The Bone-Biomaterial Interface for Load-Bearing Implants

MRS Bulletin ◽  
1991 ◽  
Vol 16 (9) ◽  
pp. 55-61 ◽  
Author(s):  
R.M. Pilliar ◽  
J.E. Davies ◽  
D.C. Smith
Keyword(s):  
Fibrous Tissue ◽  
Orthopedic Implants ◽  
Minimal Risk ◽  
Implant Fixation ◽  
Load Bearing ◽  
Joint Replacements ◽  
Surgical Implants ◽  
Equal Importance ◽  
Order Of Magnitude

Bone-interfacing surgical implants used in orthopedics and dentistry must bear the forces of normal patient activity with minimal risk of mechanical failure of the implant. This requires using appropriate materials and designs for implant fabrication. Additionally, reliable long-term implant attachment to host bone must be assured so that effective force transfer between implant and bone occurs for the patient's lifetime without the implant loosening. With recent advances in implant designs and techniques for their placement, effective implant fixation to bone can last for years (decades) either directly or through an acceptable intermediate fibrous tissue layer at the bone-implant interface. With approximately 500,000 artificial hips implanted annually worldwide and the demand for other joint replacements approaching the same order of magnitude, as well as the recent major growth in the use of dental implants (300,300 projected for insertion in North America alone in 1991), the assurance of effective implant-to-bone fixation is extremely important.Studies of implant biocompatibility have resulted from concerns over the cumulative effects of foreign element release through implant corrosion and wear. Accumulation of this debris in tissues both local and remote to implant sites over the long term is a concern. Of equal importance, for load-bearing implants, are studies to determine the important factors for successful long-term implant fixation. Current trends in design and use of both dental and orthopedic implants reflect the trial-and-error approach that has characterized this field for decades.

Osseointegration of Ti–6Al–4V Alloy Implants with a Titanium Nitride Coating Produced by a PIRAC Nitriding Technique: A Long-Term Time Course Study in the Rat

2014 ◽  
Vol 21 (1) ◽  
pp. 179-189 ◽  
Author(s):  
Guy Sovak ◽  
Irena Gotman ◽  
Anna Weiss
Keyword(s):  
Time Course ◽  
Close Contact ◽  
Orthopedic Implants ◽  
Compact Bone ◽  
Implant Fixation ◽  
Marrow Cavity ◽  
Distal Epiphysis ◽  
Time Course Study ◽  
Bone Trabeculae

AbstractThis study examined bone tissue responses to Ti–6Al–4V alloy implants with a hard TiN coating applied by an original powder immersion reaction-assisted coating (PIRAC) nitriding method. Progression of implant fixation in the distal epiphysis and within the medullary cavity of the rat femur was evaluated between 3 days and 6 months postimplantation by scanning electron microscopy, oxytetracycline incorporation, and histochemistry. After 6 months, successful osseointegration was achieved in both epiphyseal and diaphyseal sites. Throughout, implant portions located within the epiphysis remained in close contact with bone trabeculae that gradually engulfed the implant forming a bone collar continuous with the trabecular network of the epiphysis. In the diaphysis, woven bone was first formed within the marrow cavity around the implant and later was replaced by a shell of compact bone around the implant. In general, higher osseointegration rates were measured for TiN-coated versus the uncoated implants, both in the epiphysis and in the diaphysis. In conclusion, our findings indicate an excellent long-term biocompatibility of TiN coatings applied by the PIRAC nitriding technique and superior osteoinductive ability in comparison with uncoated Ti–6Al–4V alloy. Such coatings can, therefore, be considered for improving the corrosion and wear resistance of titanium-based orthopedic implants.

