Christof Birkenmaier

Prof. Christof Birkenmaier

Department of Orthopaedics, Physical Medicine & Rehabilitation, University of Munich (LMU)
orcid

Research Focus & Metrics

Academic Career Length

35Years (1992-Present)

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

Representative Publications

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24 August 2018 in BMC Cancer
Verified
Journal Article
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JFJulian Fromm
Julian Fromm
AKAlexander Klein
Alexander Klein
ABAndrea Baur-Melnyk
Andrea Baur-Melnyk
TKThomas Knösel
Thomas Knösel
LLLars Lindner
Lars Lindner
HDHans Roland Dürr
Hans Roland Dürr
Chondrosarcoma is the second most frequent primary malignant bone tumor. Treatment is mainly based on surgery. In general, wide resection is advocated at least in G2 and G3 tumors. But which margins should be achieved? Does localization as for example in the pelvis have a higher impact on survival than surgical margins themselves? From 1982 to 2014, 87 consecutive patients were treated by resection. The margin was defined as R0 (wide resection), R1 (marginal resection) or, R2 if the tumor was left intentionally. All patients were followed for evidence of local recurrence or distant metastasis. Overall and recurrence-free survival were calculated, significance analysis was performed. In 54 (62%) cases a R0 resection, in 31 (36%) a R1 and in 2 (2%) patients a R2-resection was achieved. Histology proved to be G1 in 37 patients (43%), G2 in 41 (47%) and G3 in 9 cases (10%). 5-year local recurrence-free survival (LRFS) was 75%. Local recurrence-free survival showed a significant association with the margin status and the localization of the tumor with pelvic lesions doing worst. Metastatic disease was initially seen in 4 patients (4.6%), 19 others developed metastatic disease during follow-up. Overall survival of the entire group at 5 and 10 years were 79 and 75%, respectively. The quality of surgical margins and the presence of local recurrence did not influence overall survival in a multivariate analysis. Pelvic lesions had a worse prognosis as did higher grades of the tumor, metastatic disease and age. The mainstay of therapy in Chondrosarcoma remains surgery. Risk factors as grading, metastatic disease, age and location significantly influence overall survival. Margin status (R0 vs. R1) did influence local recurrence-free survival but not overall survival. Chondrosarcomas of the pelvis have a higher risk of local recurrence and should be treated more aggressively.

10 July 2008 in European Spine Journal
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Journal Article
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BWBernd Wegener
Bernd Wegener
CBChristof Birkenmaier
Christof Birkenmaier
AFAndreas Fottner
Andreas Fottner
VJVolkmar Jansson
Volkmar Jansson
HDHans Roland Dürr
Hans Roland Dürr
Pedicle screw instrumentation has become increasingly popular during the past 20 years and a vast selection of products is available on the market. With rising implantation rates, reports about specific complications also have increased. The main reason for these complications is the fact that the course of the pedicle and in turn the positioning of the pedicle screw cannot be adequately controlled visually. Based on the anatomy of the surrounding structures, complications caused by malpositioning can be divided into three main groups: mechanical, neurological and vascular. Beyond mechanical limitations of spinal motion, nerve injury can lead to neurological problems while injuries to vascular structures usually cause hemorrhage. These typical problems in general become apparent intraoperatively or in the immediate postoperative course. We report on a rare delayed complication and analyze the factors that led to it. In addition, we outline our treatment strategy. The goal has to be to avoid such problems in the future by using suitable navigational aids.

1 July 2006 in Journal of Orthopaedic Science
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Journal Article
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AVAndreas Veihelmann
Andreas Veihelmann
CDC. Devens
C. Devens
HTH. Trouillier
H. Trouillier
CBChristof Birkenmaier
Christof Birkenmaier
LGL. Gerdesmeyer
L. Gerdesmeyer
HRH.J. Refior
H.J. Refior

