Advanced Interventional Procedures for Knee Osteoarthritis: What Is the Current Evidence?

The prevalence of knee osteoarthritis (OA) is the highest among all joints and likely to increase over the coming decades. Advances in the repertoire of diagnostic capabilities of imaging and an expansion in the availability and range of image-guided interventions has led to development of more advanced interventional procedures targeting pain related to OA pain while improving the function of patients presenting with this debilitating condition. We review the spectrum of established advanced interventional procedures for knee OA, describe the techniques used to perform these procedures safely, and discuss the clinical evidence supporting each of them.

Radiological diagnosis of prevalent osteoporotic vertebral fracture on radiographs: an interim consensus from a group of experts of the ESSR osteoporosis and metabolism subcommittee.

When a low-energy trauma induces an acute vertebral fracture (VF) with clinical symptoms, a definitive diagnosis of osteoporotic vertebral fracture (OVF) can be made. Beyond that, a "gold" radiographic standard to distinguish osteoporotic from non-osteoporotic VFs does not exist. Fracture-shaped vertebral deformity (FSVD) is defined as a deformity radiographically indistinguishable from vertebral fracture according to the best of the reading radiologist's knowledge. FSVD is not uncommon among young populations with normal bone strength. FSVD among an older population is called osteoporotic-like vertebral fracture (OLVF) when the FSVD is likely to be associated with compromised bone strength. In more severe grade deformities or when a vertebra is collapsed, OVF diagnosis can be made with a relatively high degree of certainty by experienced readers. In "milder" cases, OVF is often diagnosed based on a high probability rather than an absolute diagnosis. After excluding known mimickers, singular vertebral wedging in older women is statistically most likely an OLVF. For older women, three non-adjacent minimal grade OLVF (< 20% height loss), one minimal grade OLVF and one mild OLVF (20-25% height loss), or one OLVF with ≥ 25% height loss, meet the diagnosis of osteoporosis. For older men, a single OLVF with < 40% height loss may be insufficient to suggest the subject is osteoporotic. Common OLVF differential diagnoses include X-ray projection artifacts and scoliosis, acquired and developmental short vertebrae, osteoarthritic wedging, oncological deformities, deformity due to high-energy trauma VF, lateral hyperosteogeny of a vertebral body, Cupid's bow, and expansive endplate, among others.

Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023-overview, and primary local imaging: how and where?

OBJECTIVES: Early, accurate diagnosis is crucial for the prognosis of patients with soft tissue sarcomas. To this end, standardization of imaging algorithms, technical requirements, and reporting is therefore a prerequisite. Since the first European Society of Musculoskeletal Radiology (ESSR) consensus in 2015, technical achievements, further insights into specific entities, and the revised WHO-classification (2020) and AJCC staging system (2017) made an update necessary. The guidelines are intended to support radiologists in their decision-making and contribute to interdisciplinary tumor board discussions. MATERIALS AND METHODS: A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements were scored online by level of agreement (0 to 10) during two iterative rounds. Either "group consensus," "group agreement," or "lack of agreement" was achieved. RESULTS: Eight sections were defined that finally contained 145 statements with comments. Overall, group consensus was reached in 95.9%, and group agreement in 4.1%. This communication contains the first part consisting of the imaging algorithm for suspected soft tissue tumors, methods for local imaging, and the role of tumor centers. CONCLUSION: Ultrasound represents the initial triage imaging modality for accessible and small tumors. MRI is the modality of choice for the characterization and local staging of most soft tissue tumors. CT is indicated in special situations. In suspicious or likely malignant tumors, a specialist tumor center should be contacted for referral or teleradiologic second opinion. This should be done before performing a biopsy, without exception. CLINICAL RELEVANCE: The updated ESSR soft tissue tumor imaging guidelines aim to provide best practice expert consensus for standardized imaging, to support radiologists in their decision-making, and to improve examination comparability both in individual patients and in future studies on individualized strategies. KEY POINTS: • Ultrasound remains the best initial triage imaging modality for accessible and small suspected soft tissue tumors. • MRI is the modality of choice for the characterization and local staging of soft tissue tumors in most cases; CT is indicated in special situations. Suspicious or likely malignant tumors should undergo biopsy. • In patients with large, indeterminate or suspicious tumors, a tumor reference center should be contacted for referral or teleradiologic second opinion; this must be done before a biopsy.

