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

A Narrative Review of Osteoid Osteomas and an Audit on the Practice of CT-Guided Radiofrequency Ablation in the Northern Irish Population: A First in the Literature

Introduction Osteoid osteoma is a benign condition of the bone, usually affecting young males. This retrospective study explores the demographics of osteoid osteomas in the Northern Irish population. It also aims to audit the practice of CT-guided radiofrequency ablation of osteoid osteomas at a major orthopaedic centre in Belfast, Northern Ireland, and to investigate the possible causes of treatment failure. Methods Forty-seven osteoid osteoma patients, diagnosed based on clinico-radiologic features and treated with CT-guided radiofrequency ablation, were found eligible for inclusion and analysis. We collected data from electronic health records (March 2011 to May 2022) and reviewed the radiological images and associated reports. Information about demographics, clinical indices, operative technique, clinical outcomes, biopsy results, and follow-up were also gathered. Data were then analysed using IBM SPSS Statistics for Mac, version 28.0.1.1 (14) (IBM Corp., Armonk, NY). Results The average age of patients was 19.3 years, with a male-to-female predilection of 2.1:1. The proximal and mid-tibial shafts were the most frequently involved sites. On average, patients had symptoms for 15.6 months, while the mean treatment delay period was 6.9 months. Primary clinical success was observed in 37 patients (78.7%), while ten patients had a clinical failure. Two out of the 10 patients with treatment failure underwent subsequent successful ablations, raising the secondary clinical success rate to (83.0%). Chi-Square association tests found no correlation between primary treatment outcomes and other qualitative variables (gender, bone type, lesion location, and Kayser classification). Moreover, binary logistic regression tests found no predictability of age and treatment delay on treatment outcomes. The overall observed complication rate was 4%, with only one significant side effect reported (third-degree skin burn). Conclusion We concluded that the demographics of osteoid osteomas in the Northern Irish population are comparable to what is previously established in the literature. Furthermore, we reasoned that CT-guided radiofrequency ablation is an efficient, safe, and effective minimally invasive technique in the management of osteoid osteomas.

Radiofrequency ablation is as safe and effective as surgical excision for spinal osteoid osteoma: a systematic review and meta-analysis

BACKGROUND

Osteoid osteoma (OO) is a primary benign tumor that affects mainly young patients. Ten percent of all OO are located in the vertebral column. Treatment of spinal OO is challenging and there is no consensus in the literature on the best operative approach.

PURPOSE

The aim of this systematic review and meta-analysis was to determine safety and efficacy of radiofrequency ablation (RFA) versus surgical excision for the treatment of spinal OO.

METHODS

A literature search was performed on PubMed, Web of Science, and Embase from inception up to 22 March 2022. Studies addressing surgical excision or RFA for the treatment of spinal OO were included. The main outcomes evaluated were pain before and after intervention, the treatments success rate, defined as complete pain relief with no recurrence until the last follow-up, and the number and type of complications.

RESULTS

Thirty-one studies (749 patients) were included. For patients who underwent surgical excision, 19 studies reported a mean treatment success rate of 85.6%, while in the RFA treatment group, 18 studies reported a mean success rate of 88.6%. At last follow-up, the pooled mean difference in pain scores from baseline on a 0-10 scale was 5.8 points in the surgical excision group and 6.7 points in the RFA group. Recurrences were observed in 5.6% of the patients who underwent surgical excision and in 6.7% of the patients treated with RFA. The complication rate was 7.8% in the surgical excision group and 4.4% in the RFA group.

CONCLUSIONS

This meta-analysis found high global success rates for both surgical and RFA treatments. Both treatments were efficient in pain relief and presented a low rate of recurrences. The complication rate was low for both treatments. Compared to surgical excision, RFA is a less invasive procedure which proved to be a safe and as effective option for the treatment of spinal OO.

Radiofrequency ablation for spinal osteoid osteoma: A systematic review of safety and treatment outcomes

AIM

We sought to systematically assess and summarize the available literature on the clinical outcomes and complications following radiofrequency ablation (RFA) for painful spinal osteoid osteoma (OO).

METHODS

PubMed, Scopus, and CENTRAL databases were searched in accordance with PRISMA guidelines. Studies with available data on safety and clinical outcomes following RFA for spinal OO were included.

