A modular prosthetic femoral component for implantation upon the distal articular portion of a surgically prepared femur for articulating with an implanted complementary tibial component. A condylar component includes medial and lateral condyles, with an interposed trochlear notch and a patella guide interconnecting the medial and lateral condyles. A frustoconical primary receptacle extends from a proximal fixation surface of the condylar portion. A posterior stabilizing housing is disposed within the trochlear notch and includes a frustoconical post operatively engaged within the receptacle of the condylar portion. The posterior stabilizing housing may include a secondary frustoconical receptacle disposed in end-to-end fashion with the post for receiving a complementary distal end fitting on an elongated fixation stem. The distal end fitting of the stem is structured so that it is receivable into the primary receptacle of the condylar portion in the event the posterior stabilizing housing is not required.