Publications by authors named "Dominik Kaiser"

24 Publications

  • Page 1 of 1

Extra-abdominal desmoid tumor fibromatosis: a multicenter EMSOS study.

BMC Cancer 2021 Apr 20;21(1):437. Epub 2021 Apr 20.

Orthopaedic Oncology Department, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.

Background: Extra-abdominal desmoid tumor fibromatosis (DTF) is a rare, locally aggressive soft tissue tumour. The best treatment modality for this patient cohort is still object of debate.

Questions/purpose: This paper aimed to (1) to compare the outcomes of DTF after different treatment modalities, (2) to assess prognostic factors for recurrence following surgical excision, and (3) to assess prognostic factors for progression during observation.

Methods: This was a retrospective multicenter study under the patronage of the European Musculoskeletal Oncology Society (EMSOS). All seven centres involved were tertiary referral centres for soft tissue tumours. Baseline demographic data was collected for all patients as well as data on the diagnosis, tumour characteristics, clinical features, treatment modalities and whether they had any predisposing factors for DTF.

Results: Three hundred eighty-eight patients (240 female, 140 male) with a mean age of 37.6 (±18.8 SD, range: 3-85) were included in the study. Two hundred fifty-seven patients (66%) underwent surgical excision of ADF, 70 patients (18%) were observed without therapy, the residual patients had different conservative treatments. There were no significant differences in terms of tumour recurrence or progression between the different treatment groups. After surgical excision, younger age, recurrent disease and larger tumour size were risk factors for recurrence, while tumours around the shoulder girdle and painful lesions were at risk of progression in the observational group.

Conclusion: Local recurrence rate after surgery was similar to progression rates under observation. Hence, observation in DTF seems to be justified, considering surgery in case of dimensional progression in 2 consecutive controls (3 and 6 months) and in painful lesions, with particular attention to lesions around the shoulder girdle.
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http://dx.doi.org/10.1186/s12885-021-08189-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8059004PMC
April 2021

The quantitative influence of current treatment options on patellofemoral stability in patients with trochlear dysplasia and symptomatic patellofemoral instability - a finite element simulation.

Clin Biomech (Bristol, Avon) 2021 Mar 27;84:105340. Epub 2021 Mar 27.

Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.

Background: Trochlear dysplasia is highly associated with patellofemoral instability. The goal of conservative and surgical treatment is to stabilize the patella while minimizing adverse effects. However, there is no literature investigating the quantitative influence of different treatment options on patellofemoral stability in knees with trochlear dysplasia. We created and exploited a range of finite element models to address this gap in knowledge.

Methods: MRI data of 5 knees with trochlear dysplasia and symptomatic patellofemoral instability were adapted into this previously established model. Vastus medialis obliquus strengthening as well as double-bundle medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty were simulated. The force necessary to dislocate the patella by 10 mm and fully dislocate the patella was calculated in different flexion angles.

Findings: Our model predicts a significant increase of patellofemoral stability at the investigated flexion angles (0°-45°) for a dislocation of 10 mm and a full dislocation after medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty compared to trochleodysplastic (P = 0.01) and healthy knees (P = 0.01-0.02). Vastus medialis obliquus strengthening has a negligible effect on patellofemoral stability.

Interpretations: This is the first objective quantitative biomechanical evidence supporting the place of medial patellofemoral ligament reconstruction and medial patellofemoral ligament reconstruction combined with trochleoplasty in patients with symptomatic patellofemoral instability and trochlear dysplasia type B. Vastus medialis obliquus strengthening has a negligible effect on patellar stability at a low total quadriceps load of 175 N.
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http://dx.doi.org/10.1016/j.clinbiomech.2021.105340DOI Listing
March 2021

Long-term follow-up of conservative treatment of Charcot feet.

Arch Orthop Trauma Surg 2021 Apr 7. Epub 2021 Apr 7.

Divisions of "Prosthetics and Orthotics" and "Foot and Ankle Surgery", Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, 8008, Zürich, Switzerland.

Background: Charcot arthropathy (CN) can ultimately lead to limb loss despite appropriate treatment. Initial conservative treatment is the accepted treatment in case of a plantigrade foot. The aim of this retrospective study was to investigate the mid- to long-term clinical course of CN initially being treated conservatively, and to identify risk factors for reactivation and contralateral development of CN as well as common complications in CN.

Methods: A total of 184 Charcot feet in 159 patients (median age 60.0 (interquartile range (IQR) 15.5) years, 49 (30.1%) women) were retrospectively analyzed by patient chart review. Rates of limb salvage, reactivation, contralateral development and common complications were recorded. Statistical analysis was performed to identify possible risk factors for limb loss, CN reactivation, contralateral CN development, and ulcer development.