RESULTS

In the 14 included studies (11 retrospective; 3 prospective), 354 patients underwent RFA for spinal OO. The mean ages ranged from 16.4 to 28 years (Females = 31.3%). Lesion diameters ranged between 3 and 20 mm and were frequently seen in the posterior elements in 211/331 (64%) patients. The mean distance between OO lesions and neural elements ranged between 1.7 and 7.4 mm. The estimated pain reduction on the numerical rating scale was 6.85/10 (95% confidence intervals [95%CI] 4.67-9.04) at a 12-24-month follow-up; and 7.29/10 (95% CI 6.67-7.91) at a >24-month follow-up (range 24-55 months). Protective measures (e.g., epidural air insufflation or neuroprotective sterile water infusion) were used in 43/354 (12.1%) patients. Local tumor progression was seen in 23/354 (6.5%) patients who were then successfully re-treated with RFA or open surgical resection. Grade I-II complications such as temporary limb paresthesia and wound dehiscence were reported in 4/354 (1.1%) patients. No Grade III-V complications were reported.

CONCLUSION

RFA demonstrated safety and clinical efficacy in most patients harboring painful spinal OO lesions. However, further prospective studies evaluating these outcomes are warranted.

CT-guided radiofrequency ablation for osteoid osteomas: a systematic review

OBJECTIVES

CT-guided radiofrequency ablation (CT-RFA) is considered to be the gold standard for treatment of osteoid osteoma (OO) yet treatment failures (TFs) continue to be reported. This systematic review was conducted to evaluate factors associated with TF, such as ablation time, lesion location, and patient age as well as evaluating how TF has trended over time.

METHODS

Original studies reporting on patients undergoing CT-RFA of OO published between 2002 and 2019 were identified. TF was defined as patients with (1) recurrent or persistent pain +/- (2) imaging evidence of persistent OO. TFs were subdivided into those occurring after the index procedure (primary TF) or those occurring after repeat RFA (secondary TF). Subgroup analysis was performed for TF based on the study date (2002-2010 or 2010-2019), time duration of ablation at 90 °C (6 min or > 6 min), patient age, and tumor location (spinal vs. appendicular).

RESULTS

Sixty-nine studies were included for a total of 3023 patients. The global primary TF rate was 8.3% whereas the secondary TF rate was 3.1%. The TF rate reported in studies published after 2011(7%) was about half that during the earlier time period 2002-2010 (14%). There was no statistical difference in TF corrected for age, OO location, or duration of ablation (respectively p = 0.39, 0.13, and 0.23). The global complication rate was 3%, the most frequent being skin burns (n = 24; 0.7%).

CONCLUSIONS

A decrease in TF observed between 2011-2019 compared to 2002-2010 may reflect improvements in operator technique or advancements in equipment. Duration of ablation, patient age, or location of OO failed to significantly correlate with TF.

KEY POINTS

• CT-guided radiofrequency ablation of osteoid osteomas is a safe technique with a low rate of treatment failure (8.3% failure rate after the primary radiofrequency reducing to 3.1% following a secondary treatment). • The treatment failure rate has decreased over time, possibly due to an improved understanding of the disease process, better technique, and advances in equipment. • Duration of ablation, patient age, or lesion location did not significantly correlate with treatment failure.

Percutaneous thermal ablation for treatment of osteoid osteoma: a systematic review and analysis

OBJECTIVE

Although radiofrequency ablation is well validated for treatment of osteoid osteoma, newer technologies, namely cryoablation, have been less thoroughly studied. The purpose is to perform a systematic review and pooled analysis of percutaneous ablation technologies for treatment of osteoid osteoma with subset analysis of intra-articular and spinal tumors.

MATERIAL AND METHODS

A total of 36 of 79 identified manuscripts met inclusion criteria, comprising 1863 ablations in 1798 patients. Inclusion criteria were (1) retrospective or prospective analysis of thermal ablation of osteoid osteomas in any location, (2) at least 6 months of clinical follow-up, (3) 10 or more patients, (4) patients not included in a second study included in this review, and (5) English language or English translation available. Success rate was defined as all ablations minus technical failures, clinical failures, and recurrences. Subset analysis of intra-articular and spinal tumors was performed.

RESULTS

Overall success rate was 91.9% (95% CI 91-93%). Technical failure, clinical failure, and recurrence rates were 0.3%, 2.1%, and 5.6% respectively. Complications were seen in 2.5% (95% CI 1.9-3.3%) patients. There was no significant difference when comparing radiofrequency ablation and cryoablation (p = 0.92). Success rates for intra-articular (radiofrequency ablation) and spinal tumors (radiofrequency and cryoablation) were 97% and 91.6% respectively.

CONCLUSION

Percutaneous ablation of osteoid osteomas was highly successful with low complication rates. Efficacy of radiofrequency ablation and cryoablation is similar, which is consequential because cryoablation is associated with decreased pain, predictable nerve regeneration, and theoretical immunotherapy benefits. Treatment of more challenging intra-articular and spinal lesions demonstrated similarly high success and low complication rates.

