Fluid-fluid levels detected on MRI and mimicking primary aneurismal bone cysts in a case of spinal bone metastasis.

INTRODUCTION: Spinal bone metastases may be lytic or sclerotic lesions. Sometimes aneurismal bone cyst (ABC)-like areas (also called "secondary ABC") can be found in giant-cell tumors, osteoblastomas and chondroblastomas but are rare in metastatic tumors. CASE REPORT: A retrospective study on 518 patients surgically treated for metastatic lesions of the spine from 1995 to 2012 was performed to evaluate the radiographic presentation. We propose a case report of a metastatic lesion associated with imaging features suggestive of aneurismal bone cyst. The patient was treated by intralesional surgery, after embolization of the lesion. CONCLUSIONS: Fluid-fluid levels detected on imaging can be found in bone metastases and may be similar to a primary aneurismal bone cyst. Embolization of metastastic tumor was useful to help the surgeon.

Imaging tumors of the patella.

BACKGROUND: Patellar tumors are rare; only a few series have been described in the literature and radiographic diagnosis can be challenging. We reviewed all patellar tumors at one institution and reviewed the literature. MATERIALS AND METHODS: In an evaluation of the database at one institution from 1916 to 2009, 23,000 bone tumors were found. Of these, 41 involved the patella. All had imaging studies and microscopic diagnostic confirmation. All medical records, imaging studies, and pathology were reviewed. RESULTS: There were 15 females and 26 males, ranging from 8 to 68 years old (average 30). There were 30 benign tumors; eight giant cell tumors, eight chondroblastomas, seven osteoid osteomas, two aneurysmal bone cysts, two ganglions, one each of chondroma, exostosis, and hemangioma. There were 11 malignant tumors: five hemangioendotheliomas, three metastases, one lymphoma, one plasmacytoma, and one angiosarcoma. CONCLUSION: Patellar tumors are rare and usually benign. As the patella is an apophysis, the most frequent lesions are giant cell tumor in the adult and chondroblastoma in children. Osteoid osteomas were frequent in our series and easily diagnosed. Metastases are the most frequent malignant diagnoses in the literature; in our series malignant vascular tumors were more common. These lesions are often easily analyzed on radiographs. CT and MR define better the cortex, soft tissue extension, and fluid levels. This study presents the imaging patterns of the more common patellar tumors in order to help the radiologist when confronted with a lesion in this location.

Palliative embolisation for advanced bone sarcomas.

PURPOSE: Managing patients with advanced bone sarcomas - namely, recurrent, unresectable and metastatic - is mostly aimed at palliation. The role of embolisation for pain relief for these patients has not been previously reported. We therefore performed this study to emphasise the palliative role of embolisation for pain relief of advanced bone sarcoma patients. MATERIALS AND METHODS: We retrospectively studied 43 patients with advanced bone sarcomas treated with palliative embolisation with N-2-butyl-cyanoacrylate from 2004 to 2011. All patients had primary treatments including chemotherapy, radiation therapy, radiofrequency thermal ablation, and/or surgery for their advanced sarcomas and were referred for embolisation as end-stage treatment for continuous severe local pain. The effect of embolisation was evaluated with a pain score scale and analgesic use. Mean follow-up was 7 (range, 1-19) months); all patients were dead at the last follow-up. RESULTS: In all patients, angiography showed increased pathological vascularisation of the sarcomas; three to six feeding vessels were embolised in each procedure. Almost complete pain relief and >50% reduction in analgesic use was experienced by 36 patients with highly hypervascular sarcomas and sarcomas in the pelvis and shoulder girdle. Moderate pain relief and 50% reduction in analgesic use was experienced by seven patients with spinal and sacral lesions. Within the available follow-up, no patient had recurrent pain with the same intensity as before embolisation. All patients experienced ischaemic pain at the site of embolisation that resolved completely with analgesics. Six patients with advanced pelvic bone sarcomas experienced paraesthesias at the distribution of the sciatic nerve that resolved completely with methylprednisolone. CONCLUSIONS: Embolisation is a safe and effective local palliative treatment for patients with advanced sarcomas, providing optimum pain relief with the least discomfort and the possibility of minor complications only.

