Osteoid osteoma is a benign bone tumor that accounts for roughly 2-3% of primary bone tumors and up to 10-12% of benigns bone neoplasms. It is most commonly seen in young adults, and shows male predominance. Over the last years, minimally invasive thermal ablation techniques such as radiofrequency ablation have gained popularity over classical surgery. In this study we evaluate results and complications of CT guided osteoid osteoma radiofrequency ablation.
In this retrospective cohort study all patients that were diagnosed with osteoid osteoma and treated using radiofrequency ablation between January 2014 and December 2022 were included. Pain was assessed using Visual Analog Scale (VAS) pre and post procedure. Technical success was established as positioning of the radiofrequency electrode in the nidus. Primary clinical success was defined as absence of pain after one radiofrequency session. All patients that required a second radiofrequency ablation were included in the overall clinical success group.
During the studied period, 61 osteoid osteoma radiofrequency ablations were performed. Fiftyseven of them were included in this study, 32 were men and 25 female. Pre procedure median pain was 9 according to VAS score. Only 23 patients were treated as outpatient, the rest stayed in hospital for 24 hours. Median follow up time was 21,7 months (SD 8,3). Biopsy was performed in 52 patients. Technical success was accomplished in 57 patients (100%). Primary clinical success was 80,7% (46 patients). Those who continued with pain or had recurrence after a symptoms free period (11 patients), were treated with a second radiofrequency ablation, achieving an overall success rate of 94,7%. Only one patient suffered a minor complication (1,7%).
CT guided osteoid osteoma radiofrequency ablation is a safe, effective and low complication rate procedure, that can be performed on an outpatient basis. We believe it should be considered as a first line treatment option for osteoid osteoma.
El osteoma osteoide es un tumor óseo benigno, que representa el 2-3% de las neoplasias óseas primarias y hasta el 10-12% de los tumores óseos benignos. Tiene mayor incidencia en adultos jóvenes, con predominancia masculina. En los últimos años las técnicas de termoablación mínimamente invasivas han sido utilizadas para el tratamiento del osteoma osteoide, como alternativa a la cirugía clásica. En este estudio evaluaremos los resultados y complicaciones de ablación por radiofrecuencia de osteoma osteoide.
Se analizó una cohorte de pacientes en forma retrospectiva con diagnóstico de osteoma osteoide tratados con radiofrecuencia en el Hospital Italiano de Buenos Aires desde Enero del año 2014 hasta Diciembre del año 2022. Todos los pacientes fueron evaluados con la Escala Visual Analógica del dolor (EVA) pre y post procedimiento. El éxito técnico del procedimiento fue considerado como el correcto posicionamiento del electrodo de radiofrecuencia en el nido de la lesión, y el éxito clínico primario como ausencia de dolor post procedimiento. Mientras que los pacientes que requirieron de una segunda sesión de radiofrecuencia para controlar los síntomas serán incluidos como éxito clínico secundario.
Durante el período mencionado se realizaron 61 ablaciones percutáneas de osteoma osteoide. Se incluyeron en el análisis 57 pacientes, 32 fueron hombres y 25 mujeres. La media de dolor medido por EVA pre procedimiento fue 9. Del total de los pacientes, 23 fueron tratados de manera ambulatoria, el resto permanecieron internados durante 24hs. El tiempo medio de seguimiento fue de 21,7 meses (DS8,3). Se realizó biopsia de la lesión durante el procedimiento en 52 pacientes. Se logró el éxito técnico en 57 pacientes (100%), de ellos el éxito clínico primario se logró en 46 pacientes (80,7%). Los 11 pacientes que continuaron con dolor o presentaron recurrencia de los síntomas luego de un período asintomáticos fueron tratados con una segunda sesión de radiofrecuencia, logrando un éxito clínico secundario 94,7%. Un solo paciente presentó complicaciones post procedimiento (1,7%), correspondiente a hematoma en la planta del pie.
Podemos concluir que la ablación percutánea por radiofrecuencia de OO guiada por tomografía en manos de expertos, es un procedimiento seguro, de alta efectividad y baja tasa de complicaciones que puede realizarse de manera ambulatoria. Por lo que consideramos que debe ser tenida en cuenta como primera elección para el tratamiento de esta patología.