Selective MR neurography-guided lumbosacral plexus perineural injections: techniques, targets, and territories.

The T12 to S4 spinal nerves form the lumbosacral plexus in the retroperitoneum, providing sensory and motor innervation to the pelvis and lower extremities. The lumbosacral plexus has a wide range of anatomic variations and interchange of fibers between nerve anastomoses. Neuropathies of the lumbosacral plexus cause a broad spectrum of complex pelvic and lower extremity pain syndromes, which can be challenging to diagnose and treat successfully. In their workup, selective nerve blocks are employed to test the hypothesis that a lumbosacral plexus nerve contributes to a suspected pelvic and extremity pain syndrome, whereas therapeutic perineural injections aim to alleviate pain and paresthesia symptoms. While the sciatic and femoral nerves are large in caliber, the iliohypogastric and ilioinguinal, genitofemoral, lateral femoral cutaneous, anterior femoral cutaneous, posterior femoral cutaneous, obturator, and pudendal nerves are small, measuring a few millimeters in diameter and have a wide range of anatomic variants. Due to their minuteness, direct visualization of the smaller lumbosacral plexus branches can be difficult during selective nerve blocks, particularly in deeper pelvic locations or larger patients. In this setting, the high spatial and contrast resolution of interventional MR neurography guidance benefits nerve visualization and targeting, needle placement, and visualization of perineural injectant distribution, providing a highly accurate alternative to more commonly used ultrasonography, fluoroscopy, and computed tomography guidance for perineural injections. This article offers a practical guide for MR neurography-guided lumbosacral plexus perineural injections, including interventional setup, pulse sequence protocols, lumbosacral plexus MR neurography anatomy, anatomic variations, and injection targets.

MRI- Versus CT-Guided Renal Tumor Cryoablation: Is There a Difference?

PURPOSE: To compare procedure-related variables, safety, renal function, and oncologic outcomes in patients undergoing percutaneous cryoablation (CA) of renal tumors with MRI- or CT-guidance. MATERIALS AND METHODS: Patient, tumour, procedure, and follow-up data were collected and analysed. MRI and CT groups were matched using a coarsened exact approach according to patient's gender and age, tumour grade, size and location. P < 0.05 was considered statistically significant. RESULTS: Two-hundred fifty-three patients (266 tumors) were retrospectively selected. Following the coarsened exact matching 46 patients (46 tumors) in the MRI group and 42 patients (42 tumors) in the CT group were matched. There were no significant baseline differences between the two populations except for the duration of follow-up (P = 0.002) and renal function (P = 0.002). On average MRI-guided CA lasted 21 min longer than CT-guided ones (P = 0.005). Following CA, complication rates (6.5% for MRI vs 14.3% for CT; P = 0.30) and GFR decline (mean - 13.1 ± 15.8%; range - 64.5-15.0 for MRI; mean - 8.1 ± 14.8%; range - 52.5-20.4; for CT; P = 0.13) were similar in both groups. The 5-year local progression-free, cancer-specific and overall survivals in the MRI and CT groups were 94.0% (95% CI 86.3%-100.0%) and 90.8% (95% CI 81.3%-100.0%; P = 0.55), 100.0% (95% CI 100.0%-100.0%) and 100.0% (95% CI 100.0%-100.0%; P = 1), and 83.7% (95% CI 64.0%-100.0%) and 76.2% (95% CI 62.0%-93.6%; P = 0.41), respectively. CONCLUSIONS: Apart from increased procedural times associated with MRI-guided CA of renal tumors compared to CT-guidance, both modalities demonstrate similar safety, GFR decline and oncologic outcomes.

Interdisciplinary consensus statements on imaging of DRUJ instability and TFCC injuries.

