Considerations on the animal model and the biomechanical test arrangements for assessing the osseous integration of orthopedic and dental implants.

In implant research, a central objective is to optimize the osseous integration of implants according to their function and scope of application. In the preclinical stage, the animal model is commonly used to study implants for in vivo host tissue response and biomechanical tests are a frequently applied method for characterization of contact phenomena. However, the individual parameters and options for both the animal model and the biomechanical test arrangements vary widely, which can negatively affect the reliability and comparability of the results.

Osseointegration of a novel 3D porous Ti-6Al-4V implant material - Histomorphometric analysis in rabbits.

Porous structure properties are known to conduct initial and long-term stability of titanium alloy implants. This study aims to assess the histomorphometric effect of a 3-D porosity in Ti-6Al-4V implants (PI) on osseointegration in comparison to solid Ti-6Al-4V implants (SI). The PI was produced in a spaceholder method and sintering and has a pore size of mean 400 µm (50 µm to 500 µm) and mimics human trabecular bone.

Sequential osseointegration from osseohealing to osseoremodeling - Histomorphological comparison of novel 3D porous and solid Ti-6Al-4V titanium implants.

In the present study, we analyzed the histological characteristics of osseointegration of an open-porous Ti-6Al-4V material that was produced in a space holder method creating a 3-D through-pores trabecular design that mimics the inhomogeneity and size relationships of trabecular bone in macro- as well as microstructure. Pairs of cylindrical implants with a porosity of 49 % and an average pore diameter of 400 µm (PI) or equal sized solid, corundum blasted devices (SI) as reference were bilaterally implanted press fit in the lateral condyles of 16 rabbits. Histological examination was performed after 4 weeks of short-term osseohealing and 12 weeks of mid-term osseoremodeling and we summarized the criteria for sequential osseointegration.

Biomechanical evaluation of self-cinching stitch techniques in rotator cuff repair: The single-loop and double-loop knot stitches.

In rotator cuff repair, strong and reliable suturing is necessary to decrease failure rates. The biomechanics of two self-cinching stitches - the single-loop knot stitch (SLKS) and the double-loop knot stitch (DLKS) - and the modified Mason-Allen stitch (mMAS) were compared. Twenty-seven porcine infraspinatus tendons were randomized among the three stitches.

Osseointegration of 3D porous and solid Ti-6Al-4V implants - Narrow gap push-out testing and experimental setup considerations.

Porosity in titanium alloy materials improves the bony integration and mechanical properties of implants. In certain areas of application such as vertebral spacers or trabecular bone replacement (e.g.

Comparison of the double loop knot stitch and Kessler stitch for Achilles tendon repair: A biomechanical cadaver study.

Tendon elongation after Achilles tendon (AT) repair is associated with the clinical outcome. Reliable suture techniques are essential to reduce gap formations and to allow early mobilization. Cyclic loading conditions represent the repetitive loading in rehabilitation.

The induction of CXCR4 expression in human osteoblast-like cells (MG63) by CoCr particles is regulated by the PLC-DAG-PKC pathway.

Background: Osteolysis which leads to aseptic loosening of implants is a fundamental problem in joint replacement surgery (arthroplasty) and the leading cause for implant failure and revision surgery. Metal (CoCr) particles separated from implants by wear cause osteolysis and the failure of orthopedic implants, but the molecular mechanism is not clear. The chemokine receptor CXCR4 has been shown to play a pivotal role in periprosthetic osteolysis.

Release of zirconia nanoparticles at the metal stem-bone cement interface in implant loosening of total hip replacements.

Unlabelled: In a previous failure analysis performed on femoral components of cemented total hip replacements, we determined high volumes of abraded bone cement. Here, we describe the topography of the polished surface of polymethyl methacrylate (PMMA) bone cement containing zirconia radiopacifier, analyzed by scanning electron microscopy and vertical scanning interferometry. Zirconia spikes protruded about 300nm from the PMMA matrix, with pits of former crystal deposition measuring about 400nm in depth.

Metallic debris from metal-on-metal total hip arthroplasty regulates periprosthetic tissues.

