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MS Annual 2018 - Paper II: Orthopaedics (Principles of General Surgery)

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Question 1 (35 marks): Emergency Management of a Polytrauma Patient

Definition

Initial Approach: The "Golden Hour" - ATLS Protocol

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PRIMARY SURVEY (Life-threatening conditions - identify and treat simultaneously)

• Assess airway patency - look for blood, vomit, foreign body, laryngeal fracture
• In unconscious patients: jaw thrust (not head-tilt), suction, oropharyngeal airway
• Definitive airway (endotracheal intubation) if GCS ≤8, respiratory distress, or airway burns
• Cervical spine immobilization (hard collar + manual in-line stabilization) until C-spine cleared
• Surgical airway (cricothyrotomy) if intubation fails

• Expose the chest; assess rate, depth, symmetry, and work of breathing
• Immediately treat life-threatening chest injuries:
  • Tension pneumothorax: needle decompression (2nd ICS, MCL) → chest drain
  • Open pneumothorax: three-sided occlusive dressing → chest drain
  • Massive haemothorax: large-bore chest drain; autotransfusion if available
  • Flail chest: O2, analgesia, positive-pressure ventilation if paradoxical movement causes respiratory failure
• Pulse oximetry and supplemental O2 to all patients

• Assess: pulse rate, blood pressure, capillary refill, skin colour
• External haemorrhage: direct pressure, tourniquet for limb bleeding
• Two large-bore (≥16G) IV cannulae; send blood for cross-match, FBC, coagulation, metabolic panel
• Fluid resuscitation: balanced crystalloid (Ringer's lactate), then blood products
• Massive Transfusion Protocol (MTP): 1:1:1 ratio of packed RBCs : FFP : platelets
• Avoid trauma-induced coagulopathy (TAC) - correct hypothermia, acidosis, coagulopathy (the "lethal triad")
• Identify internal bleeding: FAST ultrasound to check pleural, pericardial, peritoneal spaces
• Five spaces blood can accumulate: (1) pleural, (2) intra-abdominal, (3) pelvic/retroperitoneal, (4) soft tissues around long-bone fractures, (5) external wounds
• Pelvic binder for open-book pelvic fractures
• Emergency laparotomy if FAST shows free fluid in hypotensive patient

• Glasgow Coma Scale (GCS) - see Question 3b
• Pupillary size and reaction (unequal pupils suggest herniation)
• Blood glucose - treat hypoglycaemia
• GCS ≤8 = severe TBI; requires urgent neurosurgical assessment

• Fully undress the patient (log-roll for posterior examination)
• Prevent hypothermia: warm blankets, warm IV fluids, warm environment

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SECONDARY SURVEY (Head-to-toe examination after primary survey and initial resuscitation)

• Systematic examination: head, neck, chest, abdomen, pelvis, extremities, back
• Detailed history: AMPLE (Allergies, Medications, Past illness, Last meal, Events)
• Imaging: chest X-ray, pelvic X-ray, FAST; CT head/cervical/thoracoabdominal as indicated

DAMAGE CONTROL ORTHOPAEDICS (DCO)

• In haemodynamically unstable patients, avoid early definitive fracture fixation
• Temporary external fixation for long-bone fractures
• Definitive fixation (intramedullary nailing) only when patient is physiologically stable
• Femoral fracture stabilization within 24 hours is generally safe once stabilized

Monitoring

• Urinary catheter (monitor urine output ≥0.5 mL/kg/hr in adults)
• Nasogastric tube (decompress stomach, prevent aspiration)
• Continuous ECG, SpO2, ETCO2
• Repeat primary survey after any intervention

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Question 2 (35 marks): Ideal Below-Knee Amputation Stump - Precautions in Children, Elderly, and Diabetics

Characteristics of an Ideal BKA Stump

• Ideal residual tibial length: 12-15 cm from the tibial tuberosity (or 50-55% of tibial length)
• Too short: poor prosthetic control and socket suspension
• Too long: inadequate soft tissue coverage, poor blood supply distally

• Cylindrical or gently tapered - NOT bulbous or conical
• Avoids bony prominences at the end of the stump