Embolisation of bone metastases from renal cancer.

PURPOSE: This study was done to evaluate embolisation for palliative and/or adjuvant treatment of bone metastases from renal cell carcinoma and discuss the clinical and imaging results. MATERIALS AND METHODS: We retrospectively studied 107 patients with bone metastases from renal cell carcinoma treated from December 2002 to January 2011 with 163 embolisations using N-2-butyl cyanoacrylate (NBCA). Mean tumour diameter before embolisation was 8.8 cm and mean follow-up 4 years. Clinical and imaging effects of treatment were evaluated at follow-up examinations with a pain score scale, analgesic use, hypoattenuating areas, tumour size and ossification. RESULTS: A clinical response was achieved in 157 (96%) and no response in six embolisations of sacroiliac metastases. Mean duration of clinical response was 10 (range 1-12) months. Hypoattenuating areas resembling tumour necrosis were observed in all patients. Variable ossification appeared in 41 patients. Mean maximal tumour diameter after embolisation was 4.0 cm. One patient had intraprocedural tear of the left L3 artery and iliopsoas haemorrhage and was treated with occlusion of the bleeding vessel with NBCA. All patients had variable ischaemic pain that recovered completely within 2-4 days. Postembolisation syndrome was diagnosed after 15 embolisations (9.2%). Transient paraesthesias in the lower extremities were observed after 25 embolisations (25%) of pelvis and sacrum metastatic lesions. CONCLUSIONS: Embolisation with NBCA is recommended as primary or palliative treatment of bone metastases from renal cell carcinoma. Strict adherence to the principles of transcatheter embolisation is important to avoid complications.

Conservative treatment of spontaneous osteonecrosis of the knee in the early stage: pulsed electromagnetic fields therapy.

HYPOTHESIS: pulsed electromagnetic fields treatment might improve symptoms in the early stage of spontaneous osteonecrosis of the knee. METHODS: Twenty-eight patients (19M/9F, age 49.8±16.4 years) suffering from symptomatic (pain) Koshino stage I spontaneous osteonecrosis of the knee, confirmed by magnetic resonance imaging (MRI) were treated with local pulsed electromagnetic fields therapy (6 h daily for 90 days). Clinical evaluation: baseline, 6- and 24-month follow-up by VAS for pain, knee society score (KSS), Tegner and EQ-5D scales. MRI evaluation: baseline and 6-month follow-up, measuring bone marrow lesion's areas and grading these lesions by WORMS score. Failures: patients undergoing knee arthroplasty. RESULTS: Pain significantly reduced at 6 months (from 73.2±20.7 to 29.6±21.3, p<0.0001), which remained almost unchanged at final follow-up (27.0±25.1). KSS significantly increased in first 6 months (from 34.0±13.3 to 76.1±15.9, p<0.0001) and was slightly reduced at final follow-up (72.5±13.5, p=0.0044). Tegner median level increased from baseline to 6-month follow-up (1(1-1) and 3(3-4), respectively, p<0.0001) and remained stable. EQ-5D improved significantly throughout the 24 months (0.32±0.33, baseline; 0.74±0.23, 6-month follow-up (p<0.0001); 0.86±0.15, 24-month follow-up (p=0.0071)). MRI evaluation: significant reduction of total WORMS mean score (p<0.0001) and mean femoral bone marrow lesion's area (p<0.05). This area reduction was present in 85% and was correlated to WORMS grading both for femur, tibia and total joint (p<0.05). Four failures (14.3%) at 24-month follow-up. CONCLUSIONS: Pulsed electromagnetic fields stimulation significantly reduced knee pain and necrosis area in Koshino stage I spontaneous osteonecrosis of the knee already in the first 6 months, preserving 86% of knees from prosthetic surgery at 24-month follow-up. No correlation was found between MRI and clinical scores. LEVEL OF EVIDENCE: Level IV; case series.

