Influence of the Crosshead Rate on the Mechanical Properties of Fixation Systems of ACL Tendon Grafts

2009 ◽  
Vol 25 (4) ◽  
pp. 313-321 ◽  
Author(s):  
Oscar Martel ◽  
Juan F. Cárdenes ◽  
Gerardo Garcés ◽  
José A. Carta
Keyword(s):  
Mechanical Properties ◽  
Cruciate Ligament ◽  
Testing Machine ◽  
Interference Screw ◽  
In Vitro Tests ◽  
Biomechanical Test ◽  
Pull Out ◽  
Fixation Devices ◽  
Tendon Grafts

Anterior cruciate ligament (ACL) reconstruction is one of the most important aspects of knee surgery. For this purpose, several fixation devices have been developed, although the interference screw is the most frequently used. The most typical biomechanical test of these devices consists of placing them in a testing machine and subjecting them to a pull-out test. However, insufficient attention has been paid to the influence of the displacement test rate on the mechanical properties of the fixation system. The aim of this study is to compare the influence of the crosshead rate in the biomechanical test of two different devices for the fixation of ACL tendon grafts. One hundred in vitro tests were performed using porcine tibiae and bovine tendons. The fixation devices used were (1) an interference screw and (2) a new expansion device. All ACL reconstructions were subjected to pull-out test to failure. Five crosshead rates were employed in a range from 30 mm/min to 4000 mm/min. Statistical analyses of the results show that, for the two devices, the rate has a significant effect on both maximum force and stiffness. Moreover, the new expansion device showed lesser dependency on the crosshead rate than the interference screw.

scholarly journals Comparison of mechanical properties in interference screw fixation technique and organic anterior cruciate ligament reconstruction method: a biomechanical study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Amirhossein Borjali ◽  
Amir Nourani ◽  
Hadi Moeinnia ◽  
Mahdi Mohseni ◽  
Hossein Korani ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Anterior Cruciate Ligament ◽  
Cruciate Ligament ◽  
Healing Process ◽  
Interference Screw ◽  
Fixation Strength ◽  
Reconstruction Method ◽  
Pull Out ◽  
Anterior Cruciate

Abstract Background Bone and Site Hold Tendon Inside (BASHTI) technique is an organic implant-less technique for anterior cruciate ligament (ACL) reconstruction with some clinical advantages, such as speeding up the healing process, over implantable techniques. The study aims to compare the mechanical properties of BASHTI technique with the conventional interference screw technique. Methods To investigate the mechanical properties, 20 in-vitro experimental tests were conducted. Synthetic dummy bone, along with fresh digital bovine tendons, as a graft, were used for experiments. Three loading steps were applied to all specimens, including a preconditioning, a main cyclic, and a pull-out loading. Results The mechanical characters of an interference screw technique using an 8 mm tendon diameter, including fixation strength, average cyclic stiffness (ACS), and average pull-out stiffness (APS) were found to be 439 ± 132 N, 10.3 ± 5.3 kN/mm, and 109 ± 40 N/mm, respectively. In the case of an interference screw using a 9 mm tendon, the fixation strength, ACS, and APS were obtained 549 ± 87 N, 10.3 ± 4.7 kN/mm, and 91 ± 13 N/mm, respectively. In parallel, the fixation strength, APS, and ACS of BASHTI technique using an 8 mm tendon were 360 ± 123 N, 3.3 ± 0.6 kN/mm, and 79 ± 27 N/mm, respectively, while, for 9 mm tendon 278 ± 103 N, 2.4 ± 1.2 kN/mm, and 111 ± 40 N/mm, were reported for fixation strength, APS, and ACS respectively when BASHTI technique was used. Conclusion About 50% of interference screw samples showed superior mechanical properties compared to BASHTI technique, but in another half of the samples, the differences were not significant (N.S.). However, due to organic advantages of BASHTI technique and lower cost, it could be used as a substitute for interference screw technique, especially where fast recovery is expected.

