Ch. 4 Biomechanics of Human Bone Growth and Development

The water content of bone makes up approximately what percentage of the total bone weight? A. 39-48% B. 15-20% C. 25-30% D. 5-10%

25-30%

After age 60, what percentage of fractures are osteoporosis related? A. 30% B. 1% C. 5% D. 60% E. 90%

90%

Which of the following statements is/are true regarding the strength of bone? A. Cortical bone can withstand more stress than trabecular bone. B. Trabecular bone can withstand more strain than cortical bone. C. both A and B D. none of the above

A. Cortical bone can withstand more stress than trabecular bone. B. Trabecular bone can withstand more strain than cortical bone.

Which of the following is true regarding Osgood-Schlatter's disease? A. It occurs at the tibial tubercle where the patellar tendon attaches. B. It is more common in children than adults. C. It is an epiphyseal injury D. both A and B E. all of the above

A. It occurs at the tibial tubercle where the patellar tendon attaches. B. It is more common in children than adults. C. It is an epiphyseal injury

Which of the following statements regarding bone growth is true? A. Longitudinal growth continues only as long as the epiphyses exist. B. Circumferential growth continues throughout most of the lifespan C. both A and B are true D. both A and B are false

A. Longitudinal growth continues only as long as the epiphyses exist. B. Circumferential growth continues throughout most of the lifespan

Which of the following is true regarding epiphyseal plate injuries? A. These injuries can terminate longitudinal bone growth. B. These injuries can result from acute trauma. C. These injuries can result from repetitive loading of a low magnitude. D. all of the above

A. These injuries can terminate longitudinal bone growth. B. These injuries can result from acute trauma. C. These injuries can result from repetitive loading of a low magnitude.

Which of the following is true regarding greenstick fractures? A. They are incomplete fractures. B. They are caused by bending or torsional loads. C. They are more common in adults than children. D. both A and B E. all of the above

A. They are incomplete fractures. B. They are caused by bending or torsional loads.

Which of the following statements is/are true regarding bone growth? . When bone remodeling occurs, bone mass may stay the same. B. When bone remodeling occurs, bone mass may decrease. C. When bone modeling occurs, bone mass increases. D. both A and B E. all of the above

A. When bone remodeling occurs, bone mass may stay the same. B. When bone remodeling occurs, bone mass may decrease.

Undesirably low body weight in young female athletes can lead to what? A. amenorrhea B. osteoporosis C. menopause D. both A and B E. all of the above

A. amenorrhea B. osteoporosis

Loss of bone mass has been found in which of the following? A. bed-ridden patients B. astronauts C. tennis players D. both A and B E. A, B, and C

A. bed-ridden patients B. astronauts

What happens when osteoblast activity exceeds osteoclast activity? A. bone hypertrophy B. bone modeling C. increased bone mass D. all of the above

A. bone hypertrophy B. bone modeling C. increased bone mass

Which of the following is/are part of the "female athlete triad"? A. osteoporosis B. disordered eating C. cessation of menses D. both A and B E. all of the above

A. osteoporosis B. disordered eating C. cessation of menses

In a child, severe injury to an epiphysis may result in which of the following? A. premature closure of the epiphyseal junction B. termination of bone growth C. both A and B D. none of the above

A. premature closure of the epiphyseal junction B. termination of bone growth

Which of the following is/are known risk factor(s) for developing osteoporosis? A. smoking B. calcium deficiency C. excessive caffeine consumption D. all of the above

A. smoking B. calcium deficiency C. excessive caffeine consumption

The "female athlete triad" can result in which of the following? A. stress fractures B. irreversible bone loss C. death D. both A and B E. all of the above

A. stress fractures B. irreversible bone loss C. death

A fracture caused by a tendon or ligament pulling a small chip of bone away from the rest of the bone is called what? A. simple fracture B. spiral fracture C. avulsion fracture D. compound fracture

avulsion fracture

Which of the following components of bone provides it with flexibility? A. calcium carbonate B. calcium phosphate C. collagen D. water

collagen

Cortical bone is strongest in resisting which type of stress? A. tensile stress B. shear stress C. compressive stress D. none of the above

compressive stress

Which of the following is an example of a flat bone? A. talus B. maxilla C. radius D. scapula

scapula

The tarsals are examples of what type of bones? A. flat B. short C. long D. irregular

short

Bone __________ refers to the increase in bone mass.