Effect of long-term loading on timber load-bearing elements

2015 ◽  
Vol 10 (2) ◽  
pp. 25-34
Author(s):  
Kristian Sogel
Keyword(s):  
Load Bearing

RESULTS OF SURGICAL TREATMENT OF PATIENTS WITH CHRONIC PANCREATITIS AND THE RISK OF CANCER AFTER SURGICAL TREATMENT

2018 ◽  
Vol 64 (2) ◽  
pp. 228-233
Author(s):  
Vladimir Lubyanskiy ◽  
Vasiliy Seroshtanov ◽  
Ye. Semenova
Keyword(s):  
Pancreatic Cancer ◽  
Chronic Pancreatitis ◽  
Surgical Treatment ◽  
Fibrous Tissue ◽  
Pancreatic Head ◽  
Head Region ◽  
Intestinal Anastomoses ◽  
Resection Of The Pancreas ◽  
Risk Of Cancer

The aim: To analyze results of surgical treatment of patients with chronic pancreatitis (CP) and to assess the causes of pancreatic cancer after surgical treatment. Materials and methods: 137 patients had duodenum-preserving resections of the pancreas. Results: In the histological examination of the pancreas it was established that the growth of fibrous tissue was registered in patients with CP., which in 19 (13.8%) almost completely replaced the acinar tissue. In the long term after the operation from 6 months to 2 years in 8 patients (5.8%) pancreatic cancer was detected. Possible causes of tumor origin were analyzed, the value of preservation of ductal hypertension, which affects the state of the duct’s epithelium, was established. The most commonly used for treatment of chronic pancreatitis the Frey surgery removed pancreatic hypertension but in two patients during the operation an insufficient volume of the pancreatic head was reconstructed. In the case of the abandonment of a large array of fibrous tissue, local hypertension was retained in the region of the ductal structures of the head, which led to the transformation of the duct epithelium. An essential factor in the problem of the preservation of pancreatic hypertension were the stenosis of pancreatic intestinal anastomoses, they arose in the long term in 4 operated patients. With stenosis of anastomosis after duodenum-preserving resection both the hypertension factor and the regeneration factor could be realized, which under certain circumstances might be significant. Conclusion: After resection of the pancreas for CP cancer was diagnosed in 5.8% of patients. The main method of preventing the risk of cancer was performing the Frey surgery for CP eliminating pancreatic hypertension in the head region of the pancreas. Diagnosis of stenosis in the late period after resection of the pancreas was an important element in the prevention of recurrence of cancer since a timely reconstructive operation could improve the drainage of duct structures.

Physiological Pacing: A New Road to Future

2021 ◽  
pp. 263246362097804
Author(s):  
Vanita Arora ◽  
Pawan Suri
Keyword(s):  
Side Effects ◽  
Fibrous Tissue ◽  
Cardiac Pacing ◽  
His Bundle ◽  
Anatomy And Physiology ◽  
Long Term Follow Up ◽  
Pacing Lead ◽  
The Right

Anatomy and physiology are the basis of human body functioning and as we have progressed in management of various diseases, we have understood that physiological intervention is always better than an anatomical one. For more than 50 years, a standard approach to permanent cardiac pacing has been an anatomical placement of transvenous pacing lead at the right ventricular apex with a proven benefit of restoring the rhythm. However, the resultant ventricular dyssynchrony on the long-term follow-up in patients requiring more than 40% ventricular pacing led to untoward side effects in the form of heart failure and arrhythmias. To counter such adverse side effects, a need for physiological cardiac pacing wherein the electrical impulse be transmitted directly through the normal conduction system was sought. His bundle pacing (HBP) with an intriguing alternative of left bundle branch pacing (LBBP) is aimed at restoring such physiological activation of ventricles. HBP is safe, efficacious, and feasible; however, localization and placement of a pacing lead at the His bundle is challenging with existing transvenous systems due to its small anatomic size, surrounding fibrous tissue, long-learning curve, and the concern remains about lead dislodgement and progressive electrical block distal to the HBP lead. In this article, we aim to take the reader through the challenging journey of HBP with focus upon the hardware and technique, selective versus nonselective HBP, indications and potential disadvantages, and finally the future prospects.

scholarly journals Statistically rigorous calculations do not support common input and long-term synchronization of motor-unit firings

