Osteoid osteoma of the spine: CT-guided monopolar radiofrequency ablation

CT-guided percutaneous radiofrequency ablation and laser photocoagulation have become the methods of choice for the treatment of all osteoid osteomas except those in contact with neural structures.We report 10 patients with spinal osteoid osteoma adjacent to the neural elements treated with 12 sessions of CT-guided monopolar radiofrequency ablation. The size range of the lesion was 3-14 mm (mean, 7.5 mm) and the distance between the nidus and the adjacent spinal cord or nerve root was 2-12 mm (mean, 5 mm). No intact cortex between the tumor and the spinal cord or nerve roots constituted an exclusion criterion because of a higher risk of undesirable neurotoxic effects.Patients were under general anesthesia. After location of the lesion, a 11G-bone biopsy was introduced into the nidus. The radiofrequency electrode was inserted through the biopsy needle and heated at 90 °C for 4 min.Primary success was obtained in eight patients.At follow-up (mean, 19.5 months; range, 6-24 months), pain persisted in two patients after 2 months. Both of them were re-treated. All patients are currently pain-free and complications were not detected.In our opinion, radiofrequency ablation can also be considered the treatment of choice for spinal osteoid osteoma.     

Osteoid osteoma: percutaneous treatment with radiofrequency energy

PURPOSE: To report our experience with technical success, complications, and long-term clinical success of radiofrequency (RF) ablation of osteoid osteoma. MATERIALS AND METHODS: After needle biopsy, computed tomography (CT)-guided percutaneous RF ablation was performed with general or spinal anesthesia. With an RF electrode, the lesion was heated to 90 degrees C for 6 minutes. Patient age and sex, lesion size and location, biopsy results, and complications were recorded. Clinical success was assessed at a minimum of 2 years after the procedure. Significance of patient age and sex and lesion location and size as a predictor of biopsy result was tested by means of chi2 analysis. In addition, effects of patient age and sex, lesion location and size, and biopsy results on clinical success were tested with the Fisher exact test. RESULTS: During an 11-year period, 263 patients who were suspected of having osteoid osteoma underwent 271 ablation procedures. All procedures were technically successful. There were two anesthesia-related complications (aspiration, cardiac arrest) and two minor procedure-related complications (cellulitis, sympathetic dystrophy). Results at biopsy were positive in 73% (197 of 271 biopsies). Two-year follow-up data were available for 126 procedures. The other procedures had been performed more recently or the patients could not be contacted. There was complete relief of symptoms after 112 of the 126 procedures (89%). For procedures performed as the initial treatment, the success rate was 91% (107 of 117 procedures). Procedures for recurrent lesions had a significantly lower success rate (six of 10 procedures [60%], P <.001). Clinical outcome was not dependent on biopsy result, patient age or sex, or lesion size or location. CONCLUSION: CT-guided percutaneous RF ablation of osteoid osteoma is a safe and effective technique.     

Osteoid osteoma: CT-guided percutaneous radiofrequency ablation and follow-up in 47 patients