Palliative treatments for advanced osteosarcoma.

Advances in diagnostic imaging, interventional radiology, chemotherapy and surgery greatly improved the outcome of patients with osteosarcoma, and made limb salvage possible without compromising survival. In these patients, the prognosis is influenced by the site and resectability of the tumor, prior malignancy, and histological response to preoperative chemotherapy. Unfortunately, the progress has not been as significant in the treatment of advanced osteosarcoma, namely metastatic, recurrent and unresectable tumor. Yet, although advanced and forecasting a dismal prognosis, advanced osteosarcoma is not necessarily untreatable. Aggressive local and medical treatments, including surgical removal of primary and/or metastatic disease are currently available; however, yet, most treatments aim at palliation. Palliative local treatments including isolated limb perfusion, radiation therapy, embolization, chemoembolization, thermal ablation and cryoablation, all have an important role for these patients. The aim of palliative treatments is to achieve a mild response by offering the least discomfort to the patient with the minimum possible complications, and possibly increase of survival.

Embolisation for vascular injuries complicating elective orthopaedic surgery.

OBJECTIVES: The study aims to present the indications and emphasise the role of embolisation for vascular injuries in orthopaedic surgery. METHODS: Thirty-one patients with vascular injuries complicating elective orthopaedic surgery had embolisation from 2003 to 2010. N-2-butyl cyano-acrylate (NBCA) was used as embolic agent in 28 patients, gelatin sponge in three and coil embolisation in addition to NBCA or gelatin sponge in two patients. The mean follow-up period was 37 months (range, 4-96 months). RESULTS: The most common orthopaedic operations associated with vascular injuries amenable to embolisation were hip-joint procedures; and the most common injuries were arterial tears of branch vessels or non-critical axial vessels, most commonly of the superior glutaeal artery. In all cases, angiography showed the bleeding point, and a single embolisation session effectively stopped bleeding. Embolisation-related complications were not observed. CONCLUSIONS: Embolisation should be considered the treatment of choice for vascular injuries of branch vessels or non-critical axial vessels following elective orthopaedic surgery because of the advantages of minimally invasive therapy and the lack of complications.

Fine tuning of protein kinase C (PKC) isoforms in cancer: shortening the distance from the laboratory to the bedside.

The serine/threonine protein kinase C (PKC) family was first identified as intracellular receptor(s) for the tumor promoting agents phorbol esters. Thirty years after the discovery of PKC, the role of specific PKC isoforms has been described in relationship with an altered pattern of expression in different types of cancer and a good number of small molecule inhibitors (inhibitory peptides, antisense oligonucleotides or natural compounds) targeting PKC are now available. Despite all these achievements and a huge amount of basic research studies on the biochemical regulation of PKC, there has been a delay in clinical trials with drugs targeting PKC function. This delay is easily explained taking into account the extreme biological complexity of the PKC family of isoforms and the incomplete understanding of the specific role of each PKC isozyme in different types of cancers. Some of the difficulties in developing pharmacological compounds selectively tuning the different PKCs have started to be overcome. In this review, the growing evidences of the role of the PKC isoforms α, ßII, δ, ε, ζ and ι is in promoting or counteracting tumor progression will be discussed in relationship with promising therapeutic perspectives.

Selective arterial embolisation for bone tumours: experience of 454 cases.

