A condition that is characterized by a decrease in bone mass and density, causing bones to become fragile.

Bone diseases affect the development and structure of bone. They include: *Bone cyst*Bone spur (Osteophytes)*Craniosynostosis *Fibrous dysplasia*Bone tumor*Giant cell tumor of bone*Hypophosphatasia *Osteoporosis*Primary hyperparathyroidism *Klippel-Feil syndrome *Osteitis Condensans Ilii *Osteochondritis Dissecans*Osteochondroma (Bone Tumor)*Osteosarcoma (Bone Tumor)*Osteomyelitis *Osteopenia *Renal Osteodystrophy*Osteomalacia