PURPOSE: To evaluate computed tomography (CT)-guided radiofrequency (RF) ablation as a minimally invasive therapy for osteoid osteoma with regard to technical and clinical success and immediate and delayed complications. MATERIALS AND METHODS: Forty-seven patients (age range, 8-41 y; mean age, 19.6 y) with osteoid osteomas (femur, n = 25; tibia, n = 15; pelvis, n = 2; humerus, n = 1; ulna, n = 1; talus, n = 1; calcaneus, n = 1; vertebral body, n = 1) were treated with CT-guided RF ablation in 15 cases after one (n = 10) or two (n = 5) unsuccessful attempts at open surgical resection. Percutaneous therapy was performed with use of general or spinal anesthesia. After localization of the nidus with 1-3-mm CT sections, osseous access was established with either a 2-mm coaxial drill system or an 11-gauge Jamshidi needle. RF ablation was performed at 90 degrees C for a period of 4-5 minutes with use of a rigid RF electrode with a diameter of 1 mm. The procedures were regarded as technically successful if the tip of the RF electrode could be placed within the center of the nidus and could be heated to the desired temperature. Clinical success of treatment was defined as permanent relief of pain and return to normal function without additional treatment. In case of persistence or recurrence of symptoms after RF ablation, treatment was regarded as secondarily successful if permanent relief of symptoms could be achieved in a second procedure. RESULTS: All procedures were technically successful. Clinical success was achieved in 94% of patients (44 of 47). Three patients had recurrence of pain 3, 5, and 7 months after treatment, respectively (mean observation interval, 22 mo). All recurrences were treated successfully in a second procedure (secondary success rate, 100%). No immediate or delayed complications were observed. CONCLUSION: CT-guided percutaneous RF ablation is a simple, minimally invasive, safe and highly effective technique for treatment of osteoid osteoma.     

Radiofrequency Ablation of Osteoid Osteoma: Initial Experience with a New Monopolar Ablation Device

The purpose of this article is to report our initial experience with the “off-label” use of a new monopolar radiofrequency (RF) probe for percutaneous ablation of osteoid osteomas. Seventeen patients (12 male and 5 female, mean age 24.8 [range 9–49]) with osteoid osteoma were treated by computed tomography (CT)-guided RF ablation (RFA). All procedures were performed with the patient under general aesthesia. After localization of the nidus, a 13G hollow drill was introduced into the nidus through a 7F introducer sheath. A monopolar 16.5G RF probe with a 9-mm active tip (Soloist; Boston Scientific, Natick, MA) was inserted through the introducer sheath and connected to the RF generator. Energy application was started at 2 W and subsequently increased every 2 min by 1 W to a maximum of 8 W. The procedure ended if impedance increased by 500 Ω. Mean duration of energy deposition was 14.2 ± 3.3 min. Fourteen of 17 patients (82%) were free of symptoms at 29.9 ± 14.8 (range 4 to 47) months of follow-up. The primary and secondary success rates were 83% and 100%, respectively. In 3 patients, recurrence of pain at 6 (n = 1) and 15 (n = 2) months after the initial procedure was successfully treated by reablation. There were no complications. Monopolar RFA using the Soloist probe is effective and safe for the treatment of osteoid osteoma. It results in comparable success rates as other monopolar or bipolar RF systems in the treatment of osteoid osteoma.     

Percutaneous radio-frequency ablation of osteoid osteoma: technique and preliminary results]

PURPOSE: To report our personal experience with the percutaneous technique for in situ destruction of osteoid osteoma using radio-frequency ablation. MATERIAL AND METHODS: From January 2000 to January 2001 we performed 16 radio-frequency ablations in 15 patients. All candidates for treatment had previously undergone clinical and radiologic examinations to confirm features typical of osteoid osteoma. After administration of spinal anesthetic, procedures were performed with CT-guidance, using a Kirschner wire introduced into the localized lesion, and a guiding cannula. A hole was first cut into the bone with a cutter, then a few biopsy specimens were obtained with a Jamshidi needle. Finally, we introduced a small radio-frequency electrode into the bone, through the biopsy track. Sufficient current was used to heat the electrode tip to 85-90 degrees C with consequent thermal necrosis of the tissue. The healing was continued for 6 minutes. RESULTS: All patients well tolerated the percutaneous procedure and only 1 underwent a second, successful radio-frequency ablation. In all cases, pain relief was noted to occur very rapidly and all patients could bear full weight on the treated extremity within 24 hours after the procedure. No late complications attributable to the ablation were noted, except for a small eschar next to the puncture site. DISCUSSION AND CONCLUSIONS: The results of the present study suggest that percutaneous ablation is preferred to operative excision because it generally requires shorter hospital stay and is not associated with complications. Furthermore, in our experience, pain relief was noted to occur very rapidly in 100% of cases. In agreement with the literature data, our results show that CT-guided percutaneous radio-frequency ablation can actually replace operative excision in the treatment of osteoid osteoma as it achieves the same clinical outcomes with significantly lower costs.     