Results: Major amputation-free survival could be achieved in 92.9% feet after a median follow-up of 5.2 (IQR 4.25, range 2.2-11.25) years. CN recurrence occurred in 13.6%. 32.1% had bilateral CN involvement. Ulcers were present in 72.3%. 88.1% patients were ambulating in orthopaedic footwear without any further aids. Presence of Diabetes mellitus was associated with reactivation of CN, major amputation and ulcer recurrence. Smoking was associated with ulcer development and necessity of amputations.

Conclusions: With consistent conservative treatment of CN with orthopaedic footwear or orthoses, limb preservation can be achieved in 92.9% after a median follow-up of 5.2 years. Patients with diabetic CN are at an increased risk of developing complications and CN reactivation. To prevent ulcers and amputations, every effort should be made to make patients stop smoking.

Level Of Evidence: III, long-term retrospective cohort study.
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http://dx.doi.org/10.1007/s00402-021-03881-5DOI Listing
April 2021

Patellofemoral instability in trochleodysplastic knee joints and the quantitative influence of simulated trochleoplasty - A finite element simulation.

Clin Biomech (Bristol, Avon) 2021 Jan 9;81:105216. Epub 2020 Nov 9.

Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland.

Background: Patellofemoral instability is a debilitating condition mainly affecting young patients and has been correlated with trochlear dysplasia. It can occur when the patella is insufficiently guided through its range of motion. Currently, there is no literature describing patellofemoral stability in trochleodysplastic knees and the effect of isolated trochleoplasty on patellofemoral stability.

Methods: The effect of isolated trochleoplasty in trochleodysplastic knees of patients with symptomatic patellofemoral instability was investigated using a quasi-static finite element model. MRI data of five healthy knees were segmented, meshed and a finite element analysis was performed in order to validate the model. A second validation was performed by comparing simulated patellofemoral kinematics to in-vivo values obtained from upright- weight bearing CT scans. Subsequently, five trochleodysplastic knees were modelled before and after simulated trochleoplasty. The force necessary to dislocate the patella by 10 mm and to fully dislocate the patella was calculated in various knee flexion angles between 0 and 45°.

Findings: The developed models successfully predicted outcome values within the range of reference values from literature. Lateral stability was significantly lower in trochleodysplastic knees compared to healthy knees. Trochleoplasty was determined to significantly increase the force necessary to dislocate the patella in trochleodysplastic knees to comparable values as in healthy knees.

Interpretation: This is the first study to investigate lateral patellofemoral stability in patients with symptomatic patellofemoral instability and dysplasia of the trochlear groove. We confirm that patellofemoral stability is significantly lower in trochleodysplastic knees than in healthy knees. Trochleoplasty increases patellofemoral stability to levels similar to healthy.
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http://dx.doi.org/10.1016/j.clinbiomech.2020.105216DOI Listing
January 2021

The influence of different patient positions on the preoperative 3D planning for surgical resection of soft tissue sarcoma in the lower limb-a cadaver pilot study.

Surg Oncol 2020 Dec 21;35:478-483. Epub 2020 Oct 21.

Department of Orthopedics, Balgrist University Hospital, Investigation Performed at Balgrist University Hospital, Zurich, Switzerland.

Introduction: Complete surgical resection remains the mainstay of the treatment of soft tissue sarcomas. Intraoperative positioning of the patient is dictated by tumor location, whereas preoperative imaging is always performed in the supine position. The effect of changing the patient position on the exact location of the tumor with regard to neurovascular structures and bone is unknown.

Material And Methods: Two fresh frozen cadavers (pelvis and legs) were thawed and warmed. Three standardized tumor models were implanted in the thigh and calf. MR/CT images of the cadavers were obtained sequentially in four different patient positions. The minimal distance of each "tumor" to neurovascular structures was measured on axial MR images and the 3D shift of the center of the tumor to the bone was measured after segmentation of the CT images.

Results: A significant difference of the minimal distance of the "tumor" to the femoral artery (P = 0.019/0.023) and a significantly greater number of deviations of more than 5mm/10 mm in the thigh between the supine position and the other positions compared to two supine positions (p = 0.027/0.028) were seen. The center of the "tumor" compared to the bone shifted significantly in the thigh (P < 0.001/0.002) but not the lower leg.

Conclusion: Obtaining images in the same patient position as the planned tumor resection may become particularly relevant if computer assisted surgery, which is based on preoperative imaging, is introduced into soft tissue sarcoma surgery as the patient position significantly influences the spatial position of the tumor.
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http://dx.doi.org/10.1016/j.suronc.2020.10.008DOI Listing
December 2020

Systematic Biomechanical Analysis of Prerequisites for Reliable Intraoperative Bonding of Polymethylmethacrylate Bone Cement in Preexisting Cement in Revision Arthroplasty.

Orthopedics 2021 Jan 22;44(1):e55-e60. Epub 2020 Oct 22.