Full endoscopic resection of a lumbar osteoblastoma: technical note

Osteoblastomas are a rare, benign primary bone tumor accounting for 1% of all primary bone tumors, with 40% occurring within the spine. Gross-total resection (GTR) is curative, although depending on location, this can require destabilization of the spine and necessitate instrumented fixation. Through the use of minimally invasive, muscle-sparing approaches, these lesions can be resected while maintaining structural integrity of the spine. The authors present a case report and technical note of a single patient describing the use of a purely endoscopic technique to resect a right L5 superior articulating process osteoblastoma in a 45-year-old woman. The patient underwent an image-guided endoscopic resection of her superior articulating facet osteoblastoma. Intraoperative CT demonstrated GTR. On postoperative examination, she remained neurologically intact with resolution of her pain. At follow-up, she remained pain free. Resection of lumbar osteoblastoma through a fully endoscopic approach was a safe and effective technique in this patient. This technique allowed for GTR without compromising spinal structural integrity, thus eliminating the need for instrumented fixation.

Percutaneous radiofrequency ablation versus open surgical resection for spinal osteoid osteoma

BACKGROUND CONTEXT

Both open surgical resection (OSR) and radiofrequency ablation (RFA) have been reported for spinal osteoid osteoma (OO).

PURPOSE

To verify the clinical safety and efficiency of RFA with OSR in treating spinal OO.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Twenty-eight consecutive patients with spinal OO who underwent either RFA or OSR in our institute between September 2006 and December 2016.

OUTCOME MEASURES

The age, gender, lesion distribution, surgical time, estimated blood loss, complications, local recurrence, visual analogue scale (VAS), and the modified Frankel grade were documented.

METHODS

We retrospectively reviewed 28 patients with spinal OO who had been treated in our hospital from September 2006 to December 2016. Patients were followed at 3, 6, 12, and 24 months after the index surgery. The minimum follow-up period was 12 months. This study was funded by Peking University Third Hospital (Y71508-01) (¥ 400,000).

RESULTS

Twelve and 16 patients were treated with CT-guided percutaneous RFA and OSR, respectively. Spinal OO locations were cervical in 4, thoracic in 4, lumbar in 3, and sacral vertebra in 1 in the RFA group and cervical in 12, thoracic in 1, and lumber in 3 in the OSR group. RFA showed shorter operating time, less blood loss, and less in-hospital stay than open surgery [105.0 ± 33.8 minutes vs. 186.4 ± 53.5 minutes (p < .001), 1 (0 to 5) ml vs. 125 (30-1200) ml (p < .001) and 1 (1-3) days vs. 6 (3-10) days (p < .001), respectively]. At last follow-up, one patient underwent a secondary RFA for recurrence. VAS improvement was 7.5 (3-10) and 6.5 (4-9) (p = .945) in the RFA and OSR groups, respectively. The overall complication rate was 8.3% (1/12) and 18.8% (3/16) in the RFA and OSR groups, respectively.

CONCLUSIONS

If there is sufficient cerebrospinal fluid between the spinal OO lesion and spinal cord/nerve root (more than 1 mm), RFA is effective and safe for treatment of well-selected spinal OO, showing reduced operating time, blood loss, in-hospital stay, and complications compared to OSR. However, OSR is still recommended in cases with spinal cord/nerve root compression.

Radiofrequency ablation of osteoid osteoma: Aiming for excellent outcomes in an Australasian context

INTRODUCTION

To report a series of patients with osteoid osteoma treated by radiofrequency ablation in whom no complications or recurrences occurred.

METHODS

Over a 13-year period, 32 consecutive patients with osteoid osteoma were treated by radiofrequency ablation in an Australasian teaching centre.

RESULTS

All patients had resolution of symptoms with no complication or recurrence.

CONCLUSIONS

This series is further evidence for the use of radiofrequency ablation as the primary treatment for osteoid osteoma.

Percutaneous radiofrequency ablation in osteoid osteoma: Tips and tricks in special scenarios

OBJECTIVES

To define specific characteristics of osteoid osteomas treated with radiofrequency ablation, that may benefit from special technical recommendations.

METHODS

Retrospective analysis of all radiofrequency ablations performed by our group from January 2001 to March 2015. A descriptive study was conducted. We compared our results with the available literature to determine the most frequent special scenarios.

RESULTS

207 radiofrequency ablations were performed in 200 patients. We defined the following scenarios: osteoid osteomas located in the spine, close to neurovacular structures, osteoid osteomas in small bones (hands and feet), intra-articular, deeply located or superficial and lesions with extensive periosteal reaction.

CONCLUSIONS

The scenarios defined required special considerations and technical variations. Implementing the different tips and tricks shown in the article, the most complex osteoid osteomas could be successfully ablated.

