Pathologic fractures occur through bone weakened by underlying disease, most commonly metastatic carcinoma (breast, lung, prostate, renal, thyroid) or multiple myeloma. The Mirels' scoring system (site, pain, lesion type, size) guides prophylactic fixation decisions - a score ≥9 indicates high fracture risk warranting stabilization. The principle of biopsy before fixation applies unless the primary tumor is known with certainty. Reconstruction choice depends on expected survival: short survival favours load-sharing devices (IM nails, endoprostheses), while longer survival may warrant more durable reconstructions. Lytic lesions in the femur (especially peritrochanteric) carry highest fracture risk.

Bone Weakening Mechanisms

History Components

Pain Characterization:

• Onset: Gradual vs sudden (fracture event)
• Duration: Weeks to months of preceding pain typical
• Character: Dull, aching, progressive
• Timing: Night pain suggests tumor
• Relieving factors: Activity modification, NSAIDs often ineffective
• Red flag symptoms: Fever, night sweats, weight loss, anorexia

Mechanism of Injury:

• Detailed mechanism assessment critical
• "Twisted getting out of chair" or "stepping off curb" suggests pathologic
• High-energy trauma can occur through pathologic bone (confounding)
• Pain before the fall indicates pre-existing pathology
• Multiple witnesses may clarify mechanism

Medical History:

• Current or previous malignancy (type, stage, treatments)
• Radiation therapy to bone (radiation-induced fractures)
• Prolonged corticosteroid use (osteoporosis, osteonecrosis)
• Metabolic bone disease history
• Previous fractures (pattern recognition)
• Family history (hereditary bone disorders)

Functional Impact:

• Pre-fracture ambulatory status
• Weight-bearing ability
• Pain limiting function
• Social support and home environment
• Goals and expectations (align with prognosis)

Physical Examination

Inspection:

• Swelling, ecchymosis (may be disproportionate)
• Deformity, limb shortening, rotation
• Previous surgical scars (biopsy sites)
• Skin changes (radiation, infection, tumor ulceration)
• Muscle wasting (chronic pain, denervation)

Palpation:

• Point tenderness over fracture site
• Palpable mass or cortical defect
• Temperature (infection, inflammation)
• Crepitus with gentle range of motion
• Proximal and distal joint examination

Neurovascular Examination:

• Pulse assessment (ABI if concern)
• Capillary refill
• Sensory examination (nerve compression or injury)
• Motor function (avoid stressing fracture)
• Document findings precisely (medicolegal, surgical planning)

Systematic Survey:

• Spine palpation and percussion
• Pelvis compression and distraction
• Contralateral limb examination
• Abdominal examination (organomegaly)
• Chest auscultation (lung metastases)

The examination should identify fracture complications while gathering clues to underlying diagnosis without causing additional patient discomfort or fracture displacement.

Imaging Modalities

Biopsy Principles

Non-Operative Management

Surgical Management

Prognostic Factors

Primary Tumor Type (Most Important):

Favorable Prognosis (Median Survival greater than 12 Months):

• Breast cancer (especially hormone receptor positive)
• Prostate cancer
• Thyroid cancer (follicular)
• Multiple myeloma
• Renal cell carcinoma (selected patients)

Intermediate Prognosis (6-12 Months):

• Renal cell carcinoma
• Colorectal cancer
• Melanoma
• Unknown primary

Poor Prognosis (Less than 6 Months):

• Lung cancer (especially small cell)
• Pancreatic cancer
• Gastric cancer
• Hepatocellular carcinoma

Burden of Disease:

• Solitary skeletal metastasis: better prognosis
• Multiple skeletal sites: intermediate
• Visceral metastases present: poor prognosis
• Spinal cord compression: worse outcomes
• Hypercalcemia: poor prognostic sign

Performance Status:

• Ambulatory, independent: better survival and quality of life
• Requires assistance: intermediate
• Bedridden: poor prognosis, limited benefit from surgery

Laboratory Markers:

• Elevated alkaline phosphatase: worse prognosis
• Anemia: associated with reduced survival
• Hypoalbuminemia: malnutrition, poor outcomes
• Hypercalcemia: advanced disease

Functional Outcomes

Expected Functional Recovery:

Lower Extremity Fractures:

• 75-85% regain ambulatory status
• Median time to weight-bearing: 3-7 days
• Ambulation level may not return to baseline
• Walking aids often required
• Rehabilitation limited by systemic disease progression

Upper Extremity Fractures:

• Greater than 90% achieve functional use
• Earlier return to activities of daily living
• Pain relief more consistent
• Better overall satisfaction

Quality of Life Improvements:

• Pain reduction (most consistent benefit)
• Independence in activities of daily living
• Psychological benefit (sense of control)
• Reduced caregiver burden
• Ability to receive oncologic treatments
• Facilitation of hospice care at home vs hospital

Factors Limiting Recovery:

• Disease progression (new metastases, visceral involvement)
• Complications (infection, nonunion, implant failure)
• Deconditioning during recovery
• Chemotherapy side effects
• Depression and anxiety
• Inadequate social support

Survival Data by Treatment

Key Insights:

• Surgery does not prolong survival (systemic disease determines longevity)
• Surgery dramatically improves quality of life metrics
• Functional outcomes justify surgical morbidity in appropriate candidates
• Patient selection critical (avoid surgery in moribund patients)
• Goals: palliation, function, independence - not cure

The evidence supports surgical stabilization for functional restoration and quality of life, even in patients with limited prognosis, provided they are medically fit for anesthesia.