OBJECTIVES: The purpose of this agreement was to establish evidence-based consensus statements on imaging of distal radioulnar joint (DRUJ) instability and triangular fibrocartilage complex (TFCC) injuries by an expert group using the Delphi technique. METHODS: Nineteen hand surgeons developed a preliminary list of questions on DRUJ instability and TFCC injuries. Radiologists created statements based on the literature and the authors' clinical experience. Questions and statements were revised during three iterative Delphi rounds. Delphi panelists consisted of twenty-seven musculoskeletal radiologists. The panelists scored their degree of agreement to each statement on an 11-item numeric scale. Scores of "0," "5," and "10" reflected complete disagreement, indeterminate agreement, and complete agreement, respectively. Group consensus was defined as a score of "8" or higher for 80% or more of the panelists. RESULTS: Three of fourteen statements achieved group consensus in the first Delphi round and ten statements achieved group consensus in the second Delphi round. The third and final Delphi round was limited to the one question that did not achieve group consensus in the previous rounds. CONCLUSIONS: Delphi-based agreements suggest that CT with static axial slices in neutral rotation, pronation, and supination is the most useful and accurate imaging technique for the work-up of DRUJ instability. MRI is the most valuable technique in the diagnosis of TFCC lesions. The main indication for MR arthrography and CT arthrography are Palmer 1B foveal lesions of the TFCC. CLINICAL RELEVANCE STATEMENT: MRI is the method of choice for assessing TFCC lesions, with higher accuracy for central than peripheral abnormalities. The main indication for MR arthrography is the evaluation of TFCC foveal insertion lesions and peripheral non-Palmer injuries. KEY POINTS: • Conventional radiography should be the initial imaging technique in the assessment of DRUJ instability. CT with static axial slices in neutral rotation, pronation, and supination is the most accurate method for evaluating DRUJ instability. • MRI is the most useful technique in diagnosing soft-tissue injuries causing DRUJ instability, especially TFCC lesions. • The main indications for MR arthrography and CT arthrography are foveal lesions of the TFCC.

Role of MRI at 1- and 3-Month Follow-up in Predicting the Likelihood of Tumor Recurrence Following Percutaneous Cryoablation of Renal Tumors.

PURPOSE: To evaluate whether ablation volume difference relatively to tumoral volume, minimal distance between ablation area and necrotic tumor, or apparent diffusion coefficient (ADC) within the ablation area, measured on 1- and 3-month follow-up MRI following cryoablation of renal tumors, are associated with tumor recurrence. MATERIALS AND METHODS: 136 renal tumors were retrospectively identified. Patients, tumor characteristics and follow-up MRI (1-, 3-, 6-month, and thereafter annually) were collected. Uni- and multivariate analyses were performed to assess the association between the investigated parameters and tumor recurrence. RESULTS: Over the follow-up period (27.7 ± 21.9 months), 13 recurrences were identified at 20.5 ± 19.4 months. At 1- and 3-month, the mean volume difference between the ablation zone and the tumor volume were + 577.5 ± 511.3% vs + 251.4 ± 209.8% (p = 0.003), and + 268.8 ± 291.1% vs + 103.8 ± 94.6% (p = 0.023) in patients without and with tumor recurrence, respectively. At 1- and 3-month, the minimum distance between the necrotic tumor and the edge of the ablation area was 3.4 ± 2.5 vs 1.8 ± 1.9 mm (p = 0.019), and 2.4 ± 2.3 vs 1.4 ± 1.8 mm (p = 0.13) in patients without and with tumor recurrence, respectively. Analysis of ADC values was not associated with tumor recurrence. After performing the multivariate analysis, only volume difference of the ablation area compared to tumor volume was associated with absence of tumor recurrence at 1- (OR = 14.1; p = 0.001) and 3-month (OR = 8.2; p = 0.01). CONCLUSIONS: Evaluation of volume difference between the ablation area and tumor volume on early (≤ 3 months) MRI follow-up identifies patients at risk of tumor recurrence.

Bone Consolidation: A Practical Guide for the Interventional Radiologist.

In recent years, interventional radiologists have been increasingly involved in the management of bone fractures resulting from benign (osteoporosis and trauma), as well as malignant (tumor-related impending or pathologic fractures) conditions. Interventional techniques used to fix fractures include image-guided osteoplasty, screw-mediated osteosynthesis, or combinations of both. In the present narrative review, we highlight the most common clinical scenarios that may benefit from such interventional techniques with specific focus on spine, pelvic ring, and long bones.

MRI-guided sacroiliac joint injections in children and adults: current practice and future developments.

