Felix Ragnar Merlin König

Dr. Felix Ragnar Merlin König

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Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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16 September 2024 in European Radiology
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Journal Article
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FKFelix Ragnar Merlin König
Felix Ragnar Merlin König
MRMarcus Raudner
Marcus Raudner
VJVladimir Juras
Vladimir Juras
PSPavol Szomolanyi
Pavol Szomolanyi
VVVeronika Vetchy
Veronika Vetchy
STSiegfried Trattnig
Siegfried Trattnig
Objectives: Bone marrow edema-like signal (BMELS) after cartilage repair is common, but its clinical significance remains uncertain. This study aimed to investigate the clinical and structural significance of BMELS following microfracturing (MFX) and matrix-induced autologous chondrocyte implantation (MACI). Methods: In this multicenter study, MRI examinations were performed over a period of 5 years after cartilage repair surgery (MFX n = 17; MACI n = 28) in 45 patients. Morphological assessments, including the MOCART 2.0 (magnetic resonance observation of cartilage repair tissue), quantitative imaging biomarkers (QIB) with T2 mapping of the repair tissue, and, specifically, assessment of the presence and size of BMELS, were conducted along with patient-reported outcome measures, such as the Knee injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC). BMELS structural and clinical assessments were obtained after 3 months, 12 months, and 60 months. Statistical analysis included the Mann–Whitney U -test, Wilcoxon rank test, Shapiro–Wilk test, and simulation-based power analysis. Results: BMELS were a common finding 60 months after cartilage repair. The size of BMELS differed significantly only between MACI and MFX patients after 3 months, with larger BMELS occurring in the MFX group. There were no significant differences in patients with or without BMELS regarding the T2 ratio of the treated area, the MOCART 2.0, or clinical scores. Conclusion: BMELS frequently appeared after cartilage repair procedures. We could show that the postoperative size and change in the size of BMELS after MACI and MFX did not affect clinical scores, morphological MRI results, or biochemical properties of the treated area after 60 months. Key Points: Question What is the clinical significance of bone marrow edema-like signal (BMELS) appearance after matrix-induced autologous chondrocyte implantation (MACI) or microfracture (MFX) ? Finding There were no significant differences in patients with or without BMELS regarding the T2 ratio of the treated area, the MOCART 2.0, or clinical scores . Clinical relevance BMELS frequently appeared after cartilage repair, the appearance or the size dynamic after MACI and MFX did not affect clinical scores, morphological MRI results, or biochemical properties after 60 months .

1 October 2024 in Cancers
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JKJohannes Kroenig
Johannes Kroenig
CGChristian Görg
Christian Görg
HPHelmut Prosch
Helmut Prosch
LSLara von Schumann
Lara von Schumann
CWChristina C. Westhoff
Christina C. Westhoff
EZEhsan Safai Zadeh
Ehsan Safai Zadeh
Purpose: Description of the perfusion of pulmonary metastasis by contrast-enhanced ultrasound (CEUS) and their correlation with vascularization patterns represented by immunohistochemical CD34 endothelial staining. Patients and methods: The data of 54 patients with histologic proven peripheral pulmonary metastasis, investigated between 2004 and 2023 by CEUS. These CEUS parameters were evaluated: time to enhancement (TE), categorized as early pulmonary-arterial (PA) or delayed bronchial-arterial (BA) patterns; extent of enhancement (EE), either marked or reduced; homogeneity of enhancement (HE), homogeneous or inhomogeneous; and decrease of enhancement (DE), rapid washout (<120 s) or late washout (≥120 s). Additionally, tissue samples in 45 cases (83.3%) were stained with CD34 antibody for immunohistochemical analysis. Results: In total, 4 lesions (7.4 %) exhibited PA enhancement, and 50 lesions (92.6%) demonstrated BA enhancement. Furthermore, 37 lesions (68.5%) showed marked enhancement, while 17 lesions (31.5%) exhibited reduced enhancement. The enhancement was homogeneous in 28 lesions (51.86%) and inhomogeneous in 26 lesions (48.14%). Additionally, 53 lesions (98.1%) displayed a rapid washout. A chaotic vascular pattern indicative of a bronchial arterial blood supply was identified in all cases (45/45, 100%), including all 4 lesions with PA enhancement. Conclusion: Pulmonary metastases in CEUS predominantly reveal bronchial arterial enhancement and a rapid washout. Regarding EE and HE, pulmonary metastases show heterogeneous perfusion patterns. A PA enhancement in CEUS does not exclude BA neoangiogenesis.

