Ex-vivo biomechanical testing of pig femur diaphysis B type fracture fixed by novel biodegradable bone glue

Abstract OBJECTIVE To determine the effects of 2-, 4-, 6- and 8-strand suture repairs on the biomechanical properties of canine gastrocnemius tenorrhaphy constructs in an ex vivo model. SAMPLE 56 cadaveric gastrocnemius musculotendinous units from 28 adult large-breed dogs. PROCEDURES Tendons were randomly assigned to 4 repair groups (2-, 4-, 6- or 8-strand suture technique; n = 14/group). Following tenotomy, repairs were performed with the assigned number of strands of 2-0 polypropylene suture in a simple interrupted pattern. Biomechanical testing was performed. Yield, peak, and failure loads, the incidence of 1- and 3-mm gap formation, forces associated with gap formation, and failure modes were compared among groups. RESULTS Yield, peak, and failure forces differed significantly among groups, with significantly greater force required as the number of suture strands used for tendon repair increased. The force required to create a 1- or 3-mm gap between tendon ends also differed among groups and increased significantly with number of strands used. All constructs failed by mode of suture pull-through. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that increasing the number of suture strands crossing the repair site significantly increases the tensile strength of canine gastrocnemius tendon repair constructs and their resistance to gap formation. Future studies are needed to assess the effects of multistrand suture patterns on tendon glide function, blood supply, healing, and long-term clinical function in dogs to inform clinical decision-making.

Download Full-text

An integrated set-up for ex vivo characterisation of biaxial murine artery biomechanics under pulsatile conditions

Scientific Reports ◽

10.1038/s41598-021-81151-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Myrthe M. van der Bruggen ◽

Koen D. Reesink ◽

Paul J. M. Spronck ◽

Nicole Bitsch ◽

Jeroen Hameleers ◽

...

Keyword(s):

Arterial Stiffness ◽

Carotid Arteries ◽

Ex Vivo ◽

Dynamic Pressure ◽

Single Point ◽

Biomechanical Testing ◽

Axial Stiffness ◽

Set Up ◽

Static Conditions

AbstractEx vivo characterisation of arterial biomechanics enables detailed discrimination of the various cellular and extracellular contributions to arterial stiffness. However, ex vivo biomechanical studies are commonly performed under quasi-static conditions, whereas dynamic biomechanical behaviour (as relevant in vivo) may differ substantially. Hence, we aim to (1) develop an integrated set-up for quasi-static and dynamic biaxial biomechanical testing, (2) quantify set-up reproducibility, and (3) illustrate the differences in measured arterial stiffness between quasi-static and dynamic conditions. Twenty-two mouse carotid arteries were mounted between glass micropipettes and kept fully vasodilated. While recording pressure, axial force (F), and inner diameter, arteries were exposed to (1) quasi-static pressure inflation from 0 to 200 mmHg; (2) 300 bpm dynamic pressure inflation (peaking at 80/120/160 mmHg); and (3) axial stretch (λz) variation at constant pressures of 10/60/100/140/200 mmHg. Measurements were performed in duplicate. Single-point pulse wave velocities (PWV; Bramwell-Hill) and axial stiffness coefficients (cax = dF/dλz) were calculated at the in vivo value of λz. Within-subject coefficients of variation were ~ 20%. Dynamic PWVs were consistently higher than quasi-static PWVs (p < 0.001); cax increased with increasing pressure. We demonstrated the feasibility of ex vivo biomechanical characterisation of biaxially-loaded murine carotid arteries under pulsatile conditions, and quantified reproducibility allowing for well-powered future study design.

Download Full-text

Biomechanical evaluation of annulus fibrosus repair with scaffold and soft anchors in an ex vivo porcine model

SICOT-J ◽

10.1051/sicotj/2018020 ◽

2018 ◽

Vol 4 ◽

pp. 38 ◽

Cited By ~ 2

Author(s):

Kresten Rickers ◽

Michael Bendtsen ◽

Dang Quang Svend Le ◽

Albert Jvan der Veen ◽

Cody Eric Bünger

Keyword(s):

