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EXAM 04 - Ward Assessment Examination

Bone Tumour, Polytrauma, Mass Casualty, Amputation

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Q1. Neoplasm (3.5 marks)

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• Osteosarcoma: distal femur > proximal tibia > proximal humerus (metaphysis of long bones)
• Ewing sarcoma: diaphysis of long bones (femur, tibia, humerus); also flat bones (pelvis, ribs)
• Giant cell tumour (GCT): epiphysis of long bones around the knee, distal radius, proximal humerus

• Common primaries: Breast, Bronchus (lung), Kidney, Thyroid, Prostate (mnemonic: Bad Boys Kick Their Parents)
• Common sites of metastases: vertebrae, pelvis, ribs, skull, proximal femur

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Q2. Classification and Bone Tumours (3.5 marks)

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1. Onion peel (onion skin) periosteal reaction - most characteristic: multiple parallel layers of periosteal new bone
2. Permeative / moth-eaten lytic lesion in the diaphysis
3. Codman's triangle - elevation of the periosteum at the edge of the tumour (also seen in osteosarcoma)
4. Soft tissue mass - often large, seen on MRI
5. "Hair on end" periosteal reaction - spiculated pattern
6. Bone scan: increased uptake; MRI shows extensive medullary involvement beyond plain film appearance

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Q3. Case Scenario - Osteosarcoma (3.5 marks)

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• Plain X-ray (AP & lateral): sun ray spiculation, Codman's triangle, mixed sclerotic-lytic lesion
• MRI of affected limb (extent of tumour, neurovascular involvement, skip lesions)
• CT chest (lung metastases - most common site)
• Bone scan / PET-CT (systemic staging, skip lesions)

• FBC, ESR, CRP
• Serum ALP (elevated in osteosarcoma)
• LDH (elevated; poor prognostic marker)
• Serum calcium, phosphate

• Core needle biopsy (image-guided; performed by surgeon who will do definitive surgery, through the planned incision tract)
• Open biopsy if needle biopsy inconclusive
• Biopsy confirms malignant osteoid-producing cells

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• MAP regimen: Methotrexate (high-dose) + Adriamycin (doxorubicin) + Cisplatin
• Given for 3-4 months; shrinks tumour, treats micrometastases, assesses chemosensitivity

• Limb salvage surgery (preferred when wide clear margins achievable, no neurovascular invasion, good chemotherapy response)
  • Wide excision of tumour with surrounding cuff of normal tissue
  • Reconstruction: endoprosthesis (modular tumour prosthesis), allograft, allograft-prosthesis composite
• Amputation - if limb salvage not feasible (neurovascular invasion, infection, poor response, pathological fracture with contamination)

• Same MAP regimen continued for total 6-9 months
• Histological response to neoadjuvant chemo assessed (>90% necrosis = good prognosis - Huvos grading)

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Q4. Mass Casualty / Polytrauma (3.5 marks)

1. Can they walk? (Yes = Green)
2. Breathing? (No = Black after airway manoeuvre)
3. Respiratory rate (>30 or <10 = Red)
4. Capillary refill >2 seconds OR radial pulse absent = Red
5. Otherwise = Yellow

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1. Trauma - mangled limb (MESS score ≥7), traumatic amputation, blast injury with non-reconstructible vascular injury
2. Infection - gas gangrene (clostridial myonecrosis), severe osteomyelitis unresponsive to treatment, necrotising fasciitis
3. Malignancy - primary bone tumours where limb salvage not feasible; recurrent tumours
4. Ischaemia - peripheral vascular disease with gangrene; diabetic foot with non-healing ulcer
5. Deformity/disability - congenital limb deformity, failed reconstructive procedure where amputation + prosthesis gives better function

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• Haemorrhage (primary or reactionary)
• Infection / wound breakdown / necrosis of flap
• DVT / pulmonary embolism
• Gas gangrene

1. Phantom limb pain - pain perceived in amputated limb (most common late complication)
2. Stump neuroma - painful nodule from regenerating nerve
3. Skin problems - dermatitis, pressure sores, ulceration over stump
4. Bone problems - bony spur/exostosis, osteomyelitis
5. Joint contracture - e.g., hip flexion contracture after AK amputation
6. Psychological - depression, body image issues
7. Prosthesis problems - ill-fitting prosthesis causing skin breakdown
8. Causalgia / reflex sympathetic dystrophy
9. Recurrence of tumour at stump margin (if amputation for malignancy)

