Periodic Reporting for period 3 - MEFISTO (MEFISTO - Meniscal functionalised scaffold to prevent knee Osteoarthritis onset after meniscectomy)
Reporting period: 2022-06-01 to 2024-05-31
Meniscal injuries are one of the most common orthopaedic disorders with increasing incidence due to active lifestyles across all age groups. Current treatments, including meniscal repair and replacement, are limited. While meniscectomy (the removal of a damaged meniscus) has been a preferred approach, the meniscus-deficient knee has been associated with poor clinical outcomes and progression to osteoarthritis (OA). This is especially challenging for younger, active patients as this may lead to early knee replacements.
MEFISTO aims to prevent post-meniscectomy OA by developing innovative approaches using bioactive, functionalised materials to treat meniscal loss. The specific objectives include creating 2 solutions for treatment of meniscal loss, a predictive treatment algorithm based on morphological profiling of meniscectomized patients, and analysis of the socio-economic impact of the meniscus solutions. The treatment solutions focus on a bioactive degradable scaffold for younger patients and a non-degradable implant with drug delivery for older patients with advanced knee OA.
MEFISTO aims to prevent post-meniscectomy OA by developing innovative approaches using bioactive, functionalised materials to treat meniscal loss. The specific objectives include creating 2 solutions for treatment of meniscal loss, a predictive treatment algorithm based on morphological profiling of meniscectomized patients, and analysis of the socio-economic impact of the meniscus solutions. The treatment solutions focus on a bioactive degradable scaffold for younger patients and a non-degradable implant with drug delivery for older patients with advanced knee OA.
For the morphological profiling of meniscectomized patients clinical and MRI data were collected from 120 asymptomatic (low-risk) and 120 symptomatic (high-risk) patients. 240 accurate 3D post-meniscectomy knee models were created from manually segmented MRI scans. Neural networks were trained to perform automatic segmentation of bone and cartilage from MRI scans. Landmark identification on the distal femur and proximal tibia was automated and validated. Statistical shape models were also used to characterize patient-specific bone morphology.
A pilot finite element (FE) model investigated the relationship between bone shape and contact force in the knee. FE simulations performed under static loading on two previously defined extreme knee morphotypes (wide versus small medial femoral condyle) showed differences in stress and strain patterns within the cartilaginous tissues for different meniscus configurations.
A morphology-based predictive algorithm for partial meniscectomy response was developed and an impressive accuracy in identifying medial post-meniscectomy syndrome at two years post-surgery was achieved.
For the design and production of a bioactive, degradable, meniscal scaffold, several approaches were taken. A collagen bio-ink was selected for 3D printing of collagen scaffold samples and a human-sized medial meniscus collagen implant. Post-processing of the printed collagen scaffolds was established, and printability was optimized for porosity and a dual-zone meniscus structure. Functionalization of the 3D printed collagen scaffold was achieved with peptide complexes and drugs that modulate angiogenesis and stem cell response. The active compounds were incorporated into the 3D printed collagen scaffolds in a zone-dependent manner, mimicking the anisotropic meniscus structure.
The 3D-printed dual-zone meniscus collagen implant required reinforcement for suturing which was done by embedding polymer structures in the printed collagen scaffold or wrapping the scaffold with a collagen membrane. Handling and suture pull-out tests indicated that polymeric reinforcement of the scaffold was insufficient, thus the dual-zone approach was abandoned, and the collagen membrane was used for reinforcement. Post-processing and X-ray sterilization were followed by physicochemical and mechanical characterization of the 3D printed and reinforced collagen menisci as well as on the neat and functionalized 3D-printed collagen samples. In vitro tests evaluated cell infiltration and survival and the efficacy of the functionalizing compounds. Handling tests of the human-sized 3D printed reinforced menisci in a human cadaver knee showed that the size and shape of the meniscus prototypes could be adapted to fit a human meniscus, but the prototypes were considered inadequate because the collagen membrane delaminated, and the pore size was too small.
This led to a change in manufacturing method from 3D printing to casting the collagen scaffold from collagen slurry. The casted scaffold was reinforced with a collagen membrane and re-characterized. Mechanical test results were similar to those seen for the 3D printed collagen samples, but larger pore size and no delamination were observed. The casted collagen scaffolds were functionalized using the two methods and an appropriate number of neat and functionalized sterile samples were prepared for the rabbit study.
The non-biodegradable meniscal implant made from medical grade PCU, was manufactured by injection molding. Functionalization of the PCU implant involved a drug-releasing polymer coating. The surface area of the PCU structure was modified to increase the amount of drug loaded into the bulk material. In-vitro testing assessed immunotoxicology, biocompatibility and efficacy of the PCU implants with and without functionalization and showed delamination of the polymer coating from the PCU substrate that was improved by plasma treatment of the PCU surface.
For in vivo testing in animals, two pilot studies were conducted in sheep. The first pilot study revealed issues with screw fixation of the implants to the tibial plateau and coating delamination that required further optimization of the plasma treatment and applying an additional adhesion layer to the coating. An alternative process for functionalization of the PCU meniscus implant by dendrimers was developed to inhibit macrophage activation and promote stem cell adhesion and differentiation. Implant fixation was improved by adding long fibers for transtibial fixation. A portion of additionally manufactured implants was functionalized with the drug coating whilst the other portion was coated with dendrimers. The 2nd pilot study confirmed sufficient implant fixation and coating adhesion.
