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Dive into the research topics where Stefan M. Zimmermann is active.

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Featured researches published by Stefan M. Zimmermann.


Journal of Bone and Joint Surgery, American Volume | 2016

Long-term Restoration of Anterior Shoulder Stability: A Retrospective Analysis of Arthroscopic Bankart Repair Versus Open Latarjet Procedure.

Stefan M. Zimmermann; Max J. Scheyerer; Mazda Farshad; Sabrina Catanzaro; Stefan Rahm; Christian Gerber

BACKGROUND Various operative techniques are used for treating recurrent anterior shoulder instability, and good mid-term results have been reported. The purpose of this study was to compare shoulder stability after treatment with the 2 commonly performed procedures, the arthroscopic Bankart soft-tissue repair and the open coracoid transfer according to Latarjet. METHODS A comparative, retrospective case-cohort analysis of 360 patients (364 shoulders) who had primary repair for recurrent anterior shoulder instability between 1998 and 2007 was performed. The minimum duration of follow-up was 6 years. Reoperations, overt recurrent instability (defined as recurrent dislocation or subluxation), apprehension, the subjective shoulder value (SSV), sports participation, and overall satisfaction were recorded. RESULTS An open Latarjet procedure was performed in 93 shoulders, and an arthroscopic Bankart repair was done in 271 shoulders. Instability or apprehension persisted or recurred after 11% (10) of the 93 Latarjet procedures and after 41.7% (113) of the 271 arthroscopic Bankart procedures. Overt instability recurred after 3% of the Latarjet procedures and after 28.4% (77) of the Bankart procedures. In the Latarjet group, 3.2% of the patients were not satisfied with their result compared with 13.2% in the Bankart group (p = 0.007). Kaplan-Meier analysis of survivorship, with apprehension (p < 0.001), redislocation (p = 0.01), and operative revision (p < 0.001) as the end points, documented the substantial superiority of the Latarjet procedure and the decreasing effectiveness of the arthroscopic Bankart repair over time. Twenty percent of the first recurrences after arthroscopic Bankart occurred no earlier than 91 months postoperatively, as opposed to the rare recurrences after osseous reconstruction, which occurred in the early postoperative period, with only rare late failures. CONCLUSIONS In this retrospective cohort study, the arthroscopic Bankart procedure was inferior to the open Latarjet procedure for repair of recurrent anterior shoulder dislocation. The difference between the 2 procedures with respect to the quality of outcomes significantly increased with follow-up time. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.


BMC Research Notes | 2014

Anterior subcutaneous internal fixation for treatment of unstable pelvic fractures

Max J. Scheyerer; Stefan M. Zimmermann; Georg Osterhoff; Simon Tiziani; Hans-Peter Simmen; Guido A. Wanner; Clément M. L. Werner

BackgroundFractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations – especially when associated with abdominal trauma and the need to perform laparotomies – both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase.FindingsFour patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases.ConclusionMinimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates.


Injury-international Journal of The Care of The Injured | 2013

Echinomycin in the prevention of heterotopic ossification – An experimental antibiotic agent shows promising results in a murine model

Stefan M. Zimmermann; C.C. Würgler-Hauri; Guido A. Wanner; H.-P. Simmen; Clément M. L. Werner

BACKGROUND Heterotopic ossification (HO) frequently causes complications following orthopaedic and trauma surgery and may drastically reduce the postoperative outcome due to pain and joint contracture. Current therapeutic options include NSAIDs and local radiation. However, both options of prevention show disadvantages such as delayed fracture healing and impaired ossification as well as other side effects.(9) Our goal was to investigate a novel approach in the prevention of heterotopic ossification by pharmacologically interfering with the molecular signalling pathways involved in this process. Hypoxia leads to numerous effects on a cellular level, one of which is the activation of the transcriptional complex hypoxia-inducible factor (HIF).(19) Among several other actions, the HIF1-α signalling pathway in turn regulates angiogenesis through induction of the expression of vascular endothelial growth factor (VEGF).(21) We hypothesised that by pharmacologically interfering with the HIF-1α signalling pathway, the amount of HO formation may be reduced. Echinomycin is a known inhibitor of HIF-1-alpha and was used in our study with the aim to prevent HO from forming. METHODS We examined the effect of Echinomycin on HO formation in a murine model where an Achilles tenotomy was performed. This has previously been shown to reliably produce islets of heterotopic ossification within the soft tissue of mouse hind limbs at 10 weeks after surgery. The control group underwent Achilles tenotomy only, whereas the Echinomycin group additionally received Echinomycin subcutaneously. After trial completion, the limbs were harvested and Micro-CT was performed. Heterotopic bone volume was then identified in 3d images and quantified. RESULTS We found a highly significant reduction in the bone volume following subcutaneous administration of Echinomycin compared to the control group. CONCLUSION Although a substantial reduction could be achieved, it was not possible to completely prevent heterotopic ossification from forming. Further studies have yet to be conducted to optimise the results by altering the dosage and duration of administration as well as investigate the mechanism by which Echinomycin led to the reduction of HO formation.


