Microwave ablation of osteoid osteoma: initial experience and efficacy

Percutaneous CT-Guided Microwave Ablation for the Treatment of Osteoid Osteomas: A Single Center Experience

RATIONALE AND OBJECTIVES

The aim of the current study was to evaluate the feasibility and effectiveness of CT-guided microwave ablation (MWA) in the treatment of osteoid osteomas (OO).

MATERIALS AND METHODS

Data from 59 consecutive patients who underwent percutaneous CT-MWA for OO treatment were examined in the current retrospective study. The period of this study spanned from January 2021 to May 2023 at a single institution. The study involved an evaluation of clinical and radiological characteristics, procedural data, Visual Analog Scale (VAS) pain scores, complication incidences, as well as clinical and technical success rates. Statistical analyses were performed by using the Wilcoxon test with Bonferroni correction, Friedman, Spearman, Mann-Whitney U test.

RESULTS

59 patients with an average age of 17.31 ± 8.53 years underwent CT-guided MWA for the treatment of OO. The procedure demonstrated a high success rate, with 96.6% of cases achieving both technical and clinical success. However, recurrence was observed in two patients (3.4%) at the three-month follow-up. These cases were successfully managed with a second MWA procedure. The median VAS pain scores reported by the patients was significantly improved post-procedure: from 8.64 ± 1.14 before treatment to 0.63 ± 0.98 in the first month, 0.41 ± 1.02 in the third month, and 0.15 ± 0.45 in the sixth month. Only one patient (1.7%) experienced a minor complication; no major complications were recorded in this study.

CONCLUSION

CT-guided percutaneous MWA is a minimally invasive and a highly effective and safe approach for the treatment of OO.

A review of the development of histotripsy for extremity tumor ablation with a canine comparative oncology model to inform human treatments

Cancer is a devasting disease resulting in millions of deaths worldwide in both humans and companion animals, including dogs. Treatment of cancer is complex and challenging and therefore often multifaceted, as in the case of osteosarcoma (OS) and soft tissue sarcoma (STS). OS predominantly involves the appendicular skeleton and STS commonly develops in the extremities, resulting in treatment challenges due to the need to balance wide-margin resections to achieve local oncological control against the functional outcomes for the patient. To achieve wide tumor resection, invasive limb salvage surgery is often required, and the patient is at risk for numerous complications which can ultimately lead to impaired limb function and mobility. The advent of tumor ablation techniques offers the exciting potential of developing noninvasive or minimally invasive treatment options for extremity tumors. One promising innovative tumor ablation technique with strong potential to serve as a noninvasive limb salvage treatment for extremity tumor patients is histotripsy. Histotripsy is a novel, noninvasive, non-thermal, and non-ionizing focused ultrasound technique which uses controlled acoustic cavitation to mechanically disintegrate tissue with high precision. In this review, we present the ongoing development of histotripsy as a non-surgical alternative for extremity tumors and highlight the value of spontaneously occurring OS and STS in the pet dog as a comparative oncology research model to advance this field of histotripsy research.

Benign Bone Tumors Beyond Osteoid Osteoma: Percutaneous Minimally Invasive Image-Guided Interventions

Painful benign bone tumors often adversely influence quality of life primarily due to skeletal-related events such as unremittable pain, pathologic fracture, neurologic deficit, as well as skeletal growth disturbance. Substantial advances in percutaneous minimally invasive interventions for treatment of painful benign bone tumors beyond osteoid osteoma have been established as safe, efficacious, and durable treatments to achieve definitive cure. This article details the available armamentarium and most recent advances in minimally invasive percutaneous interventions and the role of radiologists for the management of patients with benign bone tumors beyond osteoid osteoma.

