Anchor Material Research Articles

Failure analysis of a rock anchor made of stainless steel in marine environment

Anchors made of stainless steel have been widely used for rock anchoring in marine environments. The presence of the corrosive environment, the tightening induced stresses and the susceptibility of the anchor material to stress corrosion cracking are the most critical parameters that may influence the longevity of the anchor. Failure investigation was carried out on fragments of a broken rock climbing anchor. Optical and scanning electron microscopy for structural and fractographic evaluation along with numerical modeling are used as the principal techniques in the context of the present investigation. Failure analysis findings suggest that the failure was caused by stress corrosion cracking. The anchor experienced extensive cracking during its lifetime and eventually broke when an unsuspected climber attempted to hang from it.

Poly-L/D-Lactic Acid Anchors Are Associated With Reoperation and Failure of SLAP Repairs

This study investigates factors associated with failure and reoperation after glenoid labrum repair. We studied a nonconcurrent cohort of consecutive patients undergoing arthroscopic superior labrum repair at a single institution by 2 fellowship-trained surgeons over a 10-year period. There were 348 patients included in this study with a mean age of 33.4 years (95% confidence interval [CI], 32.1 to 35.9) and a mean clinical follow-up of 12.3 months (95% CI, 10.9 to 13.8). The overall reoperation rate was 6.3%, with a revision labrum repair rate of 4.3%. Subsequent surgery and failure after arthroscopic labrum repair were significantly correlated with Workers' Compensation claims (odds ratio [OR], 4.6; P < .001; 95% CI, 1.8 to 11.7), the use of tobacco (OR, 12.0; P = .03; 95% CI, 1.2 to 114.9), and the use of absorbable poly-L/D-lactic acid (PLDLA) anchors (100% correlation, P < .001). The OR for having repeat surgery was 12.7 (95% CI, 4.9 to 32.9; P < .001) with poly-96L/4D-lactic acid (Mini-Revo; Linvatec, Largo, FL) and also increased with the use of poly-70L/30D-lactic acid (Bio-Fastak and Bio-Suturetak; Arthrex, Naples, FL) anchor material (P = .04) after removal of the patients exposed to poly-96L/4D-lactic acid anchors. The rates of repeat surgery with PLDLA anchors from Linvatec and PLDLA anchors from Arthrex were 24% and 4%, respectively. None of the patients treated with nonabsorbable suture anchors (polyether ether ketone or metallic) returned to the operating room (P < .001). After we controlled for associated factors in a multivariate analysis, the use of absorbable anchors, in particular poly-96L/4D-lactic acid anchors (OR, 14.7; P < .001), and having a work-related injury (OR, 8.1; P < .001) remained independent factors associated with both repeat surgery and revision superior labrum repair. Bioabsorbable PLDLA anchor material led to significantly more SLAP repair failures and reoperations compared with nonabsorbable suture anchors. Our recommendation is that glenoid labrum repairs be performed with nondegradable material and, specifically, that the use of anchors composed of PLDLA material should be avoided.

ASSESSING THE FALSIFIABILITY OF EXTREME LINKING

ABSTRACTExtreme linkings are performed in settings in which neither equivalent groups nor anchor material is available to link scores on two assessments. Examples of extreme linkages include links between scores on tests administered in different languages or between scores on tests administered across disability groups. The strength of interpretation attached to a linkage depends on the proper design and execution of a sound data collection plan. The current paper uses a real data set to illustrate how to indirectly assess the quality of linking the scores on two assessments that contain neither equivalent groups nor common anchor material.

Poly Lactic Acid (PLDLA) Anchors Are Associated With Reoperation and Failure of Glenoid Labrum Repairs (SS-11)

