High Yield Overview

LIMB SALVAGE SURGERY PRINCIPLES

Oncological Margins | Enneking Staging | Reconstruction Options | Functional Outcomes

85-90%Limb salvage rate for bone sarcomas

WideMinimum acceptable surgical margin

70-80%5-year prosthesis survival

MSTSFunctional outcome scoring system

SURGICAL MARGIN TYPES (ENNEKING)

Intralesional

PatternThrough tumour (curettage)

TreatmentContaminated - unacceptable for sarcoma

Marginal

PatternThrough reactive zone

TreatmentMicroscopic residual disease likely

Wide

PatternThrough normal tissue (cuff)

TreatmentMinimum acceptable for sarcoma

Radical

PatternEntire compartment removed

TreatmentRarely performed, maximum local control

Critical Must-Knows

Wide margin = minimum 2cm bone, cuff of normal tissue (fascia/muscle) for sarcoma
Enneking staging: Stage I = low grade, II = high grade, III = metastatic
Endoprosthesis = gold standard for periarticular reconstruction after tumour resection
Growing prostheses essential in paediatrics to address limb length inequality
Rotationplasty = biological alternative providing excellent function for distal femur tumours

Examiner's Pearls

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Local recurrence with intralesional/marginal margins approaches 50-100% for high-grade sarcoma
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Skip metastases occur in 1-5% - whole bone MRI essential before resection
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Allograft-prosthetic composite combines biological fixation with prosthetic joint
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Infection rate 10-15% for endoprostheses - higher than primary arthroplasty

Clinical Imaging

Imaging Gallery

Six-panel anteroposterior pelvic radiographic series demonstrating surgical treatment progression of pelvic osteosarcoma from initial presentation through post-treatment reconstruction — Six-panel anteroposterior pelvic radiographic series demonstrating surgical treatment progression of pelvic osteosarcoma from initial presentation thrCredit: Outcome of surgical treatment of pelvic osteosarcoma study via Open-i (NIH) via Open-i (NIH) (Open Access (CC BY))

Four-panel multimodality workflow: pre-op radiograph, MRI showing tumor extent, gross pathology specimen, post-op reconstruction radiograph with plate fixation — Four-panel multimodality workflow: pre-op radiograph, MRI showing tumor extent, gross pathology specimen, post-op reconstruction radiograph with plateCredit: Qu H et al. via World J Surg Oncol via Open-i (NIH) (Open Access (CC BY))

Six-panel follow-up series: serial radiographs showing fibula graft incorporation and hypertrophy (a-d), plus clinical photos demonstrating functional outcomes (e-f) — Six-panel follow-up series: serial radiographs showing fibula graft incorporation and hypertrophy (a-d), plus clinical photos demonstrating functionalCredit: Petersen MM et al. via Sarcoma via Open-i (NIH) (Open Access (CC BY))

Critical Limb Salvage Exam Points

Surgical Margins

Wide margin is minimum for sarcoma. Intralesional = curettage through tumour (contamination). Marginal = through reactive zone (microscopic disease). Wide = through normal tissue cuff (acceptable). Radical = entire compartment (rarely needed). Local recurrence correlates directly with margin adequacy.

Enneking Staging

Stage determines prognosis and treatment. Stage I = low grade (A intra, B extracompartmental). Stage II = high grade (A intra, B extracompartmental). Stage III = any grade with metastases. Surgical margins and adjuvant therapy guided by staging. Know benign staging too (1-3 latent to aggressive).

Reconstruction Options

Endoprosthesis is workhorse for periarticular reconstruction. Allograft provides biological stock but high complication rates. Autograft (vascularized fibula) for intercalary defects. Allograft-prosthetic composite combines benefits. Rotationplasty excellent function in young patients with distal femur tumours.

Complications

Infection 10-15% - higher than primary arthroplasty due to large dead space, adjuvant therapy effects. Aseptic loosening 5-10% at 10 years. Periprosthetic fracture 5-7%. Soft tissue failure (extensor mechanism, dislocation). Know Henderson classification for failure modes.

Reconstruction Option Selection Guide

Clinical Scenario	Preferred Reconstruction	Alternative	Key Considerations
Distal femur osteosarcoma in adult	Modular endoprosthesis	Allograft-prosthetic composite	Most common tumour site, reliable outcomes
Proximal tibia tumour in adolescent	Extendible endoprosthesis	Rotationplasty	Must address growth potential and extensor mechanism
Diaphyseal femur tumour (intercalary)	Intercalary prosthesis or vascularized fibula	Allograft with plate	Preserve joints if possible, biological healing better
Distal femur in young child (under 8)	Rotationplasty	Expandable prosthesis	Multiple lengthening procedures vs single rotationplasty
Pelvis tumour (periacetabular)	Custom hemipelvic prosthesis	Flail hip (excision only)	High complication rate, consider function vs survival
Failed limb salvage with infection	Amputation	Two-stage revision if bone stock allows	Patient safety paramount, functional amputation better than non-functional salvage