Common etiologies of low back pain include degenerative arthrosis and inflammatory arthropathy of the sacroiliac joints. The diagnostic workup revolves around identifying and confirming the sacroiliac joints as a pain generator. Diagnostic sacroiliac joint injections often serve as functional additions to the diagnostic workup through eliciting a pain response that tests the hypothesis that the sacroiliac joints do or do not contribute to the patient's pain syndrome. Therapeutic sacroiliac joint injections aim to provide medium- to long-term relief of symptoms and reduce inflammatory activity and, ultimately, irreversible structural damage. Ultrasonography, fluoroscopy, computed tomography, and magnetic resonance imaging (MRI) may be used to guide sacroiliac joint injections. The populations that may benefit most from MRI-guided sacroiliac joint procedures include children, adolescents, adults of childbearing age, and patients receiving serial injections due to the ability of interventional MRI to avoid radiation exposure. Most clinical wide-bore MRI systems can be used for MRI-guided sacroiliac joint injections. Turbo spin echo pulse sequences optimized for interventional needle display visualize the needle tip with an error margin of < 1 mm or less. Published success rates of intra-articular sacroiliac joint drug delivery with MRI guidance range between 87 and 100%. The time required for MR-guided sacroiliac joint injections in adults range between 23-35 min and 40 min in children. In this article, we describe techniques for MRI-guided sacroiliac joint injections, share our practice of incorporating interventional MRI in the care of patients with sacroiliac joint mediated pain, discuss the rationales, benefits, and limitations of interventional MRI, and conclude with future developments.

Imaging of Metabolic Bone Diseases: The Spine View, Part I.

Metabolic bone diseases comprise a wide spectrum. Of them, osteoporosis is the most frequent and the most commonly found in the spine, with a high impact on health care systems and on morbidity due to vertebral fractures (VFs).This article discusses state-of-the-art techniques on the imaging of metabolic bone diseases in the spine, from the well-established methods to the latest improvements, recent developments, and future perspectives.We review the classical features of involvement of metabolic conditions involving the spine. Then we analyze the different imaging techniques for the diagnosis, characterization, and monitoring of metabolic bone disease: dual-energy X-ray absorptiometry (DXA) and DXA-based fracture risk assessment applications or indexes, such as the geometric parameters, Bone Strain Index, and Trabecular Bone Score; quantitative computed tomography; and magnetic resonance and ultrasonography-based techniques, such as radiofrequency echographic multi spectrometry. We also describe the current possibilities of imaging to guide the treatment of VFs secondary to metabolic bone disease.

Imaging of Metabolic Bone Diseases: The Spine View, Part II.

Metabolic bone diseases comprise a wide spectrum. Osteoporosis, the most frequent, characteristically involves the spine, with a high impact on health care systems and on the morbidity of patients due to the occurrence of vertebral fractures (VFs).Part II of this review completes an overview of state-of-the-art techniques on the imaging of metabolic bone diseases of the spine, focusing on specific populations and future perspectives. We address the relevance of diagnosis and current status on VF assessment and quantification. We also analyze the diagnostic techniques in the pediatric population and then review the assessment of body composition around the spine and its potential application. We conclude with a discussion of the future of osteoporosis screening, through opportunistic diagnosis and the application of artificial intelligence.

Clinical and radiological outcomes following insertion of a novel removable percutaneous interspinous process spacer: an initial experience.

PURPOSE: To evaluate clinical and radiological outcomes of a series of patients treated with a removable percutaneous interspinous process spacer (IPS) (LobsterProject® Techlamed®) for symptomatic degenerative lumbar spinal stenosis (DLSS). METHODS: All patients treated in two centres with this IPS during 2019 were retrospectively reviewed. Procedures were performed under deep sedation or general anaesthesia by two interventional radiologists. Patients were clinically evaluated before intervention and at 3-month follow-up with Visual Analog Scales for pain (VAS), Oswestry Disability Index (ODI) and radiologically with MRI or CT scans. Neural foramina were independently measured for each patient on pre- and post-procedural CT scans by two radiologists. RESULTS: Fifty-nine patients were treated in the selected period of which fifty-eight had complete documentation (mean age 71.2 ± 9.2 years [55-92], 32 males, 26 females). Forty-eight interventions were performed under deep sedation and ten under general anaesthesia, without procedural complications. Clinical follow-up at 3 months showed a significant reduction of pain (VAS from 83 ± 9 to 29 ± 19, - 65%; p < 0.001) and an improvement in functional outcomes (ODI from 31 ± 12 to 13 ± 10%, - 58%; p < 0.001). There was one case of unsatisfactory positioning post procedure, two cases of posterior migration at 3-month follow-up and one case of spinous process fracture. Mean neural foramina area increased from 77 ± 23 to 95 ± 27 mm2 (+ 26%; p < 0.001) with very good inter-observer reliability (Cronbach's alpha = 0.899). CONCLUSION: Percutaneous minimally invasive insertion of a removable IPS device demonstrates a favourable safety profile, good clinical outcomes at 3 months, and apparent anatomical increase in foraminal dimensions. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05203666-Release Date: 21st January 2022, retrospectively registered.