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Q5. Polytrauma (3.5 marks)

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• A - Airway with C-spine control: Clear airway (chin lift, jaw thrust), suction, OPA/NPA, intubation if needed; cervical spine immobilisation
• B - Breathing and ventilation: Inspect, palpate, percuss, auscultate; treat tension pneumothorax (needle decompression), open chest wound (3-sided occlusive dressing), haemothorax (chest drain)
• C - Circulation + haemorrhage control: IV access ×2 large bore, fluid resuscitation (2L crystalloid then blood), direct pressure to external wounds, pelvic binder for suspected pelvic fracture, tourniquet for limb haemorrhage
• D - Disability (neurological status): GCS, pupils, limb movements, blood glucose
• E - Exposure + environment control: Fully undress, log roll to examine back, maintain temperature (warm blankets, warm IV fluids)

• Detailed history (AMPLE: Allergies, Medications, Past history, Last meal, Events)
• Systematic examination of all body regions
• Imaging: FAST scan, CT head/chest/abdomen/pelvis (pan-CT "trauma scan")
• X-rays: CXR, pelvis AP, lateral C-spine

• Damage control surgery (haemostasis first, delayed definitive repair)
• ICU/HDU monitoring
• Orthopaedic injury management (splinting, temporary external fixation)
• Multidisciplinary team: trauma surgeon, neurosurgeon, orthopaedic surgeon, anaesthetist

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• Total: 3-15 (minimum 3, maximum 15)
• Normal = 15; Severe TBI = ≤8; Moderate = 9-12; Mild = 13-15
• GCS ≤8 = indication for intubation (cannot protect airway)

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Q6. Short Notes (3.5 marks)

• Age: 20-45 years (after physeal closure)
• Females slightly more common
• Rare before skeletal maturity

• Pain and swelling around the joint
• Restricted joint movement
• Pathological fracture in ~10%
• "Benign" pulmonary metastases occur in ~3%

• Epiphyseal eccentric lytic lesion extending to subarticular bone
• "Soap bubble" appearance (trabeculation within lytic area)
• No periosteal reaction (unless fractured)
• Campanacci grading: Grade I (well defined), Grade II (thin cortex), Grade III (soft tissue extension)

• Intralesional curettage + high speed burr + bone graft/cement (with or without phenol/liquid nitrogen as adjuvant) - standard treatment; 15-25% local recurrence
• Wide excision for Grade III or recurrent cases (distal radius: excision + fibula autograft reconstruction)
• Denosumab (anti-RANK-L antibody) - for unresectable/recurrent GCT, or pre-operatively to reduce tumour size
• Radiotherapy - reserved for unresectable sites (risk of malignant transformation)

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• Age: 10-30 years; males > females (3:1)
• Accounts for ~10% of all benign bone tumours

• Characteristic night pain - worse at night, dramatically relieved by aspirin/NSAIDs (prostaglandin-mediated pain from the nidus)
• Localised tenderness
• If near joint: effusion, synovitis
• If in spine: painful scoliosis

• Plain X-ray: small round/oval lucent nidus (<2 cm) surrounded by dense cortical sclerosis (the sclerosis may obscure the nidus)
• CT scan: best modality - clearly shows the nidus with central calcification
• Bone scan: intense uptake ("hot spot")
• MRI: may overestimate extent due to surrounding oedema (less specific than CT)

• Percutaneous radiofrequency ablation (RFA) - treatment of choice (CT-guided); >90% success rate, minimal morbidity
• Surgical excision of the nidus (open or arthroscopic) - if RFA not available or fails; complete excision of nidus is curative
• NSAIDs: long-term medical treatment (symptoms often resolve spontaneously after ~3 years)
• The lesion may undergo spontaneous resolution after several years

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EXAM 03 - Ward Assessment Examination

Bone Infections

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Q1. Acute Haematogenous Osteomyelitis - Case (3.5 marks)

1. Acute haematogenous osteomyelitis (most likely) - of the proximal tibia or distal femur
2. Septic arthritis of the knee joint
3. Cellulitis / soft tissue infection

