Mechanisms & Characteristics of Sports Trauma

Tissue Stresses Leading to Injury Tension~ pulls or stretches tissue Stretching~ pulls beyond elastic limit Compression~ force that crushes tissue Shearing~ force that moves across the parallel organization of the tissue Bending~ force on a horizontal bone that places stress within the structure causing the bone to bend or strain

Soft-Tissue Injuries Blister~ Continuous friction causing a collection of fluid within the epidermal or dermal layers Abrasion~ scrape or strawberry Laceration~ tear of epidermis with rough edges Incision~ tear of epidermis with smooth edges

Soft-Tissue Injuries Contusion~ bruise Avulsion~ tear that results in the involved tissue being completely ripped from its source Puncture~ a foreign object penetrates the skin

Skeletal Muscle Injuries Contusion Deeper contusion = more severe Extra blood forms a membrane encapsulated blood tumor Strain Stretch, tear, or rip in muscle, fascia, or tendon MOI Forceful muscle contraction Nuero-inefficiency of agonist/antagonist contractions Strength imbalance b/w agonist/antagonist muscles Fatigue producing metabolites in the muscle

Skeletal Muscle Injuries Cramps Painful involuntary contraction Usually due to dehydration and electrolyte loss Spasm Reflex contraction caused by trauma to upper motor neuron or musculoskeletal system Guarding Protective mechanism that causes an involuntary contraction following injury

Skeletal Muscle Injuries Muscle Soreness Acute-onset Accompanies fatigue and occurs during and immediately after exercise Delayed-onset Onset is 12 hours post-exercise Most intense hours post-exercise Relief within 3-4 days Muscle Stiffness Occurs when a group of muscles have been over- exerted for a prolonged period

Chronic Skeletal Muscle Injuries Myositis~ inflammation of muscle tissue Fasciitis~ inflammation of tissue separating muscle Tendinitis~ inflammation of tendon Tenosynovitis~ inflammation of synovial sheath surrounding tendon Atrophy~ muscle wasting Contracture~ shortened muscle

Synovial Joints Ball and Socket Shoulder and hip Allows all motion Gliding Nonaxial joint Carpal/tarsals

Synovial Joints Hinge Uniaxial joint Knee/elbow Flexion/extension Saddle Biaxial joint Allows two motions Flexion/extension, ab/adduction, circumducion

Synovial Joint Phsyiology Joint Capsule Cuff of fibrous tissue that functions to maintain a relative joint position Ligaments Fibrous tissue that functions to connect bone to bone Strongest in the middle

Synovial Joint Physiology Synovial membrane Lines the joint capsule and secretes/absorbs synovial fluid Synovial fluid Joint lubricant Changes viscosity with the speed of movement Articular cartilage Hyaline: nasal septem, larynx, trachea, bone ends Fibrous: vertebral discs, symphysic pubis, menisci Elastic: external ear, Eustachian tube

Synovial Joint Phsyiology Nerve Supply Mechanorecptors provide info about the joint position Located in capsule and ligaments Myelinated fibers, unlike pain receptors Anatomical formation More movement = less joint stability –Must rely on muscles and ligaments for support Less movement = more joint stability

Synovial Joint Injuries Sprain MOI = traumatic joint twist that results in ligamentous/capsule tearing Grade 1 = pain, no instability, little swelling Grade 2 = pain, moderate instability, swelling Grade 3 = pain, instability, possible subluxation, gross swelling Acute synovitis Injured synovial membrane in conjunction with sprain

Synovial Joint Injuries Subluxation Partial separation between two articulating bones Dislocation Complete disunion between two articulating bones

Synovial Chronic Joint Injuries Osteochodrosis Degenerative changes in the ossification centers of the bone ends (epiphysis) Common in children during growth spurts Osteochondritis dissecans is a type of osteopchodrosis Apophysitis is a type of osteochodrosis Causes: Avascular necrosis Trauma causing articular cartilage fx

Synovial Chronic Joint Injuries Traumatic arthritis Trauma to articular surfaces and structures causes thickening of bone and synovium Pain, muscle spasm, and crepitus Weakened ligaments and loose bodies are possible Bursitis Inflamed bursa due to constant pressure or trauma from overused muscles and/or tendons May lead to a calcific bursa

Synovial Chronic Joint Injuries Capsulitis Inflammation of capsule following repeated microtrauma Associated with synovitis Synovitis Joint congestion with edema Synovial membrane becomes thickened and degenerative Restricts movements

Bone Fractures Open vs. Closed Depressed Mostly in flat bones (i.e. skull) Indented fx caused by falling or striking an object Greenstick Mostly in adolescent bones Incomplete fracture Impacted fx Bone is impacted causing a shortening of bone

Depressed Fx Greenstick Fx Impacted Fx

Bone Fractures Longitudinal Bone splits along its length Caused by jumping from a height or landing so to stress the longitude of the long bone Oblique Fx line is diagonal to bone length Created by a torsion force at one end with the other end fixed Serrated Two fx ends are sharp and jagged Caused by a direct blow

Oblique Fx

Bone Fractures Spiral S-shaped fx site Created by a torsion force at one end with the other end fixed Transverse Fx line is at a right angle to length of bone Caused by a direct blow Comminuted Fx site has 3 or more bone fragments Caused by a direct blow or fall in an awkward position

Bone Fractures Countrecoup Fx site on opposite side of impact Blowout Inferior orbital wall is fractured trapping inferior eye muscle Unable to look up Avulsion Separation of bone fragment from its cortex at the attachment site of ligament or tendon Caused by sudden twist or torsion

Blowout Fx

Bone Fractures Stress MOI Continuous muscle contraction Altered stress distribution from fatigue Change in group reaction forces Rhythmic repetitive stress leading to a vibratory summation point Postural conditions –Flat feet, pronated feet, leg length discrepancy Bone scan can provide an early dx

Nerve Injuries Nerve injuries typically result from compression or tension forces Compression = nerve pinch causing muscle weakness and sharp, burning, radiating pain down muscle Tension = nerve stretch causing muscle weakness and sharp, burning, radiating pain down muscle