Radiofrequency ablation of osteoid osteoma in the atlas: A case report

Osteoid osteoma of the atlas has previously been reported very rarely in the published literature. The traditional standard treatment has been a surgical resection of the nidus. Recently, computed tomography (CT)-guided radiofrequency ablation (RFA) has gained favor as a more precise alternative treatment. Here, we present a case of osteoid osteoma of the C1 lateral mass treated successfully using CT-guided RFA. A 30-year-old woman who presented with a four-month history of occipital and suboccipital pain was treated by CT-guided RFA. The visual analog scale (VAS) assessed the pain before and after RFA. The patient reported significant pain relief and normal activities. The VAS score reduced from 8/7 to 1/0 after the procedure. Therefore CT-guided percutaneous RFA of C1 vertebral osteoid osteoma is a safe and effective method. The technique might be contraindicated when the nidus is less than 2 mm away from the neural structures.

Spinal osteoid osteoma: efficacy and safety of radiofrequency ablation

OBJECTIVE

The aim of this study was to evaluate the efficacy and complications of CT-guided radiofrequency ablation (RFA) of spinal osteoid osteoma (OO).

MATERIALS AND METHODS

Between 2002 and 2012, a total of 61 patients (46 male and 15 female, mean age 26.4 ± 12.7 years) were subjected to RFA for spinal OO. The diagnosis of OO was made after a period of pain and symptoms of 20.6 ± 14.4 months. RFA was performed under conscious sedation and local analgesia. Clinical symptoms were evaluated at 3, 6, and12 months, and at the end of the time of the present investigation. Mean follow-up was 41.5 ± 7.1 months.

RESULTS

The primary efficacy of RFA, complete regression of symptoms, was obtained in 57 out of 61 patients (93.4%). Four out of 61 (6.5%) patients showed a relapse of OO (after 3 months); 2 out of 4 were subjected to a second RFA, the remaining ones were subjected to surgery. There was one complication (case of lower limb paresthesia for 30 days after the ablation) and one possible complication (a disc herniation).

CONCLUSION

CT-guided RFA is an excellent treatment for spinal OO. Our data suggest that this procedure should be considered for the first stage of therapy for this disease.

Benign Spine Lesions: Advances in Techniques for Minimally Invasive Percutaneous Treatment

Minimally invasive percutaneous imaging-guided techniques have been shown to be safe and effective for the treatment of benign tumors of the spine. Techniques available include a variety of tumor ablation technologies, including radiofrequency ablation, cryoablation, microwave ablation, alcohol ablation, and laser photocoagulation. Vertebral augmentation may be performed after ablation as part of the same procedure for fracture stabilization or prevention. Typically, the treatment goal in benign spine lesions is definitive cure. Painful benign spine lesions commonly encountered in daily practice include osteoid osteoma, osteoblastoma, vertebral hemangioma, aneurysmal bone cyst, Paget disease, and subacute/chronic Schmorl node. This review discusses the most recent advancement and use of minimally invasive percutaneous therapeutic options for the management of benign spine lesions.

Evaluation of minimally invasive laser ablation in children with osteoid osteoma

The effects between minimally invasive percutaneous laser ablation and open surgery in the treatment of children with osteoid osteoma were compared in the present study. A total of 72 cases of children with osteoid osteoma were divided into control and observational groups, containing 36 cases in each group. The control group underwent conventional open surgery while the observational group underwent minimally invasive CT guided percutaneous laser ablation. Effects of both operations were compared. The operation duration, blood loss and plaster fixation duration of the observational group were significantly less than those of the control group. The postoperative pain score (VAS) at 1 day and 7 days were significantly lower than that of the control group, the differences were statistically significant (P<0.05). The lesion resection rate, effective rate of bone hyperplasia, effective rate of swelling and effusion and total effective rate of the observational group were significantly higher than those of the control group, the differences were statistically significant (P<0.05). Incidence of adverse reactions of observational group was significantly lower (P<0.05) than that of the control group. However, the difference was not significant when comparing 1-year recurrence rate for the two groups. The minimally invasive percutaneous laser ablation has better surgery effects compared with open surgery in the treatment of children with osteoid osteoma.

Benign Tumors of the Spine: Has New Chemotherapy and Interventional Radiology Changed the Treatment Paradigm?

STUDY DESIGN

Clinically based systematic review.

OBJECTIVE

To determine the role of (A) medical treatment and (B) interventional radiology as either adjuvant or stand-alone treatment in primary benign bone tumors of the spine.

