Osteonecrosis is not seen in -

Ans. is 'a' i.e., Olliers disease o Osteochondroses (osteonecrosis with defective enchondral ossification of ossification center) is seen in perthe's disease, kienbock's disease and Kohler's disease,o Ollier's disease is characterized by multiple enchondromas.NameSite affectedo Perthes's diseaseFemoral heado Panner's diseaseCapitulunio Kienbock's diseaseLunate boneo Osgood Shlatter's diseaseTibial tubercleo Sever's diseaseCalcaneal tuberosityo Kohler's diseaseNavicular boneo Freiberg's diseaseMetatarsal heado Scheurmann's diseaseRing epiphysis of vertebraeo Calve's diseaseCentral bony nucleus of vertebral bodyo Erie berg's diseaseOsteochondritis of 2nd metatarsal head.o Islene diseaseOsteochondritis of5th metatarsal heado Johansson-Larson 's diseaseOsteochondritis of lower pole of patella.o Preiser's diseaseSpontaneous avascular necrosis of scaphoid.