PURPOSE: The authors present the experience of a single institution with selective arterial embolisation for primary and metastatic bone tumours. MATERIALS AND METHODS: A total of 365 patients were treated with 454 embolisation procedures from December 2002 to April 2010. Embolisation was the primary treatment for benign bone tumours, adjuvant treatment to surgery for benign and malignant bone tumours and palliative treatment for bone sarcomas and metastases. Indications for repeat embolisation included pain or imaging evidence of progressive disease: 105 patients had repeat embolisation at the same location at an interval of 1-3 months; 260 patients had one embolisation, 78 had two and 29 had three or more. In all patients, N-2-butyl cyanoacrylate (NBCA) in 33% lipiodol was the embolic agent used. RESULTS: A total of 419 of the 454 embolisations (93%) were technically successful. In 35 cases, embolisation was not feasible because of poor lesion vascularisation (21 patients with bone metastases and two with aneurysmal bone cysts), origin of the Adamkiewicz artery in the embolisation field (four patients with bone metastases and one with aneurysmal bone cyst), atheromatosis and arteriosclerosis (five patients with bone metastases) and anatomical and technical problems such as small-calibre vessels, many branches and acute vessel angles (two patients with bone metastases). A clinical response was achieved in 406 of the 419 procedures (97%), and no response in 13 procedures in patients with pelvis and sacrum tumours. Complications included postembolisation syndrome in 81 patients (22%), transient paraesthesias in 41 (11%), skin breakdown and subcutaneous necrosis at the shoulder and pelvis in five (1.4%) and paresis of the sciatic nerve in one (0.3%). CONCLUSIONS: We recommend embolisation as primary or palliative treatment or an adjunct to surgery for tumours of variable histology. Strict adherence to the principles of transcatheter embolisation is important. Arteries feeding the tumour and collaterals must be evaluated carefully and catheterised superselectively to protect the normal tissues. NBCA is considered the most appropriate embolic agent for small-vessel occlusion without major complications.

Validity of T2 mapping in characterization of the regeneration tissue by bone marrow derived cell transplantation in osteochondral lesions of the ankle.

OBJECTIVE: Bone marrow derived cell transplantation (BMDCT) has been recently suggested as a possible surgical technique to repair osteochondral lesions. To date, no qualitative MRI studies have evaluated its efficacy. The aim of our study is to investigate the validity of MRI T2-mapping sequence in characterizing the reparative tissue obtained and its ability to correlate with clinical results. METHODS AND MATERIALS: 20 patients with an osteochondral lesion of the talus underwent BMDCT and were evaluated at 2 years follow up using MRI T2-mapping sequence. 20 healthy volunteers were recruited as controls. MRI images were acquired using a protocol suggested by the International Cartilage Repair Society, MOCART scoring system and T2 mapping. Results were then correlated with AOFAS clinical score. RESULTS: AOFAS score increased from 66.8±14.5 pre-operatively to 91.2±8.3 (p<0.0005) at 2 years follow-up. T2-relaxation time value of 35-45 ms was derived from healthy ankles evaluation and assumed as normal hyaline cartilage value and used as a control. Regenerated tissue with a T2-relaxation time value comparable to hyaline cartilage was found in all the cases treated, covering a mean of 78% of the repaired lesion area. A high clinical score was related directly to isointense signal in DPFSE fat sat (p=0.05), and percentage of regenerated hyaline cartilage (p=0.05), inversely to the percentage of regenerated fibrocartilage. Lesion's depth negatively related to the integrity of the repaired tissue's surface (tau=-0.523, p=0.007), and to the percentage of regenerated hyaline cartilage (rho=-0.546, p=0.013). CONCLUSIONS: Because of its ability to detect cartilage's quality and to correlate to the clinical score, MRI T2-mapping sequence integrated with Mocart score represent a valid, non-invasive technique for qualitative cartilage assessment after regenerative surgical procedures.

Three-dimensional analysis of image-free navigation system for total knee arthroplasty.

Malalignment causes abnormal forces that may lead to loosening after knee replacement. Whether a computer-assisted technique can improve the precision of implant positioning guaranteeing good long-term results in total knee arthroplasty, this is a matter of discussion. The authors evaluate the alignment accuracy of 20 primary total knee arthroplasties, performed using an image-free computer navigation systems, with standardized CT protocol and three-dimensional digital model reconstruction. The results of this study demonstrate that the image-free navigation system is able to improve accuracy in axial limb alignment and positioning of the components in the majority of cases; moreover, the difference between the mean mechanical axis value of the navigation system (179.7° ± 1.7°) and the median mean value obtained during the post-operative evaluation (180.3° ± 1.9°) is not statistically significant (P = 0.28).