Emergency Medicine Journal | 2014

Effect of elevated serum alcohol level on the outcome of severely injured patients.

Max J. Scheyerer; Joel Dütschler; Adrian T. Billeter; Stefan M. Zimmermann; Kai Sprengel; Clément M. L. Werner; Hans-Peter Simmen; Guido A. Wanner

Background The influence of high blood alcohol level (BAL) on the outcome of severely injured patients and the corresponding pathophysiological changes is a controversial issue. Objective To carry out a prognostic study to compare the physiological values and short-term outcome of severely injured patients depending on their serum alcohol level. Methods A total of 383 severely injured patients with an Injury Severity Score (ISS) ≥17 were admitted to the trauma division between October 2008 and December 2009 and enrolled into this study. Patients were grouped according to their BAL (>0.5‰,‘BAL positive’ vs <0.5‰,‘BAL negative’). Trauma mechanism, pattern of injury and its treatment, and a course of intensive care treatment, physiological parameters and outcome with respect to mortality were analysed. Results Both groups had similar ISS. In comparison with the BAL-negative group, patients in the BAL-positive group had a significantly lower Glasgow Coma Scale score (9.64 vs 12 points; p=0.005) and, although not significant, a trend towards higher values of the Abbreviated Injury Score for the head (3.29 vs 2.81 points; p=0.146). Furthermore, significantly higher lactate (3.11 mmol/L vs 2.02 mmol/L; p<0.001) levels and lower median arterial pressure values (87.9 mm Hg vs 99.4 mm Hg; p=0.006) were seen in the BAL-positive group at day of admission. However, the overall in-hospital mortality was comparable to that in BAL-negative patients (19.6% vs 21.5%). Similarly, hospital stay (15.29 vs 17.55 days) and duration of intensive care unit treatment (8.53 vs 8.36 days) were not significantly affected by a high BAL upon admission. Conclusions Severely injured patients with a raised BAL have a higher incidence of severe traumatic brain injury and worse initial physiological parameters. However, the survival rate and in-hospital stay is not influenced. This supports the theory of a neuroprotective role of alcohol.


Radiology Research and Practice | 2013

Lumbar Facet Joint Arthritis Is Associated with More Coronal Orientation of the Facet Joints at the Upper Lumbar Spine

Thorsten Jentzsch; James Geiger; Stefan M. Zimmermann; Ksenija Slankamenac; Thi Dan Linh Nguyen-Kim; Clément M. L. Werner

We retrospectively analyzed CT scans of 620 individuals, who presented to our traumatology department between 2008 and 2010. Facet joint (FJ) arthritis was present in 308 (49.7%) individuals with a mean grade of 1. It was seen in 27% of individuals ≤40 years and in 75% of individuals ≥41 years (P < 0.0001) as well as in 52% of females and 49% of males (P = 0.61). Mean FJ orientation was 30.4° at L2/3, 38.7° at L3/4, 47° at L4/5, and 47.3° at L5/S1. FJ arthritis was significantly associated with more coronal (increased degree) FJ orientation at L2/3 (P = 0.03) with a cutoff point at ≥32°. FJs were more coronally oriented (48.8°) in individuals ≤40 years and more sagittally oriented (45.6°) in individuals ≥41 years at L5/S1 (P = 0.01). Mean FJ asymmetry was 4.89° at L2/3, 6.01° at L3/4, 6.67° at L4/5, and 7.27° at L5/S1, without a significant difference for FJ arthritis. FJ arthritis is common, increases with age, and affects both genders equally. More coronally oriented FJs (≥32°) in the upper lumbar spine may be an individual risk factor for development of FJ arthritis.