Annulus Fibrosus ◽

Ex Vivo ◽

Biomechanical Testing ◽

Biomechanical Properties ◽

Neutral Zone ◽

Lateral Bending ◽

Biomechanical Behavior ◽

Flexion Extension ◽

Circular Defect ◽

Push Out

Introduction: Altered biomechanical properties, due to intervertebral disc (IVD) degeneration and missing nucleus fibrosus, could be thought as one of the reasons for the back pain many herniation patients experience after surgery. It has been suggested to repair annulus fibrosus (AF) to restore stability and allow nucleus pulposus (NP) replacement and furthermore prevent reherniation. The aim of this study was to evaluate a new method for closing a defect in AF for use in herniation surgery. Methods: Our repair method combines a polycaprolactone (PCL) scaffold plugging herniation and soft anchors to secure the plug. Ex vivo biomechanical testing was carried out in nine porcine lumbar motion segments. Flexion–extension, lateral bending and rotation were repeated three times: first in healthy specimens, second with a full thickness circular defect applied, and third time with the specimens repaired. Finally push out tests were performed to check whether the plug would remain in. Results: Tests showed that applying a defect to the AF increases the range of motion (ROM), neutral zone (NZ) and neutral zone stiffness (NZS). In flexion/extension it was found significant for ROM, NZ, and NZS. For lateral bending and rotation a significant increase in ROM occurred. After AF repair ROM, NZ and NZS were normalized. All plugs remained in the AF during push out test up until 4000 N, but NP was squeezed out through the pores of the scaffold. Discussion: A defect in the AF changes the biomechanical properties in the motion segment, changes that point to instability. Repairing the defect with a PCL plug and soft anchors brought the biomechanical behavior back to native state. This concept is promising and might be a viable way to repair the IVD after surgery.

Download Full-text

A pilot study to assess the healing of meniscal tears in young adult goats

Scientific Reports ◽

10.1038/s41598-021-93405-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

William Fedje-Johnston ◽

Casey P. Johnson ◽

Ferenc Tóth ◽

Cathy S. Carlson ◽

Arin M. Ellingson ◽

...

Keyword(s):

Failure Load ◽

Ex Vivo ◽

Relaxation Times ◽

Biomechanical Testing ◽

Quantitative Mri ◽

Meniscal Tears ◽

Orthopedic Injury ◽

Compositional Elements ◽

Magnetic Resonance Imaging Mri ◽

Surgically Induced

AbstractMeniscal tears are a common orthopedic injury, yet their healing is difficult to assess post-operatively. This impedes clinical decisions as the healing status of the meniscus cannot be accurately determined non-invasively. Thus, the objectives of this study were to explore the utility of a goat model and to use quantitative magnetic resonance imaging (MRI) techniques, histology, and biomechanical testing to assess the healing status of surgically induced meniscal tears. Adiabatic T1ρ, T2, and T2* relaxation times were quantified for both operated and control menisci ex vivo. Histology was used to assign healing status, assess compositional elements, and associate healing status with compositional elements. Biomechanical testing determined the failure load of healing lesions. Adiabatic T1ρ, T2, and T2* were able to quantitatively identify different healing states. Histology showed evidence of diminished proteoglycans and increased vascularity in both healed and non-healed menisci with surgically induced tears. Biomechanical results revealed that increased healing (as assessed histologically and on MRI) was associated with greater failure load. Our findings indicate increased healing is associated with greater meniscal strength and decreased signal differences (relative to contralateral controls) on MRI. This indicates that quantitative MRI may be a viable method to assess meniscal tears post-operatively.

Download Full-text

Comparison of Barbed Sutures in Porcine Flexor Tenorrhaphy

Hand ◽

10.1177/1558944715626928 ◽

2016 ◽

Vol 11 (4) ◽

pp. 475-478 ◽

Cited By ~ 1

Author(s):

Alan Sull ◽

Serkan Inceoglu ◽

Alicia August ◽

Stephen Gregorius ◽

Montri D. Wongworawat

Keyword(s):

Tensile Strength ◽

Ultimate Tensile Strength ◽

Ex Vivo ◽

Biomechanical Testing ◽

Barbed Suture ◽

Control Group ◽

Suture Materials ◽

Ex Vivo Model ◽

Normal Tendon ◽

Minimal Data

Background: Barbed suture use has become more popular as technology and materials have advanced. Minimal data exist regarding performance of the 2 commercially available products, V-LocTM and StratafixTM in tendon repairs. The purpose of this study was to compare gap resistance and ultimate tensile strength of both suture materials and nonbarbed suture in a porcine ex vivo model. Methods: Porcine flexor tendons were harvested and divided into 3 groups of 10 of varying suture material (3-0 PDS™, 3-0 V- V-Loc 180™, or 3-0 Stratafix™). A modified 4-strand cruciate technique was used to repair each tendon. Knotless repair was performed using barbed suture, whereas a buried 6-throw square knot was done using conventional suture. A servohydrolic tester was used for biomechanical testing of linear 2-mm gap resistance and maximum tensile strength. Results: No difference was found in 2-mm gap resistance among the 3 groups. No difference was found in ultimate tensile strength between V-Loc™ (76.0 ± 9.4 N) and Stratafix™ (68.1 ± 8.4 N) repairs, but the ultimate strength of the PDS™ control group (83.4 ± 10.0 N) was significantly higher than that of Stratafix™. Conclusions: Barbed (knotless) and nonbarbed suture repairs demonstrate equivalent 2-mm gap resistance. Stratafix™ repairs show slightly inferior performance to nonbarbed repairs in ultimate tensile strength, although this occurred at gap distances far beyond the 2-mm threshold for normal tendon gliding. Both barbed and nonbarbed 4-strand cruciate flexor tendon repairs may require peripheral repair to withstand physiologic loads.