METHODS

A multidisciplinary panel of spine surgeons, radiation oncologists, and medical oncologists elaborated specific focused questions regarding aneurysmal bone cyst, giant cell tumor, and osteoid osteoma. Denosumab, bisphosphonate, interferon, bone marrow aspirate, doxycycline, thermal ablation, and selective arterial embolization were identified as areas of interest for the article. A systematic review was performed through MEDLINE and EMBASE. Recommendations based on the literature review and clinical expertise were issued using the GRADE system.

RESULTS

The overall quality of the literature is very low with few multicenter prospective studies. For giant cell tumor, combination with Denosumab identified 14 pertinent articles with four multicenter prospective studies. Nine studies were found on bisphosphonates and six for selective arterial embolization. The search on aneurysmal bone cyst and selective arterial embolization revealed 12 articles. Combination with Denosumab, Doxycycline, and bone marrow aspirate identified four, two, and three relevant articles respectively. Eleven focused articles were selected on the role of thermal ablation in osteoid osteoma.

CONCLUSION

Alternative and adjuvant therapy for primary benign bone tumors have emerged. Their ability to complement or replace surgery is now being scrutinized and they may impact significantly the algorithm of treatment of these tumors. Most of the data are still emerging and further research is desirable. Close collaboration between the different specialists managing these pathologies is crucial.

LEVEL OF EVIDENCE

N/A.

Phase I/II Multi-Institutional Study of Percutaneous Radiofrequency Ablation for Painful Osteoid Osteoma (JIVROSG-0704)

PURPOSE

This multicenter prospective study was conducted to evaluate the safety and efficacy of percutaneous radiofrequency ablation (RFA) for painful osteoid osteoma (OO).

MATERIALS AND METHODS

Patients with OO (femur: n = 17, tibia: n = 2, humerus: n = 1, rib: n = 1) were enrolled and treated with RFA. In phase I, nine patients were evaluated for safety. In phase II, 12 patients were accrued, and an intent-to-treat analysis was performed on all patients. The primary endpoint was to evaluate the treatment safety. The secondary endpoint was to evaluate the efficacy for pain relief by the visual analogue scale (VAS) at 4 weeks after RFA. Treatment efficacy was classified as significantly effective (SE) when VAS score decreased by ≥5 or score was <2, moderately effective when VAS score decreased by <5-≥2 and score was ≥2, and not effective (NE) when VAS score decreased by <2 or score was increased. Cases where the need for analgesics increased after treatment were also NE.

RESULTS

RFA procedures were completed in all patients. Minor adverse effects (AEs) were observed as 4.8-14.3 % in 12 patients, and no major AEs were observed. Mean VAS score was 7.1 before treatment, 1.6 at 1 week, 0.3 at 4 weeks, and 0.2 at 3 months. All procedures were classified as SE. Pain recurrence was not noted in any patient during follow-up (mean: 15.1 months).

CONCLUSION

RFA is a safe, highly effective, and fast-acting treatment for painful extraspinal OO. Future studies with a greater number of patients are needed.

Primary osseous tumors of the pediatric spinal column: review of pathology and surgical decision making

Spinal column tumors are rare in children and young adults, accounting for only 1% of all spine and spinal cord tumors combined. They often present diagnostic and therapeutic challenges. In this article, the authors review the current management of primary osseous tumors of the pediatric spinal column and highlight diagnosis, management, and surgical decision making.

Spinal interventions

We review the state of the art in imaging-guided percutaneous interventional procedures used to diagnose and/or treat the diverse causes of back pain. These procedures can be used for diagnosis, treatment, or both. They are focused on the vertebral bodies, the facet joints, the intervertebral discs, and the nerve structures.

Resection of benign vertebral tumors by minimally invasive techniques

BACKGROUND CONTEXT

Benign tumors of the vertebrae are generally an uncommon cause for surgery. Complete removal of these tumors requires in most cases extensive surgical technique that consists of generous surgical exposure followed by laminectomy, facetectomy, and sometimes even an instrumented fusion.

PURPOSE

The aim was to describe our experience in performing resection of benign vertebral tumors, using a minimally invasive surgical (MIS) approach.

STUDY DESIGN

This was a retrospective review of case records.

PATIENT SAMPLE

Patients who underwent MIS, resection of benign vertebral tumors.

OUTCOME MEASURES

Complete neurologic examination and pain evaluation, as measured by the visual analog scale (VAS). Secondary outcomes included postoperative spinal instability assessment and surgical margins examinations.

METHODS

Patients were evaluated preoperatively and postoperatively at 1, 3, and 6 months intervals clinically and radiographically using plain radiographs and postoperative computed tomography (CT) scans. Final pathologic report, operative time, blood loss, complications, and hospital length of stay were also recorded.

