Hip Chondrolysis and Femoral Head Osteonecrosis: A Complication of Periacetabular Cryoablation

Thermal Protection Techniques for Image-guided Musculoskeletal Ablation

Percutaneous image-guided thermal ablation has gained wide acceptance among physicians for the treatment of benign and malignant tumors of the musculoskeletal system. Increasing evidence to support the efficacy of thermal ablation techniques in primary and adjuvant treatment of soft-tissue sarcomas, treatment of oligometastatic disease to bone and soft tissue, and metastatic pain palliation has positioned interventional oncology alongside surgery, systemic therapies, and radiation therapy as the fourth pillar of modern comprehensive cancer care. Despite the expanding indications and increasing use in clinical practice, thermal ablation carries a significant risk of injury to the adjacent vulnerable structures, predominantly the skin, bowel, and neural structures. Knowledge of the mechanism of action of each thermal ablation modality informs the physician of the attendant risks associated with a particular modality. Thermal ablation mechanisms can be divided into hypothermic (cryoablation) and hyperthermic (radiofrequency ablation, microwave ablation, high-intensity focused US, or laser). Active thermal protection techniques include hydrodissection, pneumodissection, direct skin thermal protection, and physical displacement techniques. Passive thermal protection techniques include temperature monitoring, biofeedback, and neurophysiologic monitoring. The authors provide an overview of the mechanism of action of the most commonly used thermal ablation modalities, review the thermal injury risks associated with these modalities, and introduce the active and passive thermal protective techniques critical to safe and effective musculoskeletal ablative therapy. ©RSNA, 2025 See the invited commentary by Tomasian and Jennings in this issue.

Progression of Femoral Osteolytic Metastases after Intramedullary Nailing and Subsequent Salvage Techniques

Intramedullary nailing insertion from the proximal-to-distal femur is frequently performed for impending and complete pathological femur fractures due to osteolytic metastases. After nailing through cancer-laden bone, residual chemotherapy- and/or radiation-resistant tumor may progress. Progression of osteolysis risks future nail failure or pathological fractures. This study assesses the incidence of cancer progression following intramedullary nailing in a femur-only cohort and describes a percutaneous rod-retaining salvage technique. A single-institution, retrospective study was conducted to identify adult patients who underwent intramedullary nailing for femoral osteolytic lesions for complete or impending nail failure from 2016 to 2023. Progression was defined as enlargement of the pre-existing lesion and/or appearance of new lesions on radiographs. Surgical outcomes were assessed with a combined pain and functional score. A total of 113 patients (median age 66.8 years (IQR = 16.4); median follow-up 6.0 months (IQR = 14.5)) underwent intramedullary nailing. Sixteen patients (14.2%) exhibited post-nailing cancer progression. Pre- and postoperative radiation and chemotherapy did not decrease the odds of cancer progression. Three patients underwent initial open surgical salvage consisting of proximal femur replacement arthroplasty, and six patients did not receive salvage due to poor surgical candidacy or patient choice. Seven patients (median follow-up 10.7 months (IQR = 12.9)) received percutaneous salvage. In this group, pain and functional scores improved by 4.0 points (p = 0.0078) at two-week postoperative follow-up and 2.0 points (p = 0.0312) at the most recent follow-up (mean follow-up 13.0 ± 9.4 months). All three nonambulatory patients became ambulatory, and six patients were able to ambulate independently without walking aids. No major complications were reported 30 days postoperatively. Progression of femoral osteolytic metastases may occur following intramedullary nailing. Continued monitoring of the entire femur is needed to maintain improved functional status and to prevent catastrophic progression of pre-existing lesions or appearance of new lesions. In patients with more proximal metastases only, the customary practice of bringing a long nail from the proximal femur to distal metaphysis should be reconsidered. Furthermore, there is concern of mechanical transport of cancer cells during guide wire insertion, reaming, and rod insertion through cancer laden bone to cancer free distal bone.

