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Knahr K.,Orthopaedic Hospital Vienna Speising
Total Hip Arthroplasty: Wear Behaviour of Different Articulations | Year: 2013

During the 2011 EFORT Congress in Copenhagen, many interesting topics relating to tribology in total hip arthroplasty were discussed during a special day devoted entirely to the subject. EFORT decided that, given the wide interest in these discussions, publication of the presentations would be warmly welcomed by all fellow professionals who were unable to attend. This book is the result. It provides detailed information on currently used articulating materials and their wear performance. Clinical outcomes are discussed, and important new frontiers are carefully considered. The book will be of interest both to novices who want to learn more about the field and to experienced orthopaedic surgeons wishing to keep abreast of the latest developments. © 2012 EFORT. All rights are reserved.

Knahr K.,Orthopaedic Hospital Vienna Speising
Tribology in Total Hip and Knee Arthroplasty: Potential Drawbacks and Benefits of Commonly Used Materials | Year: 2014

Wear and osteolysis are still the most important potential problems in total hip and knee arthroplasty. Although technology in arthroplasty has been improved dramatically during the past decade, the clinical data relating to some implants reveal that many concerns remain. During the "Tribology Day" within the scientific programme of the 2013 EFORT Congress in Istanbul, the main topics included these concerns as well as the benefits of the materials most commonly used in total hip and knee arthroplasty. This book includes the presentations delivered on the day and covers a range of interesting issues regarding metal, ceramic, and polyethylene articulations. It provides information on the current concepts relating to tribology in total hip arthroplasty and offers a critical outlook on possible improvements in total knee arthroplasty. © 2014 EFORT. All rights reserved.

Hannemann F.,University Hospital Carl Gustav Carus Dresden | Hannemann F.,Center for Evidence Based Health Care | Hartmann A.,University Hospital Carl Gustav Carus Dresden | Schmitt J.,Center for Evidence Based Health Care | And 19 more authors.
Orthopaedics and Traumatology: Surgery and Research | Year: 2013

Introduction: There is an ongoing debate about the optimal use of metal-on-metal (MoM) bearings in total hip replacement, since there are uncertainties about local and systemic adverse effects due to wear and corrosion of these bearings. Despite various national recommendations, efforts to achieve international harmonization of specific evidence-based recommendations for best practice are still lacking. Hypothesis: An international consensus study group should be able to develop recommendations on the use and monitoring of MoM bearings, preferably at the European level, through a multidisciplinary approach, by integrating the perspectives of various stakeholders. Materials and methods: Twenty-one experts representing three stakeholder groups and eight countries participated in this European consensus study, which consisted of a consensus meeting, subsequent structured discussion, and consensus voting. Results: The current statement defines first of all benefits, local and systemic risks, as well as uncertain issues related to MoM bearings. Safety assessment after implantation of MoM comprises all patients. A closer follow-up is recommended for large head MoM (≥36mm) and resurfacing. In these implants basic follow-up should consist of x-rays and metal ion measurement of cobalt in whole blood, performed with GF-AAS or ICP-MS. Clinical and/or radiographic abnormality as well as elevated ion levels needs additional imaging (ultrasound, CT-scan and/or MARS-MRI). Cobalt values less than 2. μg/L are probably devoid of clinical concern, the threshold value for clinical concern is expected to be within the range of 2-7. μg/L. Discussion: This is the first multinational, interdisciplinary, and multiprofessional approach for developing a recommendation for the use and monitoring of MoM bearings in total hip replacement. The current recommendations are in partial agreement with previous statements regarding the extent of follow-up and imaging techniques. They however differ from previous communications regarding measurement of metal ions and especially the investigated medium, technique, and eventual threshold levels. Level of evidence: Level V, expert opinion/agreement conference. © 2013 Elsevier Masson SAS.