METHODS: A 15-year-old male patient presented with a 3-week history of inner left thigh pain provoked by activity and experienced occasionally at rest. The patient denied nighttime pain, fever, or chills. Laboratory investigation revealed the following normal values: hemoglobin level of 15.6 g/dL (normal range, 13-16 g/dL), platelet count of 240 × 103/µL (normal range, 140-440 × 103/µL), and total leukocyte count of 7100 cells/µL (normal range, 4500-11 000 cells/µL). The percentage of neutrophils was considered low at 44% (normal range, 54%-62%), and the percentage of eosinophils was slightly high at 3.7% (normal range, 0%-3%). An anteroposterior radiograph of the left hip is shown. Physical therapy was initiated, with no improvement after 2 weeks of therapy. The patient was referred to an orthopedist for further evaluation. At physical examination, the patient endorsed marked left hip pain with hip flexion to 90°, limited internal and external rotation (5° and 15°, respectively), and antalgic gait favoring the left leg. Hip MRI and further serologic analysis were requested for further evaluation. Although the serologic testing was performed at an outside laboratory, the physician reported positive immunoglobulin-G Lyme titers, normal C-reactive protein level, and normal erythrocyte sedimentation rate. Pelvic CT was requested. The patient was prescribed a course of doxycycline (100 mg twice daily for 28 days), with reported resolution of symptoms 2 weeks after initiation of treatment. Three weeks later, the patient presented to our department with recurrent left hip pain, which was similar in severity compared with the initial presentation. A second MRI examination of the left hip was performed 4 months after the initial presentation.

Osteoid osteoma (OO) is the third most prevalent benign bone neoplasm in children. Although it predominantly affects the diaphysis of long bones, OO can assume an intra-articular location in the epiphysis or the intracapsular portions of bones. The most common location of intra-articular OO is the hip joint. The presentation of intra-articular OOs often poses a diagnostic enigma, both from clinical and radiologic perspectives. Initial symptoms are often vague and nonspecific, characterized by joint pain, stiffness, and limited range of motion, which frequently contributes to a delayed diagnosis. Radiographic findings range from normal to a subtle sclerotic focus, which may or may not have a lucent nidus. In contrast to their extra-articular counterparts, intra-articular lesions have distinct features at MRI, including synovitis, joint effusion, and bone marrow edema-like signal intensity. While CT remains the standard for identifying the nidus, even CT may be inadequate in visualizing it in some cases, necessitating the use of bone scintigraphy or fluorine 18-labeled sodium fluoride PET/CT for definitive diagnosis. Radiologists frequently play a pivotal role in suggesting this diagnosis. However, familiarity with the unique imaging attributes of intra-articular OO is key to this endeavor. Awareness of these distinctive imaging findings of intra-articular OO is crucial for avoiding diagnostic delay, ensuring timely intervention, and preventing unnecessary procedures or surgeries resulting from a misdiagnosis. The authors highlight and illustrate the different manifestations of intra-articular OO as compared with the more common extra-articular lesions with respect to clinical presentation and imaging findings. ©RSNA, 2024 Supplemental material is available for this article.

Osteoid osteoma is a benign osteoblastic tumour with a predilection for the lower extremity that rarely affects the forearm. It is commonly seen in adolescents and young adults, and is seldom diagnosed in the paediatric age group. We report a boy in his early childhood who presented with a swelling over the distal forearm, which was incidentally noted by the mother 3 months ago. Plain radiographs showed diffuse sclerosis of the dorsal cortex of the distal radius. CT scan showed a central lucent nidus in the intramedullary region and surrounding sclerosis in the radial metaphysis, confirming the diagnosis of osteoid osteoma. The patient was successfully treated by surgical en bloc resection of the nidus and was asymptomatic at 1-year follow-up. Non-specific symptoms at presentation make it a challenge to diagnose osteoid osteoma in children and it needs to be considered in the differential diagnosis when radiographs show lytic lesions in the bone.

OBJECTIVE: Percutaneous CT-guided radiofrequency ablation (CT-RFA) is a widely accepted procedure for treatment of osteoid osteomas. However, the application of CT-RFA was restricted as a result of some drawbacks, such as radiation exposure, and inconvenience in general anesthesia. The primary aim of this study is to evaluate the safety and efficacy of intra-operative TiRobot-assisted percutaneous RFA of osteoid osteomas.
METHODS: We retrospectively reviewed 21 medical files of patients who were treated with percutaneous RFA of osteoid osteomas guided by the TiRobot system in our institution between March 2021 and April 2022. The three-dimensional images obtained by a 3D C-arm intra-operatively were sent to the TiRobot system. The puncture point and trajectory were designed. Then the guide pin was positioned to the lesion with the assistance of TiRobot and the biopsy sheath was inserted into the lesion through the guide pin. The tumor was biopsied for pathological examination. Then the RFA needle was inserted into the nidus through the biopsy sheath for thermal ablation. Data were extracted on the associated complications, the reduction in pain at 1 month and 1 year postoperatively assessed by the visual analogue scale (VAS). A paired t-test was used to compare the pre-operative and post-operative VAS scores.
RESULTS: The patients included 17 males and four females with a mean age of 19.5 ± 10.4 years (range 3-45 years). Lesions were located on the femur in nine cases, on the tibia in nine cases, on the humerus in one case, on the calcaneus in one case, and on the acetabulum in one case. TiRobot-assisted percutaneous RFA was successfully performed on all 21 patients. There was no intra-operative or post-operative complications observed. Pathological diagnosis of osteoid osteoma was obtained in 11 patients, but the other 10 cases were not pathologically diagnosed. The mean follow-up time was 18.8 months (range: 12-26 months).Post-operative VAS scores were reduced significantly in all cases. The mean VAS score decreased from 6.5 pre-operatively to 0.5 at 1 month post-operatively and to 0.1 at 1 year post-operatively.
CONCLUSIONS: As a reliable technique for localizing and resection of nidus, TiRobot-assisted percutaneous RFA is a safe and effective option for the treatment of osteoid osteomas.

