Osteonecrosis Flashcards
What is osteonecrosis?
Bone infarction near a joint
When is the term ‘bone infarction’ used rather than osteonecrosis?
When the infarction occurs in a point in the bone which is not near the joint
In which areas is osteonecrosis most common?
Hip and shoulder
What is the main symptom which patient’s with osteonecrosis present with?
Pain
Osteonecrosis can be assymptomatic. T/F?
True
Describe a typical presenting complaint of a patient with osteonecrosis of the femoral head
Groin pain which worsens with weight-bearing and motion
Rest pain and night pain may also occur
As osteonecrosis progresses patients will present with the findings of arthrosis. What are these findings?
Limp
Tenderness around the affected bone
Restricted motion
What movements of the hip are particularly restricted due to osteonecrosis fo the femoral head?
Internal rotation
Abduction
What. is the peak age of prevalence of osteonecrosis?
40-60 years
Osteonecrosis is often bilateral. T/F?
True
What haematological condition is commonly associated with osteonecrosis?
Sickle cell anaemia
Which of the bone is affected first by osteonecrosis?
Medullary bone
Why is the overlying cartilage spared in osteonecrosis?
This cartilage receives nutrition from the synovial fluid, so remains viable
Describe how osteonecrosis can lead to the formation of insoluble calcium soaps
The dead bone has empty lacunae and is surrounded by necrotic adipocytes that often rupture and release fatty acids which can bind calcium to form insoluble calcium soaps
The process of osteonecrosis can be caused by intravascular coagulation in the bone. What can cause this intravascular coagulation?
Arthus
Fat embolism
Shwartzman phenomenon
Describe the process of creeping substitution in the healing process of bone in osteonecrosis?
Osteoclasts resorb necrotic trabeculae hole the remaining trabeculae serve as scaffolding for the deposition of new bone
What is bone remodelling?
The process by which osteoclasts secrete acid and proteolytic enzymes to digest the bone matrix and osteoblasts synthesis new organic matrix leading to the deposition of newer, better bone
Describe how a failure of bone healing in osteonecrosis can lead to the development of arthritis?
If bone does not remodel, micro damage does not get repaired and the mechanical properties of the bone are impaired. If enough damage accumulates, the sub-chondral bone can be weakened to the point of collapse. If the sub-chondral bone collapses, the joint surface becomes irregular. If one side fo the joint surface is not smooth then this will damage the other side.
What are the findings of osteonecrosis which may be seen on plain radiograph?
Mild density changes following by sclerosis and cysts as the condition progresses
What pathognomonic sign on x-ray can preceed subchodnral collapse in osteonecrosis?
Crescent sign (subchondral radiolucency)
What are the risk factors for the development of osteonecrosis?
History of trauma, espc. joint dislocation Corticosteroid use / cushing's Alcohol abuse Sickle cell disease / haemaglobinopathies SLE Antiphospholipid antibody syndrome Metabolic diseases such as hyperlipidaemia Renal failure HIV Prior radiation therapy Chemotherapy Decompression sickness Bisphosphonates
What are the treatment options for osteonecrosis?
Partial weight bearing
Bisphosphonates
Core decompression with or without bone graft
Total hip arthroplasty
Reperfustion and healing of the infarcted area in osteonecrosis will restore the joint surface. T/F?
False