Three-dimensional analysis of pulmonary nodules: variability of semiautomated volume measurements between different versions of the same software.

PURPOSE: This study was done to evaluate the variability of semiautomated volume measurements of solid pulmonary nodules between two different versions of the same volumetric software. MATERIALS AND METHODS: The volumes of 100 solid intraparenchymal nodules (mean volume 88.10 mm(3); range 7.36-595.25 mm(3)) studied with the same multidetector computed tomography (MDCT) protocol were determined using two different versions of the same volumetric software (LungCARE 2006G and LungCARE 2007S). The 2006G version is based on a single-segmentation algorithm, whereas the newer version features two algorithms: SmallSizeNodule and AllSizeNodule. The results obtained with the 2006G version were compared with those of the 2007S version with the SmallSizeNodule algorithm, as recommended by the user manual. In addition, we compared the volumetric measurements obtained by the two different algorithms of the 2007S version. RESULTS: The 2006G version and the 2007S version with the SmallSizeNodule algorithm agreed in only two of 100 cases and showed a mean variability of 1.66% (range 0%-8.78%). A more significant volumetric discrepancy was observed between the two different algorithms of the 2007S version, with the AllSizeNodule algorithm providing on average larger volumes (mean variability 71.08%; range 6.02%-218.80%) than SmallSizeNodule. Volume discrepancies were more pronounced in the subgroups of smaller nodules in all comparisons. CONCLUSIONS: There is variability also in the results provided by different versions of the same volumetric software, and this may affect the calculation of the nodule-doubling time. Computer-aided assessment of the growth of lung nodules should always be performed using the same version of volumetric software and the same segmentation algorithm.

Activation of PKC-epsilon counteracts maturation and apoptosis of HL-60 myeloid leukemic cells in response to TNF family members.

Protein kinase C (PKC)-epsilon, a component of the serine/threonine PKC family, has been shown to influence the survival and differentiation pathways of normal hematopoietic cells. Here, we have modulated the activity of PKC-epsilon with specific small molecule activator or inhibitor peptides. PKC-epsilon inhibitor and activator peptides showed modest effects on HL-60 maturation when added alone, but PKC-epsilon activator peptide significantly counteracted the pro-maturative activity of tumor necrosis factor (TNF)-alpha towards the monocytic/macrophagic lineage, as evaluated in terms of CD14 surface expression and morphological analyses. Moreover, while PKC-epsilon inhibitor peptide showed a reproducible increase of TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis, PKC-epsilon activator peptide potently counteracted the pro-apoptotic activity of TRAIL. Taken together, the anti-maturative and anti-apoptotic activities of PKC-epsilon envision a potentially important proleukemic role of this PKC family member.

Preliminary experience with electromagnetic navigation system in TKA.

Accuracy of implant positioning and precise reconstruction of leg alignment offers the best way to achieve good long-term results in total knee arthroplasty. Computer instrumentation was developed to improve the final position of the component and restore the mechanical axis. Current navigation systems use either optical or electromagnetic tracking. The advantage of the Electromagnetic (EM) navigation system is that no line-of-sight issues are present. However, special iron-free instruments are required. This report analyzes the postoperative radiological results of 32 knees treated using an EM system. All the measurements were recorded using software able to subtend angles automatically by five physicians, three radiologist and two orthopedic residents not involved with the surgery. Each radiograph was measured three times, in random order, and at delayed intervals. We found an ideal alignment for the mechanical axis (180+/-3 degrees ) in 30 out of 32 cases, whereas all the patients achieved a value of 90 degrees +/-3 degrees for both femoral and tibial frontal component angles. An apparently over-corrected implant position for the sagittal femoral component was reported, with a mean value of 11.2 degrees +/-3.6. The mean position of the tibial component was 90.6 degrees +/-2.8; just four measurements were outside of the +/-3 degrees of the desired value. EM is safe and there were no complications related to this system. An almost perfect correlation was found between the mechanical axis value of the EM navigation system (179.8 degrees +/-1.8) and the median value of the all reviewers (180.3 degrees +/-1.9) with a difference of 0.5 degrees .