Benign Bone Tumors: State of the Art in Minimally Invasive Percutaneous Interventions

Painful benign bone tumors most commonly affect pediatric patients and young adults. They may be associated with skeletal-related events such as intractable pain, pathologic fracture, neurologic deficit as a consequence of nerve or spinal cord compression, as well as growth disturbance. Consequently, they often result in diminished activity and adversely affect quality of life. There have been substantial recent advances in percutaneous minimally invasive image-guided interventions for treatment of painful benign bone tumors including thermal ablation (radiofrequency ablation, cryoablation, microwave ablation, laser photocoagulation, and high-intensity focused US ablation), chemical (alcohol) ablation, cementoplasty, and intralesional injections. The safety, efficacy, and durability of such interventions have been established in the recent literature and as such, the role of musculoskeletal interventional radiologists in the care of patients with benign bone lesions has substantially expanded. The treatment goal of minimally invasive musculoskeletal interventions in patients with benign bone tumors is to achieve definitive cure. The authors detail the most recent advances and available armamentarium in minimally invasive image-guided percutaneous interventions with curative intent for the management of benign bone tumors. ^© RSNA, 2022.

Effect of Thermal Ablation on Growth Plates: A Study to Explore the Thermal Threshold of Rabbit Growth Plates During Microwave Ablation

PURPOSE

To explore the temperature threshold of thermal damage to growth plates.

METHODS

Nine rabbits were divided into three groups for femoral ablation, exposing the growth plate to different temperatures (T1 = 43-45 °C; T2 = 46-48 °C; T3 = 49-51 °C). After 5 weeks, the changes in the femurs were assessed by macroscopic images, micro-CT, haematoxylin and eosin staining, and immunohistochemistry of Col2a1 (type II collagen). At the cellular level, rabbit epiphyseal chondrocytes were exposed to 37 °C, 44 °C, 47 °C and 50 °C for 5 min. Then, proliferation and chondrogenic differentiation were detected.

RESULTS

The rabbits in the T2 and T3 groups developed length discrepancies and axial deviations of femurs, abnormal newly formed bone in the marrow cavity, disorganized growth plates and decreased Col2a1 expression. At the cellular level, the cells exposed to 47 °C and 50 °C for 5 min showed decreased viability, increased apoptosis, decreased extracellular matrix synthesis and decreased matrix mineralization. However, the changes in rabbits in the T1 group and cells at 44 °C did not show a significant difference.

CONCLUSION

The ablation of growth plates at temperatures above 45 °C for 5 min results in decreased chondrocyte viability and disorganized growth plates, leading to growth disturbances. Further studies are warranted to confirm these promising initial results.

Osteoid Osteoma of the Proximal Femur: Pitfalls in Diagnosis and Performance of Open Surgical Resection

Aims

Proximal femoral osteoid osteoma (OO) is extremely easy to be misdiagnosed or missed. The purpose of this study was to retrospectively analyze the clinical data of patients with proximal femoral OO in order to determine the clinical manifestation and imaging characteristics of the disease, so as to provide help for the preoperative diagnosis and clinical treatment of proximal femoral OO.

Methods

This was a retrospective study involving 35 patients with proximal femoral OO admitted into our hospital from January 2015 to January 2021. The baseline characteristics of the participants included; 24 males and 11 females, aged between 13 and 25 (mean 16.2) years old, and the course of the disease was 1 to 14 (mean 6.3) months. We used previous medical experience records of the patients to analyze for the causes of misdiagnosis. Moreover, we compared the difference between preoperative and postoperative treatment practices in alleviating pain in OO patients and restoring hip function. Follow-ups were carried out regularly, and patients advised to avoid strenuous exercises for 3 months.

Results

We followed up 35 patients (25 intercortical, 4 sub-periosteal, and 6 medullary) for an average of 41.4 months. We found that 15 patients (42.9%) had been misdiagnosed of synovitis, perthes disease, osteomyelitis, intra-articular infection, joint tuberculosis and hip impingement syndrome, whose average time from symptoms to diagnosis were 6.3 months. Postoperative pain score and joint function score improved significantly compared with preoperative, and complications were rare.

Conclusion

Open surgical resection constitutes an effective treatment for proximal femoral OO by accurately and completely removing the nidus. Wrong choice of examination, and the complexity and diversity of clinical manifestations constitutes the main reasons for the misdiagnosis of proximal femoral OO.

CT-guided microwave ablation of osteoid osteoma: Long-term outcome in 28 patients

PURPOSE

The purpose of this study was to assess the long-term efficacy of CT-guided microwave ablation (MWA) in the treatment of osteoid osteoma. Secondary objectives were to assess early outcome and side-effects of MWA.