Osteoid osteoma of the femur in a 7-month-old infant treated with radiofrequency ablation

Osteoid osteoma occurs most commonly in children, adolescents, and young adults between the ages of 5 and 30 years. In the preschool age group, it is quite uncommon, accounting for only 3–8% of all osteoid osteoma cases. We report a case of osteoid osteoma in a 7-month-old infant, who presented with decreased use of the right lower extremity due to pain. Magnetic resonance imaging (MRI) showed an atypical appearance. A biopsy of the lesion, with histopathological examination, confirmed the diagnosis of osteoid osteoma. Radiofrequency ablation (RFA) of the nidus under computed tomography (CT) guidance was performed. The patient developed a recurrence after 3 months, which was treated with a second RFA. On subsequent follow-up, the infant did not show signs of pain after 1 month. In summary, this case report shows that osteoid osteoma can present in early infancy and can be successfully treated with RFA at this age, however, recurrence after the procedure can occur and close follow-up is recommended.     

CT-guided percutaneous laser photocoagulation of osteoid osteomas of the hands and feet

Percutaneous local ablation of osteoid osteoma has largely replaced surgery, except in the small bones of the hands and feet. The objective of this study was to describe the technical specificities and results of computed tomography (CT)-guided percutaneous laser photocoagulation in 15 patients with osteoid osteomas of the hands and feet. We retrospectively examined the medical charts of the 15 patients who were treated with CT-guided percutaneous laser photocoagulation therapy at our institution between 1994 and 2004. The 15 patients had a mean age of 24.33 years. None of them had received any prior surgical or percutaneous treatment for the osteoid osteoma. The follow-up period was 24 to 96 months (mean, 49.93). The pain resolved completely within 1 week. Fourteen patients remained symptom-free throughout the follow-up period; the remaining patient experienced a recurrence of pain after 24 months, underwent a second laser photocoagulation procedure, and was symptom-free at last follow-up 45 months later. No adverse events related to the procedure or to the location of the tumor in the hand or the foot were recorded. CT-guided percutaneous laser photocoagulation is an alternative to surgery for the treatment of osteoid osteomas of the hands and feet.     

Percutaneous radiofrequency ablation of spinal osteoid osteoma under CT guidance

Objective:

Osteoid osteoma (OO) accounts for approximately 10–12% of all benign bone tumours and 3% of all bone tumours. Spinal involvement appears in 10–25% of all cases. The purpose of this study was to evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation in the treatment of spinal OOs and report our experience.

Methods:

13 patients suffering from spinal OO and treated at the authors'' institution using CT-guided RF ablation were retrospectively evaluated. The RF probe was introduced through a 11-G Jamshidi® needle, and the lesion was heated at 90 ^°C for 6 min.

Results:

All procedures were considered technically successful as the correct positioning of the probe was proven by CT. 11 of the 13 patients reported pain relief after RF ablation. In two cases, RF ablation was repeated 1 month after the first procedure. Pain relief was achieved in both cases after the second procedure. No recurrence was reported throughout the follow-up. No complications like skin burn, soft-tissue haematoma, infection, vessel damage or neurological deficit were reported.

Conclusion:

This study demonstrates that CT-guided percutaneous RF ablation is a safe and effective method for the treatment of spinal OOs.

