Fig 2 - available from: BMC Musculoskeletal Disorders
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Background:
For focal cartilage defects, biological repair might be ineffective in patients over 45 years. A focal metallic implant (FMI) (Hemi-CAP Arthrosurface Inc., Franklin, MA, USA) was designed to reduce symptoms. The aim of this study was to evaluate the effects of a FMI on the opposing tibial cartilage in a biomechanical set-up. It is hypo...
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Osteoarthritis (OA) is a joint disease characterized by cartilage degeneration. Osteopontin (OPN) is involved in the initiation, repair, and maintenance of metabolic homeostasis in normal articular cartilage. This study investigated the role of OPN and its interaction with the integrin ανβ3 receptor in the expression of hyaluronic acid (HA) in OA c...
Citations
... However, in an in vitro study of fresh frozen porcine knees using an abrasion test machine, it was suggested that contact with HemiCAP Ò leads to opposing articular cartilage damage [16].When considering the contact pressure elicited by the device the material the implant is manufactured out of has to be considered as Koh et al demonstrated that the BioPoly Ò implant manufactured out of polyethylene showed lower contact stress in comparison to cobalt-chrome implants and hence could lead to a reduced risk of physiological damage to the articular cartilage [26]. It is also important to consider the quality of opposing cartilage when evaluating the performance of focal resurfacing implants as significant differences can be seen when comparing smooth to fibrillated cartilage on human cadaveric strips [14]. ...
... Diermeier et al. [62] investigated the effect of a focal metallic implant on the opposite cartilage in an abrasion machine. They focused on the damages of the zones of the articular cartilage of knees from young pigs. ...
... They focused on the damages of the zones of the articular cartilage of knees from young pigs. They found damages of the tangential and of the radial zone after 6 h [62]. ...
Background:
The coefficient of friction (CoF) serves as an indicator for the mechanical properties of natural and regenerated articular cartilage (AC). After tribological exposure, a height loss (HL) of the cartilage pair specimens can be measured. Our aim was to determine the CoF and HL of regenerated AC tissue and compare them with those of natural AC from non-operated joints and AC from joints where the regenerated tissues had been created after different treatments.
Methods:
In partial-thickness defects of the trochleae of the stifle joints of 60 Göttingen Minipigs, regenerated AC was created. In total, 40 animals received a Col I matrix, 20 laden with autologous chondrocytes, and 20 without. The defects of 20 animals were left empty. The healing periods were 24 and 48 weeks. A total of 10 not-operated animals, delivered the "external" control specimens. Osteochondral pins were harvested from defect and non-defect areas, the latter serving as "internal" controls. Using a pin-on-plate tribometer, we measured the CoF and the HL.
Results:
The CoF of the regenerated AC ranged from 0.0393 to 0.0688, and the HL, from 0.22 mm to 0.3 mm. The differences between the regenerated AC of the six groups and the "external" controls were significant. The comparison with the "internal" controls revealed four significant differences for the CoF and one for the HL in the operated groups. No differences were seen within the operated groups.
Conclusions:
The mechanical quality of the regenerated AC tissue showed inferior behavior with regard to the CoF and HL in comparison with natural AC. The comparison of regenerated AC tissue with AC from untreated joints was more promising than with AC from the treated joints.
Background:
Meniscal extrusion often persists after a medial meniscus root repair. If the meniscus is extruded, the function of the meniscus as a load-sharing device and secondary knee stabilizer is compromised.
Hypothesis:
It was hypothesized that repairing the meniscotibial ligament (MTL) would decrease meniscal extrusion in the settings of both an isolated MTL tear and a repaired medial meniscus root while also improving medial compartment contact mechanics.
Study design:
Controlled laboratory study.
Methods:
Ten fresh-frozen cadaveric knees (mean age, 50.5 years) were tested in 5 conditions: intact, MTL deficiency, MTL deficiency + posterior medial meniscus root deficiency, MTL deficiency + posterior medial meniscus root repair, and MTL tenodesis + posterior medial meniscus root repair. Specimens were mounted to a load frame that applied a 1000-N axial load. Joint contact pressures were measured using thin pressure sensors, and the peak and mean pressures were analyzed. Ultrasound was used to measure meniscal extrusion.
Results:
The MTL tear in isolation resulted in significant meniscal extrusion compared with the intact state (P = 0.035) without a detectable difference in medial compartment pressures. The addition of a root tear to the MTL tear state resulted in significantly more extrusion (P = 0.001) and significant increases in medial compartment pressure (P = .030) compared to the MTL tear state. Root repair alone restored extrusion, mean contact pressure, and peak contact pressure back to the intact state (P > .05).
Conclusion:
This study showed that MTL disruption led to increased meniscal extrusion in a cadaveric model. Unlike the root tear state, MTL disruption did not change contact mechanics. Furthermore, root repair alone was sufficient in restoring intact biomechanics and extrusion.
