Regional Variation in the Mechanical and Microstructural Properties of the Human Anterior Cruciate Ligament

Skelley, Nathan W.; Castile, Ryan M.; Cannon, Paul C.; Weber, C.; Brophy, Robert H.; Lake, Spencer P.

doi:10.1177/0363546516654480

Cited by 24 publications

(32 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The scaffolds investigated in this work represent a hierarchal construct that mimics the structure of the native human ACL using sheets of aligned nanofibers prepared using a standard electrospinning technique. By rolling rectangular sections of the electrospun nanofiber sheets to create nanofiber bundles it creates a robust structure which supports cell growth and proliferation, cell elongation, and has material properties that are comparable to the properties of the native human ACL [16][17][18] . Other have attempted to use stacked PCL sheets for ACL replacement and while transient immune responses were noted 15 , they subsided and the potential for heparin mediated growth factor release was noted, as a technique for further encouraging de novo extracellular matrix deposition 35,36 .…”

Section: Discussionmentioning

confidence: 99%

“…These cylindrical "nanofiber bundles" are approximately 500 µm in diameter and are composed of nanofibers aligned along the longitudinal axis that mimic the native ACL structure. Nanofiber bundles are able to support short term cell growth and elongated cell morphology and have material properties that are comparable to that of the native human ACL [16][17][18] . The smallest functional units of the ACL are collagen fibrils that range in size from 50-500 nm and are primarily oriented parallel to the longitudinal axis 19,20 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

^{Hierarchically Structured Electrospun Scaffolds with Chemically Conjugated Growth Factor for Ligament Tissue Engineering}

Sathy

Olvera

McCarthy

et al. 2017

Tissue Engineering Part A

View full text Add to dashboard Cite

The anterior cruciate ligament (ACL) of the knee is vital for proper joint function and is commonly ruptured during sports injuries or car accidents. Due to a lack of intrinsic healing capacity and drawbacks with allografts and autografts, there is a need for a tissue engineered ACL replacement. Our group has previously used aligned sheets of electrospun polycaprolactone nanofibers to develop solid cylindrical bundles of longitudinally aligned nanofibers. We have shown that these nanofiber bundles support cell proliferation and elongation and the hierarchical structure and material properties are similar to the native human ACL. It is possible to combine multiple nanofiber bundles to create a scaffold that attempts to mimic the macro-scale structure of the ACL. The goal of this work was to develop a hierarchical bioactive scaffold for ligament tissue engineering using connective tissue growth factor (CTGF) conjugated nanofiber bundles and evaluate the behavior of mesenchymal stem cells (MSCs) on these scaffolds in vitro and in vivo. CTGF was immobilized onto the surface of individual nanofiber bundles or scaffolds consisting of multiple nanofiber bundles. The conjugation efficiency and the release of conjugated CTGF was assessed using X-ray photoelectron spectroscopy, assays, and immunofluorescence staining. Scaffolds were seeded with MSCs and maintained in vitro for 7 days (individual nanofiber bundles), in vitro for 21 days (scaled-up scaffolds of 20 nanofiber bundles) or in vivo for 6 weeks (small scaffolds of 4 nanofiber bundles) and ligament specific tissue formation was assessed in comparison to non-CTGF conjugated control scaffolds. Results showed that CTGF conjugation encouraged cell proliferation and ligament specific tissue formation in vitro and in vivo. The results suggest that hierarchical electrospun nanofiber bundles conjugated with CTGF are a scalable and bioactive scaffold for ACL tissue engineering.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

^{Hierarchically Structured Electrospun Scaffolds with Chemically Conjugated Growth Factor for Ligament Tissue Engineering}

Sathy

Olvera

McCarthy

et al. 2017

Tissue Engineering Part A

View full text Add to dashboard Cite

show abstract

“…The structural stiffness results suggest that the structural stiffness of an individual band may different at different flexion angles. The result of different portions of a ligament displaying different mechanical properties has been achieved before . For the current work, this could be a result of many factors, one being the difference in alignment between the long axis of the ligament and the loading direction (Fig.…”

Section: Discussionmentioning

confidence: 54%

Correlation of Force to Deformation of the Anterior Bundle of the Medial Collateral Ligament Through Consideration of Band Laxity