20 October 2019 in BMC Musculoskeletal Disorders
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Journal Article
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HDHans Roland Dürr
Hans Roland Dürr
FGFerdinand Grahneis
Ferdinand Grahneis
ABAndrea Baur-Melnyk
Andrea Baur-Melnyk
TKThomas Knösel
Thomas Knösel
CBChristof Birkenmaier
Christof Birkenmaier
AKAlexander Klein
Alexander Klein
Background: The treatment of aneurysmal bone cysts (ABCs) has evolved and less invasive methods have been tried. Denosumab is a monoclonal antibody which inhibits osteoclasts. It has been shown to be effective in giant cell tumour of bone (GCT) of bone and hence promises some effect also in ABC. We report on 6 patients treated with Denosumab and compare our results to the cases already published. Methods: Data of 6 patients with ABCs and patients whose treatment included Denosumab were retrospectively analyzed. Denosumab was used at a dose of 120 mg on days 1, 8, 15 and 29, and every 4 weeks thereafter. In some of these patients the dose was reduced at the end of the treatment. Clinical and radiological responses were evaluated. Results: In 4 female and 2 male patients with a mean age of 17 years (range: 6–30 years) the lesions were located in the sacrum (2), in distal radius, distal femur, talus and pelvis. One of the sacral lesions healed after 12 months and has stayed stable for 3 years since. The second patient received 2 years of therapy with recalcification, but recurred 1 year later and is under renewed therapy. The pelvic lesion improved but recurred. This patient has a 13-years history of intermittent therapy including surgery, two pregnancies and remains in a stable situation. The lesion of the talus did not improve with Denosumab after surgery and was complicated by destruction of the ankle joint with osteoarthritis. Recurrent lesions of the distal femur and the distal radius, previously treated by curettage and bone grafting healed under Denosumab and have remained stable for 2 and 3 years, respectively. One case of severe hypercalcemia was observed in a 7-year old child 6 months after discontinuation of Denosumab. Conclusion: Denosumab provides a treatment option for ABCs in anatomically critical locations. Adjuvant application might reduce the rate of local recurrence. In young patients, severe rebound hypercalcemia months after discontinuation of Denosumab may occur.

1 January 2009 in Spine
Verified
Journal Article
Closed access
JLJennifer Linn
Jennifer Linn
CBChristof Birkenmaier
Christof Birkenmaier
RHRalf T. Hoffmann
Ralf T. Hoffmann
MRMaximilian Reiser
Maximilian Reiser
ABAndrea Baur-Melnyk
Andrea Baur-Melnyk
The study consisted of a retrospective and a prospective study part. We aimed to investigate the nature of the intravertebral vacuum clefts (IVC) in computed tomography (CT) in acute osteoporotic vertebral fractures in correlation with magnetic resonance imaging (MRI). IVC and intravertebral fluid accumulations have been shown to be indicative of benign vertebral fractures in CT and MRI, respectively. Twenty-eight patients (30 osteoporotic fractures) associated with intravertebral vacuum in CT in whom MRI of the spine was performed were retrospectively analyzed. Moreover, we prospectively performed MRI examinations in 12 consecutive patients with 13 osteoporotic fractures with an intravertebral vacuum in CT. T1-w SE, STIR, and 5 repetitive T2-w TSE studies were performed (1.5 Tesla system, Siemens). Two experienced readers assessed the examinations in consensus with regard to the occurrence and location of the intravertebral and intradiscal vacuum on CT and the corresponding signal alterations in MRI. Twenty-seven (90%) of the retrospectively analyzed fractures with intravertebral vacuum in CT showed a fluid like signal in the location of the vacuum in MRI. In the prospective group, a small fluid-like signal was initially present on T2-weighted sequences in 11 of 13 fractures (84.6%). During the repeated T2-weighted measurements, the fluid occurred or increased markedly in all cases. An intradiscal fluid was present either initially and/or during the course of the examination in 46% of the prospective cases and in 50% of the retrospectively evaluated fractures. The occurrence of the fluid in MRI within intravertebral clefts is a dynamic process, which is dependent on the position of the patient and is presumably secondary to the extension momentum in the supine position. This may be due to the negative pressure in the horizontal position in which the fracture site is distracted. intravertebral.

8 September 2020 in Cancers
Verified
Journal Article
Open access
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ABAnnika Bilgeri
Annika Bilgeri
AKAlexander Klein
Alexander Klein
LLLars Lindner
Lars Lindner
SNSilke Nachbichler
Silke Nachbichler
TKThomas Knösel
Thomas Knösel
HDHans Roland Dürr
Hans Roland Dürr
Background: The significance of surgical margins after resection of soft tissue sarcomas in respect to local-recurrence-free survival and overall survival is evaluated. Methods: A total of 305 patients with deep-seated, G2/3 soft tissue sarcomas (STS) of the extremity, the trunk wall, or the pelvis were reviewed. The margin was defined according to the Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) classification system (R0-2), the Union Internationale Contre le Cancer (UICC) classification (R + 1 mm) for which a margin <1 mm is included into the R1 group, and in groups of 5 mm, or >10 mm. Results: Of these patients, 31 (10.2%) had a contaminated margin, 64 (21%) a margin of 5 mm, and 40 (13.1%) a margin of >10 mm. The 5-year local recurrence-free survival (LRFS) was 81.6%. Overall survival (OS) at 5 years was 65.9%. Positive margins worsened LRFS and OS. A margin of >10 mm did not improve LRFS and OS as compared to one of >5 mm. Conclusions: A resection margin of <1 mm showed a trend but not significantly better LRFS or OS compared to a contaminated margin. This finding supports use of the UICC classification. A margin of more than 10 mm did not improve LRFS or OS.