Changes to Pediatric Bone & Muscle (10/18c) [Biomedical]

Question 1

Periods of change and variability

Answer 1

Skeletal maturation

Muscle growth

Sexual maturation

Skill acquisition

Question 2

Growth, size, volume, structure and function of the skeleton are affected by

Answer 2

Hormones

Metabolic factors

Nutrition

Mechanical forces over time

Genetics

Disease or Pathologic processes

Question 3

Muscle vs Bone Growth

Answer 3

Bone growth is affected by muscle action and activity

Muscle development and function is in turn affected by bone growth

Question 4

Bone Growth - Growth Hormone (GH)

Answer 4

Stimulates synthesis of IGF-1

GH deficiencies lead to decreased BMD during childhood

Contribute to longitudinal bone growth and mass after birth

During puberty along with sex hormones continue to contribute to bone growth and development

Question 5

Bone Growth - Insulin like growth factor 1 (IGF-1)

Answer 5

IGF-1 important during skeletal maturation for longitudinal growth, skeletal maturation, and BM acquisition

IGF-1 also important for maintenance of BMC during adulthood

Contribute to longitudinal bone growth and mass after birth

During puberty along with sex hormones continue to contribute to bone growth and development

Question 6

Bone Growth - Thyroid Hormone (TH)

Answer 6

Direct impact on bone metabolism

Children with hypothyroidism have decreased bone lengthening

Question 7

Bone Growth - Sex Hormones

Answer 7

Increased estrogens and androgens at puberty

Rapid longitudinal bone growth

Fusion of physis - leads to cessation of bone growth

Increased lean body mass

Contribute to significant variability

Question 8

Bone Growth - Fibroblast Growth Factors (FGF)

Answer 8

23 different FGFs identified

A lot of interplay, continually regulate skeletal patterning and bone growth throughout the skeletal growth period

In periosteum, perichondrium surrounding the growth plate, chondrocytes, osteoblasts, etc

Question 9

Bone Growth - Vitamin D

Answer 9

Vitamin D3 is produced in the skin following ultraviolet light exposure

Metabolized in the liver to 25D, then metabolized in the kidney to 1α,25-dihydroxyvitamin D (125D)

125D plays a critical role in the intestinal absorption of calcium and ionic phosphate

Question 10

Bone Growth - Calcium

Answer 10

Calcium can only be absorbed 500mg at a time (4-6 hrs)

Calcium supplementation has positive effects on bone mineral density (BMD)

Change in dietary habits may be easier to maintain vs taking a pill

Question 11

Anthropometrics

Answer 11

Measurements of age, growth, and development

• height
• weight
• BMI
• skeletal maturity
• sexual maturity

Question 12

Measurements of Skeletal Maturity and Bone Age

Answer 12

All use left hand and wrist (due to majority right hand dominance)

Atlas technique of Greulich and Pyle

Tanner-Whitehouse bone-specific scoring

Fels hand-wrist method

Question 13

Atlas technique of Greulich and Pyle

Answer 13

Modal maturity indicators described for a specific age

Question 14

Tanner-Whitehouse bone-specific scoring

Answer 14

Total bone maturity indicator score up to 1000

Typically used in Europe

Question 15

Fels hand-wrist method

Answer 15

Requires software to translate ratings into age

Typically used in North America

Question 16

Growth Data - Females

Answer 16

Towards the end stage of sexual development for girls (~12.6 yo), 90% had their first period already

2 years left of long bone growth after getting first period

Increasing Growth Velocity: 9-11.5 yo

Peak Growth: 11.5 yo (8.3 cm/yr)

Velocity Stops: 15 yo

Question 17

Growth Data - Males

Answer 17

Increasing Growth Velocity: 11-13.5 yo

Peak Growth: 13.5 yo (9.5 cm/yr)

Velocity Stops: 18 yo

Question 18

Timing of Growth Plates with Injury

Answer 18

Consider timing of growth in males and females when there are injuries to determine if there could be growth plates still

Can also influence decision of timing of surgeries

Females — completion of fusion 12.5-18 yo

Males — completion of fusion 15-18 yo

Question 19

Bone Mineral Content (BMC) aka mass

Answer 19

Total bone tissue in an area

Measured in grams

Question 20

Bone Mineral Density (BMD)

Answer 20

Amount of bone tissue per volume

Measured as g/cm2 or g/cm3

Question 21

Peak Bone Mass

Answer 21

Maximal amount of bone tissue following skeletal maturation

Question 22

Density and Mass Measurements

Answer 22

USE Z SCORES, NOT T SCORES

Dual-energy X-ray absorptiometry (DXA)

Quantitative computed tomography (QCT)

Peripheral QCT (pQCT)

Quantitative Ultrasound (QUS)

Magnetic resonance imaging (MRI)

Question 23

Continued increase of bone mass and density following end of height growth

Answer 23

Greater bone mass and density associated with decreased fragility fracture
- 10% increase in peak bone mass can decrease female fracture risk by 50%

