Tissue Injury and Repair Flashcards
Tissue’s Crimp
Collagen fibers have a wavy or folded appearance at rest (slack). When a force lengthens the collagen fibers this slack is taken up. This slack is called the tissue’s crimp. Crimp is different for each type of connective tissue and this provides each of these tissues with different viscoelastic properties.
Ligament injuries are called _______
Sprains
Tendinitis
Implies an inflammatory reaction to a tendon injury- a microscopic tearing and inflammation of the tendon tissue, commonly resulting from tissue fatigue rather than direct trauma
Tenosynovitis
Tenosynovitis/tenovaginitis, peritendinitis, and paratenonitis, indicate an inflammatory disorder of tissues surrounding the tendon such as the tendon sheath-usually the result of a repetitive friction of the tendon and its sheath
Tendinosis
Refers to a degenerative process of the tendon. Characterized by the presence of dense populations of fibroblasts, vascular hyperplasia, and disorganized collagen
Wolff’s Law
Forces applied to bone, including muscle contractions and weight bearing can alter bone the internal and external configuration of bone through adaptation to these stresses
Decreased Adaptation in Bone
If the adaptations of a bone to stress do not occur fast enough, the bone is resorbed faster than it is replaced, and bone strength is compromised. Causes of decreased adaptation include: an increase in the applied load, an increase in the number of applied stresses, a decrease in the size of the surface area over which the load is applied.
Muscle injury can result from
- Excessive strain
- Excessive tension
- Contusions
- Lacerations
- Thermal stress
- Myotoxic agents (local anesthetics, escessive use of corticosteroids, snake and bee venoms)
Hematoma
Contusion to a muscle belly.
Intramuscular Hematoma
Associated with a muscle strain or bruise. The size of the hemotoma is limited by the muscle fascia
Intermuscular Hematoma
This type of hematoma develops if the muscle fascia is ruptured and the extravasated blood spreads into the interfascial and interstitial spaces
Muscle Strain Grade I
Involves a tear of a few muscle fibers with minor swelling and discomfort. Associated with no or minimal loss of strength and restriction of movement.
Muscle Strain Grade II
Greater damage of the muscle and clear loss of strength and some loss of function
Muscle Strain Grade III
Involves a tear extending across the whole muscle belly. Characterized by severe pain or loss of function.
What are the 3 main phases of wound healing?
- Inflammatory
- Proliferative
- Remodeling
Inflammatory Phase of Wound Healing
Reaction that occurs immediately after wounding includes a series of defensive events that involves the recognition of a pathogen and the mounting of a reaction against it. This reaction involves both coagulation and inflammation.
Coagulation. Apart from an initial period of vasoconstriction lasting 5-10 minutes, tissue injury causes vasodilation, the disruption of blood vessels and extravasation of blood constituents, including platelets.
What are the main functions of the exudate of the inflammatory phase?
- Provide cells capable of tissue reconstruction
- Dilute microbial toxins
- Remove contaminants present in the wound
Inflammation phase in the Inflammatory phase
Inflammation is mediated by chemotactic substances, including anaphylatoxins, which attract neutrophils and monocytes.
Neutrophils
White blood cells that bind to microorganisms, internalize them, and kill them
Monocytes
White blood cells that develop into macrophages, and provide immunological defences against many infectious organisms
Time period of Inflammatory Phase
This stage can last 1-6 days to longer than 6 months
Proliferative Phase
Characteristic changes during phase include: capillary growth, granulation tissue formation, and fibroblast proliferation with collagen synthesis and increased macrophage and mast cell activity.
Lasts from 5 to 15 days, and often up to 10 weeks depending on the type of tissue, and the extent of damage
Remodeling Phase
Involves a conversion of the initial healing tissue to scar tissue. Tissue remodeling and increasing tensile strength in the wound lasts for up to a year. Imbalances in collagen synthesis and degradation during this phase of healing may result in hypertrophic scarring or keloid formation. If left untreated the scar formed is less than 20% of its original size
Primary Bone Healing
Involves a direct attempt by the cortex to reestablish itself once it has become interrupted. Bone on one side of the cortex must unite with bone on the other side of the cortex to reestablish mechanical continuity
Secondary Bone Healing
Involves responses in the periosteum and external soft tissues with the subsequent formation of a callus. The majority of fractures heal by secondary fracture healing.