• Long posterior myocutaneous flap (fish-mouth incision): brings well-vascularized gastrocnemius-soleus muscle and posterior skin over the cut tibia
• The scar should be non-adherent, non-tender, well-healed
• Scar should lie posteriorly - not on the end-bearing surface or anteriorly (where the prosthesis socket applies pressure)

• Tibia cut transversely; anterior border bevelled at 45° to prevent pressure under prosthesis
• Fibula cut 1-2 cm shorter than tibia
• Bone ends smooth (no sharp spurs)

• Myodesis (muscle to bone) or myoplasty (muscle to muscle flaps) for good padding and muscle balance
• Prevents muscle retraction, stump atrophy, and neuroma formation

• Major nerves (sural, saphenous, peroneal) divided under traction - retracts and avoids painful neuroma at weight-bearing area
• Major vessels ligated individually and securely

• Healthy, mobile, non-adherent
• Equal tension closure - no dog-ears, no excess tension

• Rigid dressing (plaster cast) or pneumatic post-amputation mobility (PPAM) aid to control oedema and shape the stump

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Special Precautions

Children

• Avoid disarticulation through a growth plate - prefer amputation through bone rather than disarticulation at a joint when possible, as a bony overgrowth (appositional bone formation at the cut end) is a well-recognized complication in children
• Bony overgrowth: tibia and fibula continue to grow but the skin/soft tissue does not grow as fast, leading to a spike that may perforate the skin; revision surgery is often needed
• Longer stumps are preferred to preserve growth potential, but this must be balanced against overgrowth risk
• Consider epiphysiodesis at the fibular distal physis if fibular overgrowth becomes problematic
• Prosthetic fitting is adjusted frequently as the child grows
• Preserve as much length and growth potential as possible

Elderly

• High incidence of vascular disease (atherosclerosis, PVD): ensure adequate blood supply for healing
  • Assess with ankle-brachial index (ABI), Doppler flowmetry, transcutaneous PO2
  • ABI <0.5 or TcPO2 <20 mmHg predicts poor healing
• Skin is thin and fragile: handle tissues gently, avoid excessive retraction
• Osteoporosis: bone more brittle; careful cutting technique
• Poor wound healing: nutritional assessment (albumin >3.5 g/dL) pre-op
• Comorbidities: cardiac and pulmonary optimization before surgery
• Prefer regional anaesthesia (spinal) over general if possible
• Early mobilization is critical - prolonged bed rest causes rapid deterioration
• Higher level amputation (AKA) may be needed if BKA healing is doubtful

Diabetic Patients

• Assess vascularity carefully: diabetics have macrovascular (atherosclerosis) and microvascular disease
  • TcPO2, toe pressure, angiography if needed; consider revascularization before amputation if feasible
• Infection: common in diabetics; debride all necrotic/infected tissue; bone biopsy to exclude osteomyelitis
  • Pre-op IV antibiotics; wound cultures
• Neuropathy: loss of protective sensation means pressure necrosis can occur post-op without patient awareness
• Poor wound healing: hyperglycaemia impairs neutrophil function, collagen synthesis, and angiogenesis
  • Tight perioperative glycaemic control (target BGL 140-180 mg/dL intraoperatively)
• Leave wound open or use delayed primary closure if there is any evidence of infection or contamination
• Scar must be posterior and non-adherent to avoid pressure areas
• Regular podiatric and stump review post-op
• Frequent prosthetic socket adjustments as stump volume changes

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Question 3: Short Notes

3a. Glasgow Coma Scale (GCS) - 10 marks

• 13-15: Mild brain injury
• 9-12: Moderate brain injury
• ≤8: Severe brain injury - intubation required

• Always record the breakdown (e.g., E3V4M5 = 12), not just the total
• Record the best response elicited from any limb
• Painful stimulus: sternal rub, supraorbital pressure, or trapezius squeeze
• Used in the D (Disability) step of ATLS primary survey
• Serial GCS monitoring is essential - a fall of ≥2 points is clinically significant
• Intubated/aphasic patients: record verbal as "T" (e.g., 10T)