RESULTS

Between 2009 and 2013, 14 patients underwent MIS, resection of benign vertebral tumors at our institution. Mean follow-up time was 4 years. There were eight men and six women with a mean age of 27 years (range 16-68 years). For tumors located in the posterior elements, a direct posterior approach was used. Tumors located at the pedicle of the vertebra were excised using a transpedicular approach, and tumors protruding into the foramen were excised using the transforaminal approach. The transcanal approach was used when decompression of the thecal sac or nerve root was required, and the retroperitoneal transpsoas approach was used for tumors located in the vertebral body. Complete removal of these tumors was achieved in all cases, and was verified by a follow-up CT scan. Pathology revealed osteoid osteoma in five patients, osteoblastoma in three patients. Eosinophilic granuloma, fibrous dysplasia, and fibroid adenoma were found in one case each. Average VAS pain score improved from 7.7 (7-9) to 2.8 (0-7) after surgery.

CONCLUSIONS

Minimally invasive techniques are a valuable choice for the treatment of benign osseous tumors of the spine. A larger, long-term study is in progress. In the meantime, we suggest surgeons experienced with both open and MIS surgery should consider these techniques.

Interstitial ultrasound ablation of vertebral and paraspinal tumours: parametric and patient-specific simulations

PURPOSE

Theoretical parametric and patient-specific models are applied to assess the feasibility of interstitial ultrasound ablation of tumours in and near the spine and to identify potential treatment delivery strategies.

METHODS

3D patient-specific finite element models (n = 11) of interstitial ultrasound ablation of tumours associated with the spine were generated. Gaseous nerve insulation and various applicator configurations, frequencies (3 and 7 MHz), placement trajectories, and tumour locations were simulated. Parametric studies with multilayered models investigated the impacts of tumour attenuation, tumour dimension, and the thickness of bone insulating critical structures. Temperature and thermal dose were calculated to define ablation (>240 equivalent minutes at 43 °C (EM43 °C)) and safety margins (<45 °C and <6 EM43 °C), and to determine performance and required delivery parameters.

RESULTS

Osteolytic tumours (≤44 mm) encapsulated by bone could be successfully ablated with 7 MHz interstitial ultrasound (8.1-16.6 W/cm(2), 120-5900 J, 0.4-15 min). Ablation of tumours (94.6-100% volumetric) 0-14.5 mm from the spinal canal was achieved within 3-15 min without damaging critical nerves. 3 MHz devices provided faster ablation (390 versus 930 s) of an 18 mm diameter osteoblastic (high bone content) volume than 7 MHz devices. Critical anatomy in proximity to the tumour could be protected by selection of appropriate applicator configurations, active sectors, and applied power schemas, and through gaseous insulation. Preferential ultrasound absorption at bone surfaces facilitated faster, more effective ablations in osteolytic tumours and provided isolation of ablative energies and temperatures.

CONCLUSIONS

Parametric and patient-specific studies demonstrated the feasibility and potential advantages of interstitial ultrasound ablation treatment of paraspinal and osteolytic vertebral tumours.

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 of the cuboid managed by percutaneous radiofrequency ablation

We present details of a case of osteoid osteoma of the tarsal cuboid bone. Osteoid osteoma arising in the foot is not very common, and localization in the cuboid is rare. To our knowledge, this is the first case of osteoid osteoma of the cuboid bone treated successfully by percutaneous radiofrequency ablation.

Radiological imaging findings of a case with vertebral osteoid osteoma leading to brachial neuralgia

Osteoid osteoma is a small, benign osteoblastic tumor consisting of a highly vascularized nidus of connective tissue surrounded by sclerotic bone. Three-quarters of osteoid osteomas are located in the long bones, and only 7-12% in the vertebral column. The classical clinical presentation of spinal osteoid osteoma is that of painful scoliosis. Other clinical features include nerve root irritation and night pain. Osteoid osteoma has characteristic computed tomography (CT) findings. Because magnetic resonance imaging (MRI) findings of the osteoid osteomas causing intense perinidal edema can be confusing, these patients should be evaluated with clinical findings and other imaging techniques. In this study, we present X-ray, CT, and MRI findings of a case with osteoid osteoma located in thoracic 1 vertebra left lamina and transverse process junction leading to brachial neuralgia symptoms.

Interstitial laser photocoagulation for the treatment of osteoid osteoma: retrospective study on 35 cases

PURPOSE

The aim of our retrospective study was to evaluate the efficacy of interstitial laser photocoagulation for the treatment of osteoid osteomas and to identify the factors leading to failure of the procedure.

MATERIAL AND METHODS

Thirty-five patients received interstitial laser photocoagulation treatment. A minimum of 3 months follow-up was required. The laser fibre was positioned within the nidus under CT guidance, and energy between 500 and 1800 J was delivered at a power of 2 Watts/s. Follow-up was by outpatient appointment and through a questionnaire sent to the patients.