Empirical Relationship Between Lengthening an Anterior Cruciate Ligament Graft and Increases in Knee Anterior Laxity: A Human Cadaveric Study

2006 ◽  
Vol 128 (6) ◽  
pp. 969-972 ◽  
Author(s):  
Dustin Grover ◽  
Dustin Thompson ◽  
M. L. Hull ◽  
S. M. Howell
Keyword(s):  
Femoral Tunnel ◽  
Cruciate Ligament ◽  
Empirical Relationship ◽  
In Vitro Tests ◽  
Fixation Device ◽  
Femoral Fixation ◽  
Fixation Devices ◽  
Anterior Laxity ◽  
Anterior Cruciate

Lengthening of an anterior cruciate ligament (ACL) graft construct can occur as a result of lengthening at the sites of tibial and/or femoral fixation and manifests as an increase in anterior laxity. Although lengthening at the site of fixation has been measured for a variety of fixation devices, it is difficult to place these results in a clinical context because the mathematical relationship between lengthening of an ACL graft construct and anterior laxity is unknown. The purpose of our study was to determine empirically this relationship. Ten cadaveric knees were reconstructed with a double-looped tendon graft. With the knee in 25° of flexion, the position of the proximal end of the graft inside the femoral tunnel was adjusted by moving the femoral fixation device until the anterior laxity at an applied anterior force of 134N matched that of the intact knee. In random order, the graft construct was lengthened 1, 2, 3, 4, and 5mm by moving the femoral fixation device distally along the femoral tunnel and anterior laxity was measured. The increase in the length of the graft construct was related to the increase in anterior laxity by a simple linear regression model. Lengthening the graft construct from 1 to 5mm caused an equal increase in anterior laxity (slope=1.0mm∕mm, r2=0.800, p<0.0001). Because an anterior laxity increase of 3mm or greater in a reconstructed knee is considered unstable clinically and because many fixation devices in widespread use clinically allow 3mm or greater of lengthening in in vitro tests, our empirical relationship indicates that lengthening at the site of fixation probably is an important cause of knee instability following ACL reconstructive surgery. Our empirical relation also indicates that an important criterion in the design of future fixation devices is that lengthening at the sites of fixation in in vitro tests should be limited to less than 3mm.

scholarly journals Goldmann Tonometry and Corneal Biomechanics

2021 ◽  
Vol 11 (9) ◽  
pp. 4025
Author(s):  
Dario Messenio ◽  
Marco Ferroni ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Anterior Chamber ◽  
Pressure Transducer ◽  
Pearson Correlation ◽  
Corneal Thickness ◽  
Applanation Tonometry ◽  
In Vitro Tests ◽  
Goldmann Tonometry ◽  
The Difference

Glaucoma is the second cause of irreversible blindness in the world. Intraocular pressure (IOP) is a recognized major risk factor for the development and progression of glaucomatous damage. Goldmann applanation tonometry (GAT) is internationally accepted as the gold standard for the measurement of IOP. The purpose of this study was to search for correlations between Goldmann tonometry and corneal mechanical properties and thickness by means of in vitro tests. IOP was measured by the Goldmann applanation tonometer (GIOP), and by a pressure transducer inserted in the anterior chamber of the eye (TIOP), at increasing pressure levels by addition of saline solution in the anterior chamber of enucleated pig eyes (n = 49). Mechanical properties were also determined by inflation tests. The GAT underestimated the real measurements made by the pressure transducer, with most common differences in the range 15–28 mmHg. The difference between the two instruments, highlighted by the Bland–Altman test, was confirmed by ANOVA, normality tests, and Mann–Whitney’s tests, both on the data arranged for infusions and for the data organized by pressure ranges. Pearson correlation tests revealed a negative correlation between (TIOP-GIOP) and both corneal stiffness and corneal thickness. In conclusion, data obtained showed a discrepancy between GIOP and TIOP more evident for softer and thinner corneas, that is very important for glaucoma detection.

scholarly journals Whether sutures reduce the graft laceration caused by interference screw in anterior cruciate ligament reconstruction? A biomechanical study in vitro

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yuanjun Teng ◽  
Xiaohui Zhang ◽  
Lijun Da ◽  
Jie Hu ◽  
Hong Wang ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Interference Screw ◽  
Biomechanical Study ◽  
Interference Screws ◽  
Suture Group ◽  
Anterior Cruciate ◽  
Biomechanical Tests ◽  
Single Insertion