Advances in knowledge:

The data of this study support the efficacy and safety of the recently applied CT-guided percutaneous RF ablation technique for the treatment of spinal OOs.Osteoid osteoma (OO) represents a benign bone tumour first described by Jaffe¹ in 1935. The lesion accounts for approximately 10–12% of all benign bone tumours and 3% of all bone tumours. It is characterized by a nidus, consisting of osteoid, osteoblasts and fibrovascular stroma, surrounded by sclerotic bone usually measuring <1.5 cm in diameter. OOs are characteristically seen in children and young adults with a predilection for long bones, particularly in lower extremities.² Spinal involvement usually affecting the posterior elements appears in 10–25% of all cases.^3,4 The typical symptom is localized pain typically worsening at night, ameliorated by the administration of salicylates (acetylsalicylic acid) or non-steroidal anti-inflammatory drugs (NSAIDs). In spinal cases of OO, radiation of pain distally to the lesion site might simulate radiculopathy similar to disc herniation especially if the lesion is located close to a nerve root. Painful antalgic scoliosis is frequent in thoracolumbar lesions in children and adolescents.^5,6 Spinal lesions are usually difficult to diagnose, and the reported delay from presentation to final diagnosis and treatment can be as long as 24 months in some cases.^7–9 Neurologic deficit does not generally appear.In the past, conventional surgical excision and more recently minimally invasive surgery techniques were the treatment of choice in cases of spinal OOs when conservative treatment with anti-inflammatory and salicylates fails or is contraindicated.^10–15Rosenthal et al¹⁶ first introduced percutaneous radiofrequency (RF) ablation for the treatment of OOs. The effectiveness of RF ablation of OOs localized in the extremities and pelvis has been proven by many studies.^16–19Percutaneous RF ablation for the treatment of spinal OOs is not widely used, probably owing to the potential danger to the adjacent neural and vascular elements. In recent years, however, some clinical studies reported good results in the management of spinal OOs using CT-guided RF ablation.^8,20–23The purpose of this study was to evaluate the safety and efficacy of CT-guided RF ablation in the treatment of spinal OOs and report our experience.     

Recurrent osteoid osteoma: interstitial laser ablation under magnetic resonance imaging guidance

Thermal ablation has become a therapy of choice in the treatment of osteoid osteomas. To date, computed tomography has been the standard imaging modality for minimally invasive treatment regimes. We report a case of a 46-year-old man with a recurrent osteoid osteoma in the right tibial head after CT-guided drill excision and repeat treatment with laser ablation under open high-field MRI guidance. We describe the steps of the interventional MRI procedure and discuss related innovative guidance and monitoring features, and potential benefits of MRI compared with CT-guided techniques. In conclusion, MR-guided laser ablation was proved to be safe and effective.     

A Bicentric Propensity Score Matched Study Comparing Percutaneous Computed Tomography–Guided Radiofrequency Ablation to Magnetic Resonance–Guided Focused Ultrasound for the Treatment of Osteoid Osteoma

PurposeTo assess the safety and efficacy of computed tomography–guided radiofrequency (RF) ablation and magnetic resonance–guided focused ultrasound (MRgFUS) in the treatment of osteoid osteoma with a long-term follow-up study.Materials and MethodsDatabase research was performed at 2 different centers with experience in musculoskeletal interventions. Both centers, one performing RF ablation and the other MRgFUS, identified 116 patients who underwent either RF ablation or MRgFUS procedures for the treatment of symptomatic osteoid osteoma and retrospectively evaluated data regarding pain scores using a visual analog scale (VAS). Complications were recorded according to the Cardiovascular and Interventional Radiological Society of Europe classification system. Propensity score matching for multiple variables was performed. Pain scores before and after therapy were compared.ResultsOf 116 patients treated, 61 and 55 underwent RF ablation and MRgFUS, respectively. Before treatment, the mean reported pain in the 2 groups were 9.1 ± 0.88 (RF ablation) and 8.7 ± 0.73 (MRgFUS) VAS units. After treatment, a statistically significant (P < .00001) overall reduction in pain symptomatology was recorded. No statistically significant difference was observed between the mean values of pain after treatment in both groups (P = .256). Over a mean of >2 years of follow-up, 4 cases of relapse (RF ablation, 1; MRgFUS, 3) and 1 complication (RF ablation) were observed. The analysis from propensity score matching that identified a matched cohort of 48 patients showed similar results.ConclusionsThe 2 techniques for the treatment of osteoid osteoma resulted in profound and similar pain relief. The presence of thick cortical bone over the nidus can reduce the effectiveness of MRgFUS.     

