Bone GrowthBone Fractures

and Bone Diseases

Lesson 2.4

Compact Bone Formation

• Compact bone begins as cartilage, osteoblasts discharge a gelatin-like substance (osteoid) in which minerals are deposited giving strength

• Short bones have a single ossification site, while long bones have three

Cancellous (spongy) Bone Formation

• Flat bones of skull

• Begin as fibrous membrane

• Osteoblasts release osteoid into membrane, which forms a sponge-like bundle of fibres

Bone Remodelling• Two phases (reabsorption and reformation):

– Osteoclasts remove old bone by releasing acids and enzymes

– Osteoblasts secrete gelatin-like substance (osteoid) and new tissue forms

• Most active during the early years of human life and declines until 35 y.o

• After 35, process is reversed; reabsorption exceeds reformation. 5-10% loss in bone mass per subsequent decade

Epiphyseal Plates and Lines

• Also known as growth plates, occur at various locations at the epiphyses of long bones

• When growth is done, become epiphyseal lines

Does weight training stunt bone growth?

• When done properly resistance training can actually facilitate growth

• Children should avoid maximum lifts

Fractures

• Simple– No separation of the bones– Hairline fractures

• Compound– Complete separation of bone; major blow

• Comminuted – Shattering of bone

Stress – Strain

Force

(N)

Deformation (cm)

Hairline Fractures

Hairline Fractures

Compound Fracture

Closed Compound Fracture

Open Compound Fractures

• Llewellyn Starks, who suffered a compound fracture to his right tibia and fibula when attempting a jump at the 1992 New York games. This injury ruined his career.

Comminuted Fracture

Spiral Fracture

Avulsion Fracture

• When a fragment of bone tears away from the main mass

• Force of muscle contraction pulls tendon and bone from periosteum

• Athletes

Avulsion Fracture

Impacted Fracture

Stress Fractures

• Type of hairline fracture that occurs after repetative stress

• Muscles become too fatigued to absorb the shock

• Common in runners. Which bones?__________

• Training too hard too soon

KRITZ

The Healing of Broken Bones

What Type of Fracture is What Type of Fracture is This?This?

Is it Open or Closed?Is it Open or Closed?

Rickets• Rickets is a disorder caused

by a lack of vitamin D, calcium, or phosphate.

• It leads to softening and weakening of the bones.

• Symptoms: Bone pain or tenderness Arms; Legs; Pelvis; Spine. Dental deformities

Osteoporosis • “porous bone”

• Leads to fragile bone and increases risk of breaks – hip wrist and spine. Why these bones?

• Called silent disease

• Post-menopausal women more at risk

• Young women with “female triad” also at risk (excessive exercise, poor diet, and weight loss)

Osteoporosis

• Work in groups of two. Using the text and the internet, each group will research one of the following and present the findings to the class:

Rickets• How common is rickets? Worldwide? Canada • What is the causal link between vitamin D and Rickets?• People living in what geographic region are more at

risk• What is the treatment for rickets?

• Osteoporosis • Why are women more at risk for osteoporosis? • Can men get osteoporosis? When are they most at risk? • What is the female triad and why are these young women at risk?• What are some treatments for osteoporosis?• What is the most current treatment?• What are some possible future treatments?