Abstract Background Interference screw is commonly used for graft fixation in anterior cruciate ligament (ACL) reconstruction. However, previous studies had reported that the insertion of interference screws significantly caused graft laceration. The purposes of this study were to (1) quantitatively evaluate the graft laceration from one single insertion of PEEK interference screws; and (2) determine whether different types of sutures reduced the graft laceration after one single insertion of interference screws in ACL reconstruction. Methods The in-vitro ACL reconstruction model was created using porcine tibias and bovine extensor digitorum tendons of bovine hind limbs. The ends of grafts were sutured using three different sutures, including the bioabsorbable, Ethibond and ultra-high molecular weight polyethylene (UHMWPE) sutures. Poly-ether-ether-ketone (PEEK) interference screws were used for tibial fixation. This study was divided into five groups (n = 10 in each group): the non-fixed group, the non-sutured group, the absorbable suture group, the Ethibond suture group and the UHMWPE suture group. Biomechanical tests were performed using the mode of pull-to-failure loading tests at 10 mm/min. Tensile stiffness (newtons per millimeter), energy absorbed to failure (in joules) and ultimate load (newtons) were recorded for analysis. Results All prepared tendons and bone specimens showed similar characteristics (length, weight, and pre-tension of the tendons, tibial bone mineral density) among all groups (P > 0.05). The biomechanical tests demonstrated that PEEK interference screws significantly caused the graft laceration (P < 0.05). However, all sutures (the bioabsorbable, Ethibond and UHMWPE sutures) did not reduce the graft laceration in ACL reconstruction (P > 0.05). Conclusions Our biomechanical study suggested that the ultimate failure load of grafts was reduced of approximately 25 % after one single insertion of a PEEK interference screw in ACL reconstruction. Suturing the ends of the grafts using different sutures (absorbable, Ethibond and UHMWPE sutures) did not decrease the graft laceration caused by interference screws.

scholarly journals Whether Sutures Reduce the Graft Laceration Caused by Interference Screw in Anterior Cruciate Ligament Reconstruction a Biomechanical Study in Vitro

2021 ◽  
Author(s):  
Yuanjun Teng ◽  
Lijun Da ◽  
Xiaohui Zhang ◽  
Hong Wang ◽  
Hua Han ◽  
...  
Keyword(s):  
Anterior Cruciate Ligament ◽  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Interference Screw ◽  
Biomechanical Study ◽  
Protective Effects ◽  
Mineral Density ◽  
Interference Screws ◽  
Anterior Cruciate

Abstract Background: Interference screw is commonly used for graft fixation in anterior cruciate ligament (ACL) reconstruction However, previous studies h a d reported that the insertion of interference screws significantly caused graft laceration . The purpose of this study was to determine whether sutures reduce d the graft laceration from the insertion of interference screws in ACL reconstruction. Methods: Porcine tibias and bovine extensor tendons were used for establishing a knee model of ACL reconstruction in vitro . The ends of grafts were sutured using three different sutures, including the bioabsorbable, Ethibond and ultra high molecular weight polyethylene (UHMWPE) sutures Poly ether ether ketone (PEEK) interference screw s w ere used fortibial fixation Biomechanical tests were performed to investigate the protective effects of different sutures on grafts Results : All prepared tendons and bone specimens showed similar characteristics (length, weight, and pre tension of the tendons, tibial bone mineral density) among all groups ( P 0.05). The biomechanical test s demonstrated that PEEK interference screw s significantly caused the graft laceration P 0.05). However, all sutures (the bioabsorbable, Ethibond and UHMWPE sutures) did not reduce the graft laceration in ACL reconstruction P 0.05). Conclusions : PEEK interference screw s significantly weakened the biomechanical properties of grafts during tibial fixation in ACL reconstruction. Absorbable Ethibond and UHMWPE sutures did not provide protective effects on grafts during ACL reconstruction.

scholarly journals Biomechanical properties of a novel biodegradable magnesium-based interference screw

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
Marco Ezechieli ◽  
Hanna Meyer ◽  
Arne Lucas ◽  
Patrick Helmecke ◽  
Christoph Becher ◽  
...  
Keyword(s):  
Cruciate Ligament ◽  
Testing Machine ◽  
Biomechanical Testing ◽  
Maximum Load ◽  
Biomechanical Properties ◽  
Interference Screw ◽  
Biomechanical Analysis ◽  
Interference Screws ◽  
Standard Implant ◽  
Biodegradable Magnesium

Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA) were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57). Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P&gt;0.05). Stiffness was 121.1±13.8 N/mm for the magnesiumbased screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32). MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future.