Jordan

Schimoler

Kharlamov

et al. 2019

Journal Orthopaedic Research

View full text Add to dashboard Cite

The anterior bundle of the medial collateral ligament (AMCL) resists the loads that arise at the elbow during overhand throwing and has commonly been divided into posterior and anterior bands. While these anterior and posterior bands have been thought to bear the load at different flexion angles, any transition of the load distribution between the two bands is poorly understood and has not considered laxity (slack). This study considers the AMCL as three bands and quantifies the mechanical response to vertical distraction, simulating valgus-load joint opening, through the sequential superposition of the band responses after the elimination of inherent laxity. Eight cadaveric elbow specimens were used for the study. The intact AMCL of each specimen was tested under vertical distraction in a specialized load frame at four elbow flexion angles and then subsequently retested after two longitudinal transections. The greatest laxity at full extension and full flexion belonged to the posterior (1.9 mm) and anterior (2.4 mm) band, respectively. At the lesser and higher flexion angles, the greatest structural stiffness belonged to the anterior and middle band. The overall AMCL was the most structurally stiff at 60°, with approximately 150 N of force required for 2% elongation. This study shows that the different bands of the AMCL may have different load bearing properties at different flexion angles, causing each band to support different proportions of an imposed load. The presence of the laxity may impose a load-bearing delay, causing load-bearing in each band to begin asynchronously.

show abstract

“…Strains were determined using the original graft length. Using a least squares method, a bilinear curve fit was applied to the force‐displacement data to quantify the stiffness in the toe and linear regions, as well as force, displacement, and strain values corresponding to the transition point of the bilinear fit

y = {A x}^{B} + C

…”

Section: Methodsmentioning

confidence: 99%

Mechanical properties of a hierarchical electrospun scaffold for ovine anterior cruciate ligament replacement

Kelly

Popat

Easley

et al. 2019

Journal Orthopaedic Research

View full text Add to dashboard Cite

The anterior cruciate ligament (ACL) acts to stabilize the knee and prevent excessive motion of the tibia relative to the femur. Tears of the ACL are common and can result in pain and damage to surrounding tissues. Thus a torn ACL is often surgically replaced with an autograft or allograft material. Drawbacks to clinically available ACL grafts motivate the development of a tissue engineered ACL replacement. Our group has previously developed a polycaprolactone electrospun scaffold that mimics the hierarchical structure of the ACL. The goal of this study was to investigate the mechanical properties of the electrospun scaffold as an ACL replacement. Scaffold mechanical properties were assessed prior to implantation via stress relaxation and pull to failure testing. Following in vitro characterization, electrospun scaffolds and soft tissue grafts were implanted into ovine cadaver stifle joints as ACL replacements. Stifle joints with ACL replacements were tested via a simulated anterior drawer test as well as in situ stress relaxation and pull to failure tests and compared to stifle joints with the native ACL intact. Prior to implantation the scaffold matched the native ovine ACL well in the range of functional strains as evidenced by stress relaxation measures and the toe region stiffness. After implantation the scaffold was more similar to the native ACL than the soft tissue graft, particularly when it came to reducing joint laxity and matching stress relaxation measures. These results demonstrate that the electrospun scaffold has the potential to be a suitable material for ACL replacement. ß

show abstract

Regional Variation in the Mechanical and Microstructural Properties of the Human Anterior Cruciate Ligament

Abstract: This AM-to-PL variation provides a more accurate description of functional tissue anatomy and can be used to assess and guide techniques of ACL reconstruction.

Cited by 24 publications

References 24 publications

^{Hierarchically Structured Electrospun Scaffolds with Chemically Conjugated Growth Factor for Ligament Tissue Engineering}

^{Hierarchically Structured Electrospun Scaffolds with Chemically Conjugated Growth Factor for Ligament Tissue Engineering}

Correlation of Force to Deformation of the Anterior Bundle of the Medial Collateral Ligament Through Consideration of Band Laxity

Mechanical properties of a hierarchical electrospun scaffold for ovine anterior cruciate ligament replacement

Contact Info

Product

Resources

About