Mnemonic

MARGIN - Surgical Margin Principles

Measure preoperatively

MRI for tumour extent, CT for cortical involvement

Avoid reactive zone

Marginal margin goes through reactive zone - inadequate

Radical rarely needed

Whole compartment excision now uncommon

Goal is wide margin

2cm bone, cuff of normal tissue minimum

Intralesional is contamination

Curettage spreads tumour - only for benign lesions

Neurovascular bundle

Tumour encasement may preclude limb salvage

Memory Hook:The MARGIN you achieve determines local recurrence and survival

Mnemonic

SALVAGE - Limb Salvage Prerequisites

Staging complete

Local imaging plus chest CT for metastases

Adequate margin achievable

Can achieve wide margin without neurovascular sacrifice

Limb function preserved

Functional outcome must exceed amputation

Vascular supply intact

Major vessel reconstruction possible if needed

Adjuvant therapy planned

Neoadjuvant chemo for osteosarcoma, radiation for soft tissue

Growth potential addressed

Growing prosthesis or rotationplasty in children

Expectations realistic

Patient understands risks, complications, functional outcomes

Memory Hook:Check all SALVAGE criteria before proceeding - if any missing, consider amputation

Mnemonic

ENDO - Endoprosthesis Complications

Extensor mechanism failure

Proximal tibia - patellar tendon reattachment critical

Neurovascular injury

Peroneal nerve at risk in proximal tibia resection

Deep infection

10-15% rate, two-stage revision or amputation

Osseous loosening

Aseptic loosening 5-10% at 10 years

Memory Hook:ENDO complications are common - counsel patients about 30% reoperation rate at 10 years

Overview and Epidemiology

Definition

Limb salvage surgery is the surgical resection of a malignant bone or soft tissue tumour with reconstruction of the resultant defect, preserving a functional limb. The fundamental principle is achieving oncologically adequate surgical margins while maintaining limb function superior to amputation.

Evolution of Limb Salvage

Historically, amputation was the standard treatment for extremity sarcomas. The development of effective chemotherapy in the 1970s-80s, combined with advances in imaging (MRI) and reconstructive techniques (modular endoprostheses), revolutionized treatment. Limb salvage is now performed in 85-90% of bone sarcoma patients, with survival rates equivalent to amputation when adequate margins are achieved.

Epidemiology

Primary Bone Sarcomas:

Osteosarcoma: Most common primary bone malignancy, peak incidence 10-25 years
Ewing sarcoma: Second most common, peak 5-15 years
Chondrosarcoma: Third most common, peak 40-60 years
Combined incidence: 8-10 per million population annually

Common Sites Requiring Limb Salvage:

Distal femur (35-40% of osteosarcoma)
Proximal tibia (15-20%)
Proximal humerus (10-15%)
Proximal femur (10%)

Survival Equivalence

Limb salvage provides equivalent survival to amputation when adequate surgical margins are achieved. Multiple studies including the landmark Rougraff et al. series demonstrate no difference in overall survival or metastasis-free survival between limb salvage and amputation. The decision is therefore based on achieving adequate margins and functional outcome.

Indications for Limb Salvage

Absolute Requirements:

Adequate surgical margin achievable (wide or radical)
Reconstruction technically feasible
Preserved or reconstructible neurovascular structures
Expected function superior to amputation

Relative Contraindications:

Tumour encasing major neurovascular bundle
Pathological fracture with haematoma contamination
Extensive soft tissue extension precluding reconstruction
Skip metastases (may still salvage if all resectable)
Patient factors (age, comorbidities, expectations)

Pathophysiology and Tumour Biology

Tumour Growth and Spread

Understanding tumour behaviour is essential for surgical planning. Bone sarcomas exhibit characteristic patterns that inform margin requirements.

Local Extension:

Intramedullary spread: Osteosarcoma extends along medullary canal - MRI essential
Cortical breakthrough: Creates reactive zone and soft tissue mass
Skip metastases: Discontinuous intramedullary lesions in 1-5% of osteosarcoma
Joint involvement: Rare but occurs through cruciate ligament insertion, direct extension

Reactive Zone: The reactive zone surrounds the tumour pseudocapsule. It contains:

Compressed normal tissue
Inflammatory cells
Oedematous tissue
Microscopic tumour extension

Marginal margins go through the reactive zone and leave microscopic disease in 40-50% of cases for high-grade sarcoma. This results in local recurrence rates of 50-100%. Wide margin through normal tissue is the minimum acceptable standard.

