A 16-year-old presents with a distal femoral osteosarcoma confined to the bone, crossing the physis, without satellite lesions or skip metastases, and with no distant metastasis. MRI shows adequate soft-tissue clearance from the neurovascular bundle. According to the Enneking staging system, this is:
- A Stage IIB ✓
- B Stage IA
- C Stage IIA
- D Stage IIIB
Correct answer: A. Stage IIB
Explanation
Enneking staging for malignant tumours: Grade I (low-grade) vs Grade II (high-grade); A = intracompartmental vs B = extracompartmental; Stage III = any grade with distant metastasis. Osteosarcoma is high-grade (Grade II). A tumour crossing the physis extends beyond the single compartment, making it IIB (high-grade, extracompartmental, no metastasis). Stage IIA would imply intracompartmental; Stage III requires distant metastasis.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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