PMC7476701_01
(a-d) Anteroposterior and lateral radiographs of the knee in a young male with anterior knee pain. No gross abnormality was detectable. (c) T2-weighted sagittal magnetic resonance imaging (MRI) section showing patellar edema. (d) T2-weighted axial MRI section showing a hypointense punctate lesion surrounded by a small hyperintense zone near the medial border of patella, close to its articular surface (arrow).
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F1
On magnetic resonance imaging (MRI), a hypointense, punctate lesion surrounded by a small hyperintense zone (edema) was noted at medial aspect of patella, close to its articular surface (Fig. 1).
(a and b) Computed tomography scan of the patient (a) coronal reformat, (b) sagittal reformat, and (c) axial cut showing central nidus surrounded by minimal sclerosis.
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F2
A CT scan was done next, which showed the lesion with a central nidus, surrounded by a sclerotic rim, confirming the diagnosis of osteoid osteoma (Fig. 2).
(a and b) Percutaneous computed tomography-guided radiofrequency ablation (a) insertion of guide wire through the dorsal approach, (b) the guide wire is in position and would be replaced by the radiofrequency probe.
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F3
Once the K-wire was in place, it was replaced with a radiofrequency ablation probe, 0.7 cm in diameter and 14.4 cm long (Cool-tipTM, Medtronic) (Fig. 3).
(a-c) At 1-year follow-up, the patient has no quadriceps wasting, no extensor lag, and full flexion of the knee.
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F4
The quadriceps wasting had improved significantly and he had full range of motion (Fig. 4).