Thermal Osteonecrosis of the Rib after Radiofrequency Ablation in the Thorax

Safety and feasibility of transbronchial microwave ablation for subpleural lung nodules

BACKGROUND

Transbronchial microwave ablation in treating lung nodules is gaining popularity. However, microwave ablation in subpleural lung nodules raised concerns about pleural-based complications due to the proximity between the pleura and the ablation zone.

METHODS

Patients who underwent transbronchial microwave ablation between March 2019 and November 2022 were included in this analysis. The lung nodules were categorized into the subpleural group-less than 5 mm distance to the nearest pleural surface; the deep nodule group-larger or equal to 5 mm distance to the nearest pleural surface. A review of the safety profile of subpleural lung nodule ablation was conducted.

RESULTS

Eighty-two lung nodules (n = 82) from 77 patients were treated. The mean nodule size was 14.2 ± 5.50 mm. The technical success rate was 100%. The mean procedural time was 133 min. No statistically significant differences were detected in the complication rate and the length of stay between the subpleural and deep nodule groups. Complications occured in 21 nodules (25.6%). No minor pneumothorax was reported. Total five cases of pneumothorax required drainage were observed (6.06% in subpleural nodules [n = 2] vs. 6.12% in deep nodules [n = 3], p = 0.991). Total seven cases of pleuritic chest pain were observed (12.1% in subpleural nodules [n = 4] vs. 6.12% in deep nodules [n = 3], p = 0.340).

CONCLUSIONS

This single-center retrospective analysis found no significant difference in the safety outcomes between subpleural and nonsubpleural lung nodule ablation. The overall rate of complications was low in the cohort. This demonstrated that transbronchial microwave was feasible and safe for most lung nodules.

Advances in experimental models of osteonecrosis of the femoral head

Background

Osteonecrosis of the femoral head (ONFH) is a devastating disease affecting young adults, resulting in significant pain, articular surface collapse, and disabling dysfunction. ONFH can be divided into two broad categories: traumatic and non-traumatic. It has been established that ONFH results from an inadequate blood supply that causes the death of osteocytes and bone marrow cells. Nonetheless, the precise mechanism of ONFH remains to be elucidated. In this regard, preclinical animal and cell models to study ONFH have been established to assess the efficacy of various modalities for preventing and treating ONFH. Nevertheless, it should be borne in mind that many models do not share the same physiologic and metabolic characteristics as humans. Therefore, it is necessary to establish a reproducible model that better mimics human disease.

Methods

We systematically reviewed the literatures in regard to ONFH experimental models over the past 30 years. The search was performed in PubMed and Web of Science. Original animal, cell studies with available full-text were included. This review summarizes different methods for developing animal and cell experimental models of ONFH. The advantages, disadvantages and success rates of ONFH models are also discussed. Finally, we provide experimental ONFH model schemes as a reference.

Results

According to the recent literatures, animal models of ONFH include traumatic, non-traumatic and traumatic combined with non-traumatic models. Most researchers prefer to use small animals to establish non-traumatic ONFH models. Indeed, small animal-based non-traumatic ONFH modeling can more easily meet ethical requirements with large samples. Otherwise, gradient concentration or a particular concentration of steroids to induce MSCs or EPCs, through which researchers can develop cell models to study ONFH.

Conclusions

Glucocorticoids in combination with LPS to induce ONFH animal models, which can guarantee a success rate of more than 60% in large samples. Traumatic vascular deprivation combines with non-traumatic steroids to induce ONFH, obtaining success rates ranging from 80% to 100%. However, animals that undergo vascular deprivation surgery may not survive the glucocorticoid induction process. As for cell models, 10-6mol/L Dexamethasone (Dex) to treat bone marrow stem cells, which is optimal for establishing cell models to study ONFH.

The translational potential of this article

This review aims to summarize recent development in experimental models of ONFH and recommended the modeling schemes to verify new models, mechanisms, drugs, surgeries, and biomaterials of ONFH to contribute to the prevention and treatment of ONFH.