The era of metal-on-metal (MoM) total hip arthroplasty has left the orthopaedic community with valuable insights and lessons on periprosthetic tissue reactions to metallic debris. Various terms have been used to describe the tissue reactions. Sometimes the nomenclature can be confusing.

Metallic wear debris may regulate CXCR4 expression in vitro and in vivo.

CXCR4, the chemokine receptor for CXCL12, also known as SDF-1 (stromal cell derived factor-1), has been shown to play a pivotal role in bone metastasis, inflammatory, and autoimmune conditions but has not been investigated in periprosthetic osteolysis. We co-cultured osteoblast-like cells with increasing concentrations of metallic (Co-35Ni-20Cr-10Mo and Co-28Cr-6Mo) and Co-ions simulating wear debris. Real-time polymerase chain reaction (RT-PCR) and Western blotting were used to quantify gene and protein expression of CXCR4.

Interface abrasion between rough surface femoral stems and PMMA cement results in extreme wear volumes--a retrieval study and failure analysis.

During the loosening cascade of cemented rough femoral stems, the destruction of the mantle and the production of cement and metal wear debris occur after the loss of constraint at the interface. Two-dimensional (2D) measurements (light microscopy based morphometry on fragments of mantles and vertical scanning interferometry of femoral stems) permitted mathematical 3D-extrapolations to estimate the wear volumes. Fragments of the cement mantles available lost volumes from 0.

Novel single-loop and double-loop knot stitch in comparison with the modified Mason-Allen stitch for rotator cuff repair.

Purpose: In rotator cuff repair, strong and long-lasting suturing techniques that do not require additional implants are needed. This study examines the ultimate load to failure and the Young's modulus at the suture-tendon interface for a novel single-loop knot stitch and double-loop knot stitch. These values are compared to those of the modified Mason-Allen stitch.

Biomechanical and magnetic resonance imaging evaluation of a single- and double-row rotator cuff repair in an in vivo sheep model.

Purpose: To investigate the biomechanical and magnetic resonance imaging (MRI)-derived morphologic changes between single- and double-row rotator cuff repair at different time points after fixation.

Methods: Eighteen mature female sheep were randomly assigned to either a single-row treatment group using arthroscopic Mason-Allen stitches or a double-row treatment group using a combination of arthroscopic Mason-Allen and mattress stitches. Each group was analyzed at 1 of 3 survival points (6 weeks, 12 weeks, and 26 weeks).

Factory-assembled polyethylene linings in metal backing show higher wear rates compared to equisized all-polyethylene sockets.

Two series of cementless total hip arthroplasty with acetabular sockets of a threaded truncated cone design were compared regarding volumetric wear rates. The first series included all-polyethylene acetabular sockets of the type Endler (E-PE); in the second series, a nonmodular titanium metal-backed polyethylene (E-MB) socket with an identical outer shape to E-PE was implanted. Bearings were articulated with alumina 32-mm diameter ball heads.

Initial load-to-failure and failure analysis in single- and double-row repair techniques for rotator cuff repair.

Aim: This experimental study aimed to compare the load-to-failure rate and stiffness of single- versus double-row suture techniques for repairing rotator cuff lesions using two different suture materials. Additionally, the mode of failure of each repair was evaluated.

Method: In 32 sheep shoulders, a standardized tear of the infraspinatus tendon was created.

Tendon-bone contact pressure and biomechanical evaluation of a modified suture-bridge technique for rotator cuff repair.

The aim of the study was to evaluate the time-zero mechanical and footprint properties of a suture-bridge technique for rotator cuff repair in an animal model. Thirty fresh-frozen sheep shoulders were randomly assigned among three investigation groups: (1) cyclic loading, (2) load-to-failure testing, and (3) tendon-bone interface contact pressure measurement. Shoulders were cyclically loaded from 10 to 180 N and displacement to gap formation of 5- and 10-mm at the repair site.

Magnetic resonance imaging evaluation of intervertebral test spacers: an experimental comparison of magnesium versus titanium and carbon fiber reinforced polymers as biomaterials.

