1. Orthopedics and Traumatology Service, School of Medicine and University Hospital ‘Dr. Jos� Eleuterio Gonz�lez’, Universidad Autonoma de Nuevo Le�n, Monterrey, Nuevo Le�n 64460, M�xico
2. Department of Biochemistry and Molecular Medicine, School of Medicine, Universidad Autonoma de Nuevo Leon, Monterrey, Nuevo Le�n 64460, M�xico