Bone Fracture: Causes

Pathogenesis (development of disease)

Healthy bone withstands the compressive, shear and bending forces acting on it without any problems. Only when the elastic properties are overtaxed in appropriate trauma does a traumatic fracture occur. A fracture can be caused by direct force, e.g. by a blow or impact, or by indirect force, e.g. by lever action remote from the fracture.A so-called fatigue fracture is caused by repeated overloading or multiple microtraumas of a bone. The so-called Schipper’s disease should be mentioned here: During unaccustomed heavy-duty shoveling work, a disproportion between muscle pull and bone stability results in an avulsion or fatigue fracture of the spinous processes of the lower cervical vertebrae and/or upper thoracic vertebrae. Another example is the marching fracture (fracture of a metatarsal). The pathological fracture is a bone fracture that occurs without adequate trauma or after inadequate trauma, due to a disease-related weakening of the bone.Spontaneous fracture is spoken of when there is a fracture without trauma. The causes are manifold, e.g. generalized as well as local skeletal diseases associated with a deterioration of bone quality, bone tissue reduction (e.g. in osteoporosis), local osteolyses (spatially circumscribed dissolution or degeneration of bone tissue, e.g. due to bone metastases or osteomyelitis/bone marrow inflammation), and inadequate mineralization (e.g. in osteomalacia/bone softening) may be responsible. So-called greenstick fractures are fractures in children or adolescents characterized by a fracture of the bone with preserved periosteum (periosteum). The very thick uninjured periosteum splints the fracture in such a case. According to their origin, fractures can be described as follows:

Course of the fracture line/ type of force involved.

• Thrust fracture/shear fracture – Direct force impact with high kinetic energy.
• Bending fracture – Direct or indirect force impact especially on long tubular bones.
• Torsion fracture (rotational, rotational, spiral or screw fracture) – Spiral fracture line course due to opposing indirect force action.
• Compression fracture/compression fracture – e.g., on vertebral bodies due to axially directed compressive force.
• Crack or avulsion fracture – tendon near avulsion of a bone fragment, by tensile force.
• Defect fracture – e.g. by a gunshot wound.

Fragment count

• Simple fracture – two fragments
• Multiple fragment fracture – splinter fracture, floor fracture, comminuted fracture, chain fracture (sequence of multiple fractures on an extremity to the trunk of the body)

Dislocation

• Dislocatio ad axim – kink in the vertical axis.
• Dislocatio ad longitudinem cum contractione or distractione – longitudinal displacement with shortening or lengthening of the total length.
• Dislocatio ad latus – displacement (lateral).
• Dislocatio ad peripheriam – rotation of fragments around the vertical axis.

Involvement of soft tissues and skin

• Closed fracture – no injury to skin and soft tissues.
• Open fracture – injury to skin and soft tissues:
  • Grade 1: exit of a bone fragment.
  • Grade 2: large skin injury without soft tissue involvement.
  • Grade 3: large-scale skin destruction with soft tissue damage (musculature, vision, blood vessels, nerves).
  • Grade 4: subtotal or total amputation.

AO classification (see Introduction)Type of continuity interruption.

• Complete fracture
• Incomplete fracture

Etiology (causes)

Biographical causes

• Genetic burden
  • Genetic diseases
    • Gaucher disease – genetic disorder with autosomal recessive inheritance; lipid storage disease due to the defect of the enzyme beta-glucocerebrosidase, resulting in the storage of cerebrosides mainly in the spleen and marrow-containing bones.
    • Osteogenesis imperfecta (OI) – genetic diseases with autosomal dominant inheritance, more rarely autosomal recessive inheritance; 7 types of osteogenesis imperfecta are differentiated; the main feature of OI type I is altered collagen, which leads to abnormally high bone fragility (brittle bone disease)
    • Osteopetrosis (marble bone disease/ osteopetrosis familiaris/ osteosclerosis congenita) – genetic diseases with both autosomal dominant and autosomal recessive inheritance; disturbance of bone resorption and thereby leading to a pathological (pathological) accumulation of bone matrix in the body.
• Age – The frequency of falls and therefore the risk of fracture increases with age.
• Hormonal factors – Because osteoporosis risk is very high in women due to postmenopausal estrogen deficiency, the risk of pathological fractures also increases.