Introduction There has been limited data regarding failure after arthroscopic repair of superior glenoid labrum tears. This study investigates factors associated with failure and re-operation in this patient population. Methods This is a non-concurrent cohort of consecutive patients undergoing arthroscopic labrum repair at a single institution by two fellowship-trained surgeons over a ten year period. Results There were 348 patients included in this study with a mean age of 33.4 (95% CI 32.1-35.9) and an average clinical follow-up of 12.3 months (95% CI 10.9-13.8). The overall re-operation rate was 6.3% with a revision labrum repair rate of 4.3%. The interval between the index procedure to the second procedure was approximately 50 weeks. Subsequent surgery and failure after arthroscopic labrum repair were significantly correlated with workers' compensation (OR 4.6, p < 0.001, CI 1.8-11.7), the use of tobacco (OR 12.0, p=0.03, CI 1.2-114.9) and the use of absorbable anchors (100% correlation, p<0.001). The Odds Ratio (OR) of having a repeat surgery was 12.7 (95% CI 4.9-32.9, p<0.001) with poly-96L/4D-lactic acid (PLDLA, Mini-Revo, Linvatec) and also increased with the use of poly-70L/30D-lactic acid (PLDLA, Bio-Fastak, Bio-Suturetak) anchor material manufactured by Arthrex (p=0.04) after removing the patients exposed to PLDLA anchors from Linvatec. The rates of repeat surgery with PLDLA anchors from Linvatec and PLDLA anchors from Arthrex were 24% and 4%, respectively. None of the patients treated with non-absorbable suture anchors (PEEK or metallic) returned to operating room (p < 0.001). After controlling for associated factors in a multivariate analysis, the use of absorbable anchors, in particular PLDA anchors from Linvatec (OR 14.7, p<0.001) and having a work-related (OR 8.1, p<0.001) injury remained independent factors associated with both repeat surgery and after labrum repair. Conclusion The results of this study strongly support a recommendation against the use of poly-lactic acid suture anchors for glenoid labrum repair surgery. There has been limited data regarding failure after arthroscopic repair of superior glenoid labrum tears. This study investigates factors associated with failure and re-operation in this patient population. This is a non-concurrent cohort of consecutive patients undergoing arthroscopic labrum repair at a single institution by two fellowship-trained surgeons over a ten year period. There were 348 patients included in this study with a mean age of 33.4 (95% CI 32.1-35.9) and an average clinical follow-up of 12.3 months (95% CI 10.9-13.8). The overall re-operation rate was 6.3% with a revision labrum repair rate of 4.3%. The interval between the index procedure to the second procedure was approximately 50 weeks. Subsequent surgery and failure after arthroscopic labrum repair were significantly correlated with workers' compensation (OR 4.6, p < 0.001, CI 1.8-11.7), the use of tobacco (OR 12.0, p=0.03, CI 1.2-114.9) and the use of absorbable anchors (100% correlation, p<0.001). The Odds Ratio (OR) of having a repeat surgery was 12.7 (95% CI 4.9-32.9, p<0.001) with poly-96L/4D-lactic acid (PLDLA, Mini-Revo, Linvatec) and also increased with the use of poly-70L/30D-lactic acid (PLDLA, Bio-Fastak, Bio-Suturetak) anchor material manufactured by Arthrex (p=0.04) after removing the patients exposed to PLDLA anchors from Linvatec. The rates of repeat surgery with PLDLA anchors from Linvatec and PLDLA anchors from Arthrex were 24% and 4%, respectively. None of the patients treated with non-absorbable suture anchors (PEEK or metallic) returned to operating room (p < 0.001). After controlling for associated factors in a multivariate analysis, the use of absorbable anchors, in particular PLDA anchors from Linvatec (OR 14.7, p<0.001) and having a work-related (OR 8.1, p<0.001) injury remained independent factors associated with both repeat surgery and after labrum repair. The results of this study strongly support a recommendation against the use of poly-lactic acid suture anchors for glenoid labrum repair surgery.

Surface Modification of SiO2 Microchannels with Biocompatible Polymer Using Supercritical Carbon Dioxide

The surface of 500-mm-long microchannels in SiO2 microchips was modified using supercritical CO2 (scCO2) and a biocompatible polymer was coated on it to confer biocompatibility to the SiO2 surface. In this method, the SiO2 surface of a microchannel was coated with poly(ethylene glycol monomethacrylate) (PEGMA) as the biocompatible polymer using allyltriethoxysilane (ATES) as the anchor material in scCO2 as the reactive medium. Results were compared with those using the conventional wet method. The surface of a microchannel could not be modified by the wet method owing to the surface tension and viscosity of the liquid, but it was modified uniformly by the scCO2 method probably owing to the near-zero surface tension, low viscosity, and high diffusivity of scCO2. The effect of the surface modification by the scCO2 method to prevent the adsorption of protein was as high as that of the modification by the wet method. Modified microchips can be used in biochemical and medical analyses.