hypertrophy

How do bones typically respond to stress? A. no change, as long as the epiphysis has sealed B. atrophy C. it is impossible to predict how a bone will respond to stress D. hypertrophy

hypertrophy

Which of the following factors can predispose runners to stress fractures? increased training duration or intensity without allowing time for bone remodeling abrupt changes in running surface both A and B runners are not predisposed to stress fractures

increased training duration or intensity without allowing time for bone remodeling abrupt changes in running surface

When a skier's body rotates in a direction opposite of the foot (held steady by the boot), what type of fracture is likely in the tibia? A. depressed B. stress C. spiral D. impacted

spiral

Which of the following terms is defined as deformation divided by original length? A. strength B. stress C. elasticity D. strain

strain

Which type of fracture results from repeated loading of relatively low magnitude? A. depressed B. stress C. impacted D. spiral

stress

Which of the following is part of the appendicular skeleton? A. the skull B. the humerus C. the sternum D. all of the above

the humerus

Which of the following is an irregular bone? A. radius B. femur C. rib D. vertebrae

vertebrae

Which of the following is a possible symptom of osteoporosis? vertebral crush fractures reduced body height dowager's hump all of the above

vertebral crush fractures reduced body height dowager's hump

Which of the following activities would likely produce the greatest bone mineral density of the lower extremities? A. swimming B. cycling C. walking D. all of the above would provide equal contribution to bone health

walking

A condition of reduced bone mineral density that predisposes the individual to fractures is called ___________________.

Osteopenia

______________ refers to an excessive loss of bone mass and strength resulting in one or

Osteoporosis

Where is articular cartilage located? A. It covers all bone surfaces. B. It covers all bone surfaces at articulations. C. It covers all long bone surfaces. D. It covers all long bone surfaces at articulations

It covers all long bone surfaces at articulations

Explain the female athlete triad.

It is very common now a days for young female athletes to want to excel at their competitive sports. This causes them to strive to achieve and undesirably low body weight. This practice commonly involves a combination of disordered eating, amenorrhea, and osteoporosis. Amenorrhea is the cessation of menses. The combination of these three are known as the female athlete triad. The negative consequences of the triad can range from irreversible bone loss to death. It is very important for friends, parents, coaches, and physicians to be alert to the signs and symptoms. 62% of female athletes in certain sports display disordered behaviors. Girls participating in gymnastics and figure skating are most likely to be involved in it.

Summarize the recommendations from the ACSM pronouncement on "Physical Activity and Bone Health" for children and adolescents.

One recommendation from the ACSM is weight-bearing physical activity. It is necessary for maintaining skeletal integrity. This benefits both humans and animals. Studies have shown that a regular program of weight-bearing exercise, such as walking, can increase bone health and strength even for people with osteoporosis. Jumping in place, with 5-10 sets of 10 jumps done 3-5 times per week, is also recommended for maintenance of bone mass. A second recommendation from the ACSM is an increased dietary calcium intake. It exerts a positive influence on bone mass for women with a dietary deficiency. A modified diet or calcium supplementation can be critical for the development of peak bone mass among adolescent females at a dietary deficiency. Lifestyles that negatively affect bone mineralization include physical inactivity, weight loss of excessive thinness, tobacco smoking, deficiencies in estrogen, and and excessive consumption of protein and caffeine.

Name four of the five genetic risk factors for osteoporosis.

