells of Bones

• Osteocytes:
  • Most abundant bone cells, derived from osteoblasts.
  • Maintain bone tissue and communicate with other bone cells.
• Osteoblasts:
  • Bone-forming cells that produce new bone matrix (collagen and other materials).
  • Crucial for bone growth and healing.
• Osteoclasts:
  • Large, multinucleated cells responsible for bone resorption.
  • Break down bone tissue by secreting acids and enzymes to release minerals into the bloodstream.

Calcium Homeostasis

• Involves vitamin D, parathyroid hormone (PTH), and calcitonin.
• Mechanism:
  • Decreased blood Ca²⁺ stimulates PTH secretion > stimulates osteoclasts > bone breakdown > Ca²⁺ in blood increases.
  • Increased blood Ca²⁺ stimulates calcitonin secretion > inhibits osteoclasts, promoting osteoblast activity > Ca²⁺ deposition in bone.

Osteoporosis

• Definition:
  • Disease that weakens bones, leading to easy fractures, primarily affecting the hip, spine, and wrist.
• Pathophysiology:
  • Loss of calcium and phosphate leads to porous, brittle bones.
  • More common in white women with a family history.

Causes and Risk Factors

• More rapid bone resorption than formation causes loss of bone mass.
• Risk Factors:
  • Menopause (loss of estrogen)
  • Malabsorption of calcium and vitamin D
  • Hyperparathyroidism
  • Smoking
  • Sedentary lifestyle

Signs and Symptoms

• Early stages usually asymptomatic.
• May present with:
  • Back pain
  • Loss of height
  • Stooped posture
  • Increased risk of fractures

Diagnosis

• Bone density assessment (DXA scan):
  • T score interpretation:
  • Normal: T score ≥ -1
  • Osteopenia: -1 > T score ≥ -2.5
  • Osteoporosis: T score < -2.5

Management

• Lifestyle and Diet:
  • Weight-bearing exercises
  • Calcium and vitamin D supplements
  • Avoid smoking and excessive alcohol
• Medications:
  • Bisphosphonates (e.g. Alendronate)
  • Denosumab
  • Hormonal therapy (estrogen replacement)

Fractures

• Definition:
  • A break in a bone.
• Types:
  • Closed Fracture: Skin intact
  • Open Fracture: Skin broken, risk of infection
  • Stress Fracture: Small crack due to overuse

Risk Factors

• Older age, female gender, osteoporosis, physical activity, lifestyle factors (smoking, alcohol), and certain medical conditions.

Causes of Fractures

• Trauma (falls, accidents)
• Repetitive stress
• Pathological fractures (weakened bones)

Signs and Symptoms

• Severe pain, swelling, bruising, deformity, and inability to use the limb.

Diagnosis

• Physical examination and imaging studies (X-rays, MRI).

Treatment

• Conservative:
  • Rest, immobilization (splints, POP)
  • Pain management
• Procedures:
  • Closed Reduction (non-surgical realignment)
  • Open Reduction and Internal Fixation (surgery)

Gout

• Definition:
  • A form of inflammatory arthritis caused by urate crystal deposition.
• Common Areas:
  • Fingers, big toes, knees, elbows.
• Risk Factors:
  • Diet high in purines, obesity, certain medical conditions, age, gender.

Pathophysiology

• High uric acid levels lead to crystal formation and inflammatory cytokine release.

Diagnosis

• Joint fluid test for urate crystals, blood test for uric acid levels, imaging studies.

Treatment

• Lifestyle:
  • Healthy diet, maintain healthy weight.
• Medications:
  • NSAIDs for pain, uric acid-lowering medications (e.g. Allopurinol).

Rheumatoid Arthritis (RA)

• Definition:
  • Autoimmune disease causing joint inflammation and damage.
• Affected Areas:
  • Joints (hands, wrists, knees) and other systems (lungs, heart).

Risk Factors

• Age, gender, genetic predisposition, smoking, and obesity.

Pathophysiology

• Immune system mistakenly attacks healthy cells leading to inflammation and joint destruction.

Signs and Symptoms

• Joint pain, stiffness, swelling, symptoms on both sides of the body, fatigue, joint deformity.

Diagnosis

• Medical history, physical examination, blood tests (rheumatoid factor, ESR, CRP), imaging studies.

Treatment

• Medications:
  • NSAIDs, corticosteroids, DMARDs (e.g., methotrexate), biologic agents.
• Surgery:
  • Synovectomy, tendon repair, joint fusion, total joint replacement.

Osteoarthritis (OA)

• Definition:
  • Degenerative joint disease, common form of arthritis.
• Causes:
  • Joint cartilage deterioration, bone exposure, and rub against each other leading to erosion.

Risk Factors

• Older age, female gender, obesity, joint injuries, repetitive joint stress, genetics.

Pathophysiology

• Inflammatory response within cartilage leads to degradation and erosion over time.

Signs and Symptoms

• Joint pain, stiffness, tenderness, loss of flexibility, crepitus, swelling.

Diagnosis

• Lab tests (ESR), X-rays, arthroscopic evaluation.

Treatment

1. Non-Pharmacological:
   • Weight management, exercise, physical therapy.
2. Pharmacological:
   • NSAIDs, intra-articular injections.
3. Surgical:
   • Arthroscopy, osteotomy, joint replacement.