RESULTS

Thirty patients replied to the questionnaire. Mean follow-up was 40 months. The technical success rate was 100%. The primary success rate (no pain at 1 month) was 94.3%. The rate of recurrence was 6%. The rate of complications was 11.4% (a skin burn, patellar enthesopathy, a broken item of material, sacro-iliac fibrous alterations). Factors likely to favour failure of the procedure are the size of the nidus (P=0.04) and poor positioning of the laser fibre (P=0.03).

CONCLUSION

Interstitial laser photocoagulation is an effective and safe treatment for osteoid osteomas.

[Radiofrequency ablation in spinal osteoid osteoma. Options and limits]

Osteoid osteoma was first described by Jaffe in 1935 as a benign bone neoplasm mainly located in the diaphyseal areas of long bones: 10% are located in the spine, mainly in the lumbar and thoracic posterior elements. Therapy is required due to nocturnal pain independent of the physical load and responds especially well to anti-inflammatory drugs due to the excessive production of prostaglandins in the nidus. Diagnosis is confirmed by multi-slice computed tomography (CT), magnetic resonance imaging (MRI) and skeletal scintigraphy scans. In cases with typical symptoms and imaging, open biopsies are rarely needed. Although CT-guided radiofrequency ablation is accepted as the gold standard treatment option for osteoid osteoma in the extremities, this technique is limited in spinal applications due to the risk of thermal damage to adjacent neurovascular structures. Technical advances in the administration of radiofrequency ablation have, however, resulted in new and expanded indications in the spine so that the necessity for open surgical excision of spinal osteoid osteoma is becoming less.

CT-guided radiofrequency ablation of osteoid osteoma in the long bones of the lower extremity

AIM: To present our initial experience with computed tomography guided radiofrequency ablation (RFA) of osteoid osteoma (OO) in our institution.

METHODS: RFA was performed on eight patients (5 males and 3 females) with clinically and radiologically diagnosed OO (femoral neck, n = 4; femoral diaphysis, n = 2; tibial diaphysis, n = 1; fibular diaphysis, n = 1). Ablation was performed using an electrode with a 10-mm exposed tip for a total of 4-6 min at a targeted temperature of 90 degrees Celsius. No cooling system was used. The intervention was accepted as technically successful if the tip of the electrode could be placed within the center of the nidus. We defined clinical success as a disappearance within 2 wk after treatment of symptoms that had manifested at presentation.

RESULTS: All procedures were technically successful. No major or immediate complications were observed. Clinical success was achieved in six of eight patients in the first procedure. A second procedure was performed for two patients who had recurrent or continued pain, and one of these cases was successfully treated. The overall rate of success was 87.5% (7/8). No complication was observed.

CONCLUSION: Our preliminary results indicate a favorable success rate and no complications and are compatible with the previous reports of RFA of OO.

Radiofrequency ablation of osteoid osteoma using tissue impedance as a parameter of osteonecrosis

INTRODUCTION

The aim of this study is to assess the safety and the efficacy of radiofrequency ablation (RFA) of osteoid osteoma with Soloist monopolar electrode using tissue impedance, rather than temperature, as an indicator of osteonecrosis.

METHODS

The medical records and imaging studies of 30 patients (males 18, females 12) who underwent RFA of osteoid osteoma at our institution were reviewed. The mean age of the patients was 15.3 years (range 5-34 years) and the mean duration of follow up was 26.9 months (range 3-52 months). The lesions were located in the femur (n=6, 53%), tibia (n = 8, 27%), hand (n = 3, 10%), foot (n = 2, 6%) and humerus (n = 1, 3%). The procedure was performed with general anaesthesia under CT guidance. The nidus was accessed with 11-gauge bone biopsy needle and then the stylet was removed and replaced by monopolar 16.5G radiofrequency probe with a 9-mm active tip through the coaxial axis. Power delivery via the radiofrequency generator was started at 2 W and increased gradually until the end point of 450-500 Ω reached and 'Roll-Off' achieved indicating coagulation necrosis of the target lesion.

RESULTS

The procedure was technically successful in all patients. The mean procedure time was 72 min and the mean RFA time was 12.7 min. The clinical success rate was 93%. In one patient, the procedure was abandoned due to immature Roll-Off despite all measures. In one patient (3%), recurrence occurred 39 months after the procedure. No major complications were encountered. Two minor skin burns occurred that were resolved with conservative measures.

CONCLUSION

RFA of osteoid osteoma using Soloist monopolar electrode is a safe and effective treatment. Tissue impedance could be used as an alternative to temperature to indicate osteonecrosis of osteoid osteoma during RFA.