European Journal of Nuclear Medicine and Molecular Imaging | 2014

SPECT/CT for imaging of the spine and pelvis in clinical routine: a physician's perspective of the adoption of SPECT/ CT in a clinical setting with a focus on trauma surgery

Max J. Scheyerer; Carsten Pietsch; Stefan M. Zimmermann; Georg Osterhoff; Hans-Peter Simmen; Clément M. L. Werner

Injuries of the axial skeleton are an important field of work within orthopaedic surgery and traumatology. Most lesions following trauma may be diagnosed by means of conventional plain radiography, computed tomography or magnetic resonance imaging. However, for some aspects SPECT/ CT can be helpful even in a trauma setting. In particular, the combination of highly sensitive but nonspecific scintigraphy with nonsensitive but highly specific computed tomography makes it particularly useful in anatomically complex regions such as the pelvis and spine. From a trauma surgeon’s point of view, the four main indications for nuclear medicine imaging are the detection of (occult) fractures, and the imaging of inflammatory bone and joint diseases, chronic diseases and postoperative complications such as instability of instrumentation or implants. The aim of the present review was to give an overview of the adoption of SPECT/CT in a clinical setting.


Emergency Medicine International | 2013

Location of Sternal Fractures as a Possible Marker for Associated Injuries

Max J. Scheyerer; Stefan M. Zimmermann; Samy Bouaicha; Hans-Peter Simmen; Guido A. Wanner; Clément M. L. Werner

Introduction. Sternal fractures often occur together with serious and life-threatening additional injuries. This retrospective study was designed to assess concomitant injuries and develop a correlation between fracture location and the severity of injury. Methods. All patients (n = 58) diagnosed with a fracture of the sternum by means of a CT scan were analysed with respect to accident circumstances, fracture morphology and topography, associated injuries, and outcome. Results. Isolated sternal fractures occurred in 9%. In all other admissions, concomitant injuries were diagnosed: mainly rip fractures (64%), injury to the head (48%), the thoracic spine (38%), lumbar spine (27%), and cervical spine (22%). Predominant fracture location was the manubrium sterni. In these locations, the observed mean ISS was the highest. They were strongly associated with thoracic spine and other chest injuries. Furthermore, the incidence of head injuries was significantly higher. ICU admission was significantly higher in patients with manubrium sterni fractures. Conclusion. Sternal fractures are frequently associated with other injuries. It appears that the fracture location can provide important information regarding concomitant injuries. In particular, in fractures of manubrium sterni, the need for further detailed clinical and radiologic workup is necessary to detect the frequently associated injuries and reduce the increased mortality.


Journal of Hand Surgery (European Volume) | 2017

Conventional Versus Computer-Assisted Corrective Osteotomy of the Forearm: a Retrospective Analysis of 56 Consecutive Cases

David E. Bauer; Stefan M. Zimmermann; Alexander Aichmair; Andreas Hingsammer; Andreas Schweizer; Ladislav Nagy; Philipp Fürnstahl

PURPOSE Accuracy and feasibility of corrective osteotomies using 3-dimensional planning tools and patient-specific instrumentation has been reported by multiple authors with promising results. However, studies describing clinical outcomes following these procedures are rare. Therefore, the purpose of this study was to compare the results of computer-assisted corrective osteotomies of the diaphyseal and distal radius with a conventional non-computer-assisted technique regarding duration of surgery, consolidation of the osteotomy, and complications. Also, subjective and objective clinical outcome parameters were assessed. METHODS We retrospectively compared the results of 31 patients who underwent a corrective osteotomy performed conventionally with 25 patients treated with a computer-assisted method (CA) using patient-specific instrumentation. Baseline data were similar among both groups. The duration of surgery, bony consolidation, complications, gain in range of motion, and subjective outcome were recorded. RESULTS The mean operating time was significantly shorter in the CA group compared with the conventional group. After 12 weeks, significantly more osteotomies were considered healed in the CA group compared with the conventional group. Two patients in the CA group required revision surgery to treat nonunion of the osteotomy. Otherwise clinical results were similar among both groups. CONCLUSIONS The results demonstrate that the computer-assisted method facilitates shorter operation times while providing similar clinical results. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.


