The Hip Fracture
Week 10: Musculoskeletal System | Difficulty: Intermediate | Time: 35 minutes
Learning Objectives
- Understand bone structure and composition
- Explain the pathophysiology of osteoporosis
- Describe the bone healing process
- Apply knowledge of bone remodeling
- Connect calcium homeostasis to bone health
Case Presentation
Patient: Dorothy Hayes, 82-year-old female
History: Osteoporosis, hypertension
Medications: Alendronate, calcium/vitamin D, amlodipine
Chief Complaint: Fell at home, severe left hip pain, unable to bear weight
History: Osteoporosis, hypertension
Medications: Alendronate, calcium/vitamin D, amlodipine
Chief Complaint: Fell at home, severe left hip pain, unable to bear weight
Dorothy slipped on a rug and fell onto her left side. She heard a "crack" and experienced immediate severe pain in her left hip. Unable to stand or bear weight. No head injury, no loss of consciousness. Brought to ED by ambulance.
Physical Examination
- Left leg: Shortened, externally rotated, adducted
- Hip: Severe tenderness over left hip, pain with any movement
- Neurovascular: Distal pulses present, sensation intact
- Skin: No bruising, no open wounds
- General: Alert, oriented, appears frail, kyphotic posture
Imaging & Labs
X-ray: Intertrochanteric fracture of left proximal femur with displacement
DEXA Scan (previous): T-score -3.2 (lumbar spine)
Labs:
DEXA Scan (previous): T-score -3.2 (lumbar spine)
Labs:
| Test | Result | Normal |
|---|---|---|
| Calcium | 2.18 mmol/L | 2.20-2.60 |
| Vitamin D | 42 nmol/L | > 50 |
| PTH | 78 ng/L | 15-65 |
| ALP | 85 U/L | 30-120 |
Clinical Reasoning Questions
1. What structural changes occur in osteoporosis that make bones prone to fracture?
Correct! Decreased bone mass with trabecular disruption
Osteoporosis is characterized by:
• Imbalance in bone remodeling: Osteoclast activity > osteoblast activity
• Decreased bone mineral density: Loss of both calcium and collagen matrix
• Trabecular thinning and perforation: The spongy bone structure becomes fragile
• Cortical thinning: Outer compact bone becomes thinner
• Results: Bone strength decreases despite normal bone mineralization quality
Osteoporosis is characterized by:
• Imbalance in bone remodeling: Osteoclast activity > osteoblast activity
• Decreased bone mineral density: Loss of both calcium and collagen matrix
• Trabecular thinning and perforation: The spongy bone structure becomes fragile
• Cortical thinning: Outer compact bone becomes thinner
• Results: Bone strength decreases despite normal bone mineralization quality
2. Why does Dorothy have secondary hyperparathyroidism (elevated PTH)?
Correct! Low vitamin D leads to reduced calcium absorption
The sequence is:
1. Low vitamin D (42 nmol/L, suboptimal) → decreased intestinal calcium absorption
2. Slightly low serum calcium (2.18 mmol/L) triggers PTH release
3. Secondary hyperparathyroidism (PTH 78, elevated) tries to maintain calcium
4. PTH increases bone resorption to release calcium
5. This worsens bone loss over time
This is why vitamin D supplementation is essential in osteoporosis management.
The sequence is:
1. Low vitamin D (42 nmol/L, suboptimal) → decreased intestinal calcium absorption
2. Slightly low serum calcium (2.18 mmol/L) triggers PTH release
3. Secondary hyperparathyroidism (PTH 78, elevated) tries to maintain calcium
4. PTH increases bone resorption to release calcium
5. This worsens bone loss over time
This is why vitamin D supplementation is essential in osteoporosis management.
3. What are the stages of bone healing after fracture?
Correct! Hematoma → Granulation tissue → Callus → Remodeling
Stage 1 - Hematoma: Bleeding forms clot; inflammatory response begins
Stage 2 - Granulation tissue: Angiogenesis, fibroblasts, chondroblasts invade
Stage 3 - Soft callus: Fibrocartilage forms, stabilizing fracture (weeks 2-3)
Stage 4 - Hard callus: Osteoblasts replace cartilage with woven bone (weeks 4-12)
Stage 5 - Remodeling: Woven bone replaced by lamellar bone, restored to original shape (months to years)
Stage 1 - Hematoma: Bleeding forms clot; inflammatory response begins
Stage 2 - Granulation tissue: Angiogenesis, fibroblasts, chondroblasts invade
Stage 3 - Soft callus: Fibrocartilage forms, stabilizing fracture (weeks 2-3)
Stage 4 - Hard callus: Osteoblasts replace cartilage with woven bone (weeks 4-12)
Stage 5 - Remodeling: Woven bone replaced by lamellar bone, restored to original shape (months to years)
Bioscience Integration
Bone Structure and Composition
- Cortical bone: Dense, compact, outer layer. Provides strength and protection
- Trabecular (cancellous) bone: Spongy, inner layer. Metabolically active
- Osteoblasts: Build bone (produce osteoid that mineralizes)
- Osteoclasts: Break down bone (resorption)
- Osteocytes: Mature bone cells that sense mechanical stress
Balance between osteoblast and osteoclast activity maintains bone mass. In osteoporosis, osteoclast activity predominates.
Nursing Implications
- Pain management: Essential for mobilization and deep breathing
- Surgery: Usually required within 24-48 hours for hip fractures
- Mobilization: Early weight-bearing as tolerated post-op
- Fall prevention: Assess home safety before discharge
- Nutrition: Adequate protein, calcium, vitamin D for healing
- Complications: Monitor for DVT, pressure ulcers, pneumonia