MATERIALS AND METHODS

Twenty-eight consecutive patients (18 men, 10 women) with a median age of 19.5 years (IQR: 16, 25.5) with a total of 28 non-spinal osteoid osteoma treated by CT-guided MWA were retrospectively included. The ablations were performed with a median power and duration of 60 Watt and 1 min 30 s, respectively. Pain referred to osteoid osteoma was assessed at predefined time points using a 0-10 numeric rating scale. At one month, contrast-enhanced follow-up MRI was performed to evaluate the nidus vascularization and the volume of necrosis induced by MWA. Clinical success was defined by the absence of osteoid osteoma-related pain, and technical success was defined by the presence of necrosis of the nidus on the one-month post-MWA MRI.

RESULTS

Long term success rate was 93% (26/28) after a follow-up of 55.5 months (IQR: 25.75, 74.5) and technical success rate was 96 % (25/26). One late failure was observed after a patient had been declared cured at one month but the formal proof of a late recurrence of osteoid osteoma could not be brought. Three minor complications were reported including mild reversible superficial radial nerve injury with a skin burn (grade 2) in one patient and moderate skin burn only in two patients.

CONCLUSION

Our results suggest that CT-guided MWA is an effective option for a minimally-invasive treatment of osteoid osteoma with a low rate of complication and no late recurrence.

Interventional Radiology’s Osteoid Osteoma Management: Percutaneous Thermal Ablation

Osteoid osteoma (OO) is one of the most common benign bone tumors with specific clinical and radiological characteristics. Analgesic therapy and surgical treatment have been considered the only therapy for a long time. Recently, safe and effective new therapeutic options have been introduced, among which percutaneous thermal ablation techniques. This review aims to describe the recent updates in the field of percutaneous thermal ablation techniques in the treatment of OO, assessing the outcomes in terms of efficacy, complications, and recurrence rate.

Finite Element Analysis Could Predict and Prevent a Pathological Femoral Shaft Fracture after En Bloc Resection of a Large Osteoid Osteoma

Osteoid osteoma is a benign tumor. Approximately 20% of these tumors are located in the femur. The tumor primarily occurs in children and is treated by surgical excision or radiofrequency ablation. Recently, bone-tumor resection using three-dimensional (3D) intraoperative imaging with an O-arm in combination with a navigation system has been reported to be effective. However, there is a risk of postoperative fracture because of the weakening of the bone after drilling for tumor resection. A 12-year-old Japanese girl presented with an osteoid osteoma in the left femoral shaft, which resulted in a fracture after en bloc resection and artificial bone grafting using a 3D image-guided (O-arm) assisted navigation system. Orthopedic oncologists should be aware of the risk of fracture. Moreover, they should consider the mechanical risk prediction of bone fracture using finite element analysis prior to treatment.

Needleless Ablation of Osteoid Osteoma and Osteoblastoma: The Emergent Role of MRgFUS

Osteoblastoma (OB) and osteoid osteoma (OO) are benign bone-forming tumors, with nearly identical basic microscopic features. The main difference is dimension (OO has usually a nidus measuring <2 cm in diameter). In addition, OB is biologically more active than OO, with a tendency to grow in size. Historically, treatments have included surgical resection and analgesics, although invasiveness and poor tolerance have led to the current standard of care moving toward interventional radiology, where radiofrequency ablation (RFA) represents the most diffuse technique. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) has recently emerged as another innovative alternative treatment, providing tumor ablation through a needleless and ionizing radiation-free modality. In addition, this technique has the ability to guarantee a very precise and controlled increase in temperature, delivering small amounts of energy that can accurately destroy only the lesion, avoiding healthy surrounding tissues. The present review focuses on MRgFUS as the less invasive, safe, effective, and durable treatment option for the management of osteoid osteoma and osteoblastoma, including a description of technical details, indications and outcomes.

Innovative Techniques Associated with Traditional Abdominal Surgery in Complex Pediatric Cases: A Tertiary Center Experience

Pediatric abdominal surgery is constantly evolving, alongside the advent of new surgical technologies. A combined use of new tools and traditional surgical approaches can be useful in the management of complex cases, allowing less invasive procedures and sometimes even avoiding multiple interventions. This combination of techniques has implications even from the anesthetic point of view, especially in post-operative pain control. Thereby, tertiary level centres, including highly-specialized professionals and advanced equipment, can maximize the effectiveness of treatments to improve the final outcomes. Our paper aims to present some possible combinations of techniques recently used at our institution to provide a one-session, minimally invasive treatment within different areas of abdominal surgery.

