ABSTRACT ID: IRIA - 1061. Osteoid osteoma is a common entity with male predilection, male to female ratio – 4:1 Most of the effected are young individuals.

RADIO-FREQUENCY ABLATION OF OSTEOID OSTEOMA – FEMORAL NECK

ABSTRACT ID: IRIA - 1061

BACKGROUND

Osteoid osteoma is a common entity with male predilection, male to female ratio – 4:1

Most of the effected are young individuals in second decade of life.

Dull aching deep bone pain - worsening in the nights, relieved by analgesics.

On physical examination tenderness is present.

Signs of inflammation including erythema, warmth are almost always absent

BACK GROUND – TREATMENT OPTIONS

The treatment options available are Surgery and Radio Frequency Ablation.

Due to the prolonged hospital stay, complications and incomplete removal of the nidus leading to recurrence; surgery is a less desired option.

Radio Frequency Ablation has proved to be quick, safe and minimally invasive method of management.

CASE REPORT

A 17 year old Indian male patient complaints of 8 months deep bone pain over left hip.

Pain was worsening at night with sleep disturbance, aggravated on walking and relieved on rest.

H/o trauma 2 years back- slip and fall from height of 10 meters.

No H/o recent fever. No H/o pain over small joints or early morning stiffness.

N/K/C/O DM/BA/TB/Jaundice

INSPECTION:

Muscle wasting was evident over the thigh and calf regions.

Scarpa triangle fullness is seen in the left hip.

Left anterior superior iliac spine is inferior compared to right side(pelvic tilt)

No limb length discrepancy or gluteal muscle wasting

PALPATION:

Scarpa triangle tenderness present.

Greater trochanter tenderness present.

No mass palpable.

Flexion and internal rotation movements of left hip joint were restricted.

Trendenlenburg test: Positive

Femoral and distal pulses felt. Active toe movements present. Sensation intact.

The patient was then admitted and all the baseline investigations were done.

All the baseline investigations were found to be within normal limits.

The patient was then subjected for Radiological investigations.

IMAGING - X Ray Pelvis

Image A : (Shows) Oval lytic lesion (nidus) at

the medial cortex of the left femoral neck near the lesser trochanter with surrounding sclerosis and adjacent cortical thickening.

Nidus measured 2.0 x 1.2 cm (Cc x Tr) with internal calcific foci.

Image A

NON CONTRAST COMPUTED TOMOGRAPHY - PELVIS

Oval lytic lesion (nidus) 2.0 x 1.2 cm at the medial cortex of the left femoral neck near the lesser trochanter with surrounding sclerosis and adjacent cortical thickening.

PRE-PROCEDURE (RADIO FREQUENCY ABLATION)

Radio Frequency Ablation was planned after radiological confirmation of the diagnosis of Osteoid osteoma.

Prothrombin time and international normalized ratio (INR) were tested and found within normal limits.

Anaesthetist’s evaluation was carried out.

Prophylactic antibiotic (Cefotaxime 1 gm ) was administered immediately before the procedure.

PROCEDURE-RADIO FREQUENCY ABLATION

Lesion localization done with 128 multi detector row CT to confirm accurate needle position within the nidus. (Image on the (L): Scout image confirming the needle position with gonadal pads Image (R)Red arrow – Bone biopsy cannula. Yellow arrow – tip of the electrode)

Under CT guidance and spinal anaesthesia, percutaneous entry into the osteoma nidus was made using osteocyte bone biopsy cannula (13 G) with a drill and Kirchner wire.

Aspiration of the nidus content was done and sent for histo pathological examination – diagnosis of osteoid osteoma was confirmed.

Nidus was ablated in two locations(cranial and caudal) by two bone tracts. Calories ablated were 1.27 Kcal and 1.6 Kcal respectively for 5 minutes each.

Injection lignocaine 2 ml was injected into the nidus at the end of the procedure.

The duration of the procedure was 120 minutes.

BONE TRACTS – RADIO FREQUENCY ABLATION

The image above is a post procedural x ray showing needle tracts.

Image above shows needle tracts taken during Radio Frequency Ablation(coronal).

Above images show needle tracts in various sections

POST PROCEDURE

The patient reported to have immense pain relief without any analgesics the very next day.

Complaining of pain only at skin entry site.

Normal sleep in the night.

Patient was advised to avoid vigorous activities, sports such as jumping long distance running for a month.

This was the first Radio frequency Ablation procedure done in the Pondicherry territory.

FOLLOW UP

A follow up X ray of pelvis was done after 30 days – needle tracts were evident.

No fresh complaints from the patient.

Bone pain relieved.

No other delayed complications were reported.

The post procedural period was uneventful

DISCUSSION

An Osteoid osteoma is a benign skeletal tumour usually less than 1.5 cm in diameter.

Composed of woven bone and an osteoid and more located in the appendicular bone.

Focal pain at the tumour site.

Pain worsens in the night and increases with activity and is relieved with analgesics and inflammatory medications.

The pain is presumed to be a result of local vasodilatation resulting from elevated levels of PGE2 at the site of the tumour.

Spinal osteoid osteoma may in addition lead to scoliosis.

These tumours usually regress spontaneously , the mechanism probably being bone infarction.

CONCLUSION

Difficulty in lesion localization, consequences of extensive dissection and need for prolonged recuperation and risk of incomplete removal and therefore recurrence of the lesion make surgery a less desired option.

Radio Frequency Ablation is proved to be safe, quick and minimally invasive method of management.

We were able to achieve a high technical and clinical success without any complications. Percutaneous Radio Frequency Ablation should be the method of choice for treating extra spinal osteoid osteoma.

REFERENCES

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Rosanthal DI, Marota JJA, Hornicok FJ osteoid osteoma :elevation of respiratory and cardiac rates at the biopsy needle entry into the tumour in 10 patients, Radiology 2003,226: 125-128 (abstract medicine)

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