The Meniscus in Knee Osteoarthritis

Deteriorating meniscal function is thought to play a role in knee osteoarthritis. Meniscal proteoglycans maintain mechanical stiffness of the tissue through electrostatic effects. This study aimed to investigate whether the mechanical properties of macroscopically intact meniscus are preserved in osteoarthritis.

Discs of lateral meniscal tissue two millimetres thick and of five millimetres diameter from osteoarthritic knees and from healthy donors were placed within a confined compression chamber, mounted in a materials testing machine and bathed in isotonic 0.14M PBS, hypotonic deionised water or hypertonic 3M PBS. Following equilibrium, a 10% ramp compressive strain was applied followed by a 7200 second hold. Resultant stress relaxation curves were fitted to a nonlinear poroviscoelastic model with strain dependent permeability using finite element modelling to determine mechanical parameters. All samples were assayed for proteoglycan content. Comparison of results was undertaken using multivariate ANOVA.

Thirty samples from osteoarthritic knees and 18 samples from healthy donors were tested. No significant differences in mechanical parameters or proteoglycan content was observed between groups. In both groups Young’s modulus (E) was significantly greater, and zero-strain permeability significantly reduced, in samples tested in deionised water compared to samples tested in 0.14M or 3M PBS (all p < 0.05).

Mechanical parameters of intact lateral meniscus in osteoarthritic knees are similar to those found in healthy knees. Proteoglycan concentration and their electrostatic contribution to mechanical stiffness of the meniscus is maintained in menisci derived from osteoarthritic knees. Whilst macroscopic tears in the meniscal ultrastructure may contribute to osteoarthritis, intact meniscal tissue maintains its function.

Meniscal scaffold implants have gained interest as a therapeutic alternative for irreparable partial meniscal defects and post-meniscectomy syndrome. However, the effect of laterality on outcomes is unclear. This study aims to assess the hypothesis that lateral meniscal scaffold implants have worse clinical or survival outcomes compared with medial scaffold implants.

The study was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and registered with PROSPERO. Three databases (PubMed, Embase, Scopus) were searched from date of database establishment to 21 January 2022. Human studies reporting clinical or survival outcome data specific to the medial or lateral meniscal scaffold implant were included. Random-effects model was used to analyse survival outcome data.

Ten studies comprising 568 patients (mean age 29.2–40 years, follow up duration 1–14 years) were included. There were 483 medial and 85 lateral meniscal scaffold implants. Amongst two studies directly comparing the survival rate of medial and lateral meniscal scaffolds, there was no significant difference in survival rates between medial and lateral meniscus scaffolds (hazard ratio = 1.24, 95 % confidence interval: 0.51–3.03, P = 0.63). There were no consistent statistically significant differences between medial and lateral meniscal scaffolds in terms of postoperative Visual Analog Scale pain, Tegner Activity, Lysholm, International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome, and Knee Society Scores.

Despite anatomical and biomechanical differences between the medial and lateral meniscus, there are no significant differences in clinical outcomes or survival rates between medial and lateral meniscal scaffold implants for irreparable partial meniscal defects at short- or mid-term follow up. Lateral meniscal scaffold implants are therefore non-inferior to medial meniscal scaffold implants.

We used convolutional neural network (CNN) technology to improve the accuracy of diagnosis of knee meniscus injury and shorten the diagnosis time.

We propose a meniscus detection method based on Fusion of CNN1 and CNN2 (CNNf), which uses Magnetic Resonance Imaging (MRI) and Computer tomography (CT) to compare the diagnosis results, verifies the proposed method through 2460 images collected from 205 patients in the hospital. We used accuracy, sensitivity, specificity, receiver operating characteristics (ROC), and damage total rate to evaluate performance.

The accuracy of our model was 93.86%, the sensitivity was 91.35%, the specificity was 94.65%, and the area under the receiver operating characteristic curve was 96.78%. The total damage rate of MRI is 91.57%, which is far greater than the total damage rate of CT diagnosis of 80.13%.

