67. Aseptic bone necroses

Osteonecrosis, also called avascular necrosis, refers to ischaemic necrosis of bone caused by impaired blood supply. It may affect any part of the bone but most commonly the knee and femoral head. It's most common in children and adolescents.

See also osteonecrosis of the foot and osteonecrosis of the hip, both of which most commonly occur in children.

Etiology

• In children
  • Idiopathic
  • Overuse
• In adults
  • Alcoholism
  • Chronic steroid treatment
  • Radiotherapy
  • Trauma
  • Sickle cell disease

Pathology

There is ischaemia of bone which leads to necrosis. In children the condition mostly resolves spontaneously, as the bone can still repair itself. In adults the condition is generally irreversible, as bone can no longer repair itself as well.

Osteonecrosis in children and adolescents

• Osgood-Schlatter disease
  • Avascular necrosis of the tibial tuberosity (the insertion of the quadriceps)
  • Occurs in adolescents, male > female
  • A characteristic lump forms on the tibia
  • Related to overuse
• Perthes disease
  • Avascular necrosis of the femoral head
  • Occurs in children, male > female
  • Idiopathic
• Kohler disease
  • Avascular necrosis of the navicular bone of the foot
  • Occurs in children, male > female
  • Idiopathic
  • Rare
  • Presents with pain on dorsal and medial surface of foot
  • It’s self-limiting, so conservative treatment with NSAIDs and immobilization is the only treatment
    • No role for surgery
• Osteonecrosis of the 2nd metatarsal head (Freiberg disease)
  • In adolescents (13 – 18)
  • Girls > boys
  • Presents with pain on forefoot
  • Treatment
    • Conservative
      • NSAIDs
      • Immobilization
    • Surgery
      • Rarely needed (only in severe disease)
      • Osteotomy/arthrotomy
• Sever disease
  • Osteonecrosis of calcaneal apophysis (the tuberosity of the calcaneus), also called calcaneal apophysitis
  • Often occurs in young athletes (8 – 12)
  • Pain in the area of the calcaneal apophysis
  • It’s self-limiting, so conservative treatment with NSAIDs and immobilization is the only treatment
    • A soft heel pad decreases the pressure on the calcaneus
    • No role for surgery

Osteonecrosis in adults

• Avascular necrosis of the hip
  • Osteonecrosis of the hip, also called femoral head necrosis, is the most common localisation of osteonecrosis. The femoral head is the most frequent area of osteonecrosis probably due to the intricate blood supply.
  • Occurs in middle-aged, male > female
  • A common indication for total hip replacement
  • Etiology
    • Idiopathic (Perthes disease)
    • Trauma
      • Femoral head fracture
    • Chronic steroid
    • Alcoholism
    • Radiation
  • Clinical features
    • Insidious onset of pain
    • Affects both hips most of the time
  • Diagnosis: MRI
  • Treatment
    • Conservative
      • Bisphosphonates
      • Exercise
    • Surgery
• Ahlback disease
  • Avascular necrosis of the medial femoral condyle
  • Occurs in elderly, female > male

Clinical features

• Pain
  • Usually of insidious onset
  • Exacerbated by use
• Loss of function (in late stages)

Diagnosis and evaluation

Imaging

MRI is the main imaging modality in the evaluation of osteonecrosis.

Management

Treatment depends on localization, extent, and age. In children the treatment is generally conservative with RICE and NSAIDs. In adults the management may be conservative or surgical depending on the area and etiology.