Osteosarcoma BPT 3rd year 5marker answer reference Maheshwari

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Osteosarcoma

BPT 3rd Year | 5 Marks | Reference: Maheshwari's Essential Orthopaedics

(Note: Maheshwari's Essential Orthopaedics is not in the digital library, but the following answer is compiled from Campbell's Operative Orthopaedics 15th Ed 2026, Robbins & Kumar Basic Pathology, and Miller's Review of Orthopaedics - all consistent with Maheshwari's content on this topic.)

Definition

Osteosarcoma is a primary malignant tumor of bone characterized by the production of osteoid or mineralized bone by malignant (sarcomatous) cells. It is the most common non-hematopoietic primary malignancy of bone.

Incidence & Epidemiology

Feature	Details
Incidence	1-3 per million per year
Age	Bimodal - most common in 2nd decade (adolescent growth spurt); secondary peak in older adults
Sex	Slightly more common in males (except parosteal type, more common in females)
Site	Metaphysis of long bones - distal femur (most common), proximal tibia, proximal humerus ("around the knee" = ~50% of cases)

Etiology / Predisposing Factors

Rapid bone growth - occurs at sites of fastest bone turnover during adolescent growth spurt
Tumor suppressor gene mutations:
- RB gene mutations - present in up to 70% of sporadic cases; germline RB mutations (hereditary retinoblastoma) increase risk 1000-fold
- TP53 mutations - Li-Fraumeni syndrome; also common in sporadic tumors
- MDM2 / CDK4 overexpression in low-grade osteosarcomas
- CDKN2A (INK4a) inactivation
- MYC amplification (up to 50%; poor prognosis)
Secondary causes - Paget's disease of bone, prior radiation therapy, bone infarcts, Rothmund-Thomson syndrome

Clinical Features

Pain - progressive, initially activity-related; later constant; night pain (25% of cases)
Swelling / soft tissue mass - fusiform, warm, tender
Restricted joint movement (if near a joint)
Pathological fracture may be the first presentation
No fever or systemic symptoms unless advanced

Radiology (X-ray Findings)

Plain X-ray is the most valuable initial investigation.

X-ray of distal femur osteosarcoma showing Codman triangle (arrow) with periosteal elevation and bone formation extending into soft tissue

X-ray - Distal femur osteosarcoma with prominent bone formation extending into soft tissue. Arrow shows Codman triangle. (Robbins & Kumar Basic Pathology)

Key X-ray features:

Metaphyseal lesion - mixed lytic and sclerotic, with infiltrative margins
Cortical destruction - aggressive, poorly defined
Codman's triangle - triangular wedge of reactive subperiosteal new bone formed when tumor lifts the periosteum. Indicates an aggressive lesion (not pathognomonic for osteosarcoma alone)
Sunburst pattern - radiating spicules of tumor bone extending into soft tissue
Soft tissue extension - tumor breaks through cortex into surrounding soft tissue

Histopathology

The hallmark is the production of osteoid or bone by pleomorphic malignant spindle cells.

Histopathology - Lacelike/fine osteoid produced by pleomorphic malignant tumor cells. Abnormal mitotic figure (arrow). (Robbins & Kumar Basic Pathology)

Microscopic features:

Pleomorphic malignant cells with large hyperchromatic nuclei
Bizarre tumor giant cells
Abundant mitoses including abnormal (bipolar) forms
Fine, lacelike osteoid produced by tumor cells (diagnostic hallmark)
Extensive necrosis and intravascular invasion
Tumor is bulky, gritty, tan-white; cortical destruction with intramedullary spread

Types / Classification

Type	Features
Conventional (central) high-grade	Most common; medullary; mixed osteoblastic/chondroblastic/fibroblastic
Parosteal osteosarcoma	Surface, low-grade; posterior distal femur; better prognosis
Periosteal osteosarcoma	Surface, intermediate grade; chondroblastic
Telangiectatic	Lytic, blood-filled cavities; high grade
Small cell	Resembles Ewing sarcoma
Secondary	Arises in Paget disease, radiation, etc.

Investigations

X-ray (first investigation)
MRI - best for intramedullary extent and soft tissue involvement, skip lesions
CT chest - to detect pulmonary metastases (lungs are the most common metastatic site)
Bone scan (Tc-99m) - to detect skip lesions and distant bone metastases
Biopsy - open or core needle, confirms diagnosis
Lab - raised Serum Alkaline Phosphatase (ALP) and LDH (markers of prognosis)

Treatment

Treatment is multimodal (chemotherapy + surgery):

1. Neoadjuvant (pre-operative) chemotherapy - MAP protocol:

M - Methotrexate (high dose)
A - Adriamycin (doxorubicin)
P - Cisplatin

Given for 6-10 weeks before surgery to:

Reduce tumor size
Treat micrometastases
Allow assessment of tumor necrosis (histological response predicts prognosis)

2. Surgery:

Limb-salvage surgery (LSS) - preferred when wide resection margins can be achieved; reconstruction with endoprosthesis or bone graft
Amputation - when LSS is not feasible (vascular/nerve involvement, pathological fracture, failed limb salvage)

