Bone consists of a resilient protein framework strengthened by calcium and phosphate deposits. While people often think of bone as lifeless and unchanging, it is actually a living tissue, supplied with nerves and blood vessels, that is continually being broken down and rebuilt. Bone can be weakened by nutritional and hormonal factors and by certain long-term disorders.
This section starts by discussing the bone disorder osteoporosis, which is common in elderly people. This disorder affects the natural processes of bone breakdown and replacement, causing bones to become brittle and fracture more easily. The section also covers the other main disorders that affect bone formation, including osteomalacia and rickets, both of which are due to lack of vitamin D, and Paget’s disease of the bone, the cause of which has yet to be established. Kyphosis, lordosis, and scoliosis, bone disorders that affect the curvature of the spine, are described next. Further articles discuss the bone infection osteomyelitis and noncancerous and cancerous tumours of the bones. Defects in the bone marrow are covered elsewhere in the guide (see Blood disorders).
For more information on the structure and function of bone, see The Backbone.
Joints occur where bones meet, and they allow our bodies to be flexible. Lubricated tissue called cartilage lines the ends of bones and prevents friction during movement, and fibrous ligaments surrounding the joint give strength and support. Joints may be damaged by arthritis, injury, infection, or degeneration of bone, cartilage, and ligaments caused by aging or disease.
Joint disorders are a major cause of disability and immobility, but the treatment of long-term joint disorders has greatly improved during the past 25 years, partly due to the availability of safe, reliable artificial joints.
The first article describes the many types of arthritis, a general term for disease of one or more joints. This is followed by separate articles on the most common types, including osteoarthritis, rheumatoid arthritis, gout, and reactive arthritis. Septic arthritis, which in the past was a major cause of crippling joint disease, is now usually curable with antibiotics. Next in this section is a detailed look at lower back pain together with self-help measures that can be taken to prevent back pain from occurring. The section ends with articles on nonarthritic conditions such as bursitis, in which the fluid-filled cushions around the joints become swollen and inflamed.
There is a similar but distinct form of rheumatoid arthritis that can develop in children (see Juvenile chronic arthritis).
For more information on the structure and function of joints and ligaments, see How Bone Repairs itself.
Skeletal muscles contract and relax to move the body and are connected to bones by fibrous tissue known as tendons. Both muscles and tendons can be temporarily or permanently damaged by injury, overexertion, infection, or other disorders, causing pain, weakness, restricted movement, and tiredness.
Skeletal muscles account for half the weight of the body but are only rarely affected by disease. Injury to a muscle or tendon, either through strenuous exercise or as a result of a repetitive physical activity, is the cause of some of the disorders described in this section, including muscle cramps, torticollis, repetitive strain injury, and tennis and golfer’s elbow. The next articles discuss inflammation of a tendon (tendinitis) or tendon sheath (tenosynovitis) and ganglia, which are fluid-filled cysts that commonly arise on the wrist or the back of the hand.
Some disorders that affect the skeletal muscles are covered in other parts of the guide. These conditions include the immune system disorders polymyalgia rheumatica and polymyositis and the inherited disease muscular dystrophy. Musculoskeletal injuries are also covered elsewhere.
For more information on the structure and function of muscles and tendons, see The Body’s Muscles.
The bones, joints, muscles, and connective tissues of the body’s musculoskeletal system are susceptible to injury from the stresses and strains placed on them during routine and leisure activities. The healing of minor injuries is usually rapid and complete, but major ones require expert treatment to avoid permanent damage.
Today, many people are aware of the health benefits of exercise and use part of their leisure time to pursue athletic activities. However, such pursuits may lead to musculoskeletal injuries if care is not taken. The first article in this section gives an overview of the main types of sports injury, the treatment of which has now become a specialized branch of medicine.
Injury may result in bone fractures of various types and these are covered next. The treatment of fractures has changed a great deal in the past 25 years as a result of various technical innovations, particularly for more complicated fractures in which the damaged bone is fragmented.
Injuries occurring in other parts of the musculoskeletal system, including joints, ligaments, muscles, and tendons, are also discussed. As with fractures, these injuries may cause long-term disability if not treated properly.
Damage to the musculoskeletal system may also occur as part of more widespread damage to the body following serious trauma, such as a motor vehicle accident (see Serious injuries).
For more information on the structure of the musculoskeletal system, see The Body’s Skeleton.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.