Download Full-text

Ablation of Proliferating Osteoblast Lineage Cells After Fracture Leads to Atrophic Nonunion in a Mouse Model

10.1101/2020.10.06.327288 ◽

2020 ◽

Author(s):

Katherine R. Hixon ◽

David A.W. Sykes ◽

Susumu Yoneda ◽

Jennifer A. McKenzie ◽

Austin Hensley ◽

...

Keyword(s):

Cell Proliferation ◽

Ex Vivo ◽

Fibrous Tissue ◽

Biomechanical Testing ◽

Suicide Gene ◽

Fracture Site ◽

Fracture Callus ◽

Atrophic Nonunion ◽

Osteoblast Lineage

ABSTRACTNonunion is defined as the permanent failure of a fractured bone to heal, often necessitating surgical intervention. Atrophic nonunions are a subtype that are particularly difficult to treat. Animal models of atrophic nonunion are available; however, these require surgical or radiation-induced trauma to disrupt periosteal healing. These methods are highly invasive and not representative of many clinical nonunions where osseous regeneration has been arrested by a “failure of biology”. We hypothesized that arresting osteoblast cell proliferation after fracture would lead to atrophic nonunion in mice. Using mice that express a thymidine kinase (tk) “suicide gene” driven by the 3.6Col1a1 promoter (Col1-tk), proliferating osteoblast lineage cells can be ablated upon exposure to the nucleoside analog ganciclovir (GCV). Wild-type (WT; control) and Col1-tk littermates were subjected to a full femur fracture and intramedullary fixation at 12 weeks age. We confirmed abundant tk+ cells in fracture callus of Col-tk mice dosed with PBS. The remainder of mice were dosed with GCV twice daily for 2 or 4 weeks. Histologically, we observed diminished periosteal cell proliferation in Col1-tk mice 3 weeks post fracture. Moreover, Col1-tk mice had less osteoclast activity, mineralized callus, and vasculature at the fracture site compared to WT mice. Additional mice were monitored for 12 weeks with in vivo radiographs and microCT scans, revealing delayed bone bridging and reduced callus size in Col1-tk mice. Following sacrifice, ex vivo microCT and histology demonstrated failed union with residual bone fragments and fibrous tissue in Col1-tk mice. Biomechanical testing demonstrated a failure to recover torsional strength in Col1-tk mice, in contrast to WT. Our data indicates that suppression of proliferating osteoblast-lineage cells for at least 2 weeks after fracture blunts the formation and remodeling of a mineralized callus leading to a functional nonunion. We propose this as a new murine model of atrophic nonunion.

Download Full-text

Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of 2 different LCP systems

Tierärztliche Praxis Ausgabe G Großtiere / Nutztiere ◽

10.1055/a-1067-3819 ◽

2020 ◽

Vol 48 (01) ◽

pp. 25-34

Author(s):

Aleksandar Vidović ◽

Dorothea Jansen ◽

Stefan Schwan ◽

Alexander Goldstein ◽

Christopher Ludtka ◽

...

Keyword(s):

Ex Vivo ◽

Statistical Significance ◽

Biomechanical Testing ◽

Test System ◽

Proximal Interphalangeal Joint ◽

Interphalangeal Joint ◽

Test Model ◽

Locking Screws ◽

Cortical Screw ◽

The Alps

Abstract Objective This study compares the mechanical stability and surgical usability of 2 locking plate systems (Kyon ALPS-20 and Synthes PIP-LCP system) for arthrodesis of the equine proximal interphalangeal joint (PIJ). Material and methods The experimental ex vivo study included 6 pairs of cadaver distal limbs (n = 12). All specimens were derived from Warmblood horses of various ages that were euthanized for non-orthopedic reasons. Of the 12 limbs collected, 3 left and 3 right distal limb specimens were randomly assigned to each system for implantation. Two abaxial 4.5-mm cortical screws were inserted transarticularly in all cases. Both systems were implanted according to the manufacturer’s instructions with the plates placed centrally between the 2 transarticular screws. The ALPS-20 systems were implanted using Kyon B-6.4-mm monocortical locking screws in all positions. The LCP systems were implanted axially using 2 Synthes 5-mm locking screws in the proximal and distal positions, with a standard 4.5-mm cortical screw inserted in the middle position. All constructs underwent CT-scans after implantation and biomechanical testing to detect implant deformation. Uniaxial mechanical loading was applied via a servo-hydraulic test system at a test speed of 50 mm/s, up to a maximum displacement of 80 mm. The resulting load-displacement curves were used to calculate yield point, stiffness, and maximum force for each construct. The measured values were evaluated for statistical significance (p < 0.05) between the 2 plate systems via one-factor ANOVA (Tukey test). The statistical power was verified for yield force, stiffness, and maximum load. Results No statistically significant differences between the 2 preparation groups were calculated across all of the measured parameters (p > 0.05). The ALPS system implants showed no signs of deformation, either in the plates or the screws. In contrast, the LCP demonstrated visible deformation, which had already occurred at the time of implantation from the tightening of the middle screw, as well as during the subsequent testing of the implants. After biomechanical testing, deformations ranging between 3.1° and 7.0° were measured in 4 LCPs. A total implant failure was observed for 2 LCPs. Conclusion and clinical relevance Both systems demonstrated comparable mechanical properties in the present study’s ex vivo test model for equine PIJ arthrodesis. As such, the Kyon ALPS-20 may be a good alternative to the Synthes LCP for equine PIJ arthrodesis.

