Musculoskeletal Injuries, Diseases, and Disorders – Learning Objectives

• Pain along the shinbone associated with repeated trauma (excessive running or walking) that has damaged Sharpey’s (collagen) fibers that connect fascia to the periosteum of the tibia (where it inserts into the tibia bone).
• Risk factors include: improper footwear, overdoing it without proper conditioning or training

Signs & Symptoms of Bone Fractures:

• Pain
• Numbness
• Deformity
• Swelling
• Muscle spasms
• Tenderness
• Crepitus = grating sound if bone ends move over each other
• Decreased mobility
• Bleeding (if open fracture)
• Shock (low blood pressure) = pallor, diaphoresis tachycardia, nausea/vomiting

Emergency Treatment of Bone Fractures in the Field:

• Cover open wound with sterile dressing material.
• Splint for support, & immobilize for transport including joint above & below fracture.
• Elevate limb slightly; Apply cold compress.
• Keep patient warm; check for signs of shock.

Describe Fracture Healing of Cortical/Compact and Cancellous/Trabecular/Spongy Bone – 5 Stages

• Stage 1: Hematoma Formation – collection of blood & subsequent clot and inflammation zone forms at fracture line; stage lasts 1-3 days; macrophages begin removing dead osteocytes and debris
• Stage 2: Hematoma Organization – fibrin (ropy protein) in blood clot (thrombocytes & RBCs) strengthens, organizes into mesh and contracts – granulation tissue in that zone fills with chondroblasts as mesenchymal stem cells within the periosteum produce more and more daughter chondroblasts and osteoblasts, capillary buds form and neovascularization begins; stage lasts 3 days – 2 weeks
• Stage 3: Pro-callus Formation – chondroblasts are producing fibrocartilage-like extracellular matrix as they mature to chondrocytes, creating an external and internal pro-callus;  this replaces the hematoma which is degraded by phagocytes (e.g. macrophages)  and fibrin which is dissolved by plasmin; the pro-callus is full of collagen and joining the two bone ends and forming a bulge (collar) around the fracture
• Stage 4: Bony Callus Formation – daughter osteoblasts being to produce more and more osteoid (extracellular matrix glycoprotein material) containing calcium phosphate hydroxyapatite minerals which turn the cartilage pro-callus into a bony callus which is stronger; the bone matrix in this zone is not organized and is termed woven bone
• Stage 5: Remodeling – as the osteoblasts mature into osteocytes, the collagen matrix becomes more organized, the compact bone of the diaphysis becomes more apparent; the osteoclasts assist in remodeling the bone to form a medullary cavity as well as trabecular bone.  Bone transitions from woven bone to lamellar bone to becoming fully regenerated and can support weight.

Discuss Healing and Factors that Affect Healing:

• Healing Time – is usually 4 months to a year;  healing time is affected by age:  Children healing fastest, and older adults healing more slowly.
• Amount of local damage
• Proximity of bone ends to each other
• Presence of foreign material or infection & acceptance of bone graft (if required)
• Blood supply to fracture site; amount of hypoxia
• Osteonecrosis (ischemic death of bone cells) can occur – usually due ischemia of bone tissue for many reasons including:  trauma, thrombosis, embolism, radiation therapy for cancer, blood vessel injury – perhaps due to vasculitis or long-term glucocorticoid use)
• Systemic factors – age (older people take longer to heal), nutrition, circulatory problems (e.g. diabetes), anemia, RA (rheumatoid arthritis), glucocorticoid use, etc.
• Low blood pressure (due to excessive bleeding or widespread inflammation)

Discuss Possible Complications of Bone Fractures: 

• Muscle spasms – triggered by pain/irritation can pull bones out of alignment & damage soft tissue
• Neurovascular damage: due to:
  • a) damage during fracture (from force, fracture fragments, joint dislocation, or hemorrhage)  or
  • b) during treatment of fracture (moving/splinting fracture)
• Infections – osteomyelitis; bacterial toxins (tetanus), risk factors: open fracture, surgery
• Septic = infected by harmful microbes
• Aseptic = free from harmful microbes
• Ischemia – ↑edema in 1st 48hr tightens cast
• Be careful that cast not become too loose later as edema decreases & muscle atrophies
• Fat emboli – fat marrow escapes into vein
• Fracture blisters (edema between epidermis & dermis)
• Failure to heal (non-union) due to infection, or gap, or repetive stress, poor circulation
• Deformity (mal-union) during healing due to improper alignment
• Residual effects such as osteoarthritis or stunted growth
• Exuberant Callus formation

Compartment Syndrome (acute, chronic, or crush) = high pressure in muscle compartment that is enclosed in fascia reduces blood flow leading to hypoxia (& therefore damage).