Removal of a stable cement mantle may be invasive and time consuming and may result in unnecessary damage to bone and surrounding soft tissue. The goal of this study was to investigate the feasibility of the use of polymethylmethacrylate cement on preexisting cement as well as to explore the prerequisites for practical clinical use under standardized laboratory conditions. The strength of the cement-cement interface was evaluated with a 4-point bending to failure test, according to International Organization for Standardization 5833, as well as standardized shear strength, according to American Society for Testing and Materials D732. Various intraoperative cleaning agents were tested to remove simulated contamination with bone marrow. Contamination of the cement-cement interface with bone marrow decreases bending strength, modulus, and shear strength. Removal of the bone marrow with a degreasing agent significantly increases bending strength as well as bending modulus and can increase shear strength up to 9% compared with use of a nondegreasing agent. The cement-cement interface may reach up to 85% of bending strength, 92% of bending modulus, and comparable shear strength compared with a uniform cement block. Meticulous removal of fatty contaminant is important. Use of a degreasing agent further increases the stability of the cement-cement interface. With these precautions, it is safe to assume that the combined molecular and mechanical interlock is sufficient for most clinical applications and will not represent the weakest link in prosthetic revision. [Orthopedics. 2021;44(1):e55-e60.].
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http://dx.doi.org/10.3928/01477447-20201007-05DOI Listing
January 2021

Midterm Fate of the Contralateral Foot in Charcot Arthropathy.

Foot Ankle Int 2020 Oct 22;41(10):1181-1189. Epub 2020 Jul 22.

Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.

Background: The contralateral foot in Charcot arthropathy or neuroarthropathy (CN) is subject to increased plantar pressure. To date, the clinical consequences of this pressure elevation are yet to be determined. The aim of this study was to evaluate ulcer and amputation rates of the contralateral foot in CN.

Methods: We abstracted the medical records of 130 consecutive subjects with unilateral CN. Rates of contralateral CN development and recurrence, contralateral ulcer development, and contralateral amputations were recorded. Statistical analysis was performed to identify possible risk factors for contralateral CN and ulcer development, and contralateral amputation. Mean follow-up was 6.2 (SD 4) years.

Results: After a mean of 2.5 years, 19.2% patients developed contralateral CN. Female gender was associated with contralateral CN development (odds ratio 3.13, 95% confidence interval 1.27, 7.7). Overall, 46.2% patients developed a contralateral ulcer. Among the patients who developed contralateral CN, 60% developed an ulcer. Sanders type 2 at the index foot (midfoot CN) was significantly associated with contralateral ulcer development. Ulcer-free survival (UFS) differed significantly between patients with diabetes type 1 (median UFS 5131 days) and patients with diabetes type 2 (median UFS 2158 days). A total of 25 amputations had to be performed in 22 (16.9%) patients. Three of those 22 patients (2.3%) needed major amputation.

Conclusion: Almost 20% of patients developed contralateral CN. Nearly half of people with CN developed a contralateral foot ulceration. Patients with type 2 diabetes had significantly shorter UFS than patients with diabetes type 1. Every sixth patient needed an amputation, with the majority being minor amputations. The contralateral foot should be monitored closely and included in the treatment in patients with CN.

Level Of Evidence: Level IV, retrospective study.
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http://dx.doi.org/10.1177/1071100720937654DOI Listing
October 2020

Modifications of the pirogoff amputation technique in adults: A retrospective analysis of 123 cases.

J Orthop 2020 Mar-Apr;18:5-12. Epub 2019 Nov 1.

Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.

Background: The Pirogoff amputation (1854) was initially developed to provide full-weight-bearing stumps and therefore allow a short ambulation without prosthesis. Modifications of the original technique including Boyd (1939) and the "Modified Pirogoff" were developed, which further reduced complications and improved the outcome. However, the current evidence regarding the techniques is scarce. The functional outcome, survivorship and complication rates are unknown. It was the purpose of this study to expand the knowledge with a retrospective case series and ultimately summarize and analyze the data with a systematic review.

Methods: A retrospective study of the Boyd procedures from our institution between 1999 and 2018 was performed. Outcome was determined based on the PLUS-M Score (Prosthetic Limb Users Survey of Mobility). Survivorship (absence of more proximal amputation), postoperative leg-length discrepancy, time to early fusion and time to mobilization were also evaluated. Finally, in the second part of the study, the results were integrated in a systematic review, which followed the Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) guidelines. The quality of all the studies were then assessed using the Joanna Briggs Institute Critical Appraisal Checklist (JBI CAC).

Results: A total of 123 procedures including 115 patients, with an average follow-up of 45 months (range, 10-300 months) could be included. A very good or good function could be achieved in 85 (69%) patients. The mean survivorship was 82.1% (range 46%-100%). In four studies, including our series, all patients remained with a functional stump at the latest follow-up. The calculated average leg-length discrepancy was 2.5 cm.

