<prompt> Osteonecrosis is not seen in -Olliers diseaseKienbochKohlers diseasePerthes disease  <response>: Ans. is a i.e., Olliers disease o Osteochondroses osteonecrosis with defective enchondral ossification of ossification center is seen in perthes disease, kienbocks disease and Kohlers disease,o Olliers disease is characterized by multiple enchondromas.NameSite affectedo Perthess diseaseFemoral heado Panners diseaseCapitulunio Kienbocks diseaseLunate boneo Osgood Shlatters diseaseTibial tubercleo Severs diseaseCalcaneal tuberosityo Kohlers diseaseNavicular boneo Freibergs diseaseMetatarsal heado Scheurmanns diseaseRing epiphysis of vertebraeo Calves diseaseCentral bony nucleus of vertebral bodyo Erie bergs diseaseOsteochondritis of 2nd metatarsal head.o Islene diseaseOsteochondritis of5th metatarsal heado Johansson-Larson s diseaseOsteochondritis of lower pole of patella.o Preisers diseaseSpontaneous avascular necrosis of scaphoid. 