1. Section of Human Anatomy and Histology, Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy
2. Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy
3. Section of Gerontology and Bone Metabolism Diseases, Department of Medical Science, University of Torino, 10126 Torino, Italy
4. Department of Orthopedics, Washington University School of Medicine, St. Louis, MO 63110, USA