STUDY OF ROMAN ANCHOR FROM THE DEAD SEA SHORE*

A wooden Roman anchor was discovered at the retreating shore of the Dead Sea, north of Ein Gedi. The anchor's wood material was coated by a thick veneer of aragonite and gypsum crusts. The wood was dated by radiocarbon to the early Roman time in the Levant. Lead isotope analyses carried out on the Pb–Fe–Cu anchor material (remains of the anchor's metal parts) yielded ratios that indicate origin of the metal in Italian ores (maybe Tuscan). For the wooden part of the anchor a local tree was used.

Investigation of the thermal mode of a high-speed electrical contact by mathematical modeling methods

The temperature mode of a metal contact upon transition to a hybrid and further on to a plasma one has been studied. Spatial (three-dimensional) mathematical modeling confirmed the existence of a dependable metal contact before melting of the anchor material and transition to an arc mode of passage of the current after the onset of boiling. The possibility of destruction of the accelerated body during the acceleration time has been investigated.

Study on mechanism of fiber grouted material in pre-stressed anchor rope

The fiber grouted material can reinforce the tension strength, shear strength as well as the index of fracture ductile, and remarkably improve the endurance of pre-stressed anchor rope under long-time loading. As a result, it has the better application foreground. Based on the shear log model and Hashin-Shtrikman upper and lower limited theorem, we have studied the mechanism of fiber grouted material applied in pre-stressed anchor rope and material property, and analyzed the effect of resistance strength of bond, resistance distribution of anchor section and the loading-deformation relationship of anchor body.

Development and Application of Anchor-Soil Interface Models

Understanding the anchor-soil interface behavior is essential to the determination of the anchor pullout capacity and prediction of the deformation of the anchor-reinforced system under working load conditions. Numerous anchor pullout tests under both lab and field conditions have generally yielded extremely high apparent interface strength, which cannot be explained by the conventional interface friction theory between the anchor material and the soil. In this paper, the mechanism and the phenomena of the anchor-soil interaction were studied, and the soil dilatancy due to shearing was regarded as the main factor contributing to the increase of the anchor-soil interface friction. Considering this effect, along with the adoption of a cylindrical shear deformation pattern of the soil, anchor-soil interface models have been developed for hardening and softening behavior, respectively. Using the developed interface model, the forward and backward calculation algorithms have been formulated and applied to predict the anchor performance for the given interface parameters and to determine the interface parameters from the given anchor pullout test, respectively. Furthermore, the prediction of the anchor pullout performance was compared favorably with two hypothetical cases, two laboratory test results, and one field case.

Bladder Neck Suspension Material Investigated in a Rabbit Model

Different principles for providing stable and durable suspension of the bladder neck and proximal urethral tissue are employed in endoscopic bladder neck suspension for female stress urinary incontinence. Six different anchor materials, some of which are currently used as tissue bolsters (anchors) for endoscopic bladder neck suspension, were implanted in the abdominal wall muscle of 45 rabbits. Tension on the anchors was measured and maintained by springs positioned between pairs of anchors. At two months evaluation, vascular graft and loops of suture retained 40% of the starting tension, while two sizes of screw anchors lost all tension. Silicone pads and kink free silicone tubing rapidly pulled through the tissue in 83% and 100% of the cases, respectively. Local tissue reaction with scar formation, physical characteristics of the anchor material (silicone, stainless steel, dacron or polypropolene) and cross sectional area of the anchor were identified as the important factors for anchor stabilization of tissue which has been repositioned under tension. (J. Urol., 142: 1361–1363, 1989)

Stress Corrosion Cracking in Austenitic Stainless Steel Fixings for Façade Panels

AbstractThe applicability of austenitic stainless steel for anchoring farade panels has been studied. It is shown that under certain conditions the possibility of stress corrosion in austenitic stainless steel fixings must be taken into account. Stress corrosion will occur only at a particular combination of stress, chloride concentration and temperature, and in practice the probability of serious damage has always been low. On the basis of ‘low-temperature’ stress corrosion tests in the laboratory, it has been decided in the Netherlands to allow the use of austenitic stainless steel for facade anchors only in conditions where the maximum anchor temperature does not rise above 50°c.Dutch views on the applicability of austenitic steel as anchor material for facade panels are discussed.