Still important to optimize bone health after adolescence

Question 24

Muscle/Lean Body Mass (US measurement study)

Answer 24

Females (3-13 yo) have greater quadriceps muscle mass than males

Possibly hormonal since most females are well into puberty at 13 yo

Question 25

Muscle/Lean Body Mass (DXA measurement study)

Answer 25

Tanner stage 5
Males have greater extremity lean soft tissue and total body skeletal muscle mass

Tanner stage < 5
No difference in extremity lean soft tissue and total body skeletal muscle mass

No differences between ethnicities

Question 26

Isometric Muscle Strength Study

Answer 26

Children Ages 4 to 16

Suggests using weight related muscle reference data especially when testing “patients suffering from growth retardation”

Unable to demonstrate gender differences in LE strength in subjects > 15 years old

Question 27

Differences Based on Socioeconomic Status, Culture, and Ethnicity - Studies

Answer 27

Black vs White

• black children have longer legs and greater long bone strength
• similar femoral density
• 0.5 SD ahead of white children in bone age, could be delayed when age-matched

US Born vs Southeast Asian Refugees
- US heavier and taller

Bone density similar prepuberty for Caucasian, Asian, Hispanic and African American

Question 28

Pediatric Skeletal Difference

Answer 28

Preosseus cartilage

Physis – growth plate

Periosteum - thicker, stronger, more osteogenic
- Faster and bigger callous

More shock absorption
- Lower BMC and greater porosity

Question 29

Pediatric Orthopedic Concerns

Answer 29

Growth Plate Injuries and conditions

• Apophysitis
• Salter Harris fractures

Lower Extremity Deformities

Growing Pains

Pediatric Fracture Remodeling

Question 30

Apophysitis

Answer 30

inflammation or stress injury to the areas on or around growth plates in children

Telltale sign no matter where it is located, if you palpate on it they will jump

To treat, you have to strengthen the muscle and do slow static stretches

Question 31

Why Does Physis Injury Occur Before Ligament Injury?

Answer 31

Younger age is more likely to have physics injury

Ligaments attach to epiphyses, transferring force to physis (most stresses occur horizontally)

Ligaments shoer and continuous tissue type (greater tensile strength)

Ligaments are generally stronger than bones in kids

Question 32

Structural Contributions to Physis Injury

Answer 32

Physis is sandwiched between epiphysis and metaphysis of growing bone
- Relatively soft tissue between relatively hard tissue

Histologically, metaphyseal trabeculae are initially oriented longitudinally in long bones

• Progress to horizontal orientation with skeletal maturity
• Predisposes the region to certain fracture modes

Question 33

Apophysitis - Osgood Schlatter Disease

Answer 33

Traction apophysitis of the tibial tuberosity

Characterized by prominent tibial tuberosity

Significant tenderness to palpation of tibial tuberosity

Question 34

Apophysitis - Sinding Larsen Johansson Syndrome

Answer 34

Traction apophysitis of the inferior pole of the patella

Significant point tenderness to inferior patella tubercle and proximal patella tendon

Question 35

Apophysitis - Sever’s Disease

Answer 35

Traction apophysitis of the posterior calcaneus

Pain with shoes, toe walking, running

Significant tenderness to posterior calcaneus

Prominent “pump bump”

Gastroc-soleus tightness

Question 36

Apophysitis - Iliac Apophysitis

Answer 36

Traction apophysitis along the iliac crest and/or spine

• TFL
• Rectus femoris
• Sartorius
• Gluteus medius
• Abdominal obliques

Track and field athletes and dancers

Question 37

Growing Pains

Answer 37

No conclusive evidence regarding cause

Diagnosis of exclusion

Anecdotally related to:

• Biochemical/hormonal factors
• Muscle strain during growth

Working while trying to keep up with the length of bone - “instability” at growing junctions

Treatment for comfort
- Massage, hot/cold packs, analgesics

Question 38

Bone Remodeling Following Fracture - Major Factors

Answer 38

Age – younger children

Proximity to a joint – closer to a physis

Joint Axis – deformity in the plane of “primary” osteokinematic motion

Question 39

Bone Remodeling Following Fracture - Overgrowth

Answer 39

< 10 yo frequently have a 1 to 3 cm overgrowth in long bone

Bayonet apposition to compensate

Due to physeal stimulation during fracture healing

Question 40

Youth Resistance Training Programs - Requirements

Answer 40

Specifically designed program

• General muscle strengthening towards end of puberty
• Avoid max lifting until at least Tanner Stage 5 (16-17 yo)

Supervised settings with low instructor : participant ratio

Proper Technique

Safety guidelines for gym behavior and and equipment use

Question 41

Strength Training Study - Changes in strength likely due to neural components

Answer 41

Motor unit recruitment

Frequency of motor unit firing

Changes in muscle activation

Changes in contractile properties

Question 42

Strength Training - Factors Contributing to Injury

Answer 42

Poorly designed/supervised programs

Excessive load

Unqualified supervision

Poorly designed equipment

Free access to equipment