The Injury Process

The Physics of Sports Injury The human body consists of many different types of tissue, each serving a specific purpose Connective tissue The most common type in the body Ligaments, retinaculum, joint capsule, bone, cartilage, fascia, and tendon (Cailliet, 1977) Epithelial Protection, secretion, and absorption Muscular Contraction Nervous Touch and conductivity

Connective tissue is involved in both acute and chronic injuries 50% of all injuries in some sports are acute in nature and involve either muscle or tendon tissue

Occur during eccentric contractions Muscles and fascia are injured when excessive tension is applied while contraction is occurring Occur during eccentric contractions The simultaneous processes of muscle contraction and stretch of the muscle-tendon unit by an extrensic force (Safran et al., 1989) Damage to strains typically is found at the proximal musculotendinous junction (MTJ)

Mechanical Forces of Injury Type of Tissue Connective (Tendons) Bone Tissue Ligament Tissue Tensile Force Resist Less effective Compressive Force Poorly Designed Absorb More vulnerable Shear Force Mechanical Forces of Injury Three types of forces: Tensile Force Compressive Force Shear Force

Axial loading = force along the long axis Ex) when the body is upright in standing position, body wgt creates axial loads on the femur and tibia Shear force ex) spondylolisthesis, involving anterior slippage of a vertebra with respect to the vertebra below it Compressive force = axial loading that produces a squeezing or crushing effect Tensile force = axial loading in the direction opposite that of compression Shear force = acts parallel or tangent to a plane passing through the object

Mechanical Forces of Injury Each tissue type has a limit to how much force it can withstand The limit has been referred to critical force (Nigg & Bobbert, 1990) Factors such as age, temperature, skeletal maturity, gender, and body weight can affect the mechanical properties of ligaments

Physiology of Sports Injury Body’s initial response to trauma is inflammation 3 phase process Inflammatory phase Fibroblastic phase Remodeling phase

Inflammatory Phase 0-6 Days Vasoconstriction promotes increased blood viscosity (thickness), reducing blood loss through bleeding The platelet reaction initiates clotting and releases growth factors that attract reparative cells to the site The coagulation cascade affects clot formation The complement and kinin cascades provoke vasodilatation and increase blood vessel wall permeability, facilitating the migration of neutrophils and macrophages in plasma exudates to cleanse the site through phagocytosis Phagocytosis = cell eating

Proliferation Phase 3 – 21 days Connective tissues heal themselves by forming scar tissue Fibroblasts (immature, fiber producing cells located in connective tissue) produce a supportive network of Types I and III collagen The platelet response and hypoxic wound environment stimulate angiogenesis (formation of capillaries, which interconnect, resulting in the formation of new vessels) Epithelial cells migrate from the periphery toward the center of the wound to enact re- epithelialization

Maturation Phase Up to 1+ years Fibroblast activity decreases and habitual loading produces increased organization of the extracellular matrix A return to normal histochemical activity allows for reduced vascularity and water content Types I and III collagen continue to proliferate, replacing immature collagen precursors and resulting in contracture of the wound Scar tissue formation results in decreased size and flexibility of the involved tissues Remodeling causes collagen fiber alignment along lines of habitual stress, with tensile strength increasing for up to 2 years post injury

How the injury process affects soft tissue and bone… Bone injuries heal similarly to soft tissues; however, osteoclasts migrate to the region of injury and remove destroyed cells and debris Fibroblasts (osteoblasts) migrate to the injured area New osteoblasts are manufactured Osteoblasts develop collagen and cartilage called a callus Callus fills the space between the fractured bone ends and can be seen on an x-ray Callus is not of sufficient strength to substitute for the original bone; however, through maturation it becomes fully functional bone -some type of immobilization is required -severely displaced fractures, surgical placement of appliances such as plates and screws may be necessary to stabilize the bony fragments

Pain and Acute Injury… Although inflammation is the most visible aspect of an acute injury, the athlete will complain of pain as the largest problem Pain is defined as, “the perception of an uncomfortable stimulus or the presentation or response to that stimulus by the individual,” (Thomas, 1997) Two types of pain Psychological (emotional) Physiologic (tissue damage) Result of sensory input received through the nervous system that indicates the location of damage An athlete with high pain tolerance may underestimate the severity of the injury An athlete with low pain tolerance may exaggerate the severity of the injury In short, pain may not be a useful indicator of the severity of an injury -everyone copes with pain differently -err on the side of caution, consertivative side

Common Modalities used to treat pain Ice Heat Electrical Stimulation (e-stim) Massage Prophylactic wrapping

