A 21-year-old male presented with left knee pain for 3 months. Clinical examination found localized tenderness over the distal femur with a full range of motion of the knee joint. CT scan revealed a bull's-eye appearance with a central nidus and surrounding reactive bone, consistent with osteoid osteoma. Conservative treatment with NSAIDs provided no relief. The patient subsequently underwent percutaneous radiofrequency ablation under CT guidance to treat the osteoid osteoma.

1. A 21 year Male with
Left knee pain
Department of Orthopaedics,
Apollo Institute of Medical Sciences & Research

2. • A 21 year Male presented with atraumatic severe
left knee pain since 3 months.
• Focal, Dull aching pain over medial knee.
• Nocturnal aggravation.
• Clinically no visible/palpable swelling.
• Localised tenderness medially over distal femur.
• Full Range of motion of knee joint.
• Distal Neurovascularity intact.

6. Computed Tomogram is the Imaging
modality of choice
• Bull’s eye appearance with central nidus &
surrounding reactive bone.
• Helps in Localisation & planning surgery
• Others:
• Technitium – 99 Bone scan – specific

7. CT scan

8. Patient was managed conservatively
with NSAIDS without any relief.

9. Percutaneous Radiofrequency Ablation
• Minimal invasive under CT guidance
• High Cost

11. Surgical
• Enbloc Excision
– requires CT localisation
– greater bone loss - requiring bone grafting &
plating.
• Burr down & curettage
– removes lesser bone , thus doesn’t weaken it.

13. CT guided localisation in our hospital

16. Intra operative

21. Osteoid Osteoma
• Benign bone lesion with well demarcated
osteoblastic mass <2cm- Nidus
• Surrounded by a sclerotic rim.
• 10% incidence
• 2nd decade, (5-30 yrs) M:F – 2:1
• Location- diaphysis or metaphysis of long
bones.
• Proximal femur> Tibia> Spine

22. • X Ray: cortical / medullary location
– Osteolytic with calcified rim.
• MRI: Nidus
– Marrrow & soft tissue Oedema

23. Pathology
• Overlying cortex is pink due to vascularity.
• Nidus is Red in colour
– Early nidus is soft
– Later becomes dense & gritty
• Microscopy: immature bone surrounded by
osteoblasts, osteoclasts & fibroblasts with
capillaries & non myelinated axons.
• High levels of prostaglandins

24. Course
• Mature spontaneously over long time by
calcification & ossification.
• Rarely transform to osteoblastoma.
• No Malignant potential.

25. Thank You