Tissue Injury and Repair 2025 Student Notes PDF

Tissue Injury and Repair PT8313 – Spring 2025 Erin Baumann, PT, DPT, OCS Adapted from 2024 course Objectives 1. Understand the typical phases of inflammation and healing process after an injury 2. Discuss potential facto...

Tissue Injury and Repair PT8313 – Spring 2025 Erin Baumann, PT, DPT, OCS Adapted from 2024 course Objectives 1. Understand the typical phases of inflammation and healing process after an injury 2. Discuss potential factors affecting the tissue healing process 3. Describe variation of healing based on type of tissue involved 4. Appreciate tissue healing variability and uncertainty First...let’s chat  Why do you think it is important to clinically appreciate and understand tissue healing? First...let’s chat  Why is knowing expected tissue healing timelines important when considering a modality? Phases of Inflammation and Healing 1. Inflammation Phase (Acute Phase)  Prepares wound for healing 2. Proliferation Phase (Repair/Subacute Phase)  Rebuilding damaged structures 3. Maturation Phase (Remodeling/Chronic Phase)  Modifies scar tissues into mature form Phases Inflammation Phase  Days ~1-6  Begins immediately  Normal and necessary  Complicated but highly coordinated process and response  No inflammation = no healing! Inflammation Phase  Vascular Response  Hemostatic Response  Cellular Response  Immune Response http://slideplayer.com/slide/3862433/13/images/18/Inflammatory+Response.jpg Inflammation Phase  Cardinal signs of inflammation  Calor – “heat”  Rubor – “redness”  Tumor – “swelling”  Dolor – “pain”  Functio Laesa – “loss of function” https://physioworks.com.au/wp-content/uploads/2024/06/ sprained-ankle-300x300.jpg Inflammation Phase Immediate Vasodilatio Clot Phagocytos vasoconstriction n formation is Proliferation Phase  Days ~3-20  Objective  Cover wound, provide (initial) strength  4 processes (occur simultaneously)  epithelialization  collagen production  wound contraction  neovascularization Proliferation Phase  Epithelialization  Reestablishment of the epidermis  Superficial to deep  Offers protection  Collagen production  Fibroblasts (make collagen)  Wound contraction  Pulls edges together  Myofibroblasts  Neovascularization  Development of new blood supply  Angiogenesis (growth of new blood vessels)  Proliferation Phase  A note on wound contraction:  If uncontrolled, contractures may result  Fixed shortening of soft tissues that have high resistance to passive stretch Maturation Phase  ~Day ~9 - >1 year  Longest phase  Fibroblasts, macrophages, myofibroblasts and capillaries decrease  Collagen maturation continues  “scar tissue”  Goal: restoration of tissue Maturation Phase  Collagen  >27 different types  Type I  Bone, skin, tendon  Mature scars  Type II  cartilage  Type III  GI tract, uterus, blood vessels  First type of collagen to be deposited during healing process Maturation Phase  Need to load healing tissue appropriately  As a PT, we need to match ”the load” to patient’s ”tissue strength” Healing takes time  Summary Duration Phase Goal (approximate) Homeostasis, Inflammatory Up to 6 days contained to injury site Remove necrotic tissue, strengthen Proliferation/Repair Up to 21 days tissue site, restore circulation Maturation/ Normalize the Remodeling Up to a year+ injury site What if this “typical healing” timeline doesn’t happen? Chronic Inflammation  Simultaneous progression of active inflammation, tissue destruction and healing 1. Continued trauma 2. Immune response  Foreign material (i.e. implant, suture, etc.)  Autoimmune disease (i.e. RA) Chronic Inflammation  Question central nervous system sensitization  Target tissue is not the only contributing factor  Rehabilitation can become more complicated *prolonged inflammation can delay tissue healing and tissue tensile strength development; thus, influencing the recovery process and the timeline Factors affecting tissue healing Local Factors  Type, size, location of the injury  Infection  Blood supply  Movement/excessive pressure Systemic Factors  Age  Diseases/co-morbidities  Medications  Nutrition  Stress Specific Tissue Type Healing Considerations Cartilage  Low healing capacity  Lack of lymphatics, blood vessels, and nerves  Injury to cartilage alone does not induce the healing response  Cartilage defect or lesion fails to heal  Injury to cartilage and subchondral bone can stimulate the inflammatory response Cartilage Injury  Less predictable healing  Options?  Surgical  Mosaicplasty – chondral https://ars.els-cdn.com/content/image/3-s2.0-B9780323763004000801-f071-001- transplant 9780323763004.jpg  OATS procedure  Microfracture surgery Tendons  Initially, type III collagen is deposited perpendicular to the tendon long axis (i.e. messy, disorganized)  With proper loading, starting ~10 days - 2 months post injury, collagen is realigned  More parallel to the long axis  Adhesions are common if the synovial sheath is injured Ligaments  Healing capacity depends on type of ligament, size of defect, and amount of stress applied  Intracapsular (i.e. ACL) typically do not stimulate adequate healing responses  Functional loss?  Extracapsular ligament (i.e. MCL of the knee) can scar/heal “better”  Mature ligamentous repair tissue = 30-50% strength of uninjured ligament  Not often functionally limiting Skeletal Muscle  Skeletal muscle cells do not proliferate  Satellite cells may proliferate and differentiate to form new skeletal muscle Bone Healing Bone Healing  Factors that can delay healing  Nutrition  Vit D/calcium  Malnutrition  Diabetes  Smoking/nicotine  Increase healing times  Can take >70% longer to heal a fracture than a non-smoker  Medication  NSAIDS, corticosteroids, etc. can limit This is a lot…Why does it all matter? Questions? Thank you!!!!