2014 ◽  
Vol 112 (11) ◽  
pp. 2729-2744 ◽  
Author(s):  
Carlo J. De Luca ◽  
Joshua C. Kline
Keyword(s):  
Motor Unit ◽  
Statistical Tests ◽  
Vastus Lateralis ◽  
Common Input ◽  
Data Set ◽  
Order Of Magnitude ◽  
Score Method ◽  
Surface Electromyographic Signal ◽  
Measure Synchronization

Over the past four decades, various methods have been implemented to measure synchronization of motor-unit firings. In this work, we provide evidence that prior reports of the existence of universal common inputs to all motoneurons and the presence of long-term synchronization are misleading, because they did not use sufficiently rigorous statistical tests to detect synchronization. We developed a statistically based method (SigMax) for computing synchronization and tested it with data from 17,736 motor-unit pairs containing 1,035,225 firing instances from the first dorsal interosseous and vastus lateralis muscles—a data set one order of magnitude greater than that reported in previous studies. Only firing data, obtained from surface electromyographic signal decomposition with >95% accuracy, were used in the study. The data were not subjectively selected in any manner. Because of the size of our data set and the statistical rigor inherent to SigMax, we have confidence that the synchronization values that we calculated provide an improved estimate of physiologically driven synchronization. Compared with three other commonly used techniques, ours revealed three types of discrepancies that result from failing to use sufficient statistical tests necessary to detect synchronization. 1) On average, the z-score method falsely detected synchronization at 16 separate latencies in each motor-unit pair. 2) The cumulative sum method missed one out of every four synchronization identifications found by SigMax. 3) The common input assumption method identified synchronization from 100% of motor-unit pairs studied. SigMax revealed that only 50% of motor-unit pairs actually manifested synchronization.

Use of small cannulated screws for fixation in foot surgery

2000 ◽  
Vol 90 (5) ◽  
pp. 240-246 ◽  
Author(s):  
AE Burns
Keyword(s):  
Effective Means ◽  
Bone Screws ◽  
Cannulated Screws ◽  
Implant Fixation ◽  
Foot Surgery ◽  
Fixation Failure ◽  
Untoward Event ◽  
Patient Noncompliance

Use of cannulated bone screws, as compared with use of traditional bone screws, has been reported to decrease surgical time, allow for more precise screw placement, and reduce sources of error. Cannulation of the smaller-size screws that are routinely used in foot surgery has not been available until the last few years. This article reports on the use of the small cannulated screws manufactured by Alphatec Manufacturing, Inc (Palm Desert, California). The screw sizes available in the Mini Lag Screw System are 2.7, 3.5, and 4.0 mm. A long-term clinical and radiographic prospective evaluation of 70 procedures performed on 49 patients was conducted. The follow-up time for all patients was 2 years. None of the 70 implants fractured, and seven procedures (in seven patients) resulted in some type of implant-fixation failure. All of the fixation failures, however, appeared to be related to an untoward event or patient noncompliance. These smaller cannulated screws proved to be a reliable and effective means of fixation in foot surgery.

scholarly journals Mineralogical, numerical and analytical studies of the coupled oxidation of pyrite and coal

2003 ◽  
Vol 67 (2) ◽  
pp. 381-398 ◽  
Author(s):  
K. A. Evans ◽  
C. J. Gandy ◽  
S. A. Banwart
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Pyrite Oxidation ◽  
Spoil Heap ◽  
Reaction Fronts ◽  
Order Of Magnitude ◽  
Magnitude Variation ◽  
Discharge Chemistry ◽  
Analytical Expressions

Mineralogical, bulk and field leachate compositions are used to identify important processes governing the evolution of discharges from a coal spoil heap in County Durham. These processes are incorporated into a numerical one-dimensional advective-kinetic reactive transport model which reproduces field results, including gas compositions, to within an order of magnitude. Variation of input parameters allows the effects of incorrect initial assumptions on elemental profiles and discharge chemistry to be assessed. Analytical expressions for widths and speeds of kinetic reaction fronts are developed and used to predict long-term development of mineralogical distribution within the heap. Results are consistent with observations from the field site. Pyrite oxidation is expected to dominate O2 consumption in spoil heaps on the decadal timescale, although C oxidation may stabilize contaminants in effluents on the centennial scale.