Temperature Monitoring in Hyperthermia Treatments of Bone Tumors: State-of-the-Art and Future Challenges

Bone metastases and osteoid osteoma (OO) have a high incidence in patients facing primary lesions in many organs. Radiotherapy has long been the standard choice for these patients, performed as stand-alone or in conjunction with surgery. However, the needs of these patients have never been fully met, especially in the ones with low life expectancy, where treatments devoted to pain reduction are pivotal. New techniques as hyperthermia treatments (HTs) are emerging to reduce the associated pain of bone metastases and OO. Temperature monitoring during HTs may significantly improve the clinical outcomes since the amount of thermal injury depends on the tissue temperature and the exposure time. This is particularly relevant in bone tumors due to the adjacent vulnerable structures (e.g., spinal cord and nerve roots). In this Review, we focus on the potential of temperature monitoring on HT of bone cancer. Preclinical and clinical studies have been proposed and are underway to investigate the use of different thermometric techniques in this scenario. We review these studies, the principle of work of the thermometric techniques used in HTs, their strengths, weaknesses, and pitfalls, as well as the strategies and the potential of improving the HTs outcomes.

Osteoid Osteoma Treatment with Microwave Ablation: A Report of Two Cases

Osteoid osteomas are one of the most common bone tumors. Although benign in nature, they can cause significant pain and distress to the afflicted patient. The main goal of treatment is to relieve pain. Historically, these tumors were treated with nonsteroidal anti-inflammatory drugs (NSAIDs) or surgery. Percutaneous ablative techniques have since gained popularity because of their efficacy and low risk profiles. Radiofrequency ablation was the first of these technologies used in the treatment of these tumors. More recently, microwave ablation has gained popularity. However, the literature is sparse regarding the safety and efficacy of this treatment. Here, we discuss our experience with microwave ablation in the treatment of osteoid osteomas in two patients and review the current literature on this technique. Microwave ablation in the treatment of osteoid osteoma seems to be a safe and effective treatment for this tumor.

Osteoid osteoma: which is the best mininvasive treatment option?

Osteoid osteoma is the third most common benign bone tumor, with well-known clinical presentation and radiological features. Although surgical excision has been the only therapeutic option for a long time, to date it has been replaced by minimally invasive techniques, which proved satisfactory success rates and low complication occurrence. Therefore, the purpose of this literature review was to describe the main updates of these recent procedures in the field of interventional radiology, with particular attention paid to the results of the leading studies relating to the efficacy, complications, and recurrence rate. Nevertheless, this study aimed to analyze the peculiarities of each reported technique, with specific focus on the possible improvements and pitfalls. Results proved that all mininvasive procedures boast a high success rate with slight number of complications and a low recurrence rate. Radiofrequency ablation is still considered the gold standard procedure for percutaneous treatment of osteoid osteoma, and it has the possibility to combine treatment with a biopsy. Interstitial laser ablation's advantages are the simplicity of use and a lower cost of the electrodes, while cryoablation allows real-time visualization of the ablated zone, increasing the treatment safety. Magnetic resonance-guided focused ultrasound surgery is the most innovative non-invasive procedure, with the unquestionable advantage to be radiation free.

Image-guided Cryotherapy for Musculoskeletal Tumors

BACKGROUND

This article represents a review of the use of image-guided cryotherapy in the treatment of musculoskeletal tumor lesions. Cryotherapy is able to induce a lethal effect on cancer cells through direct and indirect mechanisms. In this manuscript, we combined our experience with that of other authors who have published on this topic in order to provide indications on when to use cryotherapy in musculoskeletal oncology.

