What are the common causes of pathologic fractures?

Common Causes of Pathologic Fractures

The most common causes of pathologic fractures are malignancies (primary bone tumors or metastatic disease), osteoporosis, and benign bone lesions, with each requiring specific management approaches based on the underlying pathology. 1

Primary Causes by Category

Malignant Conditions

• Metastatic carcinoma: Most common cause of pathologic fractures in adults, particularly affecting the femur, spine, and humerus 1
  • Common primary sites: breast, lung, prostate, kidney, thyroid
• Multiple myeloma: Causes widespread bone destruction 1
• Primary bone malignancies:
  • Osteosarcoma
  • Chondrosarcoma
  • Spindle cell sarcomas 1

Benign Bone Lesions

• Unicameral bone cysts: Common in children, especially proximal humerus 2
• Aneurysmal bone cysts: Require surgical intervention for healing 2
• Enchondromas: Most common cause of pathologic fractures in the hand 3
• Nonossifying fibromas: Generally good outcomes with nonsurgical treatment 2
• Giant cell tumors: Can cause significant bone destruction 4
• Fibrous dysplasia: May lead to progressive deformity 2

Metabolic Bone Disorders

• Osteoporosis: Leading cause of insufficiency fractures, particularly in the elderly 1
• Osteomalacia: Reduction in bone quality leading to fracture susceptibility 5
• Paget's disease: Pathological bone remodeling causing structural weakness 5
• Osteogenesis imperfecta: Genetic disorder causing bone fragility 1
• Osteopenia of prematurity: Affects preterm infants, typically resolves by age 1 1

Other Causes

• Infections: Osteomyelitis can weaken bone structure
• Radiation-induced bone damage: Following cancer treatment
• Prolonged steroid use: Causes medication-induced osteoporosis
• Vitamin D deficiency: Can lead to rickets in children 1
• Stress fractures: From repetitive loading on normal or abnormal bone 1

Clinical Features and Identification

Red Flags for Pathologic Fractures

• Fracture with minimal or no trauma
• Pain preceding the fracture (48.2% of cases) 4
• Age-specific patterns:
  • Children/adolescents (11-20 years): Primarily benign lesions 4
  • Adults (50-80 years): Primarily metastatic disease 4
• Location-specific patterns:
  • Long bones: Femur, humerus, and tibia most commonly affected 4
  • Spine: Vertebral compression fractures common in osteoporosis and metastatic disease 1

Diagnostic Approach

1. Radiographic assessment: Initial imaging to identify bone lesions
2. Advanced imaging:
   • MRI: Best for evaluating bone marrow involvement and soft tissue extension
   • CT: Helpful for assessing cortical destruction
   • Bone scan: Sensitive but not specific for identifying areas of increased bone turnover 1
3. Biopsy: Essential for definitive diagnosis of underlying pathology 6

Management Considerations

Management depends on the underlying cause, fracture location, and patient factors:

1. Benign lesions:

   • May allow fracture healing before treating the underlying lesion
   • Nonossifying fibromas typically heal with conservative treatment
   • Unicameral bone cysts often require surgical intervention to prevent refracture 2

2. Malignant lesions:

   • Require multidisciplinary approach
   • Surgical stabilization often necessary to relieve pain and improve function
   • Prophylactic fixation indicated for:
     • Lytic lesions >2.5cm or involving >50% of cortex
     • Persistent pain despite radiation
     • Lesions in weight-bearing areas 1

3. Metastatic disease to long bones:

   • Surgical stabilization plus post-operative radiation therapy provides better functional outcomes than either treatment alone 1
   • Intramedullary nailing is generally preferred for long bone metastases 1

4. Osteoporotic fractures:

   • Medical management of underlying osteoporosis
   • Bisphosphonates reduce risk of subsequent fractures 1
   • Vertebral augmentation procedures may be considered for painful vertebral compression fractures 1

Prognosis

Prognosis varies significantly based on the underlying cause:

• Benign lesions: Generally good outcomes with appropriate treatment 2
• Malignant lesions: Poorer prognosis, with bone metastases conferring worse outcomes than lung/pleural metastases (<20% vs 20-40% 5-year survival) 1
• Metastatic disease: Average survival after surgical stabilization approximately 11.6 months 6

Early diagnosis and appropriate management are crucial to improve outcomes and quality of life for patients with pathologic fractures.