Conclusion: The "Modified Pirogoff" and Boyd amputation techniques can achieve favourable long-term functional outcome in cases of irreparable foot conditions such as osteomyelitis or trauma. Patency of the posterior tibial artery is an indispensable condition to elect for these surgical techniques. Presence of neuropathy does not preclude this amputation level. With proper patient selection, a maximal survivorship of the stump with treatable minor complications can be achieved.Level of Evidence: IV.
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http://dx.doi.org/10.1016/j.jor.2019.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7067983PMC
November 2019

Reconstruction of lateral pinch in an isolated paralysis of the first dorsal interosseous muscle - A new surgical technique.

Orthop Traumatol Surg Res 2020 04 7;106(2):353-356. Epub 2020 Feb 7.

Department of orthopedics and hand surgery, Saint-Antoine hospital, Paris, France.

Lack of function of the first interosseous muscle (FDI) might be responsible for insufficient stabilisation of the index finger during lateral pinch, and may induce disability in hand function. The first cause of FDI palsy is ulnar nerve palsy. We describe a new tendon transfer to reanimate the FDI muscle, using the extensor indicis proprius tendon. The tendon is sectioned at its distal insertion and rerouted in the first extensor tendon compartment. We report one case of isolated first interosseous muscle palsy secondary to direct trauma. Preoperatively, the patient complained of a severe lack of strength during key pinch with an ulnarly deviated index finger. Thirty months postoperatively, the patient recovered active abduction of the index finger and lateral pinch was measured at 5.5kg (54N). Compared to the original Bunnell transfer our technique restores the native moment arm of the FDI muscle and does not require a tendon graft.
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http://dx.doi.org/10.1016/j.otsr.2019.08.024DOI Listing
April 2020

Antimicrobial Prophylaxis for the Prevention of Surgical Site Infections in Orthopaedic Oncology - A Narrative Review of Current Concepts.

J Bone Jt Infect 2019 15;4(6):254-263. Epub 2019 Oct 15.

Unit of Clinical and Applied Research, Balgrist University Hospital, Zurich, Switzerland.

The incidence of surgical site infections (SSIs) after elective tumour orthopaedic surgery in adults is higher than non-oncologic orthopaedic surgery. Their causative microorganisms and antibiotic susceptibilities are also different from the non-oncologic cases; with no apparent predictable microbiological patterns. Clinicians continue to struggle to tailor the optimal prophylactic regimen for the very heterogeneous group of tumour patients. Many clinicians thus prolong the first-and second-generation cephalosporin agents, while a minority chooses to broaden the antimicrobial spectrum by combination prophylaxis. The variability in current practices and surgical techniques is enormous, even within the same setting. The scientific literature lacks adequate retrospective case-studies and there is currently only one prospective randomized trial. In this narrative review, we discuss various perioperative antibiotic concepts in oncologic orthopaedic surgery, including a summary of the state-to-the-art, opinions and difficulties related to the different prophylactic strategies.
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http://dx.doi.org/10.7150/jbji.39050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960022PMC
October 2019

Outcome of Ray Resection as Definitive Treatment in Forefoot Infection or Ischemia: A Cohort Study.

J Foot Ankle Surg 2020 Jan - Feb;59(1):27-30

Consultant Orthopaedic Surgeon, Orthopedic Department, Balgrist University Hospital, Zurich, Switzerland.

Ray resection is frequently performed in cases of infection or ischemia, but the literature is scarce concerning its outcome as a definitive treatment. In this retrospective cohort study, we reviewed our cohort with transmetatarsal ray resection with a mean follow-up of 36.3 months. Reulcerations, transfer ulcers, and reamputations were determined. Risk factor analysis for revision surgery was conducted. Among 185 patients, 71 (38.4%) had revision surgery within a mean of 1.4 ± 2.6 years (range 2 days to 12.9 years), 22 (11.9%) had major amputations, 49 (26.5%) had minor amputations, 11 (5.9%) had same-ray reulceration, 40 (21.6%) had transfer ulceration, and 2 (1.1%) had both reulceration and transfer ulceration. Occurrence of a postoperative ulcer was statistically significantly associated with revision surgery (p < .01). In conclusion, metatarsal ray resection is a reasonable treatment option in cases of forefoot ischemia or infection to prevent major amputation but fails in 11.9%, and reulceration is associated with further revisions, making ulcer prevention paramount.
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http://dx.doi.org/10.1053/j.jfas.2019.06.003DOI Listing
July 2020

Influence of Sampling Site and other Environmental Factors on the Bacterial Community Composition of Domestic Washing Machines.

Microorganisms 2019 Dec 22;8(1). Epub 2019 Dec 22.

Faculty of Medical and Life Sciences, Institute of Precision Medicine, Microbiology and Hygiene Group, Furtwangen University, 78054 Villingen-Schwenningen, Germany.