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3b. Flail Chest - 10 marks

• Paradoxical movement impairs effective ventilation
• Underlying pulmonary contusion is almost always present and is the main cause of hypoxia
• Pain from multiple rib fractures causes splinting, atelectasis, and retained secretions
• Pendulluft (movement of air between the two lungs) worsens ventilation-perfusion mismatch

• Paradoxical chest wall movement on inspection
• Severe pain, tachypnea, hypoxia (SpO2 <90%)
• Crepitus at fracture sites
• Diagnosis confirmed on CXR or CT chest

1. Oxygen - high-flow O2 to maintain SpO2 >95%
2. Analgesia - essential to allow adequate ventilation
   • Thoracic epidural anaesthesia (TEA) is the gold standard for pain control
   • IV opioids, intercostal nerve blocks, paravertebral blocks
3. Positive Pressure Ventilation (PPV) - indicated if:
   • PaO2 <60 mmHg on O2
   • PaCO2 >50 mmHg
   • Respiratory rate >35 or <8/min
   • GCS <8 (unable to protect airway)
   • This provides "internal pneumatic splinting" of the flail segment
4. Surgical rib fixation (ORIF) - considered in severe cases where weaning from ventilation fails; evidence supports reduced ICU stay and ventilator days
5. Treat associated injuries: haemopneumothorax (chest drain), pulmonary contusion (careful fluid balance)

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3c. Fat Embolism - 10 marks

• Most common: traumatic fractures of marrow-containing long bones (femur, tibia); risk increases with number of fractures
• Other causes: orthopaedic procedures (reaming/nailing), liposuction, fatty liver trauma, severe burns, pancreatitis

1. Mechanical: fat globules embolize to pulmonary capillaries causing obstruction and RV strain
2. Biochemical (more important): lipase action on neutral fat releases free fatty acids (FFA) that cause diffuse vasculitis with capillary leakage in the lungs, brain, and skin

1. Respiratory distress - dyspnoea, tachypnoea, hypoxaemia (PaO2 <60 mmHg), bilateral infiltrates on CXR
2. Neurological signs - confusion, agitation, drowsiness, coma (cerebral fat embolism)
3. Petechial rash - distributed over the head, neck, anterior chest, and axillae (only in 20-50% of cases; absence does not exclude diagnosis)

• Early stabilization of long-bone fractures (within 24 hours in stable patients)
• Prophylactic corticosteroids are controversial but some evidence supports benefit if given early

• Primarily supportive - the mainstay of treatment
• High-flow O2; mechanical ventilatory support (invasive or non-invasive) if ARDS develops
• Careful fluid balance to avoid fluid overload in injured lungs
• IV corticosteroids (methylprednisolone 1.5 mg/kg every 8 hours) - may reduce severity
• Albumin infusion (binds FFA)
• No proven benefit for heparin, ethanol, or dextran
• With meticulous supportive care, most patients survive; however, severe FES with widespread CT opacities and ARDS carries high mortality

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DCO vs ETC in Polytrauma

Background: The Core Question

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The Physiological Basis: "Double Hit" Theory

• Amplify the cytokine response beyond a critical threshold
• Precipitate SIRS → MODS (multiple organ dysfunction syndrome)
• Cause ARDS, acute renal failure, coagulopathy

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Early Total Care (ETC)

Definition

Rationale (historical - 1980s-90s evidence)

• Bone et al. (1989) showed that early femoral nailing (within 24 h) reduced pulmonary complications (ARDS, fat embolism syndrome, pneumonia) and ICU/hospital stay compared to delayed fixation
• Early fracture stabilization eliminates the ongoing source of fat embolism, pain, and blood loss
• Reduces DVT and PE risk (fracture haematoma = prothrombotic)
• Easier nursing care and early mobilization

When ETC is Appropriate - The "Fit" Patient

Procedure

• Primary intramedullary nailing of femur + tibia
• ORIF of other major fractures
• All in one sitting or within same day

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Damage Control Orthopaedics (DCO)

Definition

Concept (derived from Damage Control Surgery - DCS)

