Radiofrequency ablation in the treatment of atypical cartilaginous tumours in the long bones: lessons learned from our experience

Application of microwave ablation assisted degradation therapy in surgical treatment of intramedullary chondrosarcoma of extremities

AIM

Clinical diagnosis and surgical treatment of chondrosarcoma (CS) are continuously improving. The purpose of our study is to evaluate the effectiveness of microwave ablation (MWA) assisted degradation therapy in the surgical treatment of intramedullary chondrosarcoma of the extremities, to provide a new reference and research basis for the surgical treatment of CS.

METHODS

We recruited 36 patients with intramedullary CS who underwent MWA assisted extended curettage. Preoperative patient demographics and clinical data were recorded. Surgery was independently assisted by a medical team. Patients were followed up strictly and evaluated for oncological prognosis, radiological results, limb joint function, pain, and complications.

RESULTS

We included 15 men and 21 women (mean age: 43.5 ± 10.1). The average length of the lesion was 8.1 ± 2.5 cm. Based on preoperative radiographic, clinical manifestations, and pathological results of puncture biopsy, 28 patients were preliminarily diagnosed with CS-grade I and eight patients with CS-grade II. No recurrence or metastasis occurred in the postoperative follow-up. The average Musculoskeletal Tumor Society score was 28.8 ± 1.0, significantly better than presurgery. Secondary shoulder periarthritis and abduction dysfunction occurred in early postoperative stage CS of the proximal humerus in some, but returned to normal after rehabilitation exercise. Secondary bursitis occurred at the knee joint in some due to the internal fixation device used in treatment; however, secondary osteoarthritis and avascular necrosis of the femoral head were not observed. Overall, oncological and functional prognoses were satisfactory.

CONCLUSIONS

The application of MWA assisted degradation therapy in intramedullary CS can achieve satisfactory oncology and functional prognosis, providing a new option for the limited treatment of CS.

The national incidence of chondrosarcoma of bone; a review

BACKGROUND

Chondrosarcoma (CS) epidemiology has been studied by a number of authors using national cancer registry cohorts. Many reports share the common findings of a slight increase in incidence, but not all. The patterns and causes for these changes are divergent while reflection concerning methodological challenges are often missing.

METHOD

We have performed a structured literature review to find national analyses of CS incidence published from 2010 to 2020. We included eight studies of national incidence of CS, summarise their findings and patterns of change. We further discuss explanations given for these changes to better understand the real patterns and raise awareness in their interpretation.

RESULTS

Reported crude incidence ranges from 0.27 per million per year overall in Saudi Arabia to 5.4 in the Netherlands. Four studies from the USA, England, Switzerland and France report age standardised rates of 2.0-4.1 per million per year overall. While some countries report stable patterns, most report a slight increase. The Netherlands is the only country reporting a large increase, driven by a 10-fold increase in the incidence of ACT/grade 1 CS during the study period. We challenge the explanations given for this and suggest that this most likely is a result of variable interpretation and definition of CS at the lower levels of disease aggressiveness. This should raise awareness to possible over-treatment of CS in the Netherlands.

CONCLUSION

The most likely national incidence of CS of bone is between 2-4 per million per year. Three modern reports present an incidence of 3.4-4.1 per million per year.

Der atypische chondrogene Tumor

Hintergrund

Atypische chondrogene Tumoren (ACT) der kurzen und langen Röhrenknochen, früher als Chondrosarkome G1 bezeichnet, verhalten sich lokal aggressiv, haben aber ein sehr geringes Metastasierungspotenzial. Die Abgrenzung zu benignen Enchondromen ist aus klinischer, radiologischer und histopathologischer Sicht komplex.

Ziel der Arbeit

Epidemiologie, Diagnostik und Therapie von ACT unter besonderer Berücksichtigung der Abgrenzung zu Enchondromen werden dargestellt.

Material und Methoden

Es erfolgt die Zusammenfassung der internationalen Fachliteratur zu ACT und Enchondromen.