Recent Advances in Minimally Invasive Management of Osteolytic Periacetabular Skeletal Metastases

Painful skeletal osteolytic metastases, impending pathological fractures, and nondisplaced fractures present as a devastating clinical problem in advanced stage cancer patients. Open surgical approaches provide excellent mechanical stabilization but are often associated with high complication rates and slow recovery times. Percutaneous minimally invasive interventions have arisen as a pragmatic and logical treatment option for patients with late-stage cancer in whom open surgery may be contraindicated. These percutaneous interventions minimize soft tissue dissection, allow for the immediate initiation or resumption of chemotherapies, and present with fewer complications. This review provides the most up-to-date technical and conceptual framework for the minimally invasive management of osseous metastases with particular focus on periacetabular lesions. Fundamental topics discussed are as follows: (1) pathogenesis of cancer-induced bone loss and the importance of local cytoreduction to restore bone quality, (2) anatomy and biomechanics of the acetabulum as a weight-bearing zone, (3) overview of ablation options and cement/screw techniques, and (4) combinatorial approaches. Future studies should include additional studies with more long-term follow-up to better assess mechanical durability of minimally invasive interventions. An acetabulum-specific functional and pain scoring framework should be adopted to allow for better cross-study comparison.

Contemporary management of extracranial vascular malformations

Vascular malformations are congenital vascular anomalies that originate because of disorganized angiogenesis, most commonly from spontaneous somatic genetic mutations. The modern management of vascular malformations requires a multidisciplinary team that offers patients the gamut of medical, surgical, and percutaneous treatment options with supportive care. This manuscript discusses the standard and contemporary management strategies surrounding extracranial vascular malformations and overgrowth syndromes.

Emerging Minimally Invasive Percutaneous Procedures for Periacetabular Osteolytic Metastases

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Periacetabular osteolytic skeletal metastases are frequently associated with pain and impaired ambulatory function. Minimally invasive techniques allow for the restoration of ambulation without interrupting critical systemic cancer therapy.

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The open surgical management of massive periacetabular osteolytic lesions, such as by curettage, internal fixation, or complex total hip reconstruction, is associated with blood loss, hospitalization, rehabilitation, and complications such as infection or delayed wound-healing.

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Minimally invasive percutaneous procedures have become increasingly popular for the management of periacetabular osteolytic metastases by interventional oncologists and orthopaedic surgeons before complex open surgical procedures are considered.

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Minimally invasive procedures may include various methods of cancer ablation and reinforcement techniques. Minimally invasive procedures may entail cancer ablation, polymethylmethacrylate (PMMA) cement reinforcement, balloon osteoplasty, percutaneous screw fixation, or combinations of the aforementioned techniques (e.g., ablation-osteoplasty-reinforcement-internal fixation [AORIF]).

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.

Intra-articular hip joint osteoid osteoma: Challenging diagnosis and percutaneous radiofrequency ablation treatment

Atypical intra-articular osteoid osteoma can be difficult to diagnose and challenging to treat. We report a case of a right acetabular subchondral intra-articular osteoid osteoma in a young male patient which was initially diagnosed as femoroacetabular impingement due to its atypical clinical and radiological presentations. After fully working up the patient the lesion was successfully treated with percutaneous CT-guided low-power bipolar radiofrequency ablation using several per procedural articular cartilage thermal protective measures including intra-articular thermocouple, and continuous per procedural joint space cooling with Dextrose 5% solution. A precise RFA electrode placement, using the No-touch technique, and applying different passive and active thermal protective measures were helpful in avoiding collateral damage of the hip joint articular cartilages. atypical intra-articular osteoid osteomas necessitate pertinent correlation between the clinical and radiological presentations. As far as intra-articular or subchondral nidus ablation is concerned, thermal protective measures should be considered.