Osteoporosis is a disorder involving decreased bone mass and strength with one or more resulting factors. It is found in most elderly individuals, with earlier onset in women, and is becoming increasingly prevalent with the increasing mean age of the population. It begins with as osteopenia, which is reduced bone mass without the presence of a fracture. It progresses to osteoporosis. There are some genetic risk factors that can cause you to get osteoporosis. The risk factors include gender, ethnicity, body size, and family history. The female population is what makes gender a risk factor. After the age of 50, osteoporosis affects approximately 40% of women. The types of ethnicity that are risk factors are Caucasian and Asian. Blacks actually have more dense bones than whites. The third risk factor was body size. A small stature or frame size leads to a high risk of fractures. When a person is under 125 pounds, their optimal bone density is not reached. The final risk was family history. You are more likely to experience osteoporosis if the disorder is found in your family history. You are also more likely to get the disorder if hip fractures, smoking, thinness, or tallness run in your family.

____________________________ is the fracture resulting from repeated loading of relatively low magnitude.

Stress fracture

List and describe the four types of bones, including function and examples.

The four types of bones are short, flat, irregular, and long bones. Short bones are small, cubical skeletal structures. Examples of short bones only include the carpals and tarsals. These bones provide limited gliding movements and serve as shock absorbers. Flat bones are skeletal structures that are largely flat in shape. They protect underlying organs and soft tissues and also provide large areas for muscle and ligament attachments. Examples of flat bones include the scapulae, sternum, ribs, patellae, and some of the bones of the skull. Irregular bones have different shapes to fulfill special functions in the human body. For example, the vertebrae provides a bony, protective tunnel for the spinal cord. Other examples of irregular bones are the sacrum, coccyx, and maxilla. Lastly, long bones form the framework of the appendicular skeleton. They consist of a long, roughly cylindrical shaft of cortical bone. The long bones are adapted in size and weight for specific biomechanical functions. The tibia and femur are large and massive to support the weight of the body. The humerus, radius, and ulna are smaller and lighter to promote ease of movement. Other longer bones include the clavicle, fibula, metatarsals metacarpals, and phalanges.

Explain Wolff's law, including why it is important.

Wolff's Law states that bone grows and remodels in response to the forces that are placed upon it. After injury to bone, placing specific stress in specific directions to the bone can help it remodel and become normal healthy bone again. The densities, shapes and sizes of the bones of a given human being are a function of the magnitude and direction of the mechanical stresses that act on the bones. Your physical therapist should understand Wolff's law to help guide your rehabilitation after a fracture or broken bone. Wolff's law allows for remodeling and bone modeling to occur. Remodeling involves resorption of fatigue-damaged older bone and subsequent formation of new bone. Bone modeling is the term given to formation of new bone that is not preceded by resorption, and is the process by which immature bones grow.

Appropriate strategies to lessen the likelihood of acquiring osteoporosis include which of the following? adequate dietary calcium intake and absorption regular weight-bearing exercise both A and B none of the above

adequate dietary calcium intake and absorption regular weight-bearing exercise

What is the most common symptom of osteoporosis? A. frequent headaches B. joint pain in the extremities C. back pain derived from vertebral fractures D. swelling of the distal extremities

back pain derived from vertebral fractures

Which of the following occurs in the absence of gravitational forces? bone hypertrophy bone atrophy bone modeling all of the above

bone atrophy

What happens when osteoclast activity exceeds osteoblast activity? A. bone mass increases B. bone modeling C. bone mass decreases D. none of the above

bone mass decreases

An epiphyseal injury can terminate ______________ bone growth.

early

Which of the following is known as the longitudinal "growth center" of a bone? A. osteoblast B. osteoclast C. epiphysis D. periosteum

epiphysis

Specialized bone cells that build new bone tissue are called what? A. periosteum B. osteoblasts C. osteoclasts D. epiphysis

osteoblasts

Reduced bone mass and density without the presence of a fracture defines what? A. osteopenia B. osteoclast C. osteoporosis D. osteoblast

osteopenia

Which of the following is part of the axial skeleton? the skull the vertebrae the sternum all of the above

the skull the vertebrae the sternum

Which of the following terms is used to describe bone with relatively high porosity? A. cortical B. trabecular C. spongy D. all of the above

trabecular

Dynamic loading during gymnastics has been show to affect bone size and strength more than muscle mass. true or false

true