DISCUSSION

Image-Guided percutaneous cryotherapy is a therapeutic method now widely accepted in the treatment of patients with musculoskeletal tumors. It can be used both for palliative treatments of metastatic bone lesions and for the curative treatment of benign bone tumors, such as osteoid osteoma or osteoblastoma. In the treatment of bone metastases, cryotherapy plays a major role in alleviating or resolving disease-related pain, but it has also been demonstrated that it can have a role in local disease control. In recent years, the use of cryotherapy has also expanded for the treatment of both benign and malignant soft tissue tumors.

CONCLUSION

Percutaneous cryotherapy can be considered a safe and effective technique in the treatment of benign and malignant musculoskeletal tumors. Cryotherapy can be considered the first option in benign tumor lesions, such as osteoid osteoma, and a valid alternative to radiofrequency ablation. In the treatment of painful bone metastases, it must be considered secondarily to other standard treatments (radiotherapy, bisphosphonate therapy, and chemotherapy) when they are no longer effective in controlling the disease or when they cannot be repeated (for example, radiotherapy).

Novel Strategy of Curettage and Adjuvant Microwave Therapy for the Treatment of Giant Cell Tumor of Bone in Extremities: A Preliminary Study

Objectives

To evaluate whether curettage with adjuvant microwave therapy was successful in the treatment of giant cell tumor of the bone (GCTB) in extremities, especially for GCTB with pathological fractures and GCTB of the distal radius.

Methods

This was a retrospective study of 54 cases of GCTB of the extremities treated by curettage with adjuvant microwave therapy between 2007 and 2019. Five patients were lost to follow up and excluded from the study. A total of 33 male and 21 female patients were included in this study. Patients were aged 15–57 years (mean 29.72 ± 10.48 years). Among these patients, there were 10 cases of GCTB with pathological fractures and eight cases of GCTB of the distal radius; one of these cases was combined with a pathological fracture. Comprehensive imaging examinations (X‐rays [including lesion site and chest], CT, MRI, emission computed tomography, and pathology examination) of all patients were reviewed. The clinical staging of these patients were evaluated radiologically using the Campanacci classification system based on the extent of spread of the tumor. All patients underwent curettage with adjuvant microwave therapy. Clinical and imaging evaluations were performed in all cases to check for recurrence or metastasis. Lower limb and upper limber function were assessed using the Musculoskeletal Tumor Society score (MSTS), and wrist function was assessed according to the disabilities of the arm, shoulder and hand (DASH) score. Data on surgical‐related complications were recorded.

Results

All cases were followed up for 24–126 months (mean 60.69 ± 29.61 months). There were 24 patients with a Campanacci grade of 3 and 30 with a Campanacci grade of 2. The 52 patients were continuously disease‐free. The local recurrence rate was 3.70% (2 patients). One patient had recurrence in the proximal femur, and the other developed in soft tissue of the calf muscle. No recurrence occurred for GCTB of the distal radius. One recurrence occurred in a GCTB with pathological fractures. The intervals were 9 and 28 months, respectively. The cases of recurrence all had a Campanacci grade of 3 (8.33%). The median MSTS among the 54 patients was 27.67 ± 3.81. The mean wrist function DASH score was 8.30 ± 2.53. The mean MSTS was 28.67 ± 1.63 and 26.71 ± 5.49 for patients with GCTB of the distal radius and for those with pathological fractures, respectively. In comparing patients with and without pathological fractures, there was no significant difference in the MSTS functional score. Five patients had complications after the surgery.

Conclusion

Curettage with adjuvant microwave ablation therapy provided favorable local control and satisfactory functional outcomes in the treatment of GCTB, especially for cases with pathological fractures and those with GCTB of the distal radius.

Radiofrequency ablation vs microwave ablation for osteoid osteomas: long-term results

OBJECTIVE

Osteoid osteomas are benign bone tumors commonly treated using thermal ablation. We compare the technical success, complication rates, and long-term efficacy of the two most common ablation types: radiofrequency and microwave.

MATERIALS AND METHODS

A retrospective study was performed of all osteoid osteoma ablation procedures between 2007 and 2017. A ten-point numerical pain scale was used to quantify symptoms before and after the procedures with > 12-month follow-up. Complications were reported using the Society of Interventional Radiology Adverse Events reporting criteria.