Clinical relevance:
This study may help clinicians understand the origin of medial meniscus root tears and aid in the decision-making process for whether to add an MTL tenodesis in the setting of root repair.
To enable long lasting osteochondral defect repairs which preserve the native function of synovial joint counter-face, it is essential to develop surfaces which are optimised to support healthy cartilage function by providing a hydrated, low friction and compliant sliding interface. PEEK surfaces were modified using a biocompatible 3-sulfopropyl methacrylate potassium salt (SPMK) through UV photo-polymerisation, resulting in a ∼350 nm thick hydrophilic coating rich in hydrophilic anionic sulfonic acid groups. Characterisation was done through Fourier Transformed Infrared Spectroscopy, Focused Ion Beam Scanning Electron Microscopy, and Water Contact Angle measurements. Using a Bruker UMT TriboLab, bovine cartilage sliding tests were conducted with real-time strain and shear force measurements, comparing untreated PEEK, SPMK functionalised PEEK (SPMK-g-PEEK), and Cobalt Chrome Molybdenum alloy. Tribological tests over 2.5 h at physiological loads (0.75 MPa) revealed that SPMK-g-PEEK maintains low friction (μ< 0.024) and minimises equilibrium strain, significantly reducing forces on the cartilage interface. Post-test analysis showed no notable damage to the cartilage interfacing against the SPMK functionalised surfaces. The application of a constitutive biphasic cartilage model to the experimental strain data reveals that SPMK surfaces increase the interfacial permeability of cartilage in sliding, facilitating fluid and strain recovery. Unlike previous demonstrations of sliding-induced tribological rehydration requiring specific hydrodynamic conditions, the SPMK-g-PEEK introduces a novel mode of tribological rehydration operating at low speeds and in a stationary contact area. SPMK-g-PEEK surfaces provide an enhanced cartilage counter-surface, which provides a highly hydrated and lubricious boundary layer along with supporting biphasic lubrication. Soft polymer surface functionalisation of orthopaedic implant surfaces are a promising approach for minimally invasive synovial joint repair with an enhanced bioinspired polyelectrolyte interface for sliding against cartilage. These hydrophilic surface coatings offer an enabling technology for the next generation of focal cartilage repair and hemiarthroplasty implant surfaces.
Cartilage defects occur frequently and can lead to osteoarthritis. Hydrogels are a promising regenerative strategy for treating such defects, using their ability of mimicking the native extracellular matrix. However, commonly used hydrogels for tissue regeneration are too soft to resist load-bearing in the joint. To overcome this, an implant is being developed in which the mechanical loadbearing function originates from the osmotic pressure generated by the swelling potential of a charged hydrogel, which is restricted from swelling by a textile spacer fabric. This study aims to quantify the relationship between the swelling potential of the hydrogel and the compressive stiffness of the implant.
The friction and wear behaviors of cartilage replacement materials against articular cartilage are considered essential characteristics that determine the function and performance of the replacement. Previous studies have often been conducted under a reciprocal linear motion, while a cross-shear motion has been shown to widely exist in joints. The difference resulting between cross-shear motion and reciprocal linear motion, and the effect of bearing surface roughness on the frictional and wear behaviors of cartilage should be further investigated. In this study, experimental tribology investigations were conducted under the cross-shear motion for articular cartilage against commonly used three replacement materials, including high cross-linked polyethylene (HXLPE), polyether ether ketone (PEEK), and cobalt-chromium molybdenum alloy (CoCrMo). The experimental results showed that there was no significant difference in friction and wear behavior between cross-shear and reciprocal linear motion. For the implants with low surface roughness, the water contact angle of the bearing surface affected the friction and wear behaviors of the cartilage, while for the implants with high rough surfaces, the surface roughness of the material affected the friction and wear behaviors of the cartilage. The damage of cartilage under cross-shear motion mainly consisted of deformations and accumulations. This phenomenon was especially evident at high roughness. Of the three bearing materials considered, PEEK was more suitable for osteochondral implants.
The repair of a cartilage lesion with a hydrogel requires a method for long‐term fixation of the hydrogel in the defect site. Attachment of a hydrogel to a base that allows for integration with bone can enable long‐term fixation of the hydrogel, but current methods of forming bonds to hydrogels have less than a tenth of the shear strength of the osteochondral junction. This communication describes a new method, nanofiber‐enhanced sticking (NEST), for bonding a hydrogel to a base with an adhesive shear strength three times larger than the state‐of‐the‐art. An example of NEST is described in which a nanofibrous bacterial cellulose sheet is bonded to a porous base with a hydroxyapatite‐forming cement followed by infiltration of the nanofibrous sheet with hydrogel‐forming polymeric materials. This approach creates a mineralized nanofiber bond that mimics the structure of the osteochondral junction, in which collagen nanofibers extend from cartilage into a mineralized region that anchors cartilage to bone.