Kinematic Tibiofibular Syndesmotic Measurements as Indicators of Tibiotalar Osteoarthritis: Exploratory Analysis Using 4-Dimensional Computed Tomography.

OBJECTIVE: The aim of this study was to evaluate the association between 4-dimensional computed tomography (4DCT)-derived measurements of tibiofibular syndesmosis during active dorsiflexion-plantarflexion motion and the presence of tibiotalar osteoarthritis (OA). METHODS: Sixteen ankle joints underwent 4DCT imaging during active dorsiflexion-plantarflexion. Syndesmotic anterior distance (SAD) and syndesmotic translation (ST) were obtained by a foot-and-ankle surgeon. We used Kellgren-Lawrence (KL) grading to determine tibiotalar OA. RESULTS: Of 16 scanned ankles, 12 ankles had KL ≥2 at the tibiotalar joint. In these ankles, SAD (-0.4, P = 0.02) and ST (-0.9, P = 0.006) measurements significantly changed during the dorsiflexion-plantarflexion motion. Changes in SAD measurements were significantly correlated with the KL grades (correlation coefficient: -0.688, P = 0.003); however, the changes in ST measurements were not significantly correlated with the KL grade. CONCLUSIONS: Our exploratory cross-sectional analysis shows that SAD measurement changes during motion using 4DCT are correlated with the tibiotalar OA grading. This measurement may be used but requires confirmation in larger studies including patients with actual syndesmotic injuries.

Safety and Oncologic Outcomes of Percutaneous Cryoablation of Renal Cell Carcinoma Recurrences in the Ipsilateral Kidney Following Partial Nephrectomy.

PURPOSE: To retrospectively investigate the safety and oncological outcomes of cryoablation performed on residual/recurring renal cell carcinoma (RCC) in the ipsilateral kidney following partial nephrectomy (PN). MATERIALS AND METHODS: Data dealing with patients', RCC, procedure (including the length of the hospital stay), and follow-up (technical efficacy [TE], local tumor progression-free survival [LTPFS], disease-free survival [DFS], metastasis-free survival [MFS], cancer-specific survival (CSS), and overall survival [OS]) were retrospectively collected and analyzed. RESULTS: Between January 2008 and November 2020, 21 consecutive patients (17 [81%] men; 4 [19%] women; median age 68 years; range 43-82) underwent cryoablation due to residual/recurring RCC in the PN site (15 patients) or de-novo RCC (6 patients) in the ipsilateral kidney. Median tumor size was 2.2 cm (mean 2.3 cm; range 0.8-4; interquartile range [IQR] 1.9-3). There were two (2/21; 10%) minor self-limiting hemorrhagic complications, both occurring in the group of patients with RCC in the PN site. Median hospital stay was 2 days (mean 2.1; range 1-5; IQR 2-2). TE was 100% (21/21 patients), and 10-year estimates of LTPFS, MFS and DFS were 74.1% (95% confidence intervals [CI] 56.8-96.7%), 36.4% (95% CI 14.2-93.8%), and 43.5% (95% CI 21.9-86.4%), respectively. CSS and OS were 100% at the last available follow-up (median 56 months; mean 67.4; range: 12-147; IQR:34-95). CONCLUSION: Cryoablation in patients with residual/recurring RCC following PN is safe and results in high 10-year estimates of LTPFS.

Percutaneous osteoplasty in long bones: Current status and assessment of outcomes.