• a) Plasma protein & fluid leak into tissue causing more swelling.
  • Exudate = fluid that leaks from blood vessels
  • Edema = fluid accumulating beneath skin or in a cavity, due to increased interstial fluid (during inflammation) and/or impaired fluid removal by lymph/capillary vessels
• b) Necrosis of muscle & nerves can occur (within 4-8hr).
• c) Symptoms: 5Ps (Severe Pain, Paralysis, Paresthesia, Pallor & Pulselessness).
• d) Monitor:  Used tonometer (>30mmHg = bad);  Capillary refill time of less than 2sec (hold hand higher than heart and press fingernail until white then watch for return to colour)
• e) Acute Compartment Syndrome requires immediate surgery (Fasciotomy) to reduce pressure accompanied by skin grafts.

If not treated = Compartment Tamponade →

• 1. muscle ischemia (hypoxia) → muscle infarction and leads to Crush Injury:
  • Rhabdomyolysis = muscle cell lysis ↑ potassium, phosphate, creatine, myoglobin in ECM which draws in fluid (ECF shift) and myoglobinemia  → kidney damage (→Renal Failure)
  • and (lactic) acidosis/hyperkalemia →  Cardiac Dysrhythmia (→Shock)
  • and permanent skeletal muscle damage
  • muscle necrosis/damage fibrosis & shortening of muscle, if in forearm, leads to → Volkmann’s ischemic contracture (permanently flexed wrist  and finger joints into claw)
• 2. neural injury → if permanent → loss of function (muscle weakness and/or loss of sensations)
• *Need to watch out for Reperfusion Injury = sudden restoration of blood flow introduces a lot of Reactive Oxidative Species (ROS) which can induce apoptosis and more cell damage
• **must prevent by releasing pressure slowly and treating with bicarbonate.
• *Need to watch out for Disseminated Intravascular Coagulation (DIC) – which may occur due to necrotic muscle tissue.
• Acute Compartment Syndrome -requires immediate fasciotomy – causes include: bone fracture, burn, drug overdose, thrombosis, reperfusion injury, vascular damage.
• Crush Syndrome – worsening of untreated acute compartment syndrome, often due to crush injury
• Chronic Compartment Syndrome – usually caused by repetitive activities (e.g. running) – characterized by pain that doesn’t go away even with ibuprofen, decreased sensation, paleness of skin, weakness, swollen shiny skin, pain on movement, .

Shock = not enough blood flow to tissues

Signs of Shock = pallor, diaphoresis, hypotension, reflex tachycardia, nausea/vomiting

Rhabdomyolysis = Rapid breakdown of muscle, releasing myoglobin into extracellular space & bloodstream, which travels to kidney & is excreted in urine.

• Causes: crush, burn, compression injury, drug overdoses, earthquake victims, serious infections, toxins, diabetic ketoacidosis, extreme hypothermia/heatstroke
• Signs & Symptoms: muscle pain, weakness, swelling, & dark urine; oliguria; hyperkalemia may trigger cardiac dysrhythmias; low BP; electrolyte imbalance can cause nausea, vomiting, confusion, coma
• Urinalysis:  reveals brown urine, due to myoglobinuria
• Evaluation: ↑ serum CK, K+, PO4 levels
• Treatment: rapid IV hydration to maintain adequate urinary flow (with bicarbonate if metabolic acidosis is occurring); & possibly hemodialysis
• Potential Complications of Rhabdomyolysis:
  • myoglobin breakdown products damage kidney → Renal Failure
  • Disseminated Intravascular Coagulation (DIC, formation of small blood clots in bloodstream) initiated by released components of necrotic muscle… which can lead to organ failure & uncontrolled bleeding.