Intervention Procedures… Suggested treatments of inflammation include the application of cyrotherapy (therapeutic use of cold), Crushed ice packs, ice cups applied via massage, ice-water baths, commercially available chemical cold packs, and aerosol coolants (ethyl chloride) After the acute inflammatory phase has passed, usually 48 to 120 hours following thermotherapy (therapeutic use of heat) may be appropriate Hydrocollator packs, warm and moist towels, and ultrasound diathermy US should be done under the direct supervision of the BOC ATC, PT or physician

Cyrotherapy and Thermotherapy During first few minutes of the inflammatory phase, direct application of cold may reduce vasodilation, there by reducing the swelling RICES should then be applied which stand for Rest Ice Compression Elevation Support Standard first aid procedure for sprains, strains, dislocations, contusions and fractures -most effective way of applying cold to the body is a plastic bag filled with crushed ice -risk of frostbite during the application of a bag of crushed ice is minimal Ice helps reduce recovery time Tissue cooling reduces the metabolic activity of the cells with reduces need for O2

May be useful during the final phases of injury Thermotherapeutic agents may also have a beneficial effect on soft tissue injury Research is unanimous that such treatments should never be applied during the acute inflammatory phase If we heat the tissue during the early phases of the injury, the metabolic activity of the inflammatory agents increases, resulting in an increase in inflammation (Wilkerson, 1985) May be useful during the final phases of injury Increasing available oxygen and stimulating vasodilation Heat increases local metabolic activities

Majority prescribed by a medical doctor In addition to cold and heat therapy, pharmacologic agents – drugs designed to prevent swelling (anti-inflammatories) or drugs designed to prevent pain (analgesics) are often used to treat inflammation Majority prescribed by a medical doctor Some are available over the counter OTC Should consult with parents prior to recommending any sort of pharmacologic agent, including OTC medications Anti-inflammatories = drugs designed to prevent swelling (steroidal and nonsteroidal) Analgesics = agent that relieves pain without causing a complete loss of sensation

Pharmacologic Agents Classified into two groups: steroidal and nonsteroidal anti-inflammatory drugs (NSAIDS) Steroidal Anti-inflammatory Drugs Best known is cortisone Others commonly used include hydrocortisone, rednisone, prenisolone, trimcinolone, and dexamethasone Even introduced through the skin via phonophoresis (using ultrasound energy) or iontophoresis (using electrical current)

Nonsteroidal Anti-Inflammatory Drugs NSAID’s block specific reactions in the inflammatory process Do not negatively affect collagen formation Block the breakdown of arachindonic acid to prostaglandin, which in turn decreases the inflammatory response to injury Done by decreasing the healing time or by increasing the strength of the new tissue Commonly used NSAID on the treatment of acute ankle sprains

Best approach to treating the majority of soft-tissue injuries involves the application of RICES during the acute inflammatory phase Followed by a combination of RICES, prescribed pharmacologic agent and prescribed and properly supervised rehabilitative exercises The coach or other nonmedical personnel should provide only initial first aid to any soft-tissue injury then refer to appropriate medical authority

The Role of Exercise Rehabilitation Most effective treatment for any sports injury, especially those involving soft tissue is physical activity Need to have a properly constructed and supervised exercise regime Research indicates that rehabilitative exercise can exert a variety of positive effects on collagen formation (AAOS, 1991)

According to knight (1995), exercise is essential during the healing process for two reasons 1. Exercise results in increased circulation with a concomitant increase in oxygen supply to the healing tissue 2. Exercise stresses the healing tissue and in essence “guides” the proper structuring of collagen The process of collagen formation and tissue regeneration requires 2 to 3 weeks Have the area properly protected with adhesive taping, wrapping, or bracing Return to participation by a medical professional with experience in sports injury

An injury severe enough to warrant a medical diagnosis should be treated with a comprehensive program of exercise rehabilitation Rehabilitative exercise, often called therapeutic exercise, is a four-phase process consisting of categories of exercise based on a continuum of severity and recovery

4 Phase Process First, if the athletes injury is severe, the initial exercise involves the therapist moving the injured extremity through a series of passive exercises Reestablishment of a normal range of motion (ROM) Reduction of swelling and muscle spasm Second, as injury improves the next phase becomes active assisted Athlete becomes a working partner in the exercise process, making a voluntary effort to move the injured joint while being assisted by a therapist Improved ROM and increased muscle strength

4 Phase Process Thirdly, rehabilitation process is active exercise Athlete continues moving the joint through a full ROM, using gravity as resistance to stimulate development of muscle strength PT supervises activity, no physical assistance Fourth, the final phase is resistive External resistance is applied to the joint movements Manual resistance, resistive exercise machine, free weights Primary objective is to improve the strength of the muscles surrounding the injured area to protect the injured area from future injury Must incorporate functional activities Functional activities ex) running and cutting drills for those athletes in sports such as basketball, football and soccer