Gamma Radiation-Induced Rib Necrosis and Stereotactic Radiosurgery Failure

Stereotactic radiosurgery, or SRS, uses focused beams of gamma radiation targeted to specific areas of the body and has been used for multiple forms of non-small cell lung cancer. In this article, the authors describe two incidental cases of osteonecrosis in patients who had previously undergone stereotactic radiosurgery with recurrence of tumor. While this is a known side effect of traditional radiation therapy, it has not been described in the context of stereotactic radiosurgery. Further, these lesions were immediately deep to a rib, which may have shielded the lesion, and led to SRS failure. Osteonecrosis of the rib is a rare clinical entity but has been found to occur with glucocorticoid use, bisphosphonates, radiation therapy, and radiofrequency ablation. In the authors' review of the literature on SRS for lung cancer and intrathoracic pathology, rib osteonecrosis was not described and has not been mentioned as a possible side effect. Patients who have undergone thoracic stereotactic radiotherapy may develop side effects of traditional radiotherapy. We identified two patients who developed rib osteonecrosis though that has not been previously described as an adverse effect of stereotactic radiotherapy. The patients described in this case did not have any radiographic evidence of disease on imaging, suggesting that further research is warranted on the diagnosis and management of this rare disease entity.

Bronchoscopic ablation of peripheral lung tumors

Lung cancer is the leading cause of cancer-related death worldwide and lobectomy remains the standard of care for patients with early-stage non-small cell lung cancer (NSCLC). The combination of an aging population and the implementation of low-dose CT for lung cancer screening is leading to an increase in diagnosis of early stage NSCLC in medically "inoperable" patients. The recommended treatment for this latter group of patients is stereotactic body radiation therapy (SBRT). However, many patients cannot undergo SBRT because they have received prior radiation or because the tumor is located next to vital structures. Percutaneous ablative therapies have become an alternative to SBRT but, unfortunately, they all violate the pleura and are associated with high rate of pneumothorax. With a more favorable safety profile and the ability to provide also diagnosis and nodal staging, bronchoscopic ablation is hence emerging as a potential future therapeutic alternative for these patients. Herein we review the current state of the art including animal and human data that exists thus far. We also discuss technical and research challenges as well as future directions that this exciting new technology may take.

CT-guided percutaneous cryoablation of an osteoid osteoma of the rib☆

An osteoid osteoma is a benign bone tumor that arises from osteoblastic dysfunction and usually presents as nonspecific, nocturnal pain located in the diaphysis of long bones, with <1% occurring in the ribs. It is most commonly treated with nonsteroidal anti-inflammatory drugs or merely observed; when these treatments do no prove efficacious, either open surgery or interventional ablation are pursued. Herein, we report a rare case of an osteoid osteoma located in the rib of a 19-year-old male that was histologically diagnosed through computed tomography (CT)-guided biopsy. Using CT guidance, the tumor was ablated by creating an artificial pneumothorax in order to induce a margin of space safe enough for cryoablation. It is important to be aware of the possibility that an osteoid osteoma may be present in the ribs, as the differential diagnosis includes costochondritis, pneumonia, osteoblastoma, enchondroma, osteosarcoma, cyst, and Brodie abscess. In addition, we have shown that CT-guided cryoablation can be an effective and less invasive treatment when compared to open en bloc resection, highlighting the role of interventional radiology in bone tumor ablation.

Lung cancer ablation: complications

Although radiofrequency ablation for lung cancer is generally safe (with a mortality rate <1%), it may cause various complications. Common complications include pneumothorax, pleural effusion, and parenchymal hemorrhage. Although most complications can be treated conservatively or with minimal therapy, physicians should be aware of rare but serious complications. Potentially fatal complications include massive hemorrhage, intractable pneumothorax due to bronchopleural fistula, pulmonary artery pseudoaneurysm, systemic air embolism, and pneumonitis. Other serious complications include injury to the nearby tissues (e.g., brachial nerve plexus, phrenic nerve, diaphragm, and chest wall), needle tract seeding, lung abscess, empyema, and skin burn. Although cavitation of the ablation zone is usually insignificant clinically, such a cavity occasionally ruptures, leading to pneumothorax and bleeding. Cavities may also serve as a scaffold for fungal colonization. Precautions to minimize risk should be taken whenever possible. Nevertheless, serious complications may occur, and thus physicians should be aware of the appropriate treatments for these complications. This article reviews complications associated with lung cancer ablation.

