Diseases and Conditions Affecting the Skeletal System

Bone development, growth, and repair are influenced by a number of internal and external factors. Those factors include nutrition, hormonal secretion, sunlight exposure, and physical exercise. As we explore the diseases and conditions affecting the spinal system, you will identify these factors.

Injury

Let's take a look at what happens when a bone fractures.

Ball-and-socket injury to the joint capsule can lead to instability of that joint. Injury of this nature can tear ligaments. The shoulder is the most mobile of all joints. With increased mobility comes the risk for increased injury to this joint.

Inflammation

Joint inflammation can result from injury, infection, or rheumatic diseases. Tendonitis, or inflamed tendons, commonly occurs when the joint is overused. This can result in painful joint movement.

Two elbows: in one the tendon is inflamed, which is tendonitis. In the other, the tendon is ruptured.

Another condition, bursitis, which is inflammation of the fluid-filled sac surrounding the joint, can occur as a result of injury, infection, or rheumatic disease. Rheumatic diseases are considered autoimmune diseases, indicating that the body is inflicting injury to itself.

Nutritional Deficiency and Other Spinal Disorders

The human body depends on nutritional supplementation to maintain homeostasis. Conditions such as rickets, which cause softening and weakening of the bone, occur in children secondary to prolonged vitamin D deficiency.

An X-ray of the hips, legs, and feet of a child. The legs are bowed out.

You may recall that vitamin D is the sunshine vitamin. Yes, it is produced endogenously when ultraviolet rays of sunlight strike the skin. Foods such as milk and cereal have been fortified with vitamin D. Despite this, the prevalence rate of vitamin D deficiency was still 41.6%.

Risk Factors Associated with Low Vitamin D
Risk Factors Associated with Low Vitamin D
Lifestyle	Spending less time outdoors. Covering skin with clothing when outdoors.
Sunscreen Use	Blocks harmful ultraviolet B rays that cause skin cancer. This inhibits the skin's ability to produce vitamin D.
Geographic Location/Season	Living in higher latitudes. The sun is at too low an angle in the sky for proper exposure.
Skin Tone	A darker skin tone has more melanin. Melanin slows the production of vitamin D.
Age	Production reduces as the skin ages.
Body Weight	Excess body fat stores vitamin D so it is not available for use by other systems.

Spinal alignment deformities present in three forms:

Scoliosis - an abnormal curvature of the spine (S-shaped)
Kyphosis - the development of a hump in the spine
Lordosis - an abnormal curvature of the lower backbones

Bone Cancer

Osteosarcoma is the most common primary bone cancer in humans, according to the NIH. The origin of this cancer is not known, but the osteocyte is considered a progenitor or forerunner to this cancer. Osteosarcoma commonly begins between the ages of 10 and 19, and is more common in the knee and upper arm.

Chondrosarcoma is an uncommon type of cancer originating in the cartilage surrounding bone. This cancer is seen in the adult population older than 40 and is more common in the hipbones and thighbones.

Ewing's sarcoma is the second most common primary bone cancer and can occur at any time in the early life cycle up until young adulthood. It most commonly develops during puberty, a period characterized by rapid bone growth. This tumor is common to the long bones of the arms and legs, the pelvic girdle, and chest, but can occur in any bone. Researchers believe chromosome rearrangement occurs contributing to the development of this tumor.

Age-Related Skeletal System Changes

With age, the human organism experiences change. After spending a lifetime developing, the body begins to deteriorate much earlier than most imagine. According to the U. S. National Library of Medicine, these changes cannot be stopped, but they can be slowed with an active lifestyle. Let's take a look at when these changes begin.

Bone Changes by Age
Age	Body Change	Description	Health Risk
30	↓ bone density	Calcium levels fall	Can lead to osteoporosis - brittle bones
40	↓ bone density	Osteoclast outnumber osteoblasts	Contributes to osteoporosis
50	↓ bone density	Bone loss rapid during menopause, secondary to ↓ estrogen	Contributes to osteoporosis
>60	Brittle bones	Bones break easily	Hip fracture, vertebral compression fractures

Review

Now that you have completed the initial assessments for this module, review the lesson material with the practice activities and extra resources.

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