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case scenario - infection & tumor

4 min read

Infection & Tumors in Orthopedics

Instructor: Dr. Tarif Al Akhras

Case 1: Pediatric Elbow Infection (6 years old)

Clinical Presentation

  • Localized tenderness
  • Hotness and local redness
  • Swelling and edema
  • Reduced range of motion of the elbow

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Differential Diagnosis

  • Osteomyelitis
  • Cellulitis
  • Septic arthritis
  • Both septic arthritis and osteomyelitis (can occur simultaneously, especially proximal femur and hip)
  • Ewing sarcoma

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Laboratory Investigations

  • Complete Blood Count (CBC): Leukocytosis with neutrophilia
  • C-reactive protein (CRP): Raises very early in infection
  • Erythrocyte Sedimentation Rate (ESR): Raises several days later
  • Blood culture: Identify causative organism
  • Aspiration from sub-periosteal collection or joint:
    • Gram stain
    • Culture and sensitivity testing

Aspiration Fluid Analysis

  • Clear colorless: Normal
  • Clear yellow (can read through): Non-inflammatory
  • Turbid: Inflammatory
  • Pus: Bacterial infection
  • Blood: Hemorrhagic or traumatic tap

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Imaging Studies

  • X-ray: First signs appear at 10-14 days
    • Metaphyseal rarefaction
    • Periosteal reaction (new bone formation)
  • Bone Scan: Detects early signs of infection
  • MRI: Shows area of affection (joint vs. metaphysis vs. both)

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Note: MRI is perfect for detecting early signs of infection, replacing bone scan in many cases.

Treatment Protocol

  • Supportive treatment: Pain management and hydration
  • Splint immobilization: To prevent further damage
  • Antibiotic therapy:
    • I.V. flucloxacillin (must start early after aspiration)
    • Consult microbiologist for optimal antibiotic selection
    • Modify based on culture and sensitivity results
  • Surgical intervention: Debridement and drainage as needed

Case 2: Distal Femur Mass (16 years old)

Clinical Presentation

  • Painless swelling at the distal right femur
  • No inflammatory signs
  • No general systemic symptoms

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Initial Workup

  • X-ray imaging of the distal femur

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Diagnosis: Osteochondroma (Exostosis)

Clinical Features

  • Bony exostosis projecting from the external surface of a bone
  • Usually has a hyaline cartilaginous cap
  • Most are asymptomatic
  • Common complaint: Hard palpable mass
  • Symptoms arise due to:
    1. Location
    2. Size
    3. Pressure effects on adjacent structures

Complications

  • Growth disturbance (in multiple lesions)
  • Malignant transformation (Rare in solitary lesions: 1%)

Management and Prognosis

  • Observation for asymptomatic lesions
  • Surgical excision for symptomatic or complicated cases
  • Regular monitoring for potential malignant transformation

Case 3: Pathological Fracture (11 years old)

Clinical Presentation

  • Pain in right arm after fall at home
  • No significant medical history
  • Incidental discovery of bone lesion on X-ray

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Diagnosis: Simple Bone Cyst

Characteristics

  • Solitary (unicameral) lesion
  • Children (typically 5-15 years)
  • Metaphyseal location
  • Not seen in adults
  • Commonly discovered by pathological fracture

Treatment Options

  • Observation: Cyst might heal spontaneously
  • Multiple bone marrow injections
  • Fracture fixation: Flexible intramedullary nailing
  • Surgical curettage and bone grafting

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Differential Diagnosis: Cyst-Like Lesions in Bone

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Simple Bone Cyst

  • Fills medullary cavity
  • Does not expand bone

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Aneurysmal Bone Cyst

  • Located at metaphyseal side of physis
  • Expansile lesion

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Giant Cell Tumor

  • Occurs after physeal fusion
  • Extends to sub-articular region

Case 4: Aggressive Bone Tumor (18 years old)

Clinical Presentation

  • Painful mass at right femur
  • Limited knee joint motion
  • History of trauma 8 weeks prior (simple fall at home)
  • Initially diagnosed as simple contusion by primary care physician

Radiographic Findings

  • Radiolucency and sclerosis
  • Poorly defined margins
  • Extension into soft tissue
  • Periosteal reaction:
    • Sunburst (sun-ray) appearance
    • Codman’s triangle

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Diagnosis: Osteosarcoma

Staging Investigations

  • CT chest:
    • Mandatory staging study
    • Evaluates for pulmonary metastasis
  • MRI:
    • Very informative, must include entire involved bone
    • Determines soft tissue and marrow involvement
  • Bone scan:
    • Mandatory imaging study to discover skip lesions
    • Always shows increased uptake

Treatment Protocol

  • Metastasis workup:
    • Well-planned incision for biopsy
  • Neoadjuvant chemotherapy
  • Surgical management:
    • Wide resection
    • Custom-made prosthesis reconstruction
  • Adjuvant chemotherapy

Summary of Key Points

Infection vs. Tumor Differentiation

  • Inflammatory signs (redness, heat, tenderness) → Infection
  • Painless progressive swelling → Tumor
  • Systemic symptoms → Consider malignancy
  • Pathological fracture → Underlying bone lesion

Diagnostic Approach

  1. Clinical examination and history
  2. Laboratory studies (CBC, CRP, ESR)
  3. Imaging studies (X-ray, MRI, CT, bone scan)
  4. Biopsy when malignancy suspected
  5. Multidisciplinary management for optimal outcomes

Graph View

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