Download Full-text

In Situ and Ex Vivo Biomechanical Testing of Articular Cartilage

Experimental Methods in Orthopaedic Biomechanics ◽

10.1016/b978-0-12-803802-4.00021-4 ◽

2017 ◽

pp. 331-347

Author(s):

Joanna F. Weber ◽

Stephen D. Waldman

Keyword(s):

Articular Cartilage ◽

Ex Vivo ◽

Biomechanical Testing

Download Full-text

Functional assessment of the ex vivo vocal folds through biomechanical testing: A review

Materials Science and Engineering C ◽

10.1016/j.msec.2016.04.018 ◽

2016 ◽

Vol 64 ◽

pp. 444-453 ◽

Cited By ~ 17

Author(s):

Gregory R. Dion ◽

Seema Jeswani ◽

Scott Roof ◽

Mark Fritz ◽

Paulo G. Coelho ◽

...

Keyword(s):

Functional Assessment ◽

Ex Vivo ◽

Biomechanical Testing ◽

Vocal Folds

Download Full-text

Knotless Suture Anchors: A Comparative Biomechanical Study of Acetabular Rim Anchor Fixation with Implications for Hip Labral Repair

The Journal of Hip Surgery ◽

10.1055/s-0041-1729870 ◽

2021 ◽

Author(s):

Patrick D. Rowan ◽

James L. Cook ◽

Will A. Bezold ◽

Nathan W. Skelley

Keyword(s):

Failure Mode ◽

Suture Anchor ◽

Ex Vivo ◽

Biomechanical Testing ◽

Biomechanical Properties ◽

Biomechanical Study ◽

Labral Repair ◽

Suture Anchors ◽

Synthetic Bone ◽

Knotless Suture Anchor

AbstractThe purpose of this study was to analyze relevant initial-implantation biomechanical properties of five knotless suture anchors available for use in acetabular labral repair. Five knotless suture anchor constructs were tested: Arthrex PushLock 2.9, Arthrex PushLock 2.4, Arthrex SutureTak 3.0, Stryker CinchLock SS 2.4, and Stryker CinchLock Flex 2.4. Anchors were placed in synthetic bone blocks and in acetabular bone of cadaveric specimens. Constructs were subjected to cyclic and load-to-failure (LTF) testing. Displacement at 1, 100, 250, and 500 cycles, yield load, ultimate load, and failure mode were compared with statistically significant (p < 0.005) differences. PushLock 2.9 mm and CinchLock SS 2.4 anchor constructs had significantly less displacement than PushLock 2.4 mm after 1 cycle (p = 0.017) and 500 cycles (p = 0.043). Excluding “tare” displacement after the first cycle, all anchor constructs were associated with less than 2.0 mm of displacement after 500 cycles. Arthrex PushLock 2.4 and SutureTak 3.0 had the highest number of failures prior to completing cyclic loading. Arthrex PushLock 2.9 was associated with the highest LTF in cadaver (p = 0.00013) and synthetic (p = 0.009) bone models. Most common failure mode in cadaver bone was eyelet failure for all anchor types. Knotless suture anchors used for arthroscopic hip surgery (2.9 mm PushLock, 2.4 mm PushLock, 3.0 mm SutureTak, 2.4 mm CinchLock SS, and 2.4 mm CinchLock Flex) were associated with material properties that met or exceeded the reported thresholds for successful periarticular soft tissue repair surgeries. Based on cyclic and LTF testing in synthetic bone blocks and cadaveric acetabulums, 2.9 mm PushLocks and 2.4 mm CinchLock SS anchors may have potential biomechanical advantages over the other constructs tested. Further functional ex vivo and preclinical animal model studies are recommended to further characterize suture anchor constructs designed for acetabular labrum repair. These results provide novel and relevant biomechanical testing data that contribute to assessing knotless suture anchor constructs for use in acetabular labral repair.

Download Full-text