Journal of Shoulder and Elbow Surgery | 2016

Lengthening of the subscapularis tendon as a sign of partial tearing in continuity

Dominik C. Meyer; Stefan M. Zimmermann; Karl Wieser; Susanne Bensler; Christian Gerber; Marco Germann

BACKGROUND The quantification of a subscapularis tendon lesion may be difficult on magnetic resonance imaging, as well as during arthroscopic inspection. Consequently, the surgical decision of whether to only debride a degenerated tendon or to lateralize the more intact tendon portion may be arbitrary. This study aims to quantify the length of the subscapularis tendon as a sign of partial tendon tearing. METHODS We retrospectively identified 92 magnetic resonance arthrography studies of suspected rotator cuff lesions obtained 3 months before shoulder arthroscopy. The myotendinous junction was identified, and the subscapularis tendon and muscle lengths were measured. Findings on arthroscopy performed later were used as the diagnostic gold standard for tendon integrity and compared with the magnetic resonance data. RESULTS Arthroscopy showed an intact subscapularis tendon in 43 patients, tendinopathy in 21 patients, and a partial rupture in 28 patients. The mean subscapularis tendon lengths were 40 mm in cases of intact subscapularis musculotendinous units, 45 mm in cases of tendinopathy, and 53 mm in cases of partial tears, whereas the mean subscapularis muscle lengths were 105 mm, 94 mm, and 95 mm, respectively, in these groups. CONCLUSION Partial tears of the subscapularis tendon lead to muscle shortening by approximately 10% and elongation of the tendon by approximately 32%, which may be interpreted as muscle retraction and a tendon rupture in continuity. If the subscapularis tendon has an apparent length of greater than 60 mm, the probability of a tear is 98%. Determination of the tendon length may therefore be a useful additional tool to quantify the integrity of the subscapularis tendon and degree of myotendinous retraction.


European Radiology | 2018

Pre-procedural CT angiography inferior vena cava measurements: a predictor of mortality in patients undergoing transcatheter aortic valve implantation

Matthias Eberhard; Gianluca Milanese; Michael Ho; Stefan M. Zimmermann; Thomas Frauenfelder; Fabian Nietlispach; Francesco Maisano; Felix C. Tanner; Thi Dan Linh Nguyen-Kim

ObjectivesTo assess the value of pre-procedural computed tomography angiography (CTA) measurements of the suprahepatic inferior vena cava (IVC) to detect elevated central venous pressure (CVP) assessed by right heart catheterisation (RHC), and to predict post-procedural 1-year mortality in a cohort of patients undergoing transcatheter aortic valve implantation (TAVI).MethodsWe retrospectively evaluated 408 consecutive patients undergoing CTA before TAVI between January 2011 and December 2014. Two hundred and five patients were included in the RHC cohort, who underwent RHC and CTA within ≤1 day prior to TAVI. Two hundred and three patients not fulfilling this requirement were included in the validation cohort. Measurements of the IVC were performed between diaphragm and right atrium on axial slices. Receiver operating characteristic (ROC) analyses, Kaplan-Meier analyses and Cox regression analyses were performed.ResultsIn the RHC cohort, ROC curve analyses for IVC area measurements indicated an AUC of 0.77 (p < 0.001) to detect CVP ≥10mmHg and an area under the ROC curve (AUC) of 0.72 (p < 0.001) to predict 1-year mortality. An IVC area cut-off of ≥665 mm2 predicted 1-year mortality with a specificity of 84% and a sensitivity of 63%. Kaplan-Meier analysis showed that patients with an IVC area ≥665 mm2 had a significantly higher post-procedural 1-year mortality (38% versus 7%, log-rank p < 0.001) with a hazard ratio of 5.5 (95% CI, 2.2-13.6; p < 0.001). Applying this cut-off value to the validation cohort confirmed a significantly higher 1-year mortality after TAVI (34% versus 11%; log-rank p = 0.004) for patients with an IVC area ≥665 mm2.ConclusionsPre-procedural enlargement of the suprahepatic IVC is a predictor of post-procedural 1-year mortality in patients evaluated for TAVI.Key Points• IVC measurements are moderate predictors of an elevated CVP in TAVI patients.• Pre-procedural IVC enlargement is a predictor of 1-year mortality after TAVI.• IVC enlargement is associated with right heart dysfunction in TAVI patients.

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