A Paradigm for Functional Tissue Engineering

2000 ◽  
Author(s):  
David L. Butler
Keyword(s):  
Tissue Engineering ◽  
Tendon Repair ◽  
National Committee ◽  
New Paradigm ◽  
Functional Tissue Engineering ◽  
Functional Tissue ◽  
Tissue Engineer ◽  
Surgical Implants ◽  
The Us

Abstract Clinicians, biologists, and engineers face difficult challenges in engineering effective, cell-based composites for repair of orthopaedic and cardiovascular tissues. Whether repairing articular cartilage, bone, or blood vessel, the demands placed on the surgical implants can threaten the long-term success of the procedure. In 1998, the US National Committee on Biomechanics addressed this problem by suggesting a new paradigm for tissue engineering called “functional tissue engineering” or FTE. FTE seeks to address several important questions. What are the biomechanical demands placed upon the normal tissue and hence the tissue engineered implant after surgery? What parameters should a tissue engineer design into the implant before surgery? And what biomechanical parameters should the tissue engineer track to determine if the resulting repair is successful? To illustrate the principles, this presentation will discuss tendon repair as a model system for functional tissue engineering.

scholarly journals Cosmogenic burial dating of in cave-deposited alluvium: unravelling long-term incision rates and complex speleogenesis in multi-level cave systems

2020 ◽  
Author(s):  
Gilles Rixhon ◽  
Didier L. Bourlès ◽  
Régis Braucher ◽  
Alexandre Peeters ◽  
Alain Demoulin
Keyword(s):  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Fluvial Terrace ◽  
Base Level ◽  
Cave System ◽  
River Incision ◽  
Order Of Magnitude ◽  
History Of ◽  
Multi Level

<p>Multi-level cave systems record the history of regional river incision in abandoned alluvium-filled phreatic passages which, mimicking fluvial terrace sequences, represent former phases of fluvial base-level stability. In this respect, cosmogenic burial dating of in cave-deposited alluvium (usually via the nuclide pair <sup>26</sup>Al/<sup>10</sup>Be) represents a suitable method to quantify the pace of long-term river incision. Here, we present a dataset of fifteen <sup>26</sup>Al/<sup>10</sup>Be burial ages measured in fluvial pebbles washed into a multi-level cave system developed in Devonian limestone of the uplifted Ardenne massif (eastern Belgium). The large and well-documented Chawresse system is located along the lower Ourthe valley (i.e. the main Ardennian tributary of the Meuse river) and spans altogether an elevation difference exceeding 120 m.</p><p>The depleted <sup>26</sup>Al/<sup>10</sup>Be ratios measured in four individual caves show two main outcomes. Firstly, computed burial ages ranging from ~0.2 to 3.3 Ma allows highlighting an acceleration by almost one order of magnitude of the incision rates during the first half of the Middle Pleistocene (from ~25 to ~160 m/Ma). Secondly, according to the relative elevation above the present-day floodplain of the sampled material in the Manants cave (<35 m), the four internally-consistent Early Pleistocene burial ages highlight an “anomalous” old speleogenesis in the framework of a gradual base-level lowering. They instead point to intra-karsting reworking of the sampled material in the topographically complex Manants cave. This in turn suggests an independent, long-lasting speleogenetic evolution of this specific cave, which differs from the <em>per descensum</em> model of speleogenesis generally acknowledged for the regional multi-level cave systems and their abandoned phreatic galleries. In addition to its classical use for inferring long-term incision rates, cosmogenic burial dating can thus contribute to better understand specific and complex speleogenetic evolution.</p>

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