Modern, mainly sustainability-driven trends, such as low-temperature washing or bleach-free liquid detergents, facilitate microbial survival of the laundry processes. Favourable growth conditions like humidity, warmth and sufficient nutrients also contribute to microbial colonization of washing machines. Such colonization might lead to negatively perceived staining, corrosion of washing machine parts and surfaces, as well as machine and laundry malodour. In this study, we characterized the bacterial community of 13 domestic washing machines at four different sampling sites (detergent drawer, door seal, sump and fibres collected from the washing solution) using 16S rRNA gene pyrosequencing and statistically analysed associations with environmental and user-dependent factors. Across 50 investigated samples, the bacterial community turned out to be significantly site-dependent with the highest alpha diversity found inside the detergent drawer, followed by sump, textile fibres isolated from the washing solution, and door seal. Surprisingly, out of all other investigated factors only the monthly number of wash cycles at temperatures ≥ 60 °C showed a significant influence on the community structure. A higher number of hot wash cycles per month increased microbial diversity, especially inside the detergent drawer. Potential reasons and the hygienic relevance of this finding need to be assessed in future studies.
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http://dx.doi.org/10.3390/microorganisms8010030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7022543PMC
December 2019

Revision After Total Transmetatarsal Amputation.

J Foot Ankle Surg 2019 Nov;58(6):1171-1176

Surgeon, Orthopedic Department, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.

Total transmetatarsal amputation (TMA) can be an option for foot salvage in gangrene, sepsis, or infected necrosis. However, the literature concerning predictive outcome factors and bacterial sampling is scarce. To identify potential associations between revision surgery and underlying bacteria or other preoperative selection criteria, we reviewed all patients with TMA who were treated at our institution. We compared the patients with remissions with surgical revisions. Among 96 adult patients with TMA (105 amputations), 42 required a revision surgery (40%), 18 had a further minor proximal surgical reamputation (17%) and 18 had a major proximal surgical reamputation (14%). In group comparisons, a previous infection with Staphylococcus aureus was protective with a lower revision risk (4/26 with revision surgery vs 22/26 without revisions; p = .03). This was the opposite for postoperative persistent soft tissue or bone infections (p < .01) and delayed wound healing (p < .01), which were positively associated with a revision risk. The American Society of Anesthesiologists Score, sex, age, body mass index, diabetes, polyneuropathy, chronic renal failure, dialysis, peripheral arterial disease, smoking status, and antibiotic regimen did not influence this revision risk. These results must be interpreted cautiously because no multiple variable calculations could be conducted as a result of the paucity of cases and confounding could not be evaluated sufficiently. TMA is an option to prevent major amputations, but it may be associated with a subsequent revision risk of 40% in adult patients. In our cohort study, persistent postamputation infection and delayed wound healing were associated with revision. However, no preoperative selection criteria were found that lead to revision surgery except for an infection with Staphylococcus aureus, which protected against revision surgery.
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http://dx.doi.org/10.1053/j.jfas.2019.03.015DOI Listing
November 2019

Influence of the site of acromioplasty on reduction of the critical shoulder angle (CSA) - an anatomical study.

BMC Musculoskelet Disord 2018 Oct 13;19(1):371. Epub 2018 Oct 13.

Department of Orthopaedics, University of Zurich, Balgrist University Hospital, Uniklinik Balgrist, Forchstrasse 340, 8008, Zürich, Switzerland.

Background: A large critical shoulder angle (CSA) >35° is associated with the development of rotator cuff tearing. Lateral acromioplasty (AP) has the theoretical potential to prevent rotator cuff tearing and/ or to reduce the risk of re-tears after repair. It is, however unclear which part of the lateral acromion has to be reduced to obtain the desired CSA. It was the purpose of this study to determine which part of the lateral acromion has to be resected to achieve a desired reduction of the CSA in a given individual.

Methods: First, the influence of the exact radiographic projection on the CSA was examined. Second, the influence of anterolateral versus strict lateral AP on the CSA was studied in eight scapulae with different anatomic characteristics. Differences in CSA reduction were investigated using paired t-test or Wilcoxon test.

Results: Scapular rotation in the sagittal and axial plane had a marked influence on the radiologically measured CSA ranging from -6 to +16°. Overall, lateral AP of 5/10mm reduced the CSA significantly greater than anterolateral AP of 5mm/10mm [5mm: 2.3° (range: 0.7°-3.6°) SD±0.8° vs. 1.2° (range: 0°-3.3°) SD±1.1°, p=0.0002]/[10mm: 4.8° (range: 2.1°-7°) SD±1.3° vs. 2.7° (range: 0°-5.3°) SD±1.7°, p=0.0001]. Depending on scapular anatomy anterolateral AP did not alter CSA at all.

Conclusions: For comparison of pre- and postoperative CSA, the exact orientation of the X-ray and the spatial orientation of the scapula must be as identical as possible. Anterolateral AP may not sufficiently correct CSA in scapulae with great acromial slopes and smaller relative external rotation of the acromion as the critical acromial point (CAP) may be located too posteriorly and thus is not addressed by anterolateral acromioplasty. Consistent reduction of the CSA could be achieved by lateral AP in all eight scapulae.
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http://dx.doi.org/10.1186/s12891-018-2294-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6186126PMC
October 2018

Microbiome analysis and confocal microscopy of used kitchen sponges reveal massive colonization by Acinetobacter, Moraxella and Chryseobacterium species.