Three Stages of DCO

Conversion Timing

• External fixator → IMN for femur: safe within 3 weeks (if pin sites clean)
• External fixator → IMN for tibia: safe within 7-10 days (if pin sites clean)
• If pin sites are infected: remove fixator, allow skin healing, then stage the nailing separately

When DCO is Indicated - The "Borderline" or "Unstable" Patient

• Haemodynamic instability despite resuscitation
• Lactate >2.5 mmol/L / Base deficit >6 mEq/L
• Coagulopathy (INR >1.5, fibrinogen <1.5 g/L)
• Hypothermia <35°C
• Severe traumatic brain injury (GCS ≤8) - aggressive reaming raises ICP
• Severe thoracic injury (bilateral lung contusions, PaO2/FiO2 <200)
• ISS >40
• Damage control laparotomy already performed

• ISS 20-40 with chest injury
• Moderate TBI
• Bilateral femoral fractures
• Polytrauma + coagulopathy being corrected
• Resuscitated but not yet "fit"

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Head-to-Head Comparison

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Current Consensus: "Safe Definitive Surgery" / "Early Appropriate Care (EAC)"

• Stable patients → ETC (IMN within 24 h)
• Unstable/borderline patients → DCO
• Borderline patients who are optimized within 6-8 hours of resuscitation → may proceed to ETC

1. Stable → ETC
2. Borderline → DCO (or ETC with caution if rapidly optimized)
3. Unstable → DCO mandatory
4. In extremis → DCO + abbreviated life-saving surgery only

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Key Takeaways for Exams

1. ETC = fix it all now (within 24 h); appropriate for stable patients; reduces ARDS/FES/pneumonia
2. DCO = stabilize temporarily (Ex-Fix) → resuscitate → definitive fixation later; avoids second hit
3. The "second hit" = major surgery on a primed inflammatory state → MODS
4. DCO does NOT mean no surgery - it means rapid temporary stabilization in the OR
5. Convert femoral Ex-Fix to IMN within 3 weeks; tibial within 7-10 days
6. Modern approach = Early Appropriate Care (EAC): patient-specific decision based on physiology, not a fixed protocol

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Gas Gangrene (Clostridial Myonecrosis)

Definition

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Aetiology

Causative Organisms

• Anaerobic, spore-forming, Gram-positive rods
• Found in soil, faeces, and mucous membranes
• Spores are resistant to chemical skin sterilization
• Grow best in necrotic, ischaemic, low-oxygen tissue

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Types of Clostridial Infection (Campbell's Classification)

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Predisposing Factors / Conditions

• Traumatic wounds: crush injuries, missile/gunshot wounds, open fractures (especially with soil contamination)
• Closed fractures (also possible due to ischaemic muscle)
• Primary closure of a contaminated wound (creates anaerobic microenvironment)
• Surgery (especially bowel surgery, amputation in vascular disease)
• Immunosuppression (diabetes, malignancy, steroids)
• Chronic oedema / peripheral vascular disease
• Penetrating foreign body (especially farm or soil-contaminated)
• Aerobic co-infection (consumes remaining O2, creating anaerobic conditions)
• Intramuscular injections in drug users

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Pathophysiology

Mechanism of Toxin Action

Gas Production

• Bacterial fermentation produces hydrogen sulphide (H2S) and CO2 (not just hydrogen)
• Gas spreads along muscle planes and fascial spaces
• Creates the classic crepitus and radiographic gas shadows

Vicious Cycle

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Clinical Features

Incubation Period

• Typically < 24 hours (range: 1 hour to 6 weeks)
• Onset is sudden and dramatic - the rapidity of progression is a hallmark

Symptoms (in order of appearance)

• Rapid, severe, and disproportionate to the wound appearance
• Increases relentlessly - this is the cardinal warning sign

• Wound oedema and tense swelling of the limb
• Serosanguineous (thin, watery, "dishwater") discharge - not frank pus
• Characteristic sickly-sweet/mousy odour (very distinctive)
• Skin changes: initially pale/white → bronzed/brown → blue-black
• Haemorrhagic bullae and blebs (contain dark, non-clotting fluid)
• Crepitus on palpation (gas in tissues) - present within 24 hours
• Muscle colour: pale/grey, "cooked meat" appearance, does not bleed or contract when cut