Disseminated Intravascular Coagulation (DIC) = results from an imbalance of clotting/hemostasis factors.

• Causes: serious infections (e.g. sepsis), trauma, burn, placental abruption, pre-eclampsia, toxins, snake bites
• Pathogenesis:
  • Severe endothelial damage →
  • leads to release of large amounts of pro-inflammatory cytokines →
  • stimulate too much thrombin → lead to too many fibrin/platelet clots →
  • leads to clot obstructions of capillaries throughout the body leads to → ischemia/hypoxia/damage of tissues and multiple organ failure and
  • risk of bleeding out (as platelets are all “used up”).
• Signs & Symptoms: purpura (blood-spotted skin), pain
• Diagnostic Test: measure of coagulant (e.g. fibrin, platelets) and anti-coagulant factors

Methods to Reduce Chances of Complications of Bone Fractures:

• Wound debridement
• Windowed cast
• Realign and Reduction using: intramedullary nails, pins, plates, wire meshes, casts, and/or traction
• Tetanus booster
• Antibiotics
• Monitor for signs of fat emboli – may travel to:
  • lungs, causing ARDS (pallor, diaphoresis, chest pain, dyspnea, tachycardia, cyanosis)
  • brain, causing CVA
• Bone graft (taken from iliac crest, fibula, or rib)
• Bone cement
• Exercise – maintain muscle function

Joints – Dislocation & Subluxation:

• Dislocation: bones in joint lose contact with each other due to tearing of surrounding tissue (e.g. joint capsule, ligament(s), and or muscles/tendons)
• Subluxation: partial loss of contact between bone in a joint – often self-resolves
• Risk Factors: joint diseases (e.g. rheumatic arthritis)
• Symptoms: pain, muscle atrophy, swelling
• Diagnostic Tools: imaging (e.g. x-ray, MRI, arthroscopy)
• Treatment: PRICE, anti-inflammatories, analgesics, surgical repair, physiotherapy
• Adhesive capsulitis:  scarring and adhesions forming in connective tissue surrounding the glenohumeral joint – causing stiffness and loss of range of motion.  Prevent this from occurring by following prescribed stretching and exercise regime

Differentiate between Sprains and Strains and describe features of each:

• Sprain: ligament tear
• Strain: muscle or tendon tear (tendonitis)
  • Grade 1 or 1st degree: mild, fibers are stretched but stable; will slowly self repair
  • Grade 2 or 2nd degree: moderate, some fibers are torn; will slowly self repair, follow prescribed stretching/exercise regime to avoid scarring/shortening and to increase muscle strength surrounding joint to provide more stability and make joint more resilient against future injuries
  • Grade 3 or 3rd degree: severe, fibers are completely torn; surgical repair is required, if possible (dependent on age, co-morbidities etc.)
  • Grade 4 tear of ligament involves avulsion as well (complete tear plus bone fracture)
• Rotator Cuff tear:  tear to one of the 4 muscles that stabilize the glenohumeral shoulder joint
• Ligaments and Tendons – consists of dense regular connective tissue (e.g. organized collagen)
• Signs & Symptoms:  pain, swelling, dislocation, weakness of joint, less mobility.  Sprains tend to heal more slowly than strains
• Risk Factors: Sports; Overweight, Age – collagen fibers have decrease elasticity & are more susceptible to injury
• Diagnostic Tools: MRI, radiography, arthroscopy, or arthrography
• Prevention:  Proper warm-up; appropriate sport wear; avoid over-use; ramp up exercise slowly over months when first starting
• Treatment:  PRICE for first 48-72hrs (possibly alternate heat & cold)
  • Protection; Rest; Ice; Compression; Elevation
  • Compression bracing to provide support while healing
  • Gradual, Prolonged Rehabilitation Exercises (first without weight & only if no pain)
  • Gradual exercise & blood flow help with healing
  • Occupational Therapy – identify ergonomic problems

Describe Meniscus Tears = tears to white or red zone in knee cartilages

• Terrible Triad:  Knee injury involving tear to MCL, ACL & medial meniscus (frequent soccer injury)
  • Prevent by strengthening surrounding muscles, using proper footwear