23 July 2024 in Biomedicines
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FKFelix Ragnar Merlin König
Felix Ragnar Merlin König
AKAlfred H. Kielburg
Alfred H. Kielburg
SCSnehansh Roy Chaudhary
Snehansh Roy Chaudhary
CWChristian Wassipaul
Christian Wassipaul
AGAkash Ganguly
Akash Ganguly
INI.-M. Noebauer-Huhmann
I.-M. Noebauer-Huhmann
Background: Early detection of soft tissue sarcoma (STS) recurrence is essential; however, the role and timeline of Magnetic resonance imaging (MRI) surveillance are still under debate. The aim of this study was to determine whether local recurrence (LR) could be identified via clinical examination alone and to assess the MRI morphology of primary STS and LR. Methods: This retrospective study included all patients with STS recurrence after surveillance for at least five years from the tumor database of the Medical University of Vienna from 2000 until December 2023. The characteristics of primary STS and LR and the time interval to recurrence and clinical detectability were assessed. The MRIs of LR and posttherapeutic changes (PTC) were compared with the initial MRIs. Results: A total of 57 patients (60% male; mean age 58.5 ± 18.0 years) with STS and histologically confirmed LR were included. The mean time interval to LR was 2.3 ± 1.8 years (range 108 to 3037 days). The clinically detectable recurrences were significantly larger than the inapparent ones (71.9 cm3 vs. 7.0 cm3; p < 0.01). The MRI morphology of all LRs (26/26) closely resembled the initial STS. For comparison, nine patients were included with clinically suspected LRs, which were histologically proven to be PTC. None of these resembled the primary STS. Conclusion: Based on clinical symptoms alone, especially small and early recurrences can be missed, which supports the importance of MRI surveillance.

8 December 2025 in Journal of Clinical Medicine
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GWGregor Wollner
Gregor Wollner
SLSamuel Luisi
Samuel Luisi
FHFlorian Hruska
Florian Hruska
FPFlorian Pengg
Florian Pengg
FKFelix Ragnar Merlin König
Felix Ragnar Merlin König
THThomas Haider
Thomas Haider
Background/Objectives: Acromioclavicular (AC) joint injuries account for 9–12% of shoulder injuries, predominantly affecting young male athletes. While conservative treatment is established for Rockwood type I–II injuries and surgery is widely regarded as indicated for type V–VI, management of type III–IV injuries remains controversial. Biomechanical studies have shown superior results in combined reconstruction of the coracoclavicular and AC ligament complex, however clinical data is scarce. Therefore, the present study aimed to assess whether the addition of an acromioclavicular ligament reconstruction to an isolated coracoclavicular repair offers superior clinical and radiographic outcomes in the treatment of acute AC joint dislocations. Methods: A retrospective multicenter study was conducted on patients with Rockwood type III–VI AC joint injuries who underwent surgical treatment between 2019 and 2024. Patients were divided into two groups: isolated CC reconstruction (group I) and combined CC and AC ligament reconstruction (group II). Clinical outcome was assessed using patient-reported outcome measures (American Shoulder and Elbow Surgeons Score, Simple Shoulder Test, Single Assessment Numeric Evaluation, Visual Analogue Scale) and radiographic evaluations were performed regularly up to 6 months postoperatively. Results: Fifty-five patients (94.5% male, mean age 33.5 ± 10.9 years) were included in the present study. High patient satisfaction (group I: ASES 96.3 ± 7.9, SST 99.2 ± 3.3, SANE 95.3 ± 7.0; group II: ASES 95.8 ± 8.8, SST 96.8 ± 8.2, SANE 93.6 ± 12.8) was documented in both groups, but no significant differences were observed. The median coracoclavicular loosening ratio was 24.7% in the CC group and 32.6% in the CC and AC ligament reconstruction group (p = 0.830). Five complications occurred: two infections and three revision surgeries due to excessive secondary dislocations. Conclusions: Both surgical techniques demonstrated excellent clinical outcomes. In this study combined CC and AC ligament reconstruction did not yield superior clinical or radiological results compared to isolated coracoclavicular reconstruction. Our findings suggest that a routine AC ligament augmentation may not be necessary in all patients. Further randomized controlled trials are needed to validate these results.