Osteoplasty is a minimally invasive imaging-guided intervention providing mechanical stabilization, bone consolidation and pain relief in oncologic patients presenting with non-osteoblastic bone metastases or with insufficiency fractures. The intervention relies on the injection of an acrylic substance (ie, polymethylmethacrylate; PMMA) into the target bone. PMMA is very resistant to axial compressive loads but much less to bending, torsional and shearing stresses. Accordingly, from a biomechanical standpoint osteoplasty is adapted for the palliative treatment of small painful lytic bone defects located in the epiphyseal region of long bones in patients with clear surgical contraindications; or for increasing the anchoring of the osteosynthesis material into the target bone. Although pain relief is rapid and effective following osteoplasty, secondary fractures have been reported in up to 8-9% of long bone tumors undergoing such intervention; and following such event, fixation with endomedullary osteosynthetic material (eg, nailing) is not practicable any more. Accordingly, careful patients' selection is critical and should happen with a multidisciplinary approach.

Sporadic Desmoid Tumours: Systematic Review with Reflection on the Role of Cryoablation.

Desmoid tumours (DT) are rare locally infiltrative soft-tissue tumours which do not metastasise. DT arise sporadically or are associated with familial syndromes, with different clinical and genetic patterns. In recent years there has been an increasing therapeutic role of cryoablation for the treatment of sporadic DT. Therefore, in this present review, we: (a) summarize all the main epidemiological, clinical, and therapeutic aspects of sporadic DT that are relevant to an interventional radiologists' practice; (b) present the results of a systematic review that has been conducted with the intent of highlighting the main clinical outcomes available thus far with cryoablation; and (c) discuss the current and future potential applications of cryoablation in this field. Five studies were included in the systematic review accounting for 146 patients. Only 18.5% patients received cryoablation as a first-line treatment. Overall, the volume of the DT undergoing cryoablation was very large (mean total DT volume of 237 cm3). Major complications were noted for 13.3-30% patients and following 2.4-6.7% interventional sessions. The rates of complete tumour response ranged between 0 and 43.3%. 1- and 3-year local progression-free survival rates were 85.1-85.8%, and 77.3-82.9%, respectively. Complete pain relief was reported in 40-66.7% symptomatic patients. In conclusion, cryoablation is currently proposed as a therapeutic strategy to very large DT, which is recognized to be associated with an increased procedure-related morbidity and reduced rates of complete tumour response. Proposing cryoablation as the first-line treatment may improve these clinical outcomes.

Safety and Efficacy of Percutaneous Cryoablation of Extraspinal Thyroid Cancer Bone Metastases with Curative Intent: Single-Center Experience with a Median Follow-up of More than 5 Years.

PURPOSE: To determine the oncologic outcomes and safety profile of image-guided percutaneous cryoablation (PCA) for extraspinal thyroid cancer bone metastases with curative intent. MATERIALS AND METHODS: Between January 2010 and January 2020, 16 consecutive patients (8 men, 8 women; mean age, 61 years ± 19; range, 30-84 years) with 18 bone metastases (median bone tumor size, 19 mm; interquartile range [IQR], 12-29 mm; range, 7-58 mm) underwent PCA of oligometastatic extraspinal bone metastases. Thirteen (81%) patients were radioiodine therapy resistant. Two patients underwent 2 bone tumor ablations in a single session. Procedural data, oncologic outcomes, follow-up (with magnetic resonance imaging and positron emission tomography-computed tomography), and adverse events were retrospectively investigated. Local tumor progression-free survival, disease-free survival, and overall survival were estimated using the Kaplan-Meier method. RESULTS: A median of 2 cryoprobes (IQR, 1.25-3 cryoprobes; range, 1-7 cryoprobes) were used, with 2 freezing cycles; the median length of freezing was 20 minutes (IQR, 17-20 minutes; range, 10-20 minutes). The technical success was 100% (18/18), and the primary technical efficacy was 94.4% (17/18). The median follow-up was 68 months (IQR, 38-93 months). During follow-up, 3 of 17 (17.6%) tumors demonstrated local progression at 7, 13, and 27 months. Consequently, the 1-, 2-, 3-, 4-, and 5-year local tumor progression-free survivals were 93.3%, 84.6%, 76.9%, 75%, and 72.7%, respectively. Two of 16 (12.5%) patients died during follow-up at 43 and 88 months. The major adverse event rate was 5.5% (1/18) with 1 postablative acromion fracture. CONCLUSIONS: PCA for extraspinal thyroid cancer bone metastases demonstrated high local tumor control rates with a safe profile at long-term follow-up.