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• Onset and duration of symptoms; preceding infection (upper respiratory tract infection, skin infection, dental - bacteraemia source)
• Site and severity of pain; fever pattern
• Any trauma
• Immunisation history; general health status; sickle cell disease

• General: fever (often high, >38.5°C), tachycardia, toxic-looking
• Local: point tenderness over metaphysis (proximal tibia/distal femur), warmth, erythema, oedema, fluctuation (suggests abscess)
• Joint: assess range of movement carefully - restricted movement due to pain (not true septic arthritis unless joint involved); if joint infected = severe restriction + pain on all movements

• FBC: raised WBC (neutrophilia)
• ESR and CRP: both elevated (CRP more sensitive/specific for monitoring)
• Blood culture ×2 (before antibiotics) - positive in ~50%
• Serum procalcitonin

• Plain X-ray: normal in first 10-14 days; periosteal elevation appears after 10 days
• MRI (investigation of choice): shows bone marrow oedema, periosteal reaction, soft tissue involvement, abscess within 24-48 hours
• Ultrasound: shows subperiosteal collection/abscess; can guide aspiration
• Bone scan (Tc-99m): "hot" in early osteomyelitis; useful when MRI unavailable
• CT scan: less useful for soft tissue but shows cortical destruction

• Aspiration of subperiosteal abscess / bone under USS guidance: Gram stain + culture + sensitivity
• Throat swab / skin swab (identify source of bacteraemia)

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• Admit; bed rest; splinting of the affected limb (Thomas splint or POP backslab for comfort)
• IV access, adequate hydration, antipyretics (paracetamol)

• Start empirically after blood cultures taken; adjust when sensitivities available
• In children: Staphylococcus aureus is the most common organism
• Empirical IV antibiotics: Flucloxacillin (first line) OR Co-amoxiclav OR Cefuroxime; Clindamycin if penicillin allergic
• MRSA suspected: Vancomycin or Teicoplanin
• Neonates: cover Gram-negative organisms (Cefotaxime + Flucloxacillin)
• IV for 2-4 days until clinical improvement, then switch to oral for total 4-6 weeks
• Monitor CRP response

• Failure to respond to antibiotics within 24-48 hours
• Presence of subperiosteal/soft tissue abscess (USS-confirmed)
• Chronic osteomyelitis developing
• Procedure: Surgical drainage - incision and drainage of abscess, drilling of bone (multiple drill holes in metaphysis to decompress), lavage, temporary drain placement

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Q2. Chronic Osteomyelitis after Open Tibial Fracture (3.5 marks)

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• X-ray tibia (AP + lateral): look for sequestrum, involucrum, cortical thickening, fracture union
• MRI: extent of bone involvement, soft tissue, abscess, dead bone
• CT: best for detecting sequestrum and extent of bone destruction
• Sinus tract sinography: map sinus tract
• Swab from sinus discharge: culture + sensitivity (note: sinus swabs often colonised; deep tissue biopsy is gold standard for microbiology)
• FBC, ESR, CRP, blood cultures (if febrile)

1. Sequestrectomy - removal of all dead bone (sequestrum)
2. Saucerisation (Saucer + plate technique) - removal of the roof of the involucrum and dead bone, creating a saucer-like cavity that can heal by granulation tissue
3. Debridement of all infected soft tissue, granulation tissue, scar tissue
4. Dead space management:
   • Antibiotic-impregnated beads (calcium sulphate or PMMA beads with gentamicin/vancomycin) - local antibiotic delivery
   • Antibiotic-impregnated intramedullary nail (for intramedullary osteomyelitis)
   • Cancellous bone graft after infection controlled
5. Wound closure: primary if clean; VAC (negative pressure wound therapy) if large defect; flap coverage (local/free flap) if large soft tissue defect
6. Fracture stabilisation: external fixator preferred over internal fixation in infected setting; Ilizarov ring fixator (allows bone transport if large segment lost)
7. Bone reconstruction (if large segment lost): Masquelet technique (induced membrane technique) OR Ilizarov bone transport

• Prolonged antibiotics guided by deep tissue culture (IV 2-6 weeks, then oral; total 6-12 weeks for chronic osteomyelitis)
• Nutrition optimisation
• Diabetic control if applicable