Ergebnisse

Die Inzidenz von Enchondromen, und mehr noch von ACT, ist über die Jahre angestiegen, was auf häufiger werdende Diagnostik hinweist. Im Gegensatz zu Enchondromen können ACT mit Schmerzen verbunden sein und radiologische Zeichen aggressiven Wachstums, wie tiefes endosteales Scalloping, aufweisen. Die alleinige Biopsie zur Differenzierung zwischen Enchondromen und ACT ist oft nicht hilfreich, da aufgrund der punktuellen Probegewebsentnahme ein „sampling error“ resultieren kann. Die definitive operative Therapie von ACT der langen und kurzen Röhrenknochen hat sich über die letzten Jahre gewandelt, weg von einer radikalen Tumorentfernung hin zu intraläsionaler Kürettage. Ein Zuwarten ist bei radiologischem Verdacht auf das Vorliegen eines Enchondroms regelmäßigen Verlaufskontrollen mittels Magnetresonanztomographie (MRT) möglich.

Schlussfolgerungen

ACT weisen im Gegensatz zu Enchondromen radiologische Zeichen eines aggressiven Wachstums auf. Die heutzutage bevorzugte Therapie besteht aus einer intraläsionalen Kürettage. Sowohl Diagnostik als auch Therapie und Nachsorge von kartilaginären Tumoren sollten an einem spezialisierten Tumorzentrum erfolgen.

Computer 3D modeling of radiofrequency ablation of atypical cartilaginous tumours in long bones using finite element methods and real patient anatomy

BACKGROUND

Radiofrequency ablation (RFA) is a minimally invasive technique used for the treatment of neoplasms, with a growing interest in the treatment of bone tumours. However, the lack of data concerning the size of the resulting ablation zones in RFA of bone tumours makes prospective planning challenging, needed for safe and effective treatment.

METHODS

Using retrospective computed tomography and magnetic resonance imaging data from patients treated with RFA of atypical cartilaginous tumours (ACTs), the bone, tumours, and final position of the RFA electrode were segmented from the medical images and used in finite element models to simulate RFA. Tissue parameters were optimised, and boundary conditions were defined to mimic the clinical scenario. The resulting ablation diameters from postoperative images were then measured and compared to the ones from the simulations, and the error between them was calculated.

RESULTS

Seven cases had all the information required to create the finite element models. The resulting median error (in all three directions) was -1 mm, with interquartile ranges from -3 to 3 mm. The three-dimensional models showed that the thermal damage concentrates close to the cortical wall in the first minutes and then becomes more evenly distributed.

CONCLUSIONS

Computer simulations can predict the ablation diameters with acceptable accuracy and may thus be utilised for patient planning. This could allow interventional radiologists to accurately define the time, electrode length, and position required to treat ACTs with RFA and make adjustments as needed to guarantee total tumour destruction while sparing as much healthy tissue as possible.

Long-Term Halo Follow-Up Confirms Less Invasive Treatment of Low-Grade Cartilaginous Tumors with Radiofrequency Ablation to Be Safe and Effective

Background: Radiofrequency ablation (RFA) is a minimally invasive alternative in the treatment of bone tumors. Long-term follow-up has not been described in current literature. Detailed analysis of mid- and long-term follow-up after RFA treatment for a cohort of patients with low-grade cartilaginous tumors (atypical cartilaginous tumors and enchondroma) was performed. The results, complications, and development of halo dimensions over time are presented. Methods: Data of all patients with an RFA procedure for an ACT between 2007–2018 were included. Ablation area is visible on baseline MRI, 3 months post-procedure, and is called halo. Volume was measured on MR images and compared to different follow-up moments to determine the effect of time on halo volume. Follow-up was carried out 3 months and 1, 2, 5, and 7 years after the procedure. Occurrence of complications and recurrences were assessed. Results: Of the 137 patients included, 82 were analyzed. Mean follow-up time was 43.6 months. Ablation was complete in 73 cases (89.0%). One late complication occurred, while no recurrences were seen. Halo dimensions of height, width, and depth decreased with a similar rate, 21.5% on average in the first year. Subsequently, this decrease in halo size continues gradually during follow-up, indicating bone revitalization. Conclusion: RFA is a safe and effective treatment in low-grade cartilaginous tumors with an initial success rate of 89.0%. Extended follow-up shows no local recurrences and gradual substitution of the halo with normal bone.