Tissue Behavior and Injury Healing (Ligament, cartilage, & bone Slides: 54-70)

Whereas muscles provide dynamic stability, ligaments provide ____.

Static stability

*injury to a ligament results in loss of normal kinetic relationship between bones

3 factors that affect ligaments...

1. Weaken with age (lose stiffness, strength, mass)

2. Ligament laxity changes with hormone levels (pregnancy and menstruation ligaments become more lax)

3. Movement and exercise help maintain and improve strength and stiffness

Ligament injuries are classified into...

Grade 1 (Mild)-Stretching/tearing of fibers

Grade 2 (Moderate)-Some tearing and separation of fibers

Grade 3 (Complete)-Total rupture of ligament

___ do not heal as well as ___ due to their limited blood supply

Intra-articular ligaments (ACL)

Extra-articular ligaments

Similar to muscle healing, in that eventually a ___ is formed in the tissue gap.

Hematoma (blood clot)

*inflammatory phase begins and collagen type I, III and V are synthesized

Collagen begins to form in matrix within 1 week of the injury, signaling the proliferative phase making..

Collagen content greater than normal ligament, however, concentration is lower and the matrix is disorganized

_____ includes change in collagen type (Type I collagen is increased)

Remodeling phase

Ligament rehab is important for...

forces to be applied to the ligament during its recovery to help develop strength (in the direction the force is applied)

*Actively exercised ligaments are stronger than immobilized ones

Surgically repaired torn ligaments seem to ...

Heal faster and stronger compared to conservative approach

*sees ligament regeneration rather than scar formation

Cartilage lacks __ and ___. The nutrition occurs by diffusion from ___.

Blood supply and nerves

Synovial fluid

With aging, ____, leaving areas of exposed bone.

Chondrocyte distribution changes

*hydration decreases with aging

*these factors result in increased force transmission to the underlying subchondral bone

Appropriate and repeated application of joint loads promotes..

Normal articular cartilage structure and function

*MOTION IS LOTION

Cartilage is ___ therefore it has a limited capacity to heal and cannot produce an inflammatory response.

Avascular

*exchange of nutrients requires weight bearing and movement

Failure of chondrocytes to repair damaged articular cartilage while losing cartilage...

osteoarthritis (OA)

*influx of intracellular contents and reduction in proteoglycan production

__ , __, and ___ have all been associated with increased knee and hip osteoarthritis risk.

Previous joint injury, obesity, and occupational activity

*levels of physical activity and sport specificity remain inconclusive as risk factors

3 types of cartilage injuries...

Type I: Superficial

Type II: Partial thickness

Type III: Full thickness

Bones are strongest when ___ and weakest when ___

Compressed

Placed in tension (elongation)

Repeated ___ can result in a stress fracture.

Submaximal stress

*account for 10% of athletic injuries (50% are tibia)

___ can be a potent stimulus for bone remodeling

Exercise

What are the 5 types bone fractures?

Transverse fracture

Oblique fracture

Spiral fracture

Comminuted fracture

Avulsion fracture

Break that runs horizontally across bone, perpendicular to long axis

Transverse fracture

Break that occurs at an angle, usually in a long bone

Oblique fracture

Break that occurs with twisting motion; looks like a corkscrew

Spiral fracture

Type of broken bone where bone breaks into more than two pieces

Comminuted fracture

Type of bone failure that occurs when a small piece of bone is pulled away from the main bone by a ligament or tendon

Avulsion fracture

Bone healing is ___ rather than repair meaning...

Regeneration

Healing is accomplished by the original tissue, not scar tissue

Two steps of bone healing are..

Primary (cortical) healing

*bone on one side of fracture unites with bone on the other side

Secondary (callus) healing

*periosteum and external soft tissues establish a callus around the fracture site

Bones have a very ____ with most being healed within 6-8 weeks.

Strong healing capacity

*impacted by blood flow and generally faster healing in children