Percutaneous radiofrequency treatment of osteoid osteoma using cool-tip electrodes

ObjectivesTo report our experience with percutaneous cool-tip radiofrequency ablation of osteoid osteomas and to evaluate clinical outcome.Methods and materialForty-one patients with clinically and radiologically suspected osteoid osteoma were seen over a 48-month period (27 males and 14 females with a mean age of 18.7 years; range 5–43 years). Thirty-eight patients were treated by computed tomography (CT)-guided percutaneous radiofrequency ablation.The procedure was performed under regional or general anaesthesia. After location of the nidus, a 14G-bone biopsy needle is introduced into the nidus. Sampling is performed with a 17G-bone biopsy needle using a coaxial technique. The radiofrequency needle with a 10 mm active tip (cool-tip) is inserted through the biopsy needle and is connected to the radiofrequency generator for 6–8 min.ResultsPrimary success was obtained in 37 patients (97%) with a 100% secondary success rate. All patients are currently pain-free. No major complications occurred. Patients could resume unrestricted normal activity within 24 h.ConclusionsPercutaneous radiofrequency ablation of osteoid osteomas is an efficient and safe method that can be considered the procedure of choice for most cases.     

Percutaneous Biopsy and Radiofrequency Ablation of Osteoid Osteoma with Excess Reactive New Bone Formation and Cortical Thickening Using a Battery-Powered Drill for Access: A Technical Note

Purpose

To report our experience with the use of a battery-powered drill in biopsy and radiofrequency ablation of osteoid osteoma with excess reactive new bone formation. The battery-powered drill enables obtaining the sample while drilling.

Materials and Methods

During the last 18 months, 14 patients suffering from painful osteoid osteoma with excess reactive new bone formation underwent CT-guided biopsy and radiofrequency ablation. In order to assess and sample the nidus of the osteoid osteoma, a battery-powered drill was used. Biopsy was performed in all cases. Then, coaxially, a radiofrequency electrode was inserted and ablation was performed with osteoid osteoma protocol. Procedure time (i.e., drilling including local anesthesia), amount of scans, technical and clinical success, and the results of biopsy are reported.

Results

Access to the nidus through the excess reactive new bone formation was feasible in all cases. Median procedure time was 50.5 min. Histologic verification of osteoid osteoma was performed in all cases. Radiofrequency electrode was coaxially inserted within the nidus and ablation was successfully performed in all lesions. Median amount CT scans, performed to control correct positioning of the drill and precise electrode placement within the nidus was 11. There were no complications or material failure reported in our study.

Conclusions

The use of battery-powered drill facilitates access to the osteoid osteoma nidus in cases where excess reactive new bone formation is present. Biopsy needle can be used for channel creation during the access offering at the same time the possibility to extract bone samples.

     

Percutaneous Biopsy of Osteoid Osteomas Prior to Percutaneous Treatment Using Two Different Biopsy Needles

Biopsy is usually performed as the first step in percutaneous treatment of osteoid osteomas prior to laser photocoagulation. At our institution, 117 patients with a presumed diagnosis of osteoid osteoma had a trephine biopsy before a percutaneous laser photocoagulation. Biopsies were made using two different types of needles. A Bonopty biopsy needle (14-gauge cannula, 16-gauge trephine needle; Radi Medical Systems, Uppsala, Sweden) was used in 65 patients, and a Laurane biopsy needle (11-gauge cannula, 12.5-gauge trephine needle; Laurane Medical, Saint-Arnoult, France) in 43 patients. Overall biopsy results were positive for osteoid osteoma in 83 (70.9%) of the 117 cases. The Laurane needle provided a significantly higher positive rate (81.4%) than the Bonopty needle (66.1%; p < 0.05). This difference was not due to the size of the nidus, which was similar in the two groups (p < 0.05) and may be an effect of differences in needle caliber (12.5 vs. 14 gauge) as well as differences in needle design. The rate of positive biopsy results obtained in the present series with the Laurane biopsy needle is, to our knowledge, the highest rate reported in series dealing with percutaneous radiofrequency ablation and laser photocoagulation of osteoid osteomas.     