Introduction: Intervertebral spacers are made of different materials, which can affect the postfusion magnetic resonance imaging (MRI) scans. Susceptibility artifacts, especially for metallic implants, can decrease the image quality. This study aimed to determine whether magnesium as a lightweight and biocompatible metal is suitable as a biomaterial for spinal implants based on its MRI artifacting behavior.

Artifacts in spine magnetic resonance imaging due to different intervertebral test spacers: an in vitro evaluation of magnesium versus titanium and carbon-fiber-reinforced polymers as biomaterials.

Introduction: Intervertebral spacers are made of different materials, which can affect the postfusion magnetic imaging (MRI) scans. Susceptibility artifacts especially for metallic implants can decrease the image quality. This study aimed to determine whether magnesium as a lightweight and biocompatible metal is suitable as a biomaterial for spinal implants based on its MRI artifacting behavior.

Biomechanical characteristics of single-row repair in comparison to double-row repair with consideration of the suture configuration and suture material.

The aim of the study was to evaluate the time zero mechanical properties of single- versus double-row configuration for rotator cuff repair in an animal model with consideration of the stitch technique and suture material. Thirty-two fresh-frozen sheep shoulders were randomly assigned to four repair groups: suture anchor single-row repair coupled with (1) braided, nonabsorbable polyester suture sized USP No. 2 (SRAE) or (2) braided polyblend polyethylene suture sized No.

Biomechanical evaluation of rotator cuff repairs in a sheep model: suture anchors using arthroscopic Mason-Allen stitches compared with transosseous sutures using traditional modified Mason-Allen stitches.

Background: The optimal method for rotator cuff repair of the shoulder is not yet known. The aim of this study was to compare the time-dependent biomechanical properties of the traditional open transosseous suture technique and modified Mason-Allen stitches (group 1) versus the double-loaded suture anchors technique and so-called arthroscopic Mason-Allen stitches (group 2) in rotator cuff repair.

Methods: Eighteen adult female sheep were randomized into two groups: in an open approach in which the released infraspinatus tendon was repaired with group 1, and with group 2.

In-vitro MRI detectability of interbody test spacers made of carbon fibre-reinforced polymers, titanium and titanium-coated carbon fibre-reinforced polymers.

The purpose of this study was to investigate how different materials affect the magnetic resonance imaging (MRI) detectability of interbody test spacers (ITS). We evaluated the post-implantation MRI scans with T1 TSE sequences for three different ITS made of titanium, carbon fibre-reinforced polymers (CFRP) and titanium-coated CFRP, respectively. The main target variables were total artefact volume (TAV) and median artefact area (MAA).

Preclinical evaluation by flat-panel detector-based volumetric CT versus MRI of intervertebral spacers implanted in a porcine model.

Background Context: Image quality and implant detectability by conventional imaging methods are suboptimal for perioperative spinal diagnostics, primarily limited by implant-related artifacts.

Purpose: To evaluate the imaging quality of various intervertebral spacers examined by flat-panel detector-based volumetric computed tomography (FD-VCT) versus magnetic resonance imaging (MRI).

Study Design/setting: A preclinical comparative study on an experimental porcine model.

Postimplantation MRI with cylindric and cubic intervertebral test implants: evaluation of implant shape, material, and volume in MRI artifacting--an in vitro study.

Background Context: Interbody spacers for anterior spine fusion are made of different materials, which can affect the postfusion magnetic resonance imaging (MRI) scans. Susceptibility artifacts specially for metallic implants can decrease the image quality.

Purpose: This study focused on the influence of determined implant parameters like shape, implant volume, and implant material in MRI artifacting with regard to solid geometrical titanium and carbon test spacers.

Biomechanical comparison of double-loaded suture anchors using arthroscopic Mason-Allen stitches versus traditional transosseous suture technique and modified Mason-Allen stitches for rotator cuff repair.

Background: In recent studies objective evaluations have demonstrated that arthroscopic rotator cuff repairs can have higher failure rates than open repairs. Thus, there is a need for a stronger tissue-holding stitch for arthroscopical repair. The purpose of this study was to compare the biomechanical properties of traditional open transosseous suture technique and modified Mason-Allen stitches versus double-loaded suture anchors and arthroscopic Mason-Allen stitches in rotator cuff repair.