Spontaneous osteonecrosis was diagnosed in ninety knees in which a
roentgenographically visible lesion had developed within six months after
onset of symptoms. Scintimetry can be used to differentiate between
osteonecrosis and other painful conditions of the knee. The prognosis of
osteonecrosis is dependent on the size of the radiolucent lesion. In knees
with a lesion that is larger than 2.3 square centimeters, osteoarthritis is
likely to develop. For forty-two knees the patients were treated with
analgesics, partial weight-bearing, and quadriceps exercises. Forty-eight
knees were treated surgically. Indications for surgical treatment were
persistent severe complaints in spite of conservative treatment and a large
osteonecrotic lesion with collapse of the condyle resulting in a varus
deformity. The best results were achieved with osteotomy together with
arthrotomy, and by knee replacement arthroplasty. Arthrotomy and drilling
alone were ineffective.