Spontaneous Osteonecrosis of the Knee in Macaca mulatta Harpal K. Gahunia & Matthew J. Kessler & Joseph B. Houpt & Richard C. Renlund & Sean A. F. Peel & Paul S. Babyn & Kenneth P. H. Pritzker Received: 19 March 2007 / Accepted: 24 December 2008 / Published online: 12 March 2009 # Springer Science + Business Media, LLC 2009 Abstract Spontaneous osteonecrosis of the knee (SONK) is a common disease in elderly humans. Clinically, SONK presents with the sudden onset of severe knee joint pain, usually in the load-bearing area of the medial compartment of the knee. Articular cartilage lesions are secondary to subchondral trabecular bone necrosis. These biochemical and structural changes in the bone and cartilage alter the Int J Primatol (2009) 30:429–442 DOI 10.1007/s10764-009-9351-4 H. K. Gahunia (*) : P. S. Babyn Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G-1X8, Canada e-mail: harpal.gahunia@utoronto.ca P. S. Babyn e-mail: paul.babyn@sickkids.ca M. J. Kessler Center for Comparative Medicine, University of Virginia Health System, P.O. Box 800737, Charlottesville, VA 22908, USA e-mail: mjk4b@virginia.edu J. B. Houpt Department of Medicine, Division of Rheumatology, Mount Sinai Hospital and University of Toronto, 600 University Avenue, Toronto, Ontario M5G-1X5, Canada e-mail: jbhoupt@sympatico.ca R. C. Renlund Division of Comparative Medicine, Faculty of Medicine, University of Toronto, Medical Science Building, 1 Kings College Circle, Toronto, Ontario M5S-1A8, Canada e-mail: r.renlund@utoronto.ca S. A. F. Peel Division of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, Ontario M5G-1G6, Canada e-mail: Sean.peel@dentistry.utoronto.ca K. P. H. Pritzker Department of Pathology and Laboratory Medicine, Mount Sinai Hospital and University of Toronto, 600 University Avenue, Toronto, Ontario M5G-1X5, Canada e-mail: kpritzker@mtsinai.on.ca