Osteoid Osteoma

What is an osteoid osteoma?

An osteoid osteoma is a small, benign (non-cancerous) bone tumour. It is one of the most common benign bone tumours seen in children and young adults. The lesion itself — called the nidus — is typically less than 1.5 cm in diameter and consists of immature bone and fibrous tissue surrounded by a rim of reactive sclerotic bone. Despite its small size, it is highly vascular and contains abundant nerve fibres, which explains why it causes pain out of proportion to its size.

Symptoms

Osteoid osteoma has a very characteristic clinical presentation:

• Persistent, aching bone pain — often described as a deep, boring pain

• Pain is classically worse at night and relieved by aspirin or ibuprofen (NSAIDs) — this pattern is highly characteristic

• The most common locations are the proximal femur (near the hip) and the tibial shaft, though any bone can be affected

• If near a joint, the child may develop a painful limp

• If near the spine, scoliosis (spinal curvature) may develop as the child holds the spine in an antalgic position

How is it diagnosed?

• X-ray — may show the nidus as a small lucent area surrounded by dense reactive bone

• CT scan — the most accurate investigation for localising the nidus precisely, essential for planning ablation

• MRI scan — useful to assess soft tissue involvement but the nidus can be hard to identify

• Bone scan (isotope scintigraphy) — the nidus shows as a hot spot

Treatment options

1. Conservative management — NSAIDs

Long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen effectively controls pain in most patients. The osteoid osteoma will eventually resolve on its own over several years. This is a reasonable option for patients with well-controlled symptoms who wish to avoid a procedure.

• No procedure required

• Pain relief effective in most cases while on NSAIDs

• Requires prolonged medication use (potentially years) with adverse effect on the kidney

• Does not speed up resolution

2. CT-guided radiofrequency ablation (RFA)

Radiofrequency ablation (RFA) is currently the gold standard treatment for osteoid osteoma. It is performed by an interventional radiologist under CT guidance.

• General anaesthetic or deep sedation.

• A thin needle is guided through the skin and into the nidus using real-time CT scanning.

• A radiofrequency electrode is deployed through the needle.

• The electrode delivers controlled heat (approximately 90°C for 4-6 minutes) to destroy the nidus.

• The needle is removed. The skin entry point is covered with a small dressing.

• The patient recovers and goes home the same day in most cases.

• Success rate: approximately 88-95% with a single treatment

• Minimally invasive — no incision, no general anaesthetic in many centres (sedation is sufficient)

• Day case procedure

• Pain relief typically within 24-72 hours of the procedure

• Can be repeated if the first ablation is incomplete

• Not appropriate if the nidus is very close to major nerves, the skin surface, or articular cartilage

3. CT-guided cryoablation

Cryoablation is an alternative minimally invasive technique performed by an interventional radiologist, using extreme cold rather than heat to destroy the nidus.

• General anaesthetic or sedation.

• A cryoprobe is inserted into the nidus under CT guidance.

• The probe delivers a freeze-thaw-freeze cycle using liquid argon or liquid nitrogen, creating an ice ball around the nidus that destroys the tissue.

• The probe is removed and the skin entry point dressed.

• Advantages over RFA: the ice ball is visible on CT imaging in real time, allowing better monitoring of the ablation zone

• Potentially safer when the nidus is near a nerve — the nerve can be monitored during the procedure

• May cause less post-procedure pain than RFA

• Success rate similar to RFA — approximately 85-95%

• As with RFA, can be repeated if needed

4. Surgical excision

Before ablation techniques were available, surgical excision was the primary treatment. It remains an option when:

• Ablation is not technically possible due to lesion location (e.g. very superficial, near articular surface, or near a major nerve in the spine)

• The diagnosis is uncertain and tissue is needed for histopathological confirmation

• Ablation has failed

Open or arthroscopic excision involves removing the nidus and surrounding reactive bone through a surgical incision. Success rates are high but recovery is longer than ablation.

Which treatment is right for my child?

Note: Natural history 

Osteoid osteomas can resolve spontaneously over several years (typically 3-7 years). Conservative management with long-term NSAIDs is therefore an option for some patients. However, for children in significant pain, with sleep disruption, or with associated scoliosis or joint problems, active treatment is usually recommended. The choice between watchful waiting and intervention depends on the severity of symptoms, the duration of pain, and the lesion’s location.

Option

Best suited to NSAIDs

Mild symptoms, willingness to wait for natural resolution

RFA

Standard treatment — most locations, day case, fastest recovery

Cryoablation

Near nerve or superficial location 

Where ice ball monitoring is advantageous

Surgical excision

Ablation not possible, diagnosis uncertain, or previous ablation failed

Recovery

NSAIDs

Ongoing — symptoms managed; lesion resolves over years.

RFA / Cryoablation

Day case. Pain resolves 24-72 hrs. Back to school in days. Sport in 2-4 weeks.

Surgical excision

Day case or 1 night admission. Activity restriction 4 weeks.   Return to sport 6 weeks.

Note: When to seek urgent help 

Persistent or worsening pain after ablation beyond 2 weeks — possible incomplete treatment New scoliosis or worsening scoliosis near spine lesions Signs of infection after surgery: redness, discharge, temperature above 38.5°C Numbness or tingling near the lesion after ablation

This information is for general guidance only and is not a substitute for a consultation with Mr Wadia. If you are worried about your child, please seek medical advice.