RESULTS

Twenty-nine patients successfully underwent 15 radiofrequency ablations and 15 microwave ablations with a technical success rate of 83% for radiofrequency and 100% for microwave (p = 0.23). Long-term recurrence rates (p = 1.0) and complication rates (p = 0.60) were not significantly different for the groups. One patient developed a skin burn following microwave ablation and another developed 12 months of sciatic neuropathy following radiofrequency ablation.

CONCLUSION

Microwave and radiofrequency ablation are safe and effective methods for treating osteoid osteomas with similar long-term efficacies. Although radiofrequency ablation is more commonly reported to result in skin burns, this complication can arise during microwave ablation.

Percutaneous microwave ablation of bone tumors: a systematic review

AIM

To systematically review microwave ablation (MWA) protocols, safety, and clinical efficacy for treating bone tumors.

MATERIALS AND METHODS

A systematic literature search was conducted using PubMed, the Cochrane Library, EMBASE, and Web of Science database. Data concerning patient demographics, tumor characteristics, procedure, complications, and clinical outcomes were extracted and analyzed.

RESULTS

Seven non-comparative studies (6 retrospective, 1 prospective) were included accounting for 249 patients and 306 tumors (244/306 [79.7%] metastases; 25/306 [8.2%] myelomas, and 37/306 [12.1%] osteoid osteomas [OO]). In malignant tumors, MWA power was 30-70 W (except in one spinal tumors series where a mean power of 13.3 W was used) with pooled mean ablation time of 308.3 s. With OO, MWA power was 30-60 W with mean ablation time of 90-102 s. Protective measures were very sporadically used in 5 studies. Additional osteoplasty was performed in 199/269 (74.0%) malignant tumors. Clinically significant complications were noted in 10/249 (4.0%) patients. For malignant tumors, estimated pain reduction on the numerical rating scale was 5.3/10 (95% confidence intervals [95%CI] 4.6-6.1) at 1 month; and 5.3/10 (95% CI 4.3-6.3) at the last recorded follow-up (range 20-24 weeks in 4/5 studies). For OO, at 1-month follow-up, effective pain relief was noted in 92.3-100% of patients.

CONCLUSION

MWA is effective in achieving pain relief at short- (1 month) and mid-term (4-6 months) for painful OO and malignant bone tumors, respectively. Although MWA seems safe, further prospective studies are warranted to further assess this aspect, and to standardize MWA protocols.

KEY POINTS

• Large heterogeneity exists across literature about ablation protocols used with microwave ablation applied for the treatment of benign and malignant bone tumors. • Although microwave ablation of bone tumors appears safe, further studies are needed to assess this aspect, as current literature does not allow definitive conclusions. • Nevertheless, microwave ablation is effective in achieving pain relief at short- (1 month) and mid-term (4-6 months) for painful osteoid osteomas and malignant bone tumors, respectively.

Musculoskeletal interventional oncology: current and future practices

Management of musculoskeletal (MSK) tumours has traditionally been delivered by surgeons and medical oncologists. However, in recent years, image-guided interventional oncology (IO) has significantly impacted the clinical management of MSK tumours. With the rapid evolution of relevant technologies and the expanding range of clinical indications, it is likely that the impact of IO will significantly grow and further evolve in the near future.

In this narrative review, we describe well-established and new interventional technologies that are currently integrating into the IO armamentarium available to radiologists to treat MSK tumours and illustrate new emerging IO indications for treatment.

Harlequin syndrome following microwave ablation in a child with a symptomatic paraspinal mass

Our goal is to describe a case of Harlequin syndrome associated with microwave ablation in the treatment of a symptomatic paraspinal mass in a child, along with a summary of the literature. Our patient is the only known case of persistent Harlequin syndrome associated with microwave ablation treatment of a symptomatic paraspinal mass. Harlequin syndrome is a rare neurological condition characterised by unilateral sweating and flushing of the face, neck and/or upper chest. The specific mechanism is unclear, but the majority of cases are believed to be a result of contralateral lesions along the sympathetic chain. CT-guided microwave ablation therapy is a minimally invasive technique used as an alternative to surgery in this case due to the risk and morbidity associated with excision of the mass. There is limited literature assessing the use and inherent risk of developing complications following microwave ablation to the paraspinal region in the paediatric population.