Behavioral causes

• Nutrition
  • Alimentary osteopathy (nutritional bone disease/ starvation osteopathy due to malnutrition (calcium, calciferol and protein deficiency).
  • Micronutrient deficiency (vital substances) – see prevention with micronutrients.
• Consumption of stimulants
  • Alcohol
  • Tobacco (smoking) – Smoking leads to accelerated osteoporosis and increased fracture risk.
• Physical activity
  • Physical inactivity – Physical activity promotes bone stability, immobilization leads to osteopenia (reduction in bone density).
• Obesity (BMI ≥ 25) – Obesity promotes degenerative bone and joint disease.

Disease-related causes

• Diabetes mellitus, type 1 and type 2 – increased risk for hip fractures in patients with type 1 diabetes (risk ratio [RR] = 4.93; 95% -confidence interval [CI], 3.06-7.95) as well as type 2 diabetes (RR = 1.33; 95% CI, 1.19-1.49); increased risk of nonvertebral fractures (fractures not involving the spine) in patients with type 1 (RR = 1.92; 95% CI, 0.92-3.99) and type 2 diabetes (RR = 1.19; 95% CI, 1.11-1.28).
• Rheumatic diseases (e.g., ankylosing spondylitis/ Bekhterev’s disease).
• Diseases of the hematopoietic (blood-forming) system.
• Gorham osteolysis – osteolysis (bone dissolution) after traumatic impact on the bone.
• Jaffé-Lichtenstein syndrome (osteofibrosis deformans juvenilis; fibrous dysplasia) – systemic disease of the skeleton that begins in childhood and can affect only one bone (monostotic) and affect multiple bones (polyostotic). Due to marrow fibrosis (pathological proliferation of connective tissue) and spongiosis (porous-spongy pathological remodeling of bone tissue) of the compacta (outer marginal layer of the bone), the affected bones lose load-bearing capacity; sporadic occurrence.
• Intestinal osteopathy – skeletal changes due to malabsorption (disorder of food absorption).
• Bone tumors (benign (benign) and malignant (malignant)).
• Bone cysts
• Metastases (daughter tumors)
• Malignancies (malignant tumors)
• Paget’s disease or Paget’s syndrome (synonyms: osteodystrophia deformans, Paget’s disease, Paget’s disease) – disease of the skeletal system in which there is a gradual thickening of several bones, usually the spine, pelvis, extremities or skull.
• Osteoporosis (bone loss) → fragility fracture.
• Osteomyelitis (bone marrow inflammation)
• Osteomalacia (bone softening) – mineralization disorder of the bone e.g. disturbances in vitamin D metabolism.
• Osteitis / Ostitis (bone inflammation)
• Osteosclerosis – compaction of bone tissue with loss of elasticity.
• Renal (ren – kidney) osteodystrophy / rickets renalis – disruption of vitamin D metabolism or attack of the bone by accumulation of urinary substances.
• Plasmocytoma (synonyms: multiple myeloma, Kahler’s disease); malignant tumor of plasma cells).
• Secondary hyperparathyroidism (parathyroid hyperfunction).

Medications (fracture-associated drugs (FAD)).

• FAD and gender:
  • Females: First-generation antipsychotics (HR 1.54); opioids (HR 3.26); antiparkinsonian agents (HR 3.29); risky combinations are: Opioid + hypnotics, opioid + loop diuretic, opioid + proton pump inhibitor, SSRI + opioid, Selective Serotonin Reuptake Inhibitor (SSRI) + benzodiazepine, SSRI + loop diuretic (diuretic drugs that act on Henle’s loop, part of the kidneys’ urinary system); nitrate + loop diuretic.
  • Men: hypnotics (HR 1.51); opioids (HR 3.83); antiparkinsonian agents (HR 4.23); risky combinations are: Opioid + loop diuretic, opiod + PPI, opioid + SSRI, nitrate + loop diuretic.
• Medications that promote osteoporosis (see under “Osteoporosis due to medications”).
• Antidepressants (amitriptyline, imipramine) have an increased risk of hip fractures in elderly patients
• Glitazones – group of oral antidiabetic drugs that have been found to increase fracture risk in women and have been withdrawn from the market because of this.
• Proton pump inhibitors (PPIs; acid blockers) – increased risk (five outcomes per 10,000 patient-years) of proximal femur (hip) fracture after long-term use.

X-rays

• Osteoradionecrosis (bone destruction by radiation).

Further

• Physical abuse