Sci Rep 2017 07 19;7(1):5791. Epub 2017 Jul 19.

Faculty of Medical and Life Sciences, Institute of Precision Medicine (IPM), Microbiology and Hygiene Group, Furtwangen University, Villingen-Schwenningen, Germany.

The built environment (BE) and in particular kitchen environments harbor a remarkable microbial diversity, including pathogens. We analyzed the bacterial microbiome of used kitchen sponges by 454-pyrosequencing of 16S rRNA genes and fluorescence in situ hybridization coupled with confocal laser scanning microscopy (FISH-CLSM). Pyrosequencing showed a relative dominance of Gammaproteobacteria within the sponge microbiota. Five of the ten most abundant OTUs were closely related to risk group 2 (RG2) species, previously detected in the BE and kitchen microbiome. Regular cleaning of sponges, indicated by their users, significantly affected the microbiome structure. Two of the ten dominant OTUs, closely related to the RG2-species Chryseobacterium hominis and Moraxella osloensis, showed significantly greater proportions in regularly sanitized sponges, thereby questioning such sanitation methods in a long term perspective. FISH-CLSM showed an ubiquitous distribution of bacteria within the sponge tissue, concentrating in internal cavities and on sponge surfaces, where biofilm-like structures occurred. Image analysis showed local densities of up to 5.4 * 10 cells per cm, and confirmed the dominance of Gammaproteobacteria. Our study stresses and visualizes the role of kitchen sponges as microbiological hot spots in the BE, with the capability to collect and spread bacteria with a probable pathogenic potential.
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http://dx.doi.org/10.1038/s41598-017-06055-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5517580PMC
July 2017

A pedicle screw system and a lamina hook system provide similar primary and long-term stability: a biomechanical in vitro study with quasi-static and dynamic loading conditions.

Eur Spine J 2016 09 12;25(9):2919-28. Epub 2016 Jul 12.

Orthopädische Universitätsklinik Friedrichsheim gGmbH, Marienburgstraße 2, 60528, Frankfurt am Main, Germany.

Purpose: For the stabilization of the thoracolumbar spine area, various stabilization techniques have been developed in recent decades. The aim of these techniques is to immobilize the treated segment to repositioning or correct the spine and guaranty long-term stability to achieve a reliable fusion. The aim of this study was to simulate in an in vitro experiment the postoperative long-term situation in elderly osteoporotic patients to compare two different stabilization principles; a pedicle screw system and a lamina hook system.

Methods: Two comparable groups with respect to age and bone mineral density with each n = 6 fresh-frozen human, bi-segmental thoracolumbar spine specimens (T11-L1) were used. Antero-posterior and lateral radiographs were taken before the test, to assess the spinal status. Then the intact specimens were biomechanically characterized with pure moments in the three anatomical planes in different states in terms of range of motion and neutral zone. After implantation of either, a pedicle screw system or a lamina hook system, the primary stability was determined under the same conditions. Subsequently the specimens were cyclically loaded under complex loading, using a custom-made set-up in a dynamic materials testing machine with increasing moments from 3 to 66 Nm until 100,000 cycles or until one of the three defined "failure" criteria was reached. (1) A failure of a bony structure. (2) Exceeding of the threefold ROM of the primary stability after implantation in flexion plus extension. (3) Reaching of the ROM based on the intact state before implantation both in flexion plus extension.

Results: The results showed that the ROM was strongly reduced after instrumentation similar for both implant systems in all motion planes. The highest stabilization was found in flexion/extension. During cyclic loading with increasing moments, the ROM increased continuously for both systems. The number of load cycles until one of the failure criteria was reached varied only slightly between the two groups. In the pedicle screw group 30,000 (median) loading cycles (range 5000-80,000) with a corresponding moment of 24 Nm (range 9-54) could be reached. In the lamina hook group 32,500 load cycles (range 20,000-45,000) could be achieved with a corresponding moment of 25.5 Nm (range 18-33). There was a slight trend that the pedicle screw system is influenced more by bone mineral density.

Conclusion: Both implant systems provide similar primary stability and similar long-term stability. In the pedicle screw group, there was a stronger correlation between bone mineral density and the reached number of load cycles.
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http://dx.doi.org/10.1007/s00586-016-4679-xDOI Listing
September 2016

Double mobility cup total hip arthroplasty in patients at high risk for dislocation: a single-center analysis.

Arch Orthop Trauma Surg 2015 Dec 29;135(12):1755-62. Epub 2015 Sep 29.

Uniklinik Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland.

