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The following points highlight the ten important disorders of muscular and skeletal system. The disorders are: 1. Arthritis 2. Osteoporosis 3. Osteomalacia or Rickets 4. Bursitis 5. Dislocation 6. Sprain and Strain 7. Paget’s Disease 8. Muscular Dystrophy 9. Myasthenia Gravis 10. Tetany.
Disorder # 1. Arthritis:
It is caused by the inflammation of the joints. Some types of arthritis are described here.
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(i) Rheumatoid Arthritis (RA):
It is diagnosed by the presence of rheumatoid factor (a type of immunoglobulin IgM). Rheumatoid arthritis is an inflammation of the synovial membrane in synovial joints.
When this membrane, which is source of synovial fluid, becomes inflamed, it produces too much fluid. In fact the synovial membrane starts secreting abnormal granules called pannus, which after accumulating on the surface of the articular cartilage, cause its erosion.
The fibrous tissues are attached with the bones making the joints immovable. Several joints are affected. RA is result of auto-immune reaction. The joints swell and become extremely painful. Pain and inflammation can be reduced by heat treatment and physiotherapy. In extreme cases replacement of the damaged joints is done.
A kind of rheumatoid arthritis that occurs in younger people is *Still’s disease (Juvenile rheumatoid arthritis).
(ii) Osteoarthritis:
Osteoarthritis is also called degenerative joint disease. It is the most common type of joint disease. It is characterized by the progressive erosion of articular cartilage at synovial joint. The term osteoarthritis implies an inflammatory disease. The knees and hands are more commonly affected in women and the hips in men.
(iii) Infectious Arthritis:
Microorganisms of all types can lodge in joints during blood circulation. These types of arthritis mostly occurs due to bacterial and viral infection and are called bacterial and viral arthritis respectively.
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(iv) Gout and Gouty Arthritis:
This disease is due to defect in purine metabolism that causes an excess of uric acid and its salts (urates). The level of uric acid is raised in the blood and crystals of its salts (e.g., sodium urate) accumulate in the joints resulting gouty arthritis. The excess of urates can form stones in the kidneys. Treatment with certain drugs can increase the excretion of urates.
Disorder # 2. Osteoporosis:
Osteoporosis is a disease in which bone loses minerals and fibres from its matrix. There are more chances of fractures. Individuals who are under prolonged treatment of cortisone, are prone to bone loss, leading to osteoporosis. Major causative factors of osteoporosis are imbalances of hormones like calcitonin of thyroid, parathormone of parathyroids, and sex hormones and deficiencies of calcium and vitamin D.
Disorder # 3. Osteomalacia or Rickets:
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Osteomalacia, called rickets when it occurs in childhood, is a disease in which the bones contain insufficient amounts of calcium and phosphorus. Three causes are to be mentioned here—kidney disease, vitamin D deficiency, and an inherited defect.
Disorder # 4. Bursitis:
The bursae of joints often become inflamed, a condition known as bursitis. The inflammation can be caused by a physical injury or by constant pressure to the same joint over a long period of time.
Disorder # 5. Dislocation:
A dislocation is a displacement of the articular surfaces of a joint; it usually involves a damage to the ligaments surrounding the joint. Most dislocations result from falls, blows, or extreme exertion and are most often seen in the joints of the thumb, fingers, knee or shoulder. Symptoms of dislocation include swelling, pain and loss of motion.
Disorder # 6. Sprain and Strain:
A sprain is a twisting of a joint without dislocating it. Such an injury causes damage to ligaments and also often damages tendons, muscles, blood vessels, and nerves.
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Severe sprains are quite painful and require immobilization during the healing process. In contrast to a sprain, a strain is a less severe stretching or twisting of a joint. Muscles and tendons may be stretched and become somewhat painful, but only minor damage is done to the tissues of the joint.
Disorder # 7. Paget’s Disease:
It is caused by abnormal bone resorption by abnormal osteoclasts. It is characterised by irregular thickening and softening of bones, resulting in deformation of bones.
Disorder # 8. Muscular Dystrophy:
In this di-order the mutated gene (this is largest gene in man) on middle of the short arm of the X-chromosome is unable to produce a protein called dystrophin in the skeletal muscles.
The latter is believed to relay the nerve’s signal to the calcium storage in the muscle cell. This protein is associated with the sarcolemma (plasma membrane of muscle) where it plays a role in trans membrane signaling and in stabilizing the plasma membrane.
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Due to its deficiency, calcium is not released from the muscle cell. As a result the muscle contraction does not take place. Abnormal rise to calcium levels in the muscle releases an enzyme that destroys actin and myosin resulting in fatal muscular weakness.
There is deterioration of girdle muscles at an early age. The patient is unable to walk after the age of 12 followed by cardiomyopathy, mental impairment and death by the age of 20 due to cardiac or respiratory failure. It is common in males. Female heterozygous carriers are normal.
Disorder # 9. Myasthenia Gravis:
Autoimmune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.
Disorder # 10. Tetany:
Rapid spasms (wide contractions) in muscle due to low Ca++ in body fluid.