Activation of PKC-ε counteracts maturation and apoptosis of HL-60 myeloid leukemic cells in response to TNF family members.

Protein kinase C (PKC)-ε, a component of the serine/threo-nine PKC family, has been shown to influence the survival and differentiation pathways of normal hematopoietic cells. Here, we have modulated the activity of PKC-ε with specific small molecule activator or inhibitor peptides. PKC-ε inhibitor and activator peptides showed modest effects on HL-60 maturation when added alone, but PKC-ε activator peptide significantly counteracted the pro-maturative activity of tumor necrosis factor (TNF)-α towards the monocytic/macrophagic lineage, as evaluated in terms of CD14 surface expression and morphological analyses. Moreover, while PKC-ε inhibitor peptide showed a reproducible increase of TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis, PKC-ε activator peptide potently counteracted the pro-apoptotic activity of TRAIL. Taken together, the anti-maturative and anti-apoptotic activities of PKC-ε envision a potentially important proleukemic role of this PKC family member.

Low grade central chondrosarcoma of the fifth costotransverse joint.

Chondrosarcoma (CHS) is the third most frequent primary malignant tumour of bone exceeded only by myeloma and osteosarcoma. It usually occurs in the trunk bones (pelvic girdle, shoulder, ribs) followed by the femur and humerus and is very rare in the spine accounting for about 5% of all CHSs. The majority of patients affected are over 50 years old. We report a case of a 22-year-old woman with a 2-month history of pain on the right side of the upper thoracic spine. Complete imaging work-up with radiographs, CT, MRI and digital subtraction angiography showed an osteolytic lesion of the right transverse process of T5 with extension into the ipsilateral rib and enhancing extracompartmental tissue involving the paraspinal muscles. Both CT-guided core needle biopsy and excisional biopsy were consistent with grade I central CHS with myxoid change and focal areas of Grade II CHS.

Enhanced tibial osteotomy healing with use of bone grafts supplemented with platelet gel or platelet gel and bone marrow stromal cells.

BACKGROUND: There is great interest in the use of bone substitutes to improve bone repair. We compared the osteogenic potential of lyophilized bone chips combined with platelet gel, or with platelet gel and bone marrow stromal cells, with that of lyophilized bone chips alone in the healing of a high tibial osteotomy. METHODS: A prospective, randomized, controlled study was performed, and a standardized clinical model was applied. Thirty-three patients undergoing high tibial osteotomy to treat genu varum were enrolled and assigned to three groups. During the osteotomy, lyophilized bone chips with platelet gel were implanted into eleven patients (Group A), lyophilized bone chips with platelet gel and bone marrow stromal cells were implanted in twelve patients (Group B), and lyophilized bone chips without gel were placed in ten patients as controls (Group C). Six weeks after surgery, computed tomography-guided biopsies of the grafted areas were performed and the specimens were analyzed by histomorphometry. Clinical and radiographic evaluation was performed at six weeks, twelve weeks, six months, and one year after surgery. RESULTS: Histomorphometry at six weeks showed significantly increased osteoblasts and osteoid areas in both Group A (p = 0.006 and p = 0.03, respectively) and Group B (p = 0.009 and p = 0.001) in comparison with controls, as well as increased bone apposition on the chips (p = 0.007 and p = 0.001, respectively), which was greater in Group B than in Group A (p < 0.05). Group B showed significantly higher revascularization than the controls (p = 0.004). Radiographs revealed a significantly higher rate of osseointegration in Groups A and B than in the controls at six weeks (p < 0.005 and p < 0.0001, respectively). At the final evaluation at one year, the osseointegration was still better in Groups A and B than in Group C; however, all patients had complete clinical and functional evidence of healing. CONCLUSIONS: Adding a platelet gel or a platelet gel combined with bone marrow stromal cells to lyophilized bone chips increases the osteogenetic potential of the lyophilized bone chips and may be a useful tool in the treatment of patients with massive bone loss.