Pelvic & Acetabular Lesions

Spine Metastases with Pathologic Fracture

Spinal Instability Neoplastic Score (SINS):

Predicts spinal instability in metastatic disease (score 0-18):

Components:

1. Location (junctional vs non-junctional)
2. Pain (mechanical vs positional vs none)
3. Bone lesion (lytic vs mixed vs blastic)
4. Spinal alignment (subluxation, kyphosis, scoliosis)
5. Vertebral body collapse (greater than 50%, less than 50%, none)
6. Posterolateral involvement (bilateral, unilateral, none)

Score Interpretation:

• 0-6: Stable (radiation ± chemotherapy)
• 7-12: Potentially unstable (individualized decision)
• 13-18: Unstable (surgical stabilization indicated)

Surgical Indications:

• Spinal instability (SINS greater than or equal to 13)
• Neurologic deficit (cord compression, radiculopathy)
• Intractable pain despite radiation
• Radioresistant tumor
• Tissue diagnosis needed

Surgical Options:

Decompression + Instrumented Fusion:

• Relieves neural compression
• Provides immediate stability
• Allows early mobilization
• Does not address anterior column destruction (may fail)

Separation Surgery + Stereotactic Radiation:

• Minimal decompression (create space for radiation)
• Short-segment stabilization
• High-dose focused radiation post-op
• Emerging paradigm for radiosensitive tumors

Vertebroplasty/Kyphoplasty:

• Compression fractures without instability or cord compression
• Cement stabilization
• Pain relief in 70-90%
• Complications: cement leak, neural injury (rare)

Corpectomy + Reconstruction:

• Anterior column structural support
• Expandable cage or cement
• Combined with posterior stabilization
• Major surgery, reserved for longer survival expected

Spine pathologic fractures require neurosurgical or spine surgery expertise with oncology multidisciplinary team involvement.

Pediatric Pathologic Fractures

Unique Considerations:

Etiology Differences:

• Benign lesions more common (unicameral bone cyst, fibrous dysplasia, enchondroma)
• Primary malignant tumors (osteosarcoma, Ewing sarcoma) vs metastatic
• Langerhan cell histiocytosis
• Leukemia/lymphoma

Growth Considerations:

• Avoid physeal injury if possible
• Limb-length discrepancy potential
• Remodeling potential greater than adults
• Long-term implant effects

Management Principles:

Benign Lesions:

• Many heal spontaneously after fracture (unicameral bone cyst 15%)
• Initial treatment: fracture immobilization
• Definitive treatment after healing (curettage, grafting)
• Avoid unnecessary surgery during acute phase

Malignant Lesions:

• Multimodal treatment (chemotherapy + surgery ± radiation)
• Limb salvage preferred when feasible
• Physeal-sparing techniques when possible
• Expandable prostheses for young children (accommodate growth)

The pediatric population requires subspecialty expertise with different treatment paradigms focused on cure and long-term function.

Australian Epidemiology and Practice

Cancer Australia Epidemiology:

• Skeletal metastases affect approximately 30-40% of advanced cancer patients in Australia
• Breast cancer remains the most common primary source for bone metastases in Australian women
• Prostate cancer is the most common cause in Australian men
• Lung, renal, and thyroid cancers also frequently metastasize to bone
• Rising cancer incidence with aging population increases pathologic fracture burden

Australian Orthopaedic Oncology Services:

• Specialist bone tumour services located at major tertiary centres across Australia
• Major centres: Peter MacCallum Cancer Centre (Melbourne), Royal Prince Alfred Hospital (Sydney), Princess Alexandra Hospital (Brisbane), Royal Perth Hospital
• Multidisciplinary team approach mandated for complex oncology cases
• Access to tumour prostheses and custom implants through specialist suppliers

RACS Orthopaedic Training Relevance:

• Pathologic fracture management is a core FRACS examination topic
• Viva scenarios commonly test Mirels scoring, biopsy principles, and reconstruction decision-making
• Key exam focus: distinguishing prophylactic fixation indications, understanding prognosis by primary tumour type
• Examiners expect knowledge of staging workup sequence and multidisciplinary care principles

Australian Bone Tumour Guidelines:

• Bone Tumours Australia provides patient and clinician resources
• Australian and New Zealand Sarcoma Association (ANZSA) guidelines inform management
• State-based cancer networks coordinate care pathways
• Tumour registry data contributes to outcomes research

Radiation Oncology Considerations:

• Adjuvant radiation typically delivered 2-3 weeks post-operatively
• Australian radiation oncology services available at all major cancer centres
• Stereotactic body radiation therapy (SBRT) increasingly available for spinal metastases
• Trans-Tasman Radiation Oncology Group (TROG) research informs Australian practice

Prostheses and Implant Access:

• Tumour prostheses available through major orthopaedic implant companies
• Custom implants (3D printed, patient-specific) available for complex reconstructions
• Prostheses List determines private health insurance coverage
• Public hospital access to specialised implants through health service procurement