The adult human body has 206 bones—almost matching the monthly number of CAS-One IR procedures performed worldwide (as of this blog post). With a growing share focused on bone, we’re taking a closer look at how image-guided precision is transforming MSK interventions.
We at CASCINATION have been avid students of ablation in all organs, with all modalities. Musculoskeletal ablation is perhaps the most interesting for a number of reasons. While impossible to dig deep into the marrow of ablation in MSK, we wanted to share a few high level details - and then show how CAS-One IR is valuable in this important, and emerging indication.
Types of tumors traditionally treated, locations
As far as benign tumors go, osteoid osteoma, and desmoid tumors are the most common of the MSK indications. However bone metastasis is common in patients with primary breast, prostate, and lung cancer, nearly 85% have bone metastases at the time of death.1 Ablation has emerged to treat both benign and malignant tumors. The most common locations are the pelvis and spine, and then long bones (Femur, tibiae and fibulae). There can also be tumors in the ribs and chest walls. The goals of treatment of MSK tumors are numerous. From downsizing lesions to make other treatments suitable, to decreasing pain, to palliative, and of course ideally, curative treatment.
The CIRSE Standards of Practice on Thermal Ablation of Bone Tumours outline how to match needle-based ablation methods to the tumour type for safe, effective treatment.
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RFA (Radiofrequency Ablation) – Best for small osteolytic or mixed lesions with little soft-tissue extension. Where an extra-osseus soft tissue component exists, ablation of the soft tissue–bone interface can achieve pain palliation.
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MWA (Microwave Ablation) – reaches higher intra-tumoral temperatures than RFA and is less affected by tissue conductivity/impedance variables and perfusion-mediated tissue cooling. Thus it works better in sclerotic bone, achieving larger zones in less time and with less pain than RFA.
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Cryoablation – Offers precise visual control and is ideal for large or complex lesions near critical structures or metal implants. It’s also less painful post-procedure. The prospective, multicenter BOREALIS trial is expanding the clinical evidence for cryoablation in bone metastases. It focuses on patients with oligometastatic or oligo-progressive solid tumours who are being treated with curative intent.
- Other modalities such as laser interstitial thermotherapy or High-intensity focused ultrasound may be considered, though their use is limited to small tumours or pain palliation.
Faiella et al. (2021) analyzed 193 bone procedures (142 biopsies and 51 ablations) comparing stereotactic and standard CT-guided techniques. They found that stereotactic guidance significantly reduced procedure time, radiation dose, and CT scans, with higher diagnostic accuracy—especially for lesions under 2 cm.
While a smaller segment of total patients treated with CAS-One IR, there have still been hundreds treated. We have compiled some images and case histories of some of the more interesting ones to help more IRs discover how to " unlock" MSK ablation. Enjoy.
Cryoablation of Liposarcoma in right Femur - Switzerland - Dr. Robin Benz
- 90 year-old male
- 10cm+ Liposarcoma in right proximal femur
- Palliative intention to reduce lesion size and mobilize patient again
- Cryoablation with 8 needles placed in 70 minutes.
- 4-hour overall intervention time without adverse events
- Successful procedure with 75% size reduction
- "Top Case" January 2022
- ECIO poster 2022
Planning 3D
Fusion Preoperative vs CT Cryo
Cryoablation of a metatarsal - Switzerland - Dr. Carlo Tappero
- Young female patient
- Lesion in right foot, fifth metatarsal
- Local anesthesia used - injected in insertion region and subarachnoid spinal space
- Only 5 patients markers used and in close proximity to limit radiation to patient
- CAS-One IR used to navigate and fixate drill
Bone Core Biopsy with CAS-One® IR - Sweden - Dr. Pawel Szaro
- 49-year-old female with history of obesity and substance abuse
- Thoracal spondylodiscitis T6-7 without bacteria. MRI showed regression
- MRI showed inflammatory changes in degenerated area S1 possibly caused by low-virulence spondylodiscitis
- Previous bone core biopsy gave no result
- Re-Biopsy planned with CAS-One IR for culture bacteria-specific PCR
- MRI fusion used
- Co-axial needle planned and placed through the left hemisacrrum lateral to the S1 nerve.
- 20mm 13G biopsy of sacrum successfully taken
- ECIO 2022 Poster
Osteoid Osteoma Cuboid Ablation with CAS-One® IR - Spain - Dr. Julian Portero
Pelvic biopsy with CAS-One® IR - Vienna
- 67-year-old male with prostate cancer
- Lesion in the pelvis discoverd
- Freehand biopsy failed 3 times
- CAS-One IR was used to fuse CT with MRI. 4 biopsies were performed successfully
MRI/PET CT Fusion: Invisible - Visible
Pelvic invisible lesions treated with Cryoablation - Switzerland - Dr. Carlo Tappero
- PET-CT and MRI revealed two hypermetabolic nodular lesions in the left ischioanal fossa and left pelvis
- Cryoablation reccomended
- Lesion invisible on CT - fusion with MRI was performed
- Two needles inserted in one advancement each
- Successful overlapping ablation zone coverd the lesion and reached a MAM of 6mm
Painful metatarsal tumor treated with Cryo - Switzerland - Dr. Carlo Tappero
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Painful tumor creating poor quality of life for 17-year old female
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Patients's foot was immobilized using the CAS-One IR vaccuum matters in conjunction with plastic apparatus
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5 markers were placed, although only 4 were visible.
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Navigating the bone drill, and the cryoablation probe was quick and easy with the semi-robotic arm
- Patient awaits 3 month follow-up MRI
Humerus Ablation with CAS-One® IR
Osteoid Osteoma
Bone lesion on the right femur - Switzerland
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Patient presented with a large lesion on the right femur
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1 needles were planned
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15 minutes RFA was performed
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1. Mundy GR. Metastasis to bone: causes, consequences and therapeutic opportunities. Nat Rev Cancer. 2002;2:584-93. doi: 10.1038/nrc867
2. Ryan, A, et. al., CIRSE Standards of Practice on Thermal Ablation of Bone Tumours, Cardiovasc Intervent Radiol. 2022 https://pmc.ncbi.nlm.nih.gov/articles/PMC9018647/