Intraoperative Cryotherapy in the Treatment of Metastatic Renal Cell Carcinoma of the Bone

Osseous metastases in renal cell carcinoma (RCC) are a heterogeneous mix of cells with hypervascular and rapidly destructive properties that frequently exhibit resistance to both radiation and chemotherapy. Despite this, some patients with isolated and oligometastatic disease have the potential to be cured. Regardless, aggressive metastatic control is critical to minimizing morbidity and mortality for all patients with metastatic RCC. Percutaneous cryoprobes were developed as a minimally invasive technique for both pain relief and tumor control. However, there is little evidence describing an alternative use of this technology in the operating room to assist with open tumor resections, and no formal role for its use in orthopedics exists. Therefore, the authors added this modality to their intraoperative treatment of osseous RCC to investigate whether it would influence their ability to obtain local metastatic control. The authors performed a retrospective chart review of prospectively obtained data to evaluate the role of intraoperative cryotherapy in the treatment of osseous RCC. From 2004 to 2017, cryotherapy was used in 43 procedures, alleviating the need for additional radiation 84% (36 of 43) of the time. Local tumor control was achieved in 100% (43 of 43) of cases. There were 2 wound-related complications and 1 pathologic fracture. Despite the study's limitations, the authors believe that cryotherapy contributed to the reliability and reproducibility of their intralesional resections. Given the palliative, and potentially curative, opportunities afforded by complete locoregional tumor control, the authors support further investigation into the use of intraoperative cryotherapy to treat osseous metastases secondary to RCC. [Orthopedics. 2021;44(5):e645-e652.].

Bone Metastases: State of the Art in Minimally Invasive Interventional Oncology

Bone is the third most common site involved by cancer metastases, and skeleton-related events such as intractable pain due to direct osseous tumor involvement, pathologic fracture, and neurologic deficits as a consequence of nerve or spinal cord compression often affect patients' functional independence and quality of life unfavorably. The annual medical-economic burden related to bone metastases is a substantial component of the total direct medical cost estimated by the National Institutes of Health. There have been substantial recent advances in percutaneous image-guided minimally invasive musculoskeletal oncologic interventions for the management of patients with osseous metastatic disease. These advances include thermal ablation, cementation with or without osseous reinforcement with implants, osteosynthesis, thermal and chemical neurolyses, and palliative injections, which are progressively incorporated into the management paradigm for such patients. These interventions are performed in conjunction with or are supplemented by adjuvant radiation therapy, systemic therapy, surgery, or analgesic agents to achieve durable pain palliation, local tumor control, or cure, and they provide a robust armamentarium for interventional radiologists to achieve safe and effective treatment in a multidisciplinary setting. In addition, these procedures are shifting the patient management paradigm in modern-era practice. The authors detail the state of the art in minimally invasive percutaneous image-guided musculoskeletal oncologic interventions and the role of radiologists in managing patients with skeletal metastases. ^©RSNA, 2021.

French Multidisciplinary Approach for the Treatment of MSK Tumors

Several interventional treatments have recently been integrated into the therapeutic armamentarium available for the treatment of bone tumors. In some scenarios (e.g., osteoid osteoma), interventional treatments represent the sole and definitive applied treatment. Due to the absence of widely shared protocols and the complex multivariate scenarios underlying the clinical presentation of the remaining bone tumors including metastases, therapeutic strategies derived from a multidisciplinary tumor board are essential to provide effective treatments tailored to each patient. In the present review, we present the multidisciplinary therapeutic strategies commonly adopted for the most frequent bone tumors.

