In Vitro Engineering of High Modulus Cartilage-Like Constructs.

To date, the outcomes of cartilage repair have been inconsistent and have frequently yielded mechanically inferior fibrocartilage, thereby increasing the chances of damage recurrence. Implantation of constructs with biochemical composition and mechanical properties comparable to natural cartilage could be advantageous for long-term repair. This study attempted to create such constructs, in vitro, using tissue engineering principles.

Enamel matrix derivative enhances tissue formation around scaffolds used for tissue engineering of ligaments.

The following in vitro translational study investigated whether enamel matrix derivative (EMD), an approved biomimetic treatment for periodontal disease (Emdogain) and hard-to-heal wounds (Xelma), enhanced synovial cell colonization and protein synthesis around a scaffold used clinically for in situ tissue engineering of the torn anterior cruciate ligament (ACL). Synovial cells were enzymatically extracted from bovine synovium and dynamically seeded onto polyethylene terephthalate (PET) scaffolds. The cells were cultured in low-serum medium (0.

The potential use of enamel matrix derivative for in situ anterior cruciate ligament tissue engineering: a translational in vitro investigation.

Polyester scaffolds have been used as an alternative to autogenous tissues for the reconstruction of the anterior cruciate ligament (ACL). They are biocompatible and encourage tissue infiltration, leading to neoligament formation. However, rupture can occur, caused by abrasion of the scaffold against the bone tunnels through which it is implanted.

Cyclic straining of cell-seeded synthetic ligament scaffolds: development of apparatus and methodology.

Cyclic tensile strains acting along a ligament implant are known to stimulate cells that colonize it to proliferate and to synthesize an extracellular matrix (ECM), which will then remodel and form a new ligament structure. However, this process of tissue induction is poorly understood. As a first step toward elucidating this process, we aimed to investigate the effect of cyclic tensile strain on the proliferation of, and possible ECM synthesis by, cells colonizing ligament scaffolds.

Deformation and failure of cartilage in the tensile mode.

The aim of this study was to visualize, at the ultrastructural level, the deformation and failure mechanism of cartilage matrix in the tensile mode. Full-thickness dumbbell-shaped specimens were prepared from adult bovines. There were two specimen groups; in the 'parallel' group the specimen axis was parallel to the split lines defining the preferential orientation of the collagen in the articular surface, and in the 'perpendicular' group the specimen axis was perpendicular to the split lines.

Effect of patellar tendon shortening on tracking of the patella.

Background: Although 10% postoperative patellar tendon shortening after bone-patellar tendon-bone autograft reconstruction of the anterior cruciate ligament has been reported, there are no published studies assessing the effect of shortening on patellofemoral joint biomechanics under physiological loading conditions.

Purpose: To investigate the influence of patellar tendon shortening on patellofemoral joint biomechanics.

Study Design: Controlled laboratory study.

Effect of cyclic tensile strain on proliferation of synovial cells seeded onto synthetic ligament scaffolds--an in vitro simulation.

Objective: Cyclic tensile strain is pivotal to the remodeling of tissue induced in implants used in reconstruction of anterior cruciate ligaments whether these implants were of autogenous tissues or synthetic materials. However, this process is poorly understood. The objective of this study was to investigate the short and medium-term effect of cyclic tensile strain on the proliferation of synovial cells seeded on ligament scaffolds.

Double-band reconstruction of the ACL using a synthetic implant: a cadaveric study of knee laxity.

In this study, the anterior laxity and internal rotation of five cadaveric knee joints were compared when the anterior cruciate ligament (ACL) was intact, after its reconstruction with the anteromedial band (AMB) only, then after its reconstruction with the double band, with the posterolateral band (PLB) tensioned first at 20 degrees and then at 90 degrees, and finally with the ACL resected. The tests were performed using a mechanical apparatus that allowed the joint 6 degrees of freedom and also the application of external loads and torques on the tibia. The loads used were 50, 90, and 130 N for the anterior laxity test, and a torque of 2, 3, and 4 Nm in the internal rotation test.

Comparative study of the covered area of Leeds-Keio (LK) artificial ligament and radio frequency generated glow discharge treated Leeds-Keio (Bio-LK) ligament with synovial cells.

The Leeds-Keio artificial ligament (LK), which was developed not only as a ligament substitute but also as a scaffold for tissue induction in knee ligament reconstruction, has been in clinical use since 1982 in Europe and Japan. Recently, we have developed radio frequency generated glow discharge (RFGD)-treated LK ligament (Bio-LK) to expedite the process of tissue induction and its maturation. In this study of cell adhesion to the scaffold, we report the difference in the covered area with synovial cells when using scaffolds made from treated and untreated materials.

Hydrostatic pressure modulates proteoglycan metabolism in chondrocytes seeded in agarose.

Objective: To investigate the effect of isolated hydrostatic pressure on proteoglycan metabolism in chondrocytes.

Methods: Bovine articular chondrocytes cultured in agarose gels were subjected to 5 MPa hydrostatic pressure for 4 hours in either a static or a pulsatile (1 Hz) mode, and changes in glycosaminoglycan (GAG) synthesis, hydrodynamic size, and aggregation properties of proteoglycans and aggrecan messenger RNA (mRNA) levels were determined.

Results: The application of 5 MPa static pressure caused a significant increase in GAG synthesis of 11% (P < 0.

Radiofrequency-generated glow discharge treatment: potential benefits for polyester ligaments.

This multicenter study has revealed that treating a woven polyethylene terephthalate (polyester) ligament with a radiofrequency (RF)-generated glow discharge (RFGD) produces marked benefits in terms of increased cell attachment and proliferation on the implant surface. In vitro tests of the same material revealed that the number of synovial fibroblasts attached to the treated samples after 14 days was four times that of the untreated material. Many of the cells were spread over the surface of a single filament, and some formed bridges between one filament and the next.

Upregulation of aggrecan and type II collagen mRNA expression in bovine chondrocytes by the application of hydrostatic pressure.

The aim of this study was to investigate the effect of hydrostatic pressure on the expression of messenger ribonucleic acid (mRNA) for specific extracellular matrix proteins in chondrocytes. Chondrocytes obtained from bovine metatarsophalangeal joints were embedded in cylindrical 2% agarose gels. A novel experimental system was used to apply 5 MPa of static hydrostatic pressure to these chondrocytes for 4 hours.

Tensile fatigue behaviour of articular cartilage.

Although fatigue has been implicated in cartilage failure there are only two studies by the same author, and in both of which cartilage was tested in the direction parallel to the collagen orientation in the surface layer. In the present work articular cartilage was tested also along the perpendicular direction, being the direction in which cartilage possesses lower tensile strength. Specimens were tested under cyclic tensile load.

Estimation of forces at the interface between an artificial limb and an implant directly fixed into the femur in above-knee amputees.

This article describes the method used for estimating the forces and moments, acting during locomotion, at the interface between an artificial leg and an implant directly fixed into the femur, in above-knee amputees. Twelve transfemoral amputees completed a predefined gait assessment during which kinetic (ground reaction loads and torque) and kinematic (limb orientation) gait data were recorded. A developed mathematical model enabled the ground reaction forces to be translated to the level of amputation.

The measurement of muscle stiffness in anterior cruciate injuries -- an experiment revisited.

OBJECTIVE: To investigate the reported changes in angular stiffness of the knee due to the hamstrings muscles in the anterior cruciate ligament (ACL) deficient knee. DESIGN: The flexors of the knee were modelled as springs and the model tested on patients and controls. BACKGROUND: A previous study had used a similar model but showed no difference between an ACL deficient and an uninjured knee.