Percutaneous laser photocoagulation of osteoid osteomas under CT guidance

AIM: The aim was to evaluate laser photocoagulation and the use of the Bonopty needle system in the treatment of osteoid osteoma. MATERIALS AND METHODS: Five patients with osteoid osteomas were treated with computed tomography (CT)-guided, percutaneous laser photocoagulation using the Bonopty biopsy system. RESULTS: Complete pain relief was obtained in four patients. In one patient, pain persisted until the 6 weeks follow-up but resolved within 24 h of repeating the procedure. There were no complications, and patients remained symptom free at follow-up of 4-23 months (mean, 14 months). CONCLUSION: CT-guided laser photocoagulation of osteoid osteoma is a minimally invasive technique that represents a cost-effective alternative to surgical excision. The Bonopty needle system allows successful penetration of the sclerotic bone surrounding the nidus with manual pressure alone.     

Radiofrequency ablation of osteoid osteoma: initial results with a bipolar ablation device

PURPOSE: To report the initial results with percutaneous radiofrequency (RF) ablation of osteoid osteomas with a bipolar ablation device. MATERIALS AND METHODS: Twelve patients (seven male patients and five female patients; mean age, 17.3 years; age range, 6-36 y) with clinically and radiologically suspected osteoid osteoma were treated with computed tomography-guided percutaneous bipolar RF ablation. The procedure was performed with the patients under general anesthesia. After localization of the nidus, an 11-gauge hollow drill was introduced into the nidus through a 9-F introducer sheath. A bipolar 18-gauge RF probe with a 9-mm active tip was inserted through the introducer sheath and connected to the RF generator. Energy application was started at 2 W and subsequently increased to a maximum of 5 W. The procedure was terminated if a resistance of 900 Omega was reached. RESULTS: Mean duration of energy deposition was 8.3 +/- 4.0 minutes, with a mean energy application of 1.8 +/- 2.9 kJ (range, 0.3 - 7 kJ). In one patient, the intervention had to be repeated twice to achieve total pain relief. Eleven of 12 patients (92%) remained free of symptoms at a follow-up time of 15.1 +/- 9.5 months (range, 5 - 31 months). One patient had recurrence of pain 16 months after the procedure and was treated surgically. No complications occurred. Patients resumed normal activity within 24 hours. CONCLUSIONS: Percutaneous bipolar RF ablation is an efficient and safe treatment of osteoid osteoma. Short-term efficacy of bipolar RF ablation may rival the results of monopolar RF ablation. Further studies are needed to address the long-term efficacy of this technique.     

Intra-articular hip joint osteoid osteoma: Challenging diagnosis and percutaneous radiofrequency ablation treatment

Atypical intra-articular osteoid osteoma can be difficult to diagnose and challenging to treat. We report a case of a right acetabular subchondral intra-articular osteoid osteoma in a young male patient which was initially diagnosed as femoroacetabular impingement due to its atypical clinical and radiological presentations. After fully working up the patient the lesion was successfully treated with percutaneous CT-guided low-power bipolar radiofrequency ablation using several per procedural articular cartilage thermal protective measures including intra-articular thermocouple, and continuous per procedural joint space cooling with Dextrose 5% solution. A precise RFA electrode placement, using the No-touch technique, and applying different passive and active thermal protective measures were helpful in avoiding collateral damage of the hip joint articular cartilages. atypical intra-articular osteoid osteomas necessitate pertinent correlation between the clinical and radiological presentations. As far as intra-articular or subchondral nidus ablation is concerned, thermal protective measures should be considered.     