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1. Pathological fracture through weakened infected bone
2. Amyloidosis (secondary/AA amyloidosis) - from chronic infection; affects kidneys, liver, spleen
3. Malignant transformation - Marjolin's ulcer (squamous cell carcinoma arising in chronic sinus/scar - rare but important)
4. Septicaemia - haematogenous spread of infection
5. Septic arthritis - spread to adjacent joint
6. Non-union / malunion of fracture (especially relevant here - post-open fracture)
7. Limb length discrepancy (growth disturbance in children; bone loss in adults)
8. Joint stiffness (disuse, periarticular fibrosis)
9. Anaemia of chronic disease
10. Sinus tract recurrence despite treatment
11. Metastatic infection (lung abscess, endocarditis)

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Q3. Osteomyelitis (3.5 marks)

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• Acute (within days to weeks)
• Subacute (weeks to months)
• Chronic (months to years; usually with dead bone/sinus)

1. Haematogenous osteomyelitis (most common in children)
2. Contiguous focus osteomyelitis - with vascular insufficiency (diabetic foot, PVD) or without
3. Direct inoculation - post-operative, post-traumatic (open fractures)

• Type I: Medullary (endosteal)
• Type II: Superficial (cortical)
• Type III: Localised (cortex + medulla, stable)
• Type IV: Diffuse (entire bone segment, unstable)

• A host: Normal immune system
• B host: Compromised (local or systemic)
• C host: Treatment worse than disease (surgery not indicated)

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1. Acute haematogenous osteomyelitis begins - bacteria lodge in metaphyseal sinusoids (slow blood flow + lack of phagocytes in this area)
2. Bacteria multiply → acute inflammatory response → pus forms (increased intraosseous pressure)
3. Pus spreads through Haversian and Volkmann canals → lifts periosteum → subperiosteal abscess forms
4. Periosteal stripping → interrupts blood supply to the cortical bone (periosteal vessels cut off)
5. Medullary blood supply also compromised by pus under pressure
6. Cortical bone becomes avascular / necrotic → sequestrum forms (dead bone, which harbours bacteria and is not reached by antibiotics)
7. Periosteum lays down new bone (reactive) around the sequestrum → involucrum forms (living bone shell)
8. Cloacae form - openings in the involucrum through which pus and bone fragments discharge
9. Sinus tract develops to skin surface → chronic discharging sinus
10. Bacteria persist within sequestrum (biofilm; avascular; antibiotic-resistant) → perpetuates chronic infection → cycle continues unless sequestrum surgically removed

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Q4. Aetiology and Pathology of Osteomyelitis (3.5 marks)

1. Terminal capillary loops: The nutrient artery divides into loops at the metaphysis and turns back sharply toward the diaphysis. This causes marked slowing of blood flow in these sinusoidal loops
2. Absence of phagocytic lining cells: The metaphyseal sinusoids lack Kupffer-like phagocytic cells (unlike liver/spleen), so bacteria are not cleared
3. Low oxygen tension: Slow flow → relative hypoxia → favourable for bacterial growth
4. High vascularity / blood flow: The metaphysis is the most vascular zone of growing bone, so bacteraemic bacteria are delivered in large numbers
5. Lack of anastomoses: Terminal loops have few collaterals, so once thrombosis occurs due to infection, large areas of bone infarction follow rapidly
6. Micro-trauma: Minor trauma to metaphysis (common in active children) may cause small intraosseous haematomas that act as a focus for bacterial seeding

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• A fragment (or mass) of dead, avascular, necrotic bone that has separated from the living bone
• It is the result of cortical bone losing its blood supply (both periosteal and medullary) due to subperiosteal abscess and increased intraosseous pressure
• Sequestrum is dense and white on X-ray (appears more radio-opaque than surrounding bone because it has not been resorbed)
• Bacteria colonise the sequestrum forming a biofilm - this is why osteomyelitis is so difficult to treat and becomes chronic: antibiotics cannot penetrate avascular bone
• Treatment: surgical removal (sequestrectomy) is essential for cure

• A sheath of new periosteal bone (reactive bone) laid down by the elevated periosteum around the sequestrum
• The periosteum, despite being stripped from the cortex by pus, remains viable and capable of bone formation
• The involucrum encloses the sequestrum and pus within it
• It has openings called cloacae through which pus and sequestrum fragments may be discharged (forming sinuses to the skin surface)
• On X-ray: involucrum appears as a layer of new bone surrounding the lucent area of osteomyelitis

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