Rib fractures after percutaneous radiofrequency and microwave ablation of lung tumors: incidence and relevance

PURPOSE

To retrospectively identify the incidence and probable risk factors for rib fractures after percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) of neoplasms in the lung and to identify complications related to these fractures.

MATERIALS AND METHODS

Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Study population was 163 patients treated with MWA and/or RFA for 195 lung neoplasms between February 2004 and April 2010. Follow-up computed tomographic images of at least 3 months were retrospectively reviewed by board-certified radiologists to determine the presence of rib fractures. Generalized estimating equations were performed to assess the effect that patient demographics, tumor characteristics, treatment parameters, and ablation zone characteristics had on development of rib fractures. Kaplan-Meier curve was used to estimate patients' probability of rib fracture after ablation as a function of time. Clinical parameters (ie, pain in ribs or chest, organ damage caused by fractured rib) were evaluated for patients with confirmed fracture.

RESULTS

Rib fractures in proximity to the ablation zone were found in 13.5% (22 of 163) of patients. Estimated probability of fracture was 9% at 1 year and 22% at 3 years. Women were more likely than were men to develop fracture after ablation (P = .041). Patients with tumors closer to the chest wall were more likely to develop fracture (P = .0009), as were patients with ablation zones that involved visceral pleura (P = .039). No patients with rib fractures that were apparently induced by RFA and MWA had organ injury or damage related to fracture, and 9.1% (2 of 22) of patients reported mild pain.

CONCLUSION

Rib fractures were present in 13.5% of patients after percutaneous RFA and MWA of lung neoplasms. Patients who had ablations performed close to the chest wall should be monitored for rib fractures.

Complications of radiofrequency ablation of hepatic, pulmonary, and renal neoplasms

Percutaneous thermal ablation has emerged as a viable technique for treatment of numerous solid organ malignancies. As the number of these procedures increases, so do the complications that are seen. Most common complications are generally related to bleeding from the target organ during or after the procedure and from thermal injury to adjacent structures. The nature of these injuries depends on the particular organ being treated, therefore it it best to categorize them this way. We will review the more common complications seen following the ablation of tumors in the liver, kidney, and lung, discuss the clinical presentation associated with each, and suggest precautions to help avoid them in the future. Understanding the potential risks associated with this procedure is critical for treatment planning and fundamental for performing these procedures safely.

Emu model of full-range femoral head osteonecrosis induced focally by an alternating freezing and heating insult

The emu, a large bipedal bird with hip joint biomechanics similar to humans, was used to establish an experimental model of femoral head osteonecrosis and subsequent femoral head collapse. Focal lesions were induced in 20 adult male emus using an alternating liquid nitrogen freezing and radiofrequency heating insult. At 2, 4, 8, 12 and 16 weeks post-surgery, hip magnetic resonance imaging (MRI) was performed. Before the emus were sacrificed, barium sulphate was infused to the lower extremity to study blood vessel distribution patterns. Femoral samples were scanned by micro-computed tomography (micro-CT) and evaluated histologically. Hip MRI showed changes from broad oedema to femoral head collapse. Emus developed a crippled gait from post-operative week 6. Micro-CT scans and histology showed human-like osteonecrotic changes with an impaired local blood supply. The protocol resulted in consistent full-range osteonecrosis of the femoral head that may serve as a model for testing potential treatments.

Experimental animal models of osteonecrosis

Osteonecrosis (ON) or avascular necrosis (AVN) is a common bone metabolic disorder, mostly affecting femoral head. Although many biological, biophysical, and surgical methods have been tested to preserve the femoral head with ON, none has been proven fully satisfactory. It lacks consensus on an optimal approach for treatment. This is due, at least in part, to the lack of ability to systematically compare treatment efficacy using an ideal animal model that mimics full-range osteonecrosis of femoral head (ONFH) in humans with high incidence of joint collapse accompanied by reparative reaction adjacent to the necrotic bone in a reproducible and accessible way. A number of preclinical animal ON models have been established for testing potential efficacy of various modalities developed for prevention and treatment of ON before introduction into clinics for potential applications. This paper describes a number of different methods for creating animal experimental ON models. Advantages and disadvantages of such models are also discussed as reference for future research in battle against this important medical condition.