Introduction: Double mobility cup systems (DMCS) have gained increasing acceptance, especially in patients at high risk for dislocation. The aim of this investigation was to analyze the frequency and indications of the DMCS use in our praxis and to evaluate dislocation and cup revision rates after a minimum follow-up of 2 years.

Materials And Methods: All patients implanted with a DMCS from May 2008 to August 2011 were identified from our institutional database of primary and revision THA procedures. Patient demographics, including ASA score, were recorded, along with details of the surgical procedures, indications for DMCS use, and post-operative clinical course and any complications. Radiographs were analyzed for implant positioning and radiological signs of loosening.

Results: 1046 primary THA were implanted, of these 39 (4 %) primary DMCS. Indications were severe neuromuscular disease (SND) (14), hip abductor degeneration (HAD) (9), cognitive dysfunction (CD) (8) and others. 345 revision THA were performed, of these 50 (14 %) revision DMCS. Indications were recurrent dislocations (27), multiple prior hip surgeries (13), HAD (5), CD (3) and others. Overall dislocation rate was 2/89 (2 %); both in revision THA. Overall cup revision rate was 5/89 (6 %): 3 septic, 1 periprosthetic acetabular fracture, 1 "intraprosthetic dissociation". 67 patients were available for the standardized questionnaire at a median follow-up of 43 months (range 25-78). 19 patients were not available for two-year follow-up: 17 died and two were lost to follow-up.

Conclusions: This study supports the use of DMCS constructs in primary and revision hip arthroplasty for specific high-risk patients. We continue to indicate DMCS in this patient group. We do caution against extending indications for DMCS to lower risk patient groups due to unknown issues surrounding wear and component longevity.
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http://dx.doi.org/10.1007/s00402-015-2316-5DOI Listing
December 2015

Alginate dressing and polyurethane film versus paraffin gauze in the treatment of split-thickness skin graft donor sites: a randomized controlled pilot study.

Adv Skin Wound Care 2013 Feb;26(2):67-73

Hospital Schaffhausen, Schaffhausen, Switzerland.

Objectives: To compare postoperative healing of split-thickness skin graft (STSG) donor sites using traditional dressings (paraffin gauze) or modern wound dressings (alginate dressing and polyurethane film) in a randomized controlled trial.

Method: Thirty patients were randomly assigned to treatment of an STSG donor site with an alginate dressing and a polyurethane film or nonadherent paraffin gauze. Outcome variables were pain (measured with a visual analog scale), amount of dressing changes, healing time, cosmetic outcome, treatment costs, and overall satisfaction with the procedure.

Results: There was no significant difference in pain (postoperative day 1: 2.1 vs 1.2, P = .26; postoperative days 5-7: 1.0 vs 0.9, P = .47; final removal: 1.9 vs 1.0, P = .19) and time to healing (18.1 vs 15.4 days, P = .29) between alginate/polyurethane film dressing and nonadherent paraffin gauze. The semiocclusive dressings with polyurethane film required multiple dressing changes, whereas the nonadherent paraffin gauze could be left in place until complete epithelialization. Treatment costs were substantially lower for paraffin gauze.

Conclusions: Semiocclusive dressings with alginate dressings and polyurethane film showed no advantages over treatment with paraffin gauze. With lower costs and better patient acceptance, paraffin gauze dressings were the preferred treatment for STSG donor sites.
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http://dx.doi.org/10.1097/01.ASW.0000426715.57540.8dDOI Listing
February 2013

Self-organizing maps for identification of new inhibitors of P-glycoprotein.

J Med Chem 2007 Apr 13;50(7):1698-702. Epub 2007 Mar 13.

Emerging Focus Pharmacoinformatics, Department of Medicinal Chemistry, University of Vienna, Althanstrasse 14, 1090 Wien, Austria.

Self-organizing maps were trained to separate high- and low-active propafenone-type inhibitors of P-glycoprotein. The trained maps were subsequently used to identify highly active compounds in a virtual screen of the SPECS compound library.
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http://dx.doi.org/10.1021/jm060604zDOI Listing
April 2007

Similarity-based descriptors (SIBAR)--a tool for safe exchange of chemical information?

J Comput Aided Mol Des 2005 Sep-Oct;19(9-10):687-92. Epub 2005 Oct 26.

Department of Medicinal/Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, 1090 Wien, Austria.

Exchange of chemical information without disclosure of the respective structures would greatly increase the data sets available for model building. Within the framework of the ChemMask project we explored the principal applicability of SIBAR-descriptors to mask chemical structures. SIBAR is based on calculation of similarity values for each compound of the training set to a set of reference compounds. Although the SIBAR-approach per se does not allow to unambiguously trace back the chemical structure of a compound, similarity searching in a 1.5 million compound database spiked with compounds structurally analogous to the query structure lead to the retrieval of compounds structurally and pharmacologically highly analogous to the "hidden" query structure in all three examples investigated. Comparison to results obtained with the original descriptors used to calculate the SIBAR-values showed, that SIBAR indeed adds some fuzziness to the data matrix.
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http://dx.doi.org/10.1007/s10822-005-9000-8DOI Listing
May 2006

Targeting drug-efflux pumps -- a pharmacoinformatic approach.