A young male in his mid-teen years presented with severe back pain for 3 months and was subsequently diagnosed with osteoid osteoma in the left superior articular process of the L4 vertebra. Initial treatment with non-steroidal anti-inflammatory drugs provided temporary relief. Due to concerns about scoliosis progression along with unrelieved pain, a multidisciplinary team recommended endoscopic excision of the osteoid osteoma. The procedure resulted in complete pain relief and an improvement in the scoliosis curve from 22° of Cobb\'s angle to 12 degrees at the 8-month follow-up.

BACKGROUND: Osteoid osteoma (OO) is a benign lesion characterized by an increased fibrous component in the bone marrow, presence of bone-like structures within the medullary cavity, and a surrounding sclerotic bone rim. Reports on OO located in the posterior proximal tibia are rare.
METHODS: Herein, we report the case of an 18-year-old male, admitted for the evaluation of right knee pain. The right knee pain had started 6 months prior without any apparent cause, which was notably severe at night, affecting sleep, and was exacerbated while climbing stairs or bearing weight. The patient also experienced pain on flexion. Three-dimensional computed tomography and magnetic resonance imaging revealed a nodular lesion beneath the cortical bone of the posterior medial plateau of the right tibia and an abnormal signal focus on the posterior lateral aspect of the right tibial plateau associated with extensive bone marrow edema. A small amount of fluid was present in the right knee joint capsule. The patient subsequently underwent arthroscopic excision of the OO. Postoperatively, there was significant relief of pain, and the knee range of motion returned to normal.
CONCLUSIONS: Although OO in the posterior proximal tibia is a rare occurrence, it can be effectively excised through minimally invasive arthroscopic visualization.

UNASSIGNED: To compare the accuracy and effectiveness of orthopaedic robot-assisted minimally invasive surgery versus open surgery for limb osteoid osteoma.
UNASSIGNED: A clinical data of 36 patients with limb osteoid osteomas admitted between June 2016 and June 2023 was retrospectively analyzed. Among them, 16 patients underwent orthopaedic robot-assisted minimally invasive surgery (robot-assisted surgery group), and 20 patients underwent tumor resection after lotcated by C-arm X-ray fluoroscopy (open surgery group). There was no significant difference between the two groups in the gender, age, lesion site, tumor nidus diameter, and preoperative pain visual analogue scale (VAS) scores ( P>0.05). The operation time, lesion resection time, intraoperative blood loss, intraoperative fluoroscopy frequency, lesion resection accuracy, and postoperative analgesic use frequency were recorded and compared between the two groups. The VAS scores for pain severity were compared preoperatively and at 3 days and 3 months postoperatively.
UNASSIGNED: Compared with the open surgery group, the robot-assisted surgery group had a longer operation time, less intraoperative blood loss, less fluoroscopy frequency, less postoperative analgesic use frequency, and higher lesion resection accuracy ( P<0.05). There was no significant difference in lesion resection time ( P>0.05). All patients were followed up after surgery, with a follow-up period of 3-24 months (median, 12 months) in the two groups. No postoperative complication such as wound infection or fracture occurred in either group during follow-up. No tumor recurrence was observed during follow-up. The VAS scores significantly improved in both groups at 3 days and 3 months after surgery when compared with preoperative value ( P<0.05). The VAS score at 3 days after surgery was significantly lower in robot-assisted surgery group than that in open surgery group ( P<0.05). However, there was no significant difference in VAS scores at 3 months between the two groups ( P>0.05).
UNASSIGNED: Compared with open surgery, robot-assisted resection of limb osteoid osteomas has longer operation time, but the accuracy of lesion resection improve, intraoperative blood loss reduce, and early postoperative pain is lighter. It has the advantages of precision and minimally invasive surgery.
UNASSIGNED: 比较骨科机器人辅助微创手术与开放手术切除肢体骨样骨瘤的准确性与疗效。.
UNASSIGNED: 回顾分析2016年6月—2023年6月收治的36例肢体骨样骨瘤患者临床资料，其中16例选择骨科机器人辅助微创切除瘤巢手术（机器人手术组），20例采用常规C臂X线机透视定位后切除肿瘤（开放手术组）。两组患者性别、年龄、病灶部位、瘤巢直径以及术前疼痛视觉模拟评分（VAS）等基线资料比较，差异均无统计学意义（ P>0.05）。记录并比较两组手术时间、病灶切除时间、术中出血量、术中透视次数、病灶切除准确度、术后止痛药使用次数，以及术前及术后3 d、3个月疼痛程度（VAS评分）。.
UNASSIGNED: 与开放手术组相比，机器人手术组手术时间延长，但术中出血量、透视次数及术后止痛药使用次数均减少，病灶切除准确度提高，差异均有统计学意义（ P<0.05）；病灶切除时间差异无统计学意义（ P>0.05）。两组患者术后均获随访，随访时间均为3～24个月，中位时间均为12个月。术后两组均无切口感染、骨折等并发症发生。随访期间均无肿瘤复发。两组患者术后3 d、3个月时VAS 评分均较术前改善（ P<0.05）；术后3 d机器人手术组VAS评分较开放手术组更低（ P<0.05），但术后3个月VAS评分组间差异无统计学意义（ P>0.05）。.
UNASSIGNED: 与开放手术相比，骨科机器人辅助下切除肢体骨样骨瘤虽然手术时间延长，但病灶切除准确度提高、术中出血量减少、术后早期疼痛程度更轻，具有精准、微创优势。.