19 September 2024 in Journal of Clinical Medicine
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Journal Article
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GWGregor Wollner
Gregor Wollner
FHFlorian Hruska
Florian Hruska
FKFelix Ragnar Merlin König
Felix Ragnar Merlin König
THThomas Haider
Thomas Haider
LNLukas Leopold Negrin
Lukas Leopold Negrin
Introduction: Heterotopic ossifications (HOs) are a well-known complication following total hip arthroplasty. Yet only little is known about the development of HOs following a femoral fracture and intramedullary stabilization in polytraumatized patients. Thus, the present study aimed to investigate whether the development of HOs is being observed more frequently in patients suffering polytrauma compared to those with single-extremity trauma. Materials and Methods: The retrospective outcome study was conducted at our level I trauma center. All patients admitted from 2010 to 2020 were included if they (1) presented with multiple injuries (≥2 body regions), (2) had an Injury Severity Score ≥16, (3) suffered a femoral fracture, and (4) were treated with intramedullary stabilization. Furthermore, a control group was established to match the polytrauma group (sex, age), who were suffering from single-extremity trauma (femoral fracture) which was treated with intramedullary stabilization. Subsequently, X-rays of the hip were performed and evaluated for up to one-year post-trauma. Results: Our study group consisted of 36 patients in total (91.7% male; mean age 39.4 ± 17.4 years, range: 18–82 years). The polytrauma (PT) group included 12 patients (mean age 39.5 years, median ISS 28), whereas the control group (single-extremity-trauma) included 24 patients (mean age 39.3 years). We documented HOs in nine (75%) patients in the PT group vs. five (20.8%) patients in the single-extremity group (p = 0.03). Conclusion: In this study, we were able to demonstrate that heterotopic ossifications are being observed significantly more frequently in patients suffering from polytrauma in comparison to patients with single-extremity trauma following intramedullary stabilization after a femoral fracture.

28 April 2025 in CARTILAGE
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Journal Article
Open access
FKFelix Ragnar Merlin König
Felix Ragnar Merlin König
MRMarcus Raudner
Marcus Raudner
GWGregor Wollner
Gregor Wollner
VJVladimir Juras
Vladimir Juras
PSPavol Szomolanyi
Pavol Szomolanyi
STSiegfried Trattnig
Siegfried Trattnig
Objectives: This study aimed to assess the impact of intralesional bony overgrowth (ILBO) after cartilage repair on the integrity of opposing articulating cartilage (OpAC) using T2 mapping and to correlate these findings with clinical outcomes. Methods: In this multicenter study, magnetic resonance imaging (MRI) examinations were performed in the follow-up after cartilage repair (Microfracturing (MFX) and Matrix-Induced Autologous Chondrocyte Implantation (MACI)) in 45 patients up to 5 years after surgery. T2 values of the OpAC after 3, 12, and 60 months in patients with and without ILBO after 60 months were conducted along with clinical assessments (International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS)). Results: At 60 months post-surgery, 44.4% of patients presented with ILBO, which was associated with significantly higher T2 values in OpAC ( P = 0.004). A tendency toward increased T2 values was observed after 12 months, although this did not reach statistical significance ( P = 0.06). However, no significant differences were found in clinical outcomes between patients with or without ILBO, nor between those with or without T2 values comparable to reference cartilage. Conclusion: ILBO significantly affects the biophysical MRI properties of OpAC as indicated by higher T2 values after 60 months. These alterations, though not reflected in any clinical score, can suggest potential long-term implications for cartilage degeneration and may inform future monitoring strategies for cartilage repair. Further research is required to evaluate the long-term effects of these altered mechanical impacts on articulating cartilage and their clinical implications.