This is a 15-years old boy with a posterior tibial mid-diaphyseal osteoid osteoma. A radiofrequency ablation (RFA) procedure was performed.
The approach was through the anterior cortex to avoid potential injury to other structures with posterior or lateral approaches. The electrode was placed in the lesion (Figs. 1, 2) and the ablation was performed at 90 deg C for 5 minutes.
A repeat MRI performed a week later shows the tract well (Fig. 3) as well as the zone of ablation (arrow).
RFA is the method of choice for treating osteoid osteomas. The results compare very favorably with surgery, but with hardly any associated morbidity. Since the procedure is performed under deep sedation in an OPD /day care setting, the patient is ready to resume a normal routine within 24 hours.
One of the complications of a simple bone cyst is fracture. The fracture is often transverse and one sign that is touted is the "fallen fragment sign", due to fragments of bone that are seen in the dependent portion on erect images (Fig. 1) - usually in the inferior aspect of the cyst. Even on MRI, which is performed in the supine position, bone fragments may be seen in the inferior aspect (Figs. 2, 3).
When the infection involves a dilated PC system, there is pyonephrosis, as in this patient with a calculus in the lower third with hydronephrosis. There is reduced function with enhancement of the walls of the pelvis and calyces (Fig. 1). A focal parenchymal lesion is also noted (Fig. 2).