Fibroblasts From Common Anterior Cruciate Ligament Tendon Grafts Exhibit Different Biologic Responses to Mechanical Strain

2020 ◽  
Vol 49 (1) ◽  
pp. 215-225
Author(s):  
Sebastian Cardona-Ramirez ◽  
Aaron M. Stoker ◽  
James L. Cook ◽  
Richard Ma
Keyword(s):  
Anterior Cruciate Ligament ◽  
Acl Reconstruction ◽  
Metabolic Activity ◽  
Cruciate Ligament ◽  
Mechanical Strain ◽  
Advantages And Disadvantages ◽  
Relative Paucity ◽  
Tendon Grafts ◽  
Anterior Cruciate

Background: Different tendons are chosen for anterior cruciate ligament (ACL) reconstruction based on perceived advantages and disadvantages, yet there is a relative paucity of information regarding biologic responsiveness of commonly used tendon grafts to mechanical strain. Purpose: To evaluate the in vitro responses of graft fibroblasts derived from tendons used for ACL reconstruction to clinically relevant strain levels. Study Design: Controlled laboratory study. Methods: Twelve quadriceps tendons (QTs), 12 patellar tendons (PTs), and 9 hamstring tendons (HTs) were harvested from skeletally mature dogs (n = 16). Tendon fibroblasts were isolated and seeded onto BioFlex plates (1 × 105 cells/well). Cells were subjected to 3 strain conditions (stress deprivation, 0%; physiologic, 4%; high, 10%) for 5 days. Media were collected for proinflammatory and metabolic assays. RNA was extracted for gene expression analysis using real-time reverse transcription polymerase chain reaction. Results: Stress deprivation elicited significantly higher metabolic activity from HT and PT cells than from QT cells ( P < .001 and P = .001, respectively). There were no differences in metabolic activity among all 3 graft fibroblasts at physiologic and high strain. COL-1 expression was significantly higher in PT versus HT during physiologic strain ( P = .007). No significant differences with COL-3 expression were seen. TIMP-1 ( P = .01) expression was higher in PT versus HT under physiologic strain. Scleraxis expression was higher in PT versus HT ( P = .007) under physiologic strain. A strain-dependent increase in PGE2 levels occurred for all grafts. At physiologic strain conditions, HT produced significantly higher levels of PGE2 versus QT ( P < .001) and PT ( P = .005). Conclusion: Fibroblasts from common ACL graft tissues exhibited different metabolic responses to mechanical strain. On the basis of these data, we conclude that early production of extracellular matrix and proinflammatory responses from ACL grafts are dependent on mechanical loading and graft source. Clinical Relevance: Graft-specific differences in ACL reconstruction outcomes are known to exist. Our results suggest that there are differences in the biologic responsiveness of cells from the tendon grafts used in ACL reconstruction, which are dependent on strain levels and graft source. The biologic properties of the tissue used for ACL reconstruction should be considered when selecting graft source.

Role of pH on stability and mechanical properties of gelatin films

2012 ◽  
Vol 27 (1) ◽  
pp. 67-77 ◽  
Author(s):  
Michela Gioffrè ◽  
Paola Torricelli ◽  
Silvia Panzavolta ◽  
Katia Rubini ◽  
Adriana Bigi
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Triple Helix ◽  
Young's Modulus ◽  
In Vitro Tests ◽  
Diffraction Reflection ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Gelatin Films

The effect of the film-forming solution pH on the triple-helix content, thermal stability, and mechanical properties of gelatin films was investigated. The films were prepared from solutions at different pHs of type A pigskin gelatin, and their mechanical characteristics were determined. At pHs higher than 9 and lower than 5, Young’s modulus, E, and the stress at break, σb, of the films decreased significantly. Cross-linking with genipin reduced deformation at break, ϵb, and increased Young’s modulus. The intensity of the 1.1-nm X-ray diffraction reflection and the denaturation enthalpy decreased at these pHs, indicating that the triple helix reduced. Preliminary in vitro tests on the cross-linked samples indicated good cell proliferation and viability.

Sign in / Sign up

Export Citation Format

Share Document