Clinical Guideline for Microwave Ablation of Bone Tumors in Extremities

Microwave ablation has been used to treat bone tumors in extremities for more than 30 years. With improved recognition, updated microwave equipment, and expanded clinical application, microwave ablation has recently been widely used to treat bone tumors. To standardize the application of microwave ablation in the clinical treatment of bone tumors in the limbs, research results and clinical experience involving the use of microwave ablation to treat bone tumors in the limbs have been summarized, and a clinical guideline has been designed. This guideline is aimed at providing a reliable clinical basis for indications, preoperative evaluation and decision-making, perioperative treatment, complications, and other issues via evidence-based medicine. Two aspects are considered-percutaneous microwave ablation and intraoperative microwave ablation of bone tumors in extremities. Ultimately, the guideline is intended to standardize treatment and improve the clinical efficacy of microwave ablation of bone tumors in extremities.

Use of percutaneous microwave ablation for the treatment of bone tumors: a retrospective study of clinical outcomes in 47 patients

Objective

The present study aimed to evaluate the short-term clinical performance and safety of percutaneous microwave ablation (MWA) techniques for the treatment of bone tumors.

Methods

This single-institution retrospective study investigated 47 cases of bone tumors treated by MWA from June 2015 to June 2018. The study included 26 patients (55.3%) with benign bone tumors and 21 patients (44.7%) with malignant bone tumors. The tumors were located in the spine or sacrum (15, 31.9%), the upper extremities (6, 12.8%), the lower extremities (17, 36.2%) and the pelvis (9, 19.1%). Outcomes regarding clinical efficacy, including pain relief, quality of life, and intervention-related complications, were evaluated before and after MWA using the visual analog scale (VAS) and the 36-item Short-Form Health Survey (SF-36) scoring system.

Results

Of the 47 patients included in this study, all of them completed follow-up examinations, with a mean follow-up duration of 4.8 ± 1.6 months (range, 2–9 months). Significantly improved VAS and SF-36 scores were recorded after the initial treatment (P<0.001), suggesting that almost 100% of patients experienced pain relief and an improved quality of life following surgery. No major intervention-related complications (e.g., serious neurovascular injury or infection) occurred during or after the treatment. We recorded only three minor posttreatment complications (6.4%, 3/47), which were related to thermal injury that caused myofasciitis and affected wound healing.

Conclusion

In our study, the short-term efficacy of MWA was considerably favorable, with a relatively low rate of complications. Our results also showed that MWA was effective for pain relief and improved patients’ quality of life, making it a feasible treatment alternative for bone tumors.

Use Of Microwave Thermal Ablation In Management Of Skip Metastases In Extremity Osteosarcomas

Background

The objective of this study was to evaluate the efficiency and safety of microwave thermal ablation in the treatment of skip metastases in extremity osteosarcomas. Osteosarcoma of extremities with skip metastases has a poor prognosis, and thus, microwave thermal ablation presents an attractive minimally invasive option in this patient group.

Methods

A retrospective review included a cohort of 76 patients with extremity osteosarcoma in one institute, of which five cases (6.6%) showed skip metastases. Skip lesions located in proximal femur and primary sites were distal femur in all five patients. The authors treated skip lesions using microwave thermal ablation after primary tumors were removed at wide margins. Procedural efficacy and safety were determined with postoperative MSTS score and follow-ups of 12–62 months (median 22 months).

Results

The ablation time was five to nine minutes (mean seven minutes). Taking advantage of Microwave-induced hyperthermia, wide resections of distal femur and endoprosthesis reconstructions were performed instead of total femoral resection and replacement in four patients, and above-knee amputation was performed instead of hip disarticulation in one patient. The postoperative hip functions were intact and the mean lower extremity MSTS score was 26. Three patients died at 12–22 months after definitive surgery because of pulmonary metastases, and two patients remained disease-free at 44 and 62 months after surgery, respectively. No local recurrence either at sites of primary tumors or skip lesions was found at time of the latest follow up.

Conclusion

Microwave thermal ablation is efficacious in treating skip metastases of osteosarcoma in extremities. The modality has promise for good local control of tumors, less invasive surgeries, and intact and satisfied lower extremity functions in these relatively poor prognosis patients.

Level of evidence

Therapeutic Level III.