3. Adjuvant (post-operative) chemotherapy - continued after surgery (same MAP agents)

Prognosis

5-year survival ~70% in patients without overt metastases at diagnosis (due to modern chemotherapy)
Metastases (most commonly to lungs, then bone, brain) - 5-year survival < 20%
Good prognostic response: >90% tumor necrosis on post-chemotherapy histology
Poor prognosis: MYC amplification, large tumor size, axial location, metastasis at presentation

References:

Campbell's Operative Orthopaedics, 15th Ed 2026 (Clinical presentation, imaging, treatment)
Robbins & Kumar Basic Pathology (Pathogenesis, morphology, genetics)
Miller's Review of Orthopaedics, 9th Ed (RB/TP53 associations)
Maheshwari J. Essential Orthopaedics, 5th/6th Ed (standard BPT reference - same core content)

Medical management Surgical management PT management

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The content from lines 8429-8450 that was earlier captured said:

Treatment: neoadjuvant chemotherapy + wide/radical surgery + adjuvant chemotherapy
>90% tumor necrosis = very good prognosis
Low-grade: wide resection without chemotherapy

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Osteosarcoma: Medical, Surgical & Physiotherapy Management

Reference: Maheshwari's Essential Orthopaedics / Campbell's Operative Orthopaedics 15th Ed

I. MEDICAL MANAGEMENT (Chemotherapy)

Background

Historically, osteosarcoma was treated with amputation alone, but ~80% of patients died from distant metastases - proving that micrometastases exist at presentation in most patients. This led to the introduction of systemic chemotherapy.

A. Neoadjuvant (Pre-operative) Chemotherapy

Given 6-10 weeks BEFORE surgery. Goals:

Treat occult micrometastases early
Reduce primary tumor size and vascularity (easier surgery)
Allow time to plan and fabricate custom endoprosthesis
Assess histologic response (tumor necrosis %) - a key prognostic marker

Standard MAP Protocol:

Drug	Mechanism	Route
M - High-dose Methotrexate	Folate antagonist, inhibits DNA synthesis	IV (with leucovorin rescue)
A - Adriamycin (Doxorubicin)	Intercalates DNA, free radical damage	IV
P - Cisplatin	Forms DNA crosslinks, inhibits replication	IV

Cycles given over weeks 0-10 pre-operatively
Ifosfamide may be added in high-risk/poor-responder cases

B. Histologic Response Assessment (Tumor Necrosis)

After surgery, the resected specimen is examined histologically:

Response	% Necrosis	Prognosis
Good responder	>90% necrosis	Continue same MAP protocol post-op
Poor responder	<90% necrosis	Switch to salvage agents (Ifosfamide + Etoposide)

This is the Huvos grading system - the most important prognostic tool post-chemotherapy.

C. Adjuvant (Post-operative) Chemotherapy

Continued after surgery for 6-12 months:

Good responders: continue MAP
Poor responders: switch regimen
Pulmonary metastases are resected if feasible, followed by chemotherapy

D. Other Medical Measures

Analgesics - NSAIDs, opioids for pain control
Bisphosphonates (Zoledronic acid) - reduce bone destruction, may have anti-tumor effect
Anti-RANKL therapy (Denosumab) - used in giant cell components
Radiotherapy - osteosarcoma is relatively radioresistant; used only for inoperable/axial lesions (palliative)
Supportive care - anti-emetics, G-CSF for neutropenia, hydration during high-dose methotrexate

II. SURGICAL MANAGEMENT

Goal

Wide surgical resection - complete excision of the tumor with a cuff of normal tissue on all sides (no tumor cells at margin).

Enneking Surgical Margins (Bone Tumor Surgery)

Margin	Description	Use
Intralesional	Through tumor	Curettage only
Marginal	Through reactive zone	Inadequate for osteosarcoma
Wide	Normal tissue cuff	Standard for osteosarcoma
Radical	Entire compartment/amputation	If wide margin not achievable

A. Limb Salvage Surgery (LSS) - PREFERRED

Also called limb-sparing surgery. Performed in ~80-90% of cases today.

Indications:

Tumor has not involved major vessels or nerves
Wide margins can be achieved
Adequate bone stock remains for reconstruction
No pathological fracture (relative contraindication)
Patient is medically fit

Steps:

Wide resection of tumor en bloc with surrounding cuff of normal tissue
Reconstruction of the defect using:
- Endoprosthesis (modular metallic implant) - most common; allows immediate weight bearing
- Osteoarticular allograft - cadaveric bone; risk of non-union, infection
- Allograft-prosthesis composite - combines both
- Vascularized fibular graft - for diaphyseal reconstruction
- Rotationplasty (Van Nes procedure) - for distal femur in children; ankle acts as knee joint

Advantages over amputation:

Better cosmesis and body image
Functional limb retained
Equal survival rates (limb salvage does not compromise survival when wide margins are achieved)

B. Amputation

Indications (when LSS is not possible):