Chemotherapy Effects

Neoadjuvant Chemotherapy for Osteosarcoma:

Standard of care - improves survival from 20% to 60-70%
Reduces tumour size, facilitates limb salvage
Creates necrosis - assessed at resection (Huvos grading)
Good response (greater than 90% necrosis): Better prognosis
Poor response: Consider adjuvant modification

Histological Response (Huvos Grading):

Grade	Necrosis	Description	Prognosis
I	0-50%	Little effect	Poor
II	51-89%	Partial response	Intermediate
III	90-99%	Good response	Good
IV	100%	Complete response	Excellent

Wound Healing Considerations

Tumour surgery creates unique wound healing challenges:

Large dead space after resection
Chemotherapy impairs healing and immunity
Radiotherapy (soft tissue sarcoma) causes fibrosis
Metalwork and allografts are foreign bodies
Higher infection risk than routine arthroplasty

Classification and Staging

Enneking Surgical Staging System

The Enneking staging system is the most widely used classification for musculoskeletal tumours, guiding treatment and prognosis.

Enneking Staging for Malignant Tumours

Stage	Grade	Site	Metastases	Treatment Approach
IA	Low (G1)	Intracompartmental (T1)	None (M0)	Wide excision, consider adjuvants
IB	Low (G1)	Extracompartmental (T2)	None (M0)	Wide excision, margins critical
IIA	High (G2)	Intracompartmental (T1)	None (M0)	Neoadjuvant chemo, wide excision
IIB	High (G2)	Extracompartmental (T2)	None (M0)	Neoadjuvant chemo, wide excision
III	Any grade	Any site	Present (M1)	Palliative or aggressive if isolated mets

Compartmental Definition:

Intracompartmental (T1): Confined within anatomical compartment (bone cortex intact)
Extracompartmental (T2): Extends beyond compartment (cortical breach, soft tissue extension)

Know the Benign Staging Too

Enneking Benign Tumour Staging:

Stage 1 (Latent): Static, asymptomatic (e.g., fibrous cortical defect)
Stage 2 (Active): Symptomatic, growing (e.g., aneurysmal bone cyst)
Stage 3 (Aggressive): Locally destructive (e.g., giant cell tumour)

Stage 3 benign may require margins similar to low-grade malignancy.

Clinical Presentation and Assessment

Presentation Patterns

Bone Sarcomas:

Pain: Progressive, worse at night, not relieved by rest
Swelling: Palpable mass in 50%
Pathological fracture: 5-10% present with fracture
Duration: Weeks to months

Red Flags for Malignancy:

Night pain
Progressive pain not responsive to simple analgesia
Mass increasing in size
Constitutional symptoms (weight loss, fatigue)
Age-size mismatch (large lesion in young patient)

Do not attribute bone pain in a young person to "growing pains" or sports injury without appropriate investigation. Delayed diagnosis of osteosarcoma remains common - average delay 3-4 months from symptom onset.

Clinical Examination

Inspection:

Mass location, size, skin changes
Muscle wasting
Limb length discrepancy
Angular deformity

Palpation:

Mass characteristics: Size, consistency, mobility, tenderness
Relation to underlying bone
Neurovascular status distally

Special Assessments:

Joint range of motion (adjacent joints)
Neurovascular examination (tumour may compress/invade)
Lymph node examination (unusual for bone sarcoma but check)

Investigations

Investigation Protocol for Limb Salvage Planning

Step 1Plain Radiographs

Initial assessment:

AP and lateral of affected bone
Assess lesion location, size, matrix
Cortical involvement, periosteal reaction
Pathological fracture assessment

Classic Features:

Osteosarcoma: Sunburst periosteal reaction, Codman triangle
Ewing: Permeative "moth-eaten" destruction, onion-skin periosteal reaction
Chondrosarcoma: Rings-and-arcs calcification, endosteal scalloping

Step 2MRI - Essential for Planning

Whole bone with contrast:

T1, T2, STIR sequences
Gadolinium enhancement for soft tissue extent
Measure intramedullary extent for margin planning
Identify skip metastases (1-5%)
Assess joint involvement, neurovascular proximity

Key Measurements:

Distance from tumour to joint line
Intramedullary extent (for bone cut level)
Soft tissue mass dimensions
Proximity to neurovascular bundle

Step 3CT Scan

Complementary to MRI:

Cortical detail and matrix characterization
Staging CT chest (essential)
CT-guided biopsy if required
3D reconstruction for complex anatomy (pelvis)

Step 4Nuclear Medicine

Whole body assessment:

Bone scan: Skeletal metastases
PET-CT: Increasingly used for staging and response assessment
PET may identify occult metastases

Step 5Tissue Diagnosis

Biopsy principles:

Core needle preferred over open (less contamination)
Biopsy track excised with specimen
Longitudinal approach, not transverse
Experienced pathologist essential
Frozen section at surgery to confirm diagnosis and margins

Biopsy Placement

The biopsy track is contaminated with tumour cells. Place the biopsy in line with the planned surgical incision so the track can be excised en bloc. Incorrectly placed biopsy may compromise limb salvage or require wider excision. In complex cases, perform biopsy at the treating centre.