For the final sheep study, PCU implants and surgical technique were tested in a sheep cadaver knee. Specific packaging to avoid contamination of the functionalized implants was developed and sterile implants were provided for implantation. Surgeries were completed on four groups of sheep: a meniscectomy group, a group with uncoated implants, a group with anti-inflammatory coating, and a group with dendrimer coating. Follow-up is ongoing.
Assessment of the expected project impact was based on specific Key Performance Indicators derived from stakeholder engagement and the socio-economic impact of the two MEFISTO solutions was analyzed using a cost-effectiveness model. Dissemination of the project is ongoing and an educational TV-like documentary series with 3 episodes on meniscus topics was produced.
A pilot finite element (FE) model investigated the relationship between bone shape and contact force in the knee. FE simulations performed under static loading on two previously defined extreme knee morphotypes (wide versus small medial femoral condyle) showed differences in stress and strain patterns within the cartilaginous tissues for different meniscus configurations.
A morphology-based predictive algorithm for partial meniscectomy response was developed and an impressive accuracy in identifying medial post-meniscectomy syndrome at two years post-surgery was achieved.
For the design and production of a bioactive, degradable, meniscal scaffold, several approaches were taken. A collagen bio-ink was selected for 3D printing of collagen scaffold samples and a human-sized medial meniscus collagen implant. Post-processing of the printed collagen scaffolds was established, and printability was optimized for porosity and a dual-zone meniscus structure. Functionalization of the 3D printed collagen scaffold was achieved with peptide complexes and drugs that modulate angiogenesis and stem cell response. The active compounds were incorporated into the 3D printed collagen scaffolds in a zone-dependent manner, mimicking the anisotropic meniscus structure.
The 3D-printed dual-zone meniscus collagen implant required reinforcement for suturing which was done by embedding polymer structures in the printed collagen scaffold or wrapping the scaffold with a collagen membrane. Handling and suture pull-out tests indicated that polymeric reinforcement of the scaffold was insufficient, thus the dual-zone approach was abandoned, and the collagen membrane was used for reinforcement. Post-processing and X-ray sterilization were followed by physicochemical and mechanical characterization of the 3D printed and reinforced collagen menisci as well as on the neat and functionalized 3D-printed collagen samples. In vitro tests evaluated cell infiltration and survival and the efficacy of the functionalizing compounds. Handling tests of the human-sized 3D printed reinforced menisci in a human cadaver knee showed that the size and shape of the meniscus prototypes could be adapted to fit a human meniscus, but the prototypes were considered inadequate because the collagen membrane delaminated, and the pore size was too small.
This led to a change in manufacturing method from 3D printing to casting the collagen scaffold from collagen slurry. The casted scaffold was reinforced with a collagen membrane and re-characterized. Mechanical test results were similar to those seen for the 3D printed collagen samples, but larger pore size and no delamination were observed. The casted collagen scaffolds were functionalized using the two methods and an appropriate number of neat and functionalized sterile samples were prepared for the rabbit study.
The non-biodegradable meniscal implant made from medical grade PCU, was manufactured by injection molding. Functionalization of the PCU implant involved a drug-releasing polymer coating. The surface area of the PCU structure was modified to increase the amount of drug loaded into the bulk material. In-vitro testing assessed immunotoxicology, biocompatibility and efficacy of the PCU implants with and without functionalization and showed delamination of the polymer coating from the PCU substrate that was improved by plasma treatment of the PCU surface.
For in vivo testing in animals, two pilot studies were conducted in sheep. The first pilot study revealed issues with screw fixation of the implants to the tibial plateau and coating delamination that required further optimization of the plasma treatment and applying an additional adhesion layer to the coating. An alternative process for functionalization of the PCU meniscus implant by dendrimers was developed to inhibit macrophage activation and promote stem cell adhesion and differentiation. Implant fixation was improved by adding long fibers for transtibial fixation. A portion of additionally manufactured implants was functionalized with the drug coating whilst the other portion was coated with dendrimers. The 2nd pilot study confirmed sufficient implant fixation and coating adhesion.
For the final sheep study, PCU implants and surgical technique were tested in a sheep cadaver knee. Specific packaging to avoid contamination of the functionalized implants was developed and sterile implants were provided for implantation. Surgeries were completed on four groups of sheep: a meniscectomy group, a group with uncoated implants, a group with anti-inflammatory coating, and a group with dendrimer coating. Follow-up is ongoing.
Assessment of the expected project impact was based on specific Key Performance Indicators derived from stakeholder engagement and the socio-economic impact of the two MEFISTO solutions was analyzed using a cost-effectiveness model. Dissemination of the project is ongoing and an educational TV-like documentary series with 3 episodes on meniscus topics was produced.
Many patients experience severe symptoms after meniscectomy, and their knee is at risk of early degeneration, requiring joint replacement at a relatively young age. Currently, there are no reliable predictors of OA progression in post-meniscectomy patients. Thus, early identification and treatment of meniscectomy patients predisposed to developing knee OA is crucial.
The MEFISTO project aims to develop innovative bioactive implants that interact with the articular tissues in a predetermined manner to prevent the onset of joint degeneration after meniscectomy. This will reduce the pain and morbidity associated with early OA, as well as the cost and burden on healthcare systems, as confirmed by a health economic analysis and an impact assessment of the benefits of the MEFISTO solutions.
The MEFISTO project aims to develop innovative bioactive implants that interact with the articular tissues in a predetermined manner to prevent the onset of joint degeneration after meniscectomy. This will reduce the pain and morbidity associated with early OA, as well as the cost and burden on healthcare systems, as confirmed by a health economic analysis and an impact assessment of the benefits of the MEFISTO solutions.