Jacobs W.C.H.,Leiden University | Van Der Gaag N.A.,Leiden University | Kruyt M.C.,University Utrecht | Tuschel A.,Orthopaedic Hospital Vienna Speising | And 5 more authors.
Spine | Year: 2013

STUDY DESIGN.: Systematic literature review. OBJECTIVE.: To assess the effect of total disc replacement for chronic low back pain due to lumbar degenerative disc disease compared with fusion or other treatment options. SUMMARY OF BACKGROUND DATA.: There is an increasing use in disc replacement devices for degenerative disc disease, but their effectiveness compared with other interventions such as fusion of the motion segment or conservative treatment remains unclear. METHODS.: A comprehensive search in PubMedCentral, MEDLINE, EMBASE, BIOSIS, ClinicalTrials.gov, and FDA trials register was conducted. Randomized controlled trials comparing total disc replacement with any other intervention for degenerative disc disease were included. Risk of bias was assessed using the criteria of the Cochrane Back Review Group. Quality of evidence was graded according to the GRADE approach. Two review authors independently selected studies, assessed risk of bias, and extracted data. Results and upper bounds of confidence intervals were compared with predefined clinically relevant differences. RESULTS.: We included 7 randomized controlled trials with a follow-up of 24 months. There is risk of bias in the included studies due to sponsoring and absence of any kind of blinding. One study compared disc replacement with rehabilitation and found a significant advantage in favor of surgery, which, however, did not reach the predefined threshold. Six studies compared disc replacement with fusion and found that the mean improvement in visual analogue scale score of back pain was 5.2 mm higher (2 studies; 95% confidence interval 0.2-10.3) with a low quality of evidence. The improvement of Oswestry disability index score at 24 months in the disc replacement group was 4.3 points more than in the fusion group (5 studies; 95% confidence interval 1.85-6.68) with a low quality of evidence. Both upper bounds of the confidence intervals were below the predefined clinically relevant difference. CONCLUSION.: Although statistically significant, the differences in clinical improvement were not beyond generally accepted boundaries for clinical relevance. Prevention of adjacent level disease and/or facet joint degeneration was not properly assessed. Therefore, because we think that harm and complications may occur after some years, the spine surgery community should be prudent to adopt this technology on a large scale, despite the fact that total disc replacement seems to be effective in treating low back pain in selected patients, and in the short term is at least equivalent to fusion surgery. © 2012, Lippincott Williams &Wilkins.

Wengert G.J.,Medical University of Vienna | Bartl R.,Orthopaedic Hospital Vienna Speising | Schueller-Weidekamm C.,Medical University of Vienna | Gabriel A.,Harlem Hospital Center New York | And 3 more authors.
Materiale Plastice | Year: 2014

The aim of this study was to evaluate the topography of the main neurovascular bundle located in the posterior aspect of the shoulder and to establish a relatively safe area for a low-risk arthroscopic approach through a posterior portal. A slice anatomy study, using plastinated transparent shoulder joint sections, was performed on ten non-degenerative right shoulder body specimens. Measurements were performed at the level of the suprascapular notch, the coracoid process, and the acromion. The suprascapular nerve was 38.2 ± 0.1 mm, the suprascapular artery 39.4 ± 0.2 mm, and the circumflex scapular artery was 24.8 ± 0.5 mm away from the posterior rim of the acromion at the level of the suprascapular notch. At the level of the coracoid process the suprascapular artery was 34.2 ± 0.5 mm, and the circumflex scapular artery was 50.9 ± 0.3 mm away from the posterior rim of the acromion. Combined measurements of both arteries offered an average distance of 19.8 ± 0.3 mm. The mean distance to the posterior circumflex humeral artery and the axillary nerve was 47.7 ± 1.5 mm and 50.9 ± 0.9 mm, respectively. The present study suggests that, a posterior arthroscopic approach at a level of 4.5 to 5 cm below the posterior rim of the acromion and above the midline of the glenoid joint space poses a low risk for injuries to the neurovascular structures.

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