• Fever (often low-grade paradoxically)
• Tachycardia (out of proportion to fever)
• Anxiety and altered mental status - patients often appear apprehensive/toxic early
• Tachypnoea
• Hypotension → septic shock
• Haemolysis → haemoglobinuria → acute kidney injury
• ARDS
• Jaundice
• Death (within hours in untreated cases)

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Investigations

Bedside / Emergency

Laboratory

• FBC: haemolytic anaemia, thrombocytopaenia, leukocytosis
• Metabolic panel: metabolic acidosis, raised creatinine (AKI), elevated LFTs (jaundice)
• Coagulation: DIC in severe cases
• Blood cultures: anaerobic cultures (takes 48-72 h; do NOT delay treatment)
• Culture medium requires anaerobic environment + sodium thioglycolate (reducing agent)

Key Point: Diagnosis is CLINICAL - do NOT wait for cultures before acting.

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Differential Diagnosis

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Treatment

Principle: Time is muscle - Time is life. Do not delay surgery.

1. Resuscitation (simultaneous with surgery prep)

• ICU admission with continuous monitoring
• 2 large-bore IV access; aggressive fluid resuscitation
• Blood products for haemolysis and coagulopathy
• Endotracheal intubation if shocked or obtunded
• Urinary catheter; monitor urine output hourly
• Blood cultures before antibiotics (but do not delay antibiotics)

2. Antibiotics (IV - immediate)

• Penicillin G (high dose: 10-24 MU/day in divided doses) - kills clostridia
• Clindamycin (600-900 mg IV 8-hourly) - inhibits toxin synthesis (protein synthesis inhibitor); acts even on non-dividing organisms; synergistic with penicillin

• Add 3rd generation cephalosporin (cefotaxime/ceftriaxone) for Gram-negatives
• Crushing/farm contamination: Penicillin + Cephalosporin + Aminoglycoside
• Clindamycin-resistant C. perfringens: Vancomycin

3. Surgical Treatment (THE MAINSTAY - EMERGENCY)

• Operate immediately - every hour of delay worsens outcome
• Wide, radical surgical debridement of ALL necrotic tissue
• Muscle that does not bleed or contract to electrical stimulation = dead = must be removed
• Wounds left WIDE OPEN - never close primarily
• Pack lightly with saline-soaked gauze
• Return to OR every 24-48 hours for repeat inspection and debridement until infection controlled
• Tissue with questionable viability: leave and reassess at next debridement

• Indicated when infection is extensive, limb is non-salvageable, or patient in septic shock
• Life-saving and should not be delayed in established gas gangrene with systemic toxicity
• Amputation stump left OPEN - never closed
• Disarticulation (joint-level amputation) may be needed to get clear of infected tissue

4. Hyperbaric Oxygen (HBO)

• Adjunct - not a substitute for surgery
• Mechanism: high-pressure O2 creates hostile environment for anaerobes; inhibits alpha-toxin
• Given at 2-2.5 atmospheres, 3 sessions/day for acute infection
• Evidence suggests helps stabilize limb amputations secondary to clostridial infection
• Only if immediately available and does not delay surgery
• Controversy remains about evidence quality

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Prevention

1. Thorough wound debridement of all open/contaminated wounds - remove all devitalized tissue
2. Never close contaminated wounds primarily - leave open or use delayed primary closure
3. Repeat debridement every 24-48 h for high-risk wounds
4. IV prophylactic penicillin for contaminated crush injuries and open fractures
5. Tetanus prophylaxis (different organism but same contaminated wound mechanism)
6. Early recognition of at-risk wounds (crush, soil contamination, vascular ischaemia)

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Prognosis

• Without treatment: 100% fatal
• With optimal treatment: mortality 5-30% for extremity infections
• Trunk/abdominal/spontaneous gas gangrene: mortality up to 50-70%
• Poor prognostic factors: diabetes, cirrhosis, leucopenia, delay in diagnosis/treatment, truncal involvement

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Comparison: Gas Gangrene vs Necrotising Fasciitis

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