What are the two main types of bone tissue and their characteristics?
Cortical (compact) bone:
- Forms the outer shell of long bones
-Low porosity (5–10%)
-Provides strength and rigidity
Trabecular (spongy) bone:
-Found in cuboidal, flat bones, and at bone ends
-High porosity (75–95%)
-Absorbs impact and distributes load
What are the primary functions of bone?
Protects internal organs
Provides body shape and structural framework
Enables movement through muscle attachment
Stores minerals (calcium, phosphate)
Produces blood cells (red marrow)
Where is red and yellow bone marrow located, and what are their roles?
Red marrow: Produces blood cells
Found in most bones of children; in adults, mainly in flat bones, vertebrae, and long bones.
Yellow marrow: Stores fat, mainly in long bones of adults.
How does physical training influence bone strength? What age is peak bone strength/density?
Dynamic loading (running, jumping) increases bone mineral density (BMD).
Peak bone strength and density occur between ages 25–30.
Which cells are responsible for bone remodeling?
Osteoclasts: Break down (resorb) bone
Osteoblasts: Build new bone
What does the bone stress-strain curve illustrate?
Compact bone can withstand high stress but little amount of strain.
-stiff and brittle
Spongy bone can undergo more strain (deformation) but withstands less stress
-more flexible, low strength
What are the main types of bone injury? (7)
Traumatic fracture: Due to acute mechanical load (can be open or closed).
Pathological fracture: Occurs in weakened bone (e.g., osteoporosis, cancer).
Stress fracture (fatigue fracture): From repetitive microtrauma.
Bone contusion: Acute bone bruise without fracture.
Osteitis: Inflammation of bone.
Periostitis: Inflammation of the periosteum.
Osteochondral injury: Damage to both cartilage and underlying bone.
What are the four stages of bone healing?
Inflammation & blood clotting (3–7 days): Hematoma formation and inflammatory response.
Soft callus formation (~2 weeks): Woven bone begins forming, bridging fracture.
Hard callus formation (~2 more weeks): Mineralization of soft callus; strength increases.
Bone remodeling (months–years): Replacement of woven bone with organized lamellar bone.
What is the difference between woven and lamellar bone?
Woven bone:
-Rapidly formed, disorganized structure
-Low strength, appears during soft callus stage
Lamellar bone:
-Slowly formed, highly organized structure
-Replaces woven bone in the hard callus and remodeling stages
How common are bone stress injuries (BSIs)?
They make up 15–20% of all musculoskeletal injuries in endurance athletes (e.g., runners, triathletes).
What are the main risk factors for BSIs?
Age: Adolescent growth spurts increase risk.
Sex: Females are 2–3× more likely (especially runners/triathletes).
Menstrual disturbances and low energy availability (LEA).
Nutrient deficiencies: Vitamin D and iron.
High training load or sudden increases in volume/intensity.
What is the continuum of spinal stress injuries in young athletes?
Bone stress reaction → overuse of posterior spinal elements.
Spondylolysis → stress fracture of the pars interarticularis.
Spondylolisthesis → forward slipping of one vertebra over another.
What is the typical rehabilitation progression after surgery for spondylolisthesis?
Week 1: Light walking and stretching.
Weeks 2–9: Static core stabilization.
Weeks 6–12: Dynamic strengthening.
Weeks 9–12: Low-impact aerobic training.
RTS: Between 6 months and 1 year, depending on recovery.
What is Medial Tibial Stress Syndrome (MTSS)?
“Shin Splints”
Caused by repetitive loading (e.g., running, jumping).
Results in inflammation along the tibia.
What is a tibial stress fracture and how does it differ from MTSS?
Tibial stress fracture:
Localized pain during running, relieved by rest but returns with activity.
Microfracture within cortical bone.
MTSS:
Periosteum irritation without cortical fracture.