Acta Biochim Pol 2005 4;52(3):737-40. Epub 2005 Aug 4.

Emerging Focus Pharmacoinformatics, Department of Medicinal Chemistry, University of Vienna, Wien, Austria.

In line with our studies on propafenone-type inhibitors of P-glycoprotein (P-gp), we applied several methods to approach virtual screening tools for identification of new P-gp inhibitors on one hand and the molecular basis of ligand-protein interaction on the other hand. For virtual screening, a combination of autocorrelation vectors and selforganising artificial neural networks proved extremely valuable in identifying P-gp inhibitors with structurally new scaffolds. For a closer view on the binding region for propafenone-type ligands we applied a combination of pharmacophore-driven photoaffinity labeling and protein homology modeling. On LmrA, a bacterial homologue of P-gp, we were able to identify distinct regions on transmembrane helices 3, 5 and 6 which show significant changes in the labeling pattern during different steps of the catalytic cycle.
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May 2006

A three-dimensional model for the substrate binding domain of the multidrug ATP binding cassette transporter LmrA.

Mol Pharmacol 2004 Nov 10;66(5):1169-79. Epub 2004 Aug 10.

Institute of Medical Chemistry, Medical University of Vienna, Waehringerstrasse 10, A-1090 Vienna, Austria.

Multidrug resistance presents a major obstacle to the treatment of infectious diseases and cancer. LmrA, a bacterial ATP-dependent multidrug transporter, mediates efflux of hydrophobic cationic substrates, including antibiotics. The substrate-binding domain of LmrA was identified by using photo-affinity ligands, proteolytic degradation of LmrA, and identification of ligand-modified peptide fragments with matrix-assisted laser desorption ionization/time of flight mass spectrometry. In the nonenergized state, labeling occurred in the alpha-helical transmembrane segments (TM) 3, 5 and 6 of the membrane-spanning domain. Upon nucleotide binding, the accessibility of TM5 for substrates increased, whereas that of TM6 decreased. Inverse changes were observed upon ATP-hydrolysis. An atomic-detail model of dimeric LmrA was generated based on the template structure of the homologous transporter MsbA from Vibrio cholerae, allowing a three-dimensional visualization of the substrate-binding domain. Labeling of TM3 of one monomer occurred in a predicted area of contact with TM5 or TM6 of the opposite monomer, indicating substrate-binding at the monomer/monomer interface. Inverse changes in the reactivity of TM segments 5 and 6 suggest that substrate binding and release involves a repositioning of these helices during the catalytic cycle.
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http://dx.doi.org/10.1124/mol.104.001420DOI Listing
November 2004

Topological distance based 3D descriptors for use in QSAR and diversity analysis.

J Chem Inf Comput Sci 2004 Jan-Feb;44(1):200-9

Institute of Pharmaceutical Chemistry, University of Vienna, Universitätszentrum II, Althanstrasse 14, A-1090 Wien, Austria.

In topological autocorrelation approaches molecular descriptors are calculated by summing up properties located at given topological distances. Since the relationship between topological and Euclidean distance contains 3D structural information, in the present paper a modified version of an autocorrelation approach is proposed to include this type of information. Steric, electronic, and indicator-variable-type descriptors are calculated and used in QSAR studies with three different data sets. The results demonstrate that the descriptors can be efficiently used in cluster- and QSAR analysis. The models obtained are highly predictive and comparable to those obtained by other commonly used 3D-QSAR methods.
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http://dx.doi.org/10.1021/ci0256236DOI Listing
March 2004

Similarity based SAR (SIBAR) as tool for early ADME profiling.

J Comput Aided Mol Des 2002 Nov;16(11):785-93

Institute of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Wien, Austria.

Estimation of bioavailability and toxicity at the very beginning of the drug development process is one of the big challenges in drug discovery. Most of the processes involved in ADME are driven by rather unspecific interactions between drugs and biological macromolecules. Within the past decade, drug transport pumps such as P-glycoprotein (Pgp) have gained increasing interest in the early ADME profiling process. Due to the high structural diversity of ligands of Pgp, traditional QSAR methods were only successful within analogous series of compounds. We used an approach based on similarity calculations to predict Pgp-inhibitory activity of a series of propafenone analogues. This SIBAR approach is based on selection of a highly diverse reference compound set and calculation of similarity values to these reference compounds. The similarity values (denoted as SIBAR descriptors) are then used for PLS analysis. Our results show, that for a set of 131 propafenone type compounds, models with good predictivity were obtained both in cross validation procedures and with a 31-compound external test set. Thus, these new descriptors might be a versatile tool for generation of predictive ADME models.
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http://dx.doi.org/10.1023/a:1023828527638DOI Listing
November 2002