Percutaneous radiofrequency thermocoagulation of osteoid osteomas: factors affecting therapeutic outcome

Objective To examine factors which affect local recurrence of osteoid osteomas treated with percutaneous CT-guided radiofrequency thermocoagulation.Design and patients A prospective study was carried out on 45 patients with osteoid osteoma who underwent percutaneous radiofrequency thermocoagulation with a minimum follow-up of 12 monthsResults There were seven local recurrences (16%); all occurred within the first year. Local recurrence was significantly related to a non-diaphyseal location (P<0.01). There was no significant relationship (P=0.05) between local recurrence and age of the patient, duration of symptoms, previous treatment, size of the lesion, positive biopsy, radiofrequency generator used or the number of needle positions. There were no complications.Conclusions Osteoid osteomas in a non-diaphyseal location are statistically more likely to recur than those in a diaphyseal location when treated with CT-guided percutaneous radiofrequency thermocoagulation. This relationship between local recurrence and location has not been previously reported.     

CT-guided percutaneous cryoablation of osteoid osteoma in children: an initial study

Objective  

The purpose of this study was to evaluate the safety and efficacy of CT-guided percutaneous cryoablation for osteoid osteoma in children.     

CT-guided radiofrequency ablation of osteoid osteoma: long-term results

The aim of the study was to assess the safety and efficacy of CT-guided percutaneous radiofrequency (RF) ablation of osteoid osteoma (OO). From 1997 to 2001, RF ablation was performed on 38 patients with OO, diagnosed clinically and by radiography, scintigraphy, contrast-enhanced MRI, and CT. Treatment was performed via percutaneous (n=29) or surgical (n=9) access, under CT guidance in all cases, with an 18-gauge straight electrode. Patients were discharged within 24 h and followed up clinically (at 1 week and every 6–12 months) and with MRI (at 6 months) and scintigraphy (after 1 year). The technical success rate was 100%. Complications occurred in two patients, consisting in local skin burns. The follow-up range was 12–66 months (mean ± SD, 35.5±7.5 months). Prompt pain relief and return to normal activities were observed in 30 of 38 patients. Persistent pain occurred in eight patients; two patients refused further RF ablation and were treated surgically; RF ablation was repeated in six cases achieving successful results in five. One patient reported residual pain and is being evaluated for surgical excision. Primary and secondary clinical success rates were 78.9 (30/38 patients) and 97% (35/36 patients), respectively. CT-guided RF ablation of OO is safe and effective. Persistent lesions can be effectively re-treated. Several imaging modalities are needed for the diagnosis of OO and for the follow-up after treatment, particularly in patients with persistent symptoms.     

Percutaneous resection under computed tomography guidance of osteoid osteoma. Mid-term follow-up of 38 cases]

PURPOSE: To evaluate the mid-term outcome following CT-guided percutaneous resection of osteoid osteoma. MATERIALS AND METHODS: 38 patients who had been treated by CT-guided percutaneous resection were included. The mean follow-up of 3.7 years. Early and mid-term outcome and histology were analyzed. RESULTS: Histological samples were adequate in 92% of cases and a diagnosis of osteoid osteoma was confirmed in 73.7% of cases. In 6 cases, the lesion was not an osteoid osteoma: 2 mucoid cysts, 1 benign fibrous dysplasia, 1 fibromucoid lesion, 1 focal osteochondritis, 1 osteomyelitis. Cure was achieved in 84.2% of patients. Minor transient complications occurred in 23.7% of cases. The most serious complications included: 1 intramuscular hematoma, 2 femoral fractures, and 1 case of S. aureus osteomyelitis. CONCLUSION: This study confirms that CT-guided percutaneous resection of osteoid osteomas is effective and shows that other small lesions can also be treated using this technique.