Bone Repair & Healing

• Bone Fracture

  bone is cracked/broken

  a complere/incomplete break in the continuity of a bone

  occurs when a bone can't withstand the physical forces exerted on it
• Causes of Bone Fractures

  traumatic incident

  repeated minor trauma

  as a result of certain medical conditions that may be localised (e.g. pathological) or generalise like osteoporosis that weakens the bones
• Fracture Risk - Strength of Bone

  inherent strength of bone:

  geometry

  material properties

  applied load - direction, velocity, type of loading + size of load
• Fracture Risk - Age-Related Chnages

  increases w age-related hormonal changes affecting bone properties

  = increased porosity + decreased geometric properties, increased fatigue, decreased energy absorption - freq falls
• Fracture Risk - Heavy Lifting

  can occur due to a single loading event

  lifting a heavy load - trip/slip/abnormal muscle loading
• Fracture Risk - Microcracking

  can occur following fatigue indced microcracking

  = progresses to catastrophic failure

  e.g. progressive failure of trabeculae in vertebral bodies
• Compression Fracture

  a form of stress produced by the action of equal + opposite forces, whose effect is to reduce the length of a material

  
• Tension Fracture

  a form of stress produced by a force which acts to stretch a material

  
• Shear Fracture

  form of stress resulting from equal + opposite forces that do not act along the same line

  
• Torsion Fracture

  the twisting of an object due to an applied torque

  in circular sections, the resultant shearing stress is perpendicular to the radius

  
• Classification of Fractures - Comminuted/Displaced

  a comminuted/displacec fracure = bone has been fractured into 2 or more fragments + moves out of alignment

  
• Classification of Fractures - Non-Displaced

  bone breaks but does not move out of alignment

  
• Classification of Fractures - Open/Compound

  fractured bone penetrates the skin/loss of tissue

  risk of infection into the bone/body

  
• Classification of Fractures - Simple/Closed

  involves a single fracture line thru a bone

  skin isn't broken

  
• Subluxation of Joints

  subluxation = partial/incomplete dislocation where the bones in a joint is misaligned but still retain some contact

  joint surfaces r still partially in contact

  often self-reducing - joint may pop back into place

  can cause pain, swelling, instability or limited movement
• Dislocation of Joints

  a complete loss of contact between the joint surfaces - bones r entirely out of place

  no contact between joint surfaces

  usually requires manual redcution (medical intervention to reposition)

  causes intense pain, swelling, deformity + immobility