Limits...
Surface pretreatments for medical application of adhesion.

Erli HJ, Marx R, Paar O, Niethard FU, Weber M, Wirtz DC - Biomed Eng Online (2003)

Bottom Line: Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body.The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m).This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Prosthetic Dentistry, Section of Dental Materials, University Hospital of the University of Technology, Aachen, Germany. herli@ukaachen.de

ABSTRACT
Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques, connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body.

Show MeSH

Related in: MedlinePlus

Fatigue amplitude test. Cyclically pulling at fixation element (banjo bolt) and PVDF tendon. Angle between axis of fixation element and tendon about 120 degrees. Lower load 10% of upper load, sinusoidal time dependence of load, 3 cycles per second. Diameter of tendon 2,5 mm. Open triangles: tendon with tight network, open circles: tendon with loose network.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC222922&req=5

Figure 15: Fatigue amplitude test. Cyclically pulling at fixation element (banjo bolt) and PVDF tendon. Angle between axis of fixation element and tendon about 120 degrees. Lower load 10% of upper load, sinusoidal time dependence of load, 3 cycles per second. Diameter of tendon 2,5 mm. Open triangles: tendon with tight network, open circles: tendon with loose network.

Mentions: These advantages could also be helpful replacing the ACL in knee surgery. As mentioned above, one of the main problems of artificial ACL reconstruction is the insufficient fixation stability to the bone. With the proposed adhesive technique, it could be possible to realize a more stable fixation of the artificial tendon to the bone. In addition, a more physiological load transfer from the artificial ligament into the bone seems to be achievable. Although clinical data are missing, experimental work shows promising results for the use of artificial ACL reconstruction in the near future. Fig. 15 shows fatigue amplitude tests that lead to fatigue failure due to cyclic forces. Such a diagram relates both to material properties and structural geometry. It requires one specimen to be run to rupture in order to provide just one point on the curve. The frequency of cyclic loading is usually low (presently 3 cycles per second between maximum and minimum loads) such that one single test may go on for several days or weeks. A graph of the maximum stress force, F, in newtons (N) vs. cycles to failure (S-N curves) is plotted. By successively lowering the maximum stress, specimens fatigue-tested without rupture are determined. The maximum stress, that does not result in failure can thus be determined. This procedure provides important guidelines for the maximum serving stress that the artificial tendon in combination with the fixation element can withstand (Fig. 15).


Surface pretreatments for medical application of adhesion.

Erli HJ, Marx R, Paar O, Niethard FU, Weber M, Wirtz DC - Biomed Eng Online (2003)

Fatigue amplitude test. Cyclically pulling at fixation element (banjo bolt) and PVDF tendon. Angle between axis of fixation element and tendon about 120 degrees. Lower load 10% of upper load, sinusoidal time dependence of load, 3 cycles per second. Diameter of tendon 2,5 mm. Open triangles: tendon with tight network, open circles: tendon with loose network.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC222922&req=5

Figure 15: Fatigue amplitude test. Cyclically pulling at fixation element (banjo bolt) and PVDF tendon. Angle between axis of fixation element and tendon about 120 degrees. Lower load 10% of upper load, sinusoidal time dependence of load, 3 cycles per second. Diameter of tendon 2,5 mm. Open triangles: tendon with tight network, open circles: tendon with loose network.
Mentions: These advantages could also be helpful replacing the ACL in knee surgery. As mentioned above, one of the main problems of artificial ACL reconstruction is the insufficient fixation stability to the bone. With the proposed adhesive technique, it could be possible to realize a more stable fixation of the artificial tendon to the bone. In addition, a more physiological load transfer from the artificial ligament into the bone seems to be achievable. Although clinical data are missing, experimental work shows promising results for the use of artificial ACL reconstruction in the near future. Fig. 15 shows fatigue amplitude tests that lead to fatigue failure due to cyclic forces. Such a diagram relates both to material properties and structural geometry. It requires one specimen to be run to rupture in order to provide just one point on the curve. The frequency of cyclic loading is usually low (presently 3 cycles per second between maximum and minimum loads) such that one single test may go on for several days or weeks. A graph of the maximum stress force, F, in newtons (N) vs. cycles to failure (S-N curves) is plotted. By successively lowering the maximum stress, specimens fatigue-tested without rupture are determined. The maximum stress, that does not result in failure can thus be determined. This procedure provides important guidelines for the maximum serving stress that the artificial tendon in combination with the fixation element can withstand (Fig. 15).

Bottom Line: Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body.The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m).This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Prosthetic Dentistry, Section of Dental Materials, University Hospital of the University of Technology, Aachen, Germany. herli@ukaachen.de

ABSTRACT
Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques, connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body.

Show MeSH
Related in: MedlinePlus