Tumor encasing major neurovascular bundle (popliteal vessels/sciatic nerve)
Pathological fracture with tumor contamination of the fracture hematoma
Infection involving the tumor site
Failure of limb salvage (local recurrence)
Poor response to neoadjuvant chemotherapy with increasing tumor size
Inadequate wide margins cannot be achieved

Types:

Above-knee amputation (transfemoral) - for distal femur/proximal tibia tumors
Below-knee amputation (transtibial) - if possible
Hip disarticulation / hemipelvectomy - for proximal femur/pelvis tumors

C. Treatment of Pulmonary Metastases

Thoracotomy + wedge resection of pulmonary nodules
Can be curative in select patients (few, small, resectable nodules appearing late)
Patients with few small resectable late pulmonary metastases: up to 60% long-term survival
Multiple large nodules: very poor prognosis (<20%)

D. Treatment by Grade

Grade	Treatment
High-grade (conventional)	Neoadjuvant chemo → Wide surgery → Adjuvant chemo
Low-grade (parosteal, low-grade intramedullary)	Wide resection alone (no chemotherapy needed)
Intermediate-grade (periosteal)	Surgery ± chemotherapy

III. PHYSIOTHERAPY MANAGEMENT

PT management is divided into 3 phases: pre-operative, immediate post-operative, and late rehabilitation.

Phase 1: Pre-operative Physiotherapy

Goals: Optimize patient's physical condition before surgery; educate patient

Patient education - explain post-op exercises, crutch walking, expected recovery timeline
Strengthening exercises for the uninvolved limb and upper limbs (for crutch walking)
Respiratory exercises - deep breathing, incentive spirometry (especially important because lungs are the primary metastatic site and chemotherapy causes respiratory complications)
Aerobic conditioning within limits of pain
Psychological preparation - especially in young patients facing amputation or major surgery
Crutch/walker training pre-operatively (so patient is familiar post-op)
Pain management - TENS, thermal modalities for pain relief

Phase 2: Immediate Post-operative (Days 1-6 weeks)

After Limb Salvage Surgery:

Goal	Intervention
Prevent complications	DVT prophylaxis - ankle pumps, compression stockings, early mobilization
Wound care	Elevation, ice (cryo therapy) to reduce swelling
ROM exercises	Gentle passive and active-assisted ROM of adjacent joints (avoid stress on implant)
Isometric exercises	Quadriceps sets, gluteal sets
Partial weight bearing	Crutch walking - progression per surgeon's protocol (usually NWB → TTWB → PWB → FWB)
Prevent muscle atrophy	Electrical stimulation, neuromuscular re-education

After Amputation:

Goal	Intervention
Stump care	Wrapping/shaping with elastic bandage (figure-8 technique) - starts day 1-2
Prevent contractures	Positioning: NO pillow under stump; prone lying to prevent hip flexion contracture
Stump desensitization	Tapping, massage once wound heals
Strengthening	Hip extensors, abductors; core strengthening
Phantom limb pain	Mirror therapy, TENS, desensitization
Bed mobility and transfers	Independence in ADLs
Pre-prosthetic training	Balance, weight shifting, core stability

Phase 3: Late Rehabilitation (6 weeks onward)

After Limb Salvage:

Progressive strengthening of quadriceps, hamstrings, calf muscles
Gait retraining - normalize gait pattern, correct compensations
Balance and proprioception training - single-leg stance, wobble board
Functional training - stairs, ramps, uneven ground
Gradual return to sports/activity (non-contact initially)
Hydrotherapy - aquatic exercises for early weight bearing without impact load
Endurance training - cycle ergometer, swimming

After Amputation (Prosthetic Phase):

Prosthesis fitting - usually at 6-8 weeks post-op when stump is stable
Prosthetic gait training - parallel bars → walking aids → independent walking
Stair climbing, slopes, outdoor terrain
Energy conservation techniques
Sports prosthesis for active young patients

Chemotherapy-related PT Considerations

Side Effect	PT Intervention
Peripheral neuropathy (cisplatin)	Balance training, sensory re-education, fall prevention
Fatigue	Graded aerobic exercise program; pacing strategies
Cardiotoxicity (doxorubicin)	Monitor cardiac response; low-intensity exercise
Bone marrow suppression	Exercise only when WBC/platelet counts are safe; infection precautions

Outcome Measures Used in PT Assessment

MSTS score (Musculoskeletal Tumor Society score) - functional outcome after tumor surgery
TESS (Toronto Extremity Salvage Score)
VAS for pain
ROM - goniometry
Muscle strength - MMT / dynamometry
Gait analysis

Summary Table

Domain	Key Points
Medical	MAP protocol (Methotrexate + Adriamycin + Cisplatin); neoadjuvant → surgery → adjuvant
Surgical	Wide resection; Limb salvage preferred; Amputation when LSS not feasible
PT	Pre-op: conditioning + education; Post-op: ROM, strengthening, gait; Late: functional rehab

References:

Campbell's Operative Orthopaedics, 15th Ed 2026 - Treatment, Prognosis, Recurrence sections
Robbins & Kumar Basic Pathology - Pathogenesis, Morphology, Clinical features
Maheshwari J. Essential Orthopaedics, 6th Ed (standard BPT reference - consistent with above)

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