Osteoid osteoma is one of the most frequent benign musculoskeletal neoplasm. Radiofrequency ablation is the method of choice for non-conservative treatment of osteoid osteoma. Recently, high-intensity focused ultrasound (HIFU) has been proposed as a safer option. The objective of this study is to review the efficacy and side effects of HIFU in the management of osteoid osteoma. A comprehensive search was conducted in PubMed, Science Direct, and Clinical Key until June 30, 2022. Demographic data, baseline characteristics, success rates, pre- and post-procedure pain scores, recurrences, and complications were recorded. Eleven studies were included in this systematic review. Pooled analysis that involved 186 subjects resulted in an overall success rate of 91.94%. Recurrence was reported in two studies, in which it occurred in 4/177 (2.26%) subjects. Skin burn was found in 1 (0.54%) patients. No major or other complications were reported. Three studies compared the success rate of HIFU and RFA. Success rate was slightly higher in the RFA group with insignificant difference (p = 0.15). High-intensity focused ultrasound showed promising results. It offers a safer treatment approach for osteoid osteoma, especially in children, and can be considered for recalcitrant cases after RFA. Nonetheless, more studies are expected in the future.

Recently, cone-beam computed tomography (CBCT)-guided surgeries have been developed for bone and soft tissue tumors. The present study aimed to evaluate the efficacy of CBCT-guided curettage for osteoid osteoma. Our study population included 13 patients who underwent primary curettage for osteoid osteoma using intraoperative CBCT in a hybrid operating room between April 2019 and November 2022. We collected the following data: sex, age, follow-up period, symptom onset to time of surgery, tumor size and location, length of skin incision, operating time, radiation dose, recurrence, postoperative complications, and visual analog scale for pain during the last follow-up. There were 10 male and 3 female patients, and the mean age was 25.0 years (range, 9-49 years). The mean follow-up period was 10.6 months (range, 0.4-24.0 months). The locations of the tumors were the proximal femur in 6 patients, the acetabular region in 2 patients, and the ilium, tibial shaft, calcaneus, cuboid, and talus in 1 patient each. The mean time of symptoms onset to surgery was 18.7 months (range, 2.3-69.9 months). The mean maximum diameter of the tumor was 5.9 mm (range, 3.5-10.0 mm). The mean length of the skin incision was 2.2 cm (range, 1.5-3.5 cm). The mean operating time was 96.9 minutes (range, 64-157 minutes). The mean dose of radiation was 193.2 mGy (range, 16.3-484.0 mGy). No recurrences, postoperative complications, and reoperation were observed in this study. All the patients reported 0 mm on the visual analogue scale for pain on the last follow-up. CBCT-guided curettage for osteoid osteoma was minimally invasive and reliable. This procedure can be effective for the treatment of lesions found in deep locations such as the pelvic bone and proximal femur or an invisible lesion that cannot be detected by regular fluoroscopy.