Bones are an integral part of the anatomy of the skeletal system of the human body. While a newborn's skeletal system has about 300 bones at birth, about 206 bones of varied shapes and sizes make up an adult human skeleton. While some of the bones are hard and compact, some are light and porous. It is the bones and cartilage (fibrous connective tissue) that make up the hard inner framework of the body. Muscles, ligaments and tendons are other anatomical features that support the bones and play a vital role in helping us move. Minerals such as calcium and phosphorus, and a protein called collagen are essential for keeping the bones in a healthy condition. Deficiency of these minerals, or collagen, can therefore give rise to bone diseases. In this article, we will look into the different types of bone diseases that can affect children and adults. Types of Bone Disorders Bone disorders could occur due to a wide variety of reasons. While some people may be born with a bone disease as a result of faulty genes or inborn errors of metabolism, some people may develop degenerative bone diseases, later in life. Given below is some information on some of the common and rare bone disorders that may affect children or adults. Osteoporosis Osteoporosis is a disease which is characterized by a gradual loss of bone mineral density. Bones are calcified tissues that have the ability to repair themselves. However, as some people age, the mineralization of bones doesn't take place in the right manner. This gives rise to the development of hollow spaces within the bones. This causes the bones to become brittle and fragile. Those people who have been diagnosed with osteopenia, a condition characterized by less than normal bone mineral density, are at a greater risk of developing osteoporosis. In case of people who have been diagnosed with osteoporosis, even a mild injury can cause the bones to develop cracks or fracture. Osteoarthritis Osteoarthritis is another common bone disorder. This is a common form of arthritis that is characterized by the degeneration of joints owing to the breakdown of cartilage. Cartilage refers to the connective tissue that coats the ends of the bones and acts as a protective covering for the bones. When this tissue gets worn out with age, the bones start rubbing against each other. Friction between the bones gives rise to inflammation, and may cause development of bony outgrowths that are referred to as bone spurs. Joint pain, stiffness and reduced range of motion of the affected joint are some of the symptoms of this bone disorder. Rickets While minerals such as calcium and phosphorus are essential for healthy bones, vitamin D also figures in the list of nutrients that are required for optimal bone health. A deficiency of vitamin D can give rise to a childhood bone disorder called rickets. Rickets is a bone disorder which is attributed to improper mineralization of the bones due to deficiency of vitamin D or poor absorption of vitamin D by the intestines. Softening of the bones is the characteristic symptom of this disorder and therefore, affected individuals become susceptible to fractures. Bones may bend or break easily. Pain in the muscles and bones may also be experienced. This metabolic disease can also affect adults. In case of adults, this metabolic bone disease is referred to as osteomalacia. Osteopetrosis Also known as marble bone disease and Albers-Schonberg disease, osteopetrosis is a rare disease that is characterized by hardening of the bones. This is an inherited condition and is believed to be caused due to mutations in genes that are associated with the formation, development and functioning of specialized cells called osteoclasts. These cells play a vital role in breaking down old bone tissue and facilitate the replacement of old bone tissue with the new ones. Thus, when the osteoclasts are unable to perform their function, the new bone tissue deposits over the old tissue, thus, making the bones denser. The abnormal structure of the bones may make them susceptible to breakage. Osteogenesis Imperfecta Also known as brittle bone disease, osteogenesis imperfecta figures in the list of bone diseases and disorders that are caused due to mutations in certain genes. The mutations affect the way the body makes collagen. Those who suffer from this disease are highly susceptible to fractures. Though eight forms of osteogenesis imperfecta have been identified, the type II form is believed to be the severest form. As mentioned earlier, mutations in certain genes causes problems in the insufficient collagen production or cause defects in the structure of collagen. The genes involved in this bone disease include COL1A1, COL1A2, CRTAP and LEPRE1. Paget's Disease This is another bone disease that occurs as a result of abnormal bone remodeling process. The incidence of Paget's disease in children is quite low and it usually affects adults. Enlargement of bones or bone deformities could occur as a result of this condition. Such misshapen or abnormal bones may impinge on nerves and cause pain. Skull, spine, thigh bones, collarbone, upper arm bone and the bones in the pelvic region are commonly affected by this condition. It is believed that those with a family history of this disease are at a greater risk of developing this condition. Usually, a viral infection triggers the development of this bone disease in those who may be genetically predisposed. Bone Cancer Cancer refers to abnormal and uncontrolled cell division that leads to the development of malignant growth. Primary bone cancer refers to abnormal division of cells in the tissues that make up the bones. Osteosarcoma and chondrosarcoma are both types of cancer that originate in the bone itself. Cancer can start in another part of the body and spread to bones. Bone pain, swelling, development of a mass on the affected bone, fatigue and weakened bones are some of the symptoms of bone cancer. On a concluding note, bone diseases could be congenital or degenerative. These could also be caused due to infections, faulty metabolism or abnormal cell division. While infections can be treated with the help of drug therapy, following healthy dietary habits can help in preventing some of the diseases that occur as a result of nutritional deficiency. Extensive treatment is required for genetic bone disorders and bone cancer.