Avascular necrosis of the knee is a rare disorder. It is characterized by massive necrosis in the bone and bone marrow due to an interruption or a significant decrease in the blood supply to bone. AVN can affect any bone but is most often localized to the hip, knee, shoulder or ankle, with only local or multifocal lesions. This paper provides a review of the past decades research on the topics of etiology, treatment and prognosis of AVN of the knee. The most significant risk factor is glucocorticoid therapy, but other influences such as alcoholism, sickle cell disease, Gaucher’s disease, trauma and arthroscopy are also relatively commonly seen associated with AVN in the knee. Approximately 20 per cent of the cases are idiopathic. The mechanisms of the disease are unknown. AVN of the knee is often divided into three forms: Spontaneous AVN, secondary AVN and post arthroscopic AVN. There are many treatment options, ranging from only conservative by protected weight bearing to surgical procedures. Total knee arthroplasty is the option reported as providing best results. Likewise are spontaneous, unilateral cases with a mild course associated with better prognosis.
Case reports of two young patients with uncommon presentations of AVN of the knee are also presented. One 15-year-old from Afghanistan and one 19-year-old from Congo both have had AVN localized to the distal femur bilaterally for several years. Neither of them has known predisposing factors such as trauma or steroid-demanding illnesses. They both have been treated arthroscopically with debridement; the Afghan patient also underwent micro fracture treatment in both knees. As long as their epiphyseal discs remain unclosed, treating them with knee arthroplasy is not an alternative.
Key words: Avascular necrosis of the knee, osteonecrosis of the knee, diseases of the knee, skeletal diseases, case reports