Complications of Percutaneous Bone Tumor Cryoablation: A 10-year Experience

Background Percutaneous cryoablation has been shown to be effective in the management of painful bone tumors. However, knowledge of the complication rate and risk factors for complication is currently lacking. Purpose To report the complication rate and associated risk factors for bone tumor cryoablation. Materials and Methods This retrospective study reviewed complications in 239 consecutive patients (131 men and 108 women; median age, 64 years; age range, 6-86 years) who underwent cryoablation of 320 primary or metastatic bone tumors between January 2008 and November 2017. Common Terminology Criteria for Adverse Events was used to categorize complications as major (grade 3-4) or minor (grade 1-2). Multivariable analysis was performed for variables with P values less than .20, including age, tumor location, adjacent critical structures, number of cryoprobes, and Eastern Cooperative Oncology Group performance status (ECOG-PS). Results Among the 320 tumors, the total complication rate was 9.1% (29 of 320; 95% confidence interval [CI]: 6%, 12.2%). The major complication rate was 2.5% (eight of 320; 95% CI: 0.8%, 4.2%), with secondary fracture the most frequent complication (1.2% [four of 320]; mean delay, 71 days); cryoablation site infection, tumor seeding, bleeding, and severe hypotension were each observed in 0.3% (one of 320) of procedures. Minor complications included postprocedural pain (2.2% [seven of 320]), peripheral neuropathy (0.9% [three of 320]), and temporary paresthesia (0.9% [three of 320]). For all complications, associated risk factors included ECOG-PS greater than 2 (odds ratio [OR], 3.1 [95% CI: 3, 7.6]; P = .01), long-bone cryoablation (OR, 17.8 [95% CI: 2.3, 136.3]; P = .01), and use of more than three cryoprobes (OR, 2.5 [95% CI: 1.0, 6.0]; P = .04); for major complications, associated risk factors included age greater than 70 years (OR, 7.1 [95% CI: 1.6, 31.7]; P = .01) and use of more than three cryoprobes (OR, 23.6 [95% CI: 2.8, 199.0]; P = .01). Conclusion Bone tumor cryoablation is safe, with a 2.5% rate of major complications, most commonly secondary fracture (1.2%). Major complications are associated with age greater than 70 years and use of more than three cryoprobes. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Jennings in this issue.

Palliative Percutaneous Cryoablation and Cementoplasty of Acetabular Metastases: Factors Affecting Pain Control and Fracture Risk

PURPOSE

To characterize the response of patients with acetabular metastases following combined cryoablation and cementoplasty (CCC) for pain palliation and fracture risk reduction, based on completeness of ablation and the presence of pre-existing pathologic fracture.

MATERIALS AND METHODS

Thirty-nine consecutive acetabular CCC procedures were performed in 37 patients (24 M:13F, age 66 ± 8 years). Pain was assessed using a 0-10 numeric rating scale. Development of new or progression of pre-existing fractures and local tumor progression (LTP) were determined on follow-up imaging. Pain score reduction and fracture development rates were compared by ablation completeness and the presence of pre-existing fractures.

RESULTS

Twenty-three of 27 (85%) patients with evaluable pain scores had reduced pain, decreasing from 7.5 ± 2.1 to 3.6 ± 2.6 (p < 0.0001). Of 39 tumors, 28 (72%) were completely ablated with no significant difference in pain reduction after complete versus incomplete ablations (p = 0.9387). Six of 30 (20%) patients with follow-up imaging demonstrated new/progressive acetabular fractures. Four of 5 (80%) patients with LTP developed new/progressive fractures compared to 2 of 25 (8%) without tumor progression (p = 0.0003). Pre-existing fracture was not associated with subsequent fracture/fracture progression (p = 0.2986). However, patients with prior acetabular radiation therapy or surgery had increased fractures following treatment (p = 0.0380).

CONCLUSION

Complete acetabular tumor ablation during CCC was not associated with superior pain relief compared to subtotal ablation but did result in improved fracture stabilization. Pre-treatment pathologic fractures were not associated with fracture progression, but new/progressive fractures were more frequent in patients with prior radiation therapy or surgery.

Epithelioid hemangioma of the scapula treated with chemoembolization and microwave ablation: Α case report

Bone epithelioid hemangiomas are classified within benign vascular tumours but are commonly misdiagnosed as low-grade angiosarcomas or epithelioid hemangioendotheliomas. Current therapeutic interventions include various treatment options but local recurrence or distal lymph node involvement has been reported. We report a rare case of scapular epithelioid hemangioma that was initially treated using a combination of chemoembolization and microwave ablation. This combination has not been previously reported in the literature regarding the management of this tumour. A year after the first course of treatment, the tumour size has been reduced more than 70% and the patient has remarkable clinical improvement. Results reported in this case study demonstrated that combination of chemoembolization and microwave ablation is a feasible, safe and effective technique in the treatment of bone epithelioid hemangiomas. Even if the tumour is still present afterwards, a substantially smaller surgical excision will be needed.