Pulmonary nodules in osteosarcoma patients: differential diagnosis of central venous catheter-related infections in the lungs.

PURPOSE: The purpose of this study was to evaluate the differential diagnosis of pulmonary nodules by conventional radiography and computed tomography (CT) in osteosarcoma patients with central venous catheter. MATERIALS AND METHODS: Between March 1997 and December 2001 at our Department of Musculoskeletal Oncology, 231 patients with peripheral osteosarcoma received a central venous catheter to allow infusion therapy and blood sampling. The mean age of these patients was 16 years (range 4-63), and 90 were aged 15 years or younger. All patients underwent radiological investigation for tumour staging and comparison with the following study in accordance with the protocol in place at our Department of Oncology and Division of Diagnostic Imaging. RESULTS: Of a total of 231 patients, 13 (5.6%) developed an infection of the central venous line, with fever that was very high in some cases. In ten cases (4.3%), radiology showed damage to the alveolar interstitium typical of inflammatory forms, whereas in the remaining three (1.3%) it depicted nodular opacities, which required differentiation between lung metastases and septic emboli. After appropriate antibiotic and replacement of the central venous line, CT demonstrated disappearance of the lung nodules in all three patients, enabling a diagnosis of nodular septic embolism. CONCLUSIONS: Placement of a central venous catheter for infusion therapy, chemotherapy and blood sampling has improved the quality of life of cancer patients. The most common complications of the use of central venous catheters include infection and venous thrombosis whereas pulmonary septic emboli are rare.

Radiofrequency thermal ablation of non spinal osteoid osteoma: remarks on method.

Osteoid osteoma is a small benign tumor, with a ''nidus'' that rarely exceeds 15 mm in diameter. It is relatively common in males, especially teenagers and young adults. It involves mainly the appendicular skeleton, the femur in particular, and rarely the axial skeleton. It requires treatment because it causes intense pain. In recent years alternative, less invasive, treatments have been proposed, such as drilling combined with ethanol injections, and thermal ablation with laser or radiofrequency. This study assesses 117 patients affected by osteoid osteoma, treated by radiofrequency thermal ablation between June 2001 and November 2003. We describe the patient recruitment procedure, CT-guided technique, the percutaneous approach, thermal ablation, and the instruments used. Data were analyzed thoroughly, and modifications that have improved the effects of treatment have been highlighted. The results achieved since the method was perfected have been extremely encouraging, confirming that the technique is very effective if performed correctly. For that reason radiofrequency thermal ablation has become the treatment of choice for non-spinal osteoid osteoma at Rizzoli Orthopaedic Institute.

Radiofrequency thermoablation of primary non-spinal osteoid osteoma: optimization of the procedure.

Osteoid osteoma is a small benign tumor that requires treatment due to the intense pain it causes. Surgical therapy has been the ablative technique of choice after a failure of medical therapy. Recently, numerous less invasive, alternative procedures have been proposed: drill trepanation with or without ethanol injections, cryoablation, and thermoablation with laser or radiofrequency. The aim of this review is to retrospectively assess the effect of radiofrequency (RF) thermoablation in the treatment of primary non-spinal osteoid osteoma. From June 2001 to July 2003, we treated 106 patients affected by osteoid osteoma with RF thermoablation. Five patients with spinal osteoid osteoma and four with a previously treated osteoma were excluded from the study. In this paper, we assess the results obtained in a selected group of 97 primary non-spinal osteoid osteoma. The lesions were predominantly in the metaphysics of the femur. Central nidus calcifications were frequent and there was no prevalence for which side they occurred. Primary success was achieved in 82 patients (85%), while we obtained secondary success in 15 patients (15%). In two patients (2%), pain persisted between the two treatments and failed to be resolved, even after the second treatment; therefore, surgical excision was performed and complete resolution was obtained. No complications were reported. In conclusion, our results confirm that the treatment of choice for non-spinal osteoid osteoma is RF thermoablation, offering several advantages over ablative techniques.