Radiofrequency ablation of a spinal osteoid osteoma: low heat-load technique

The present report describes successful radiofrequency ablation of a small osteoid osteoma in the second lumbar (L2) pedicle of a 10-year-old boy who had been experiencing several months of back pain. The lesion had no cortical bone separation from the spinal canal contents and was positioned immediately adjacent to a synovial facet joint. Treatment involved a low heat-load technique to avoid damage to nearby sensitive structures. The adjacent epidural space was monitored for temperature increase.

Osteoid osteoma of the first 2 cervical vertebrae. Report of 4 cases

Osteoid osteoma affects the spine in only 10% of cases. More than 50% of the spinal cases involve the lumbar and cervical vertebrae. Involvement of C-1 and C-2 vertebrae has previously been reported only very rarely in the published literature. The authors report 4 cases of upper cervical osteoid osteoma, 1 involving C-1 and the other 3 C-2, and they discuss different aspects of management in similar cases. The patients were 14, 17, 35, and 46 years old, and all presented with neck pain and various degrees of painful limitation of head rotation not ameliorated by ordinary analgesics. Radionuclide isotope bone scans, CT scanning, and MR imaging were helpful preoperative diagnostic modalities. The first attempt at eradication of the lesions failed in 2 cases and the lesions could be excised totally at a second approach. Postoperatively, the patients all became pain free and gained full range of neck motion. There has been no tumor recurrence and no sign of instability in short- to medium-term follow-up. Among the several etiologies mentioned for neck pain and torticollis, osteoid osteoma of the first 2 cervical vertebrae should be considered as a possible but rare cause. Even though different kinds of management have been mentioned for osteoid osteoma, resection of the lesion remains the best option for achieving a cure.

A patient-mount navigated intervention system for spinal diseases and its clinical trial on percutaneous pulsed radiofrequency stimulation of dorsal root ganglion

STUDY DESIGN

Development of a patient-mount navigated intervention (PaMNI) system for spinal diseases. An in vivo clinical human trial was conducted to validate this system.

OBJECTIVE

To verify the feasibility of the PaMNI system with the clinical trial on percutaneous pulsed radiofrequency stimulation of dorsal root ganglion (PRF-DRG).

SUMMARY OF BACKGROUND DATA

Two major image guiding techniques, i.e., computed tomography (CT)-guided and fluoro-guided, were used for spinal intervention. The CT-guided technique provides high spatial resolution, and is claimed to be more accurate than the fluoro-guided technique. Nevertheless, the CT-guided intervention usually reaches higher radiograph exposure than the fluoro-guided counterpart. Some navigated intervention systems were developed to reduce the radiation of CT-guided intervention. Nevertheless, these systems were not popularly used due to the longer operation time, a new protocol for surgeons, and the availability of such a system.

METHODS

The PaMNI system includes 3 components, i.e., a patient-mount miniature tracking unit, an auto-registered reference frame unit, and a user-friendly image processing unit. The PRF-DRG treatment was conducted to find the clinical feasibility of this system.

RESULTS

The in vivo clinical trial showed that the accuracy, visual analog scale evaluation after surgery, and radiograph exposure of the PaMNI-guided technique are comparable to the one of conventional fluoro-guided technique, while the operation time is increased by 5 minutes.

CONCLUSION

Combining the virtues of fluoroscopy and CT-guided techniques, our navigation system is operated like a virtual fluoroscopy with augmented CT images. This system elevates the performance of CT-guided intervention and reduces surgeons' radiation exposure risk to a minimum, while keeping low radiation dose to patients like its fluoro-guided counterpart. The clinical trial of PRF-DRG treatment showed the clinical feasibility and efficacy of this system.

Case report: osteoid osteoma of the C2 pedicle: surgical technique using a navigation system

An osteoid osteoma of the cervical spinal pedicle is rare and carries a high surgical risk because of the close anatomic relationship to the spinal cord, nerve root, and vertebral artery. We report the case of a 12-year-old girl with an osteoid osteoma of the C2 pedicle. Computed tomograms showed an oval nidus and marked sclerosis around this lesion at the right C2 pedicle. There also was expansion of the medial and inferior cortical bone of the C2 pedicle. After failure of nonoperative treatment, we planned surgery. Owing to concerns regarding thermal damage to the spinal cord, nerve root, and/or vertebral artery using computed tomography (CT)-guided radiofrequency ablation, we curetted the nidus using a navigation system. Twenty-eight months after surgery, her pain was relieved with no limitation of cervical movement and there has been no evidence of recurrence. Navigation allowed safe curettage of the nidus through a small hole while maintaining spinal stability.