Increasing Role of Image-Guided Ablation in the Treatment of Musculoskeletal Tumors

In the last decade, percutaneous treatment of musculoskeletal (MSK) tumors has become more established in routine clinical care while also undergoing a number of advancements. Ablative techniques to palliate painful skeletal metastases have gained wide acceptance, while goals for ablation have evolved to include local control of oligometastases and desmoid tumors. Bone consolidation or augmentation is now frequently used in conjunction with or instead of ablation of skeletal tumors to stabilize pathologic fractures or prevent further morbidity that could result from fractures caused by tumor progression. These procedures have traditionally been performed with cement injection, although additional percutaneous consolidation or stabilization devices have been developed. Techniques to monitor the ablation zone and adjacent structures intraprocedurally are now applied to increase the number of tumors amenable to treatment. These include methods to depict, displace, or monitor critical structures adjacent to targeted MSK tumors. Finally, the role of ablation in the comprehensive care of patients with MSK tumors continues to change with the evolving triage of patients between radiation therapy, surgical resection and stabilization, and percutaneous ablative and consolidative management.

Expanding role of percutaneous ablative and consolidative treatments for musculoskeletal tumours

Interventional approaches to musculoskeletal tumours have significantly changed over the last several years, and new treatments continue to be developed. All ablative modalities are currently applied to the treatment of bone tumours, including radiofrequency, cryo-, microwave, and laser ablation devices. Indications for ablation of bone and soft-tissue tumours have expanded beyond palliation of painful bone metastases and eradication of osteoid osteomas to the local control of oligometastatic disease from a number of primary tumours and ablation of desmoid tumours. In addition, tools for consolidation of bone tumours at risk of pathological fracture have also expanded. With these developments, ablation has become the primary treatment for osteoid osteomas and, at some institutions, desmoid tumours. It may be the primary or secondary treatment for palliation of painful bone tumours, frequently used in patients with pain refractory to or recurrent after radiation therapy. It is used as a treatment for limited metastatic disease or for metastases that grow disproportionately in patients with multifocal metastases, either in combination with systemic therapy or to reserve systemic therapy and its toxicity for more widespread disease progression. Moreover, percutaneous methods to consolidate bone at risk of fracture have become more commonplace, aided by techniques using materials beyond typical bone cement.

Pneumodissection for skin protection in image-guided cryoablation of superficial musculoskeletal tumours

PURPOSE

Pneumodissection is described as a simple method for preventing skin injury during cryoablation of superficial musculoskeletal tumours.

METHODS

Superficial tumour cryoablations performed from 2009 to 2015 were retrospectively reviewed. Pneumodissection was performed in 13 patients when the shortest tumour-skin distance was less than 25 mm. Indications were pain palliation (n = 9) and local tumour control (n = 4). Patients, target tumours, technical characteristics and complications up to 60 days post ablation were reviewed. The ice ball-skin distances with and without pneumodissection were compared by a paired t-test and further assessed for association with covariates using ANCOVA.

RESULTS

Technical success for ablation was 12 of 13. The mean shortest tumour-skin distance was 15.0 mm (3.2-24.5 mm). The mean thickness of pneumodissection was 9.6 mm (5.2-16.6 mm) resulting in mean elevation of skin of 3.4 mm (1.2-5.3 mm). Mean shortest ice ball-skin distance after pneumodissection was 10.5 mm (4.2-19.7 mm). No infection or systemic air embolism was noted. No intraprocedural frostbite was observed.

CONCLUSION

Pneumodissection is feasible, effective and safe in protecting the skin during image-guided cryoablation of superficial tumours.

KEY POINTS

• Frostbite during image-guided cryoablation of superficial tumours is commonly under-reported. • Frostbites are painful and may introduce infection into the superficial ablation zone. • Warm compress, saline and CO ₂ have shortcomings in protecting the skin. • Pneumodissection is free, readily available, easy to use and safe and effective.