CNNf-based MRI technology of knee meniscus injury has high practical value in clinical practice. It can effectively improve the accuracy of diagnosis and reduce the rate of misdiagnosis.

Meniscus is a fibrocartilage composite tissue with three different microstructual zones, inner fibrocartilage, middle transitional, and outer fibrous zone. We hypothesized that decellularized meniscus extracellular matrix (DMECM) would have different characteristics according to zone of origin. We aimed to compare zone-specific DMECM in terms of biochemical characteristics and cellular interactions associated with tissue engineering. Micronized DMECM was fabricated from porcine meniscus divided into three microstructural zones. Characterization of DMECM was done by biochemical and proteomic analysis. Inner DMECM showed the highest glycosaminoglycan content, while middle DMECM showed the highest collagen content among groups. Proteomic analysis showed significant differences among DMECM groups. Inner DMECM showed better adhesion and migration potential to meniscus cells compared to other groups. DMECM resulted in expression of zone-specific differentiation markers when co-cultured with synovial mesenchymal stem cells (SMSCs). SMSCs combined with inner DMECM showed the highest glycosaminoglycan in vivo. Outer DMECM constructs, on the other hand, showed more fibrous tissue features, while middle DMECM constructs showed both inner and outer zone characteristics. In conclusion, DMECM showed different characteristics according to microstructural zones, and such material may be useful for zone-specific tissue engineering of meniscus.

The meniscus is crucial in maintaining the knee function and protecting the joint from secondary pathologies, including osteoarthritis. Although most of the mechanical properties of human menisci have been characterized, to our knowledge, its dynamic shear properties have never been reported. Moreover, little is known about meniscal shear properties in relation to tissue structure and composition. This is crucial to understand mechanisms of meniscal injury, as well as, in regenerative medicine, for the design and development of tissue engineered scaffolds mimicking the native tissue. Hence, the objective of this study was to characterize the dynamic and equilibrium shear properties of human meniscus in relation to its anisotropy and composition.

Specimens were prepared from the axial and the circumferential anatomical planes of medial and lateral menisci. Frequency sweeps and stress relaxation tests yielded storage (G′) and loss moduli (G″), and equilibrium shear modulus (G). Correlations of moduli with water, glycosaminoglycans (GAGs), and collagen content were investigated.

The meniscus exhibited viscoelastic behavior. Dynamic shear properties were related to tissue composition: negative correlations were found between G′, G″ and G, and meniscal water content; positive correlations were found for G′ and G″ with GAG and collagen (only in circumferential samples). Circumferential samples, with collagen fibers orthogonal to the shear plane, exhibited superior dynamic mechanical properties, with G′ ~70 kPa and G″ ~10 kPa, compared to those of the axial plane ~15 kPa and ~1 kPa, respectively. Fiber orientation did not affect the values of G, which ranged from ~50 to ~100 kPa.

To investigate the suitability of urinary collagen type-II C-terminal cleavage neoepitope (uC2C) as a marker for early knee osteoarthritis (kOA).

We examined 302 Estonian subjects (mean age, 49 years): 186 subjects with and 20 control subjects without knee symptoms, and 96 patients treated by arthroscopy. For the latter, cartilage lesions were characterized using Société Francaise d'Arthroscopie (SFA) scores. Standardized radiographs of bilateral tibiofemoral (TF) and patellofemoral (PF) joints were assessed for osteoarthritis (OA) features. Osteophytes (Ophs) and joint space narrowing (JSN) were graded separately. uC2C was measured by the uC2C-HUSA assay. Logistic and linear regression models were used for data analysis.

Of the kOA cases, 50% were isolated (TF or PF) grade 1; 10% were grade 2. JSN with Ophs was more frequent in females than in males (52% vs. 34%, p = 0.01). Increased uC2C level was associated with gradual increase in the risk of kOA grade of severity (odds ratio = 2.14–3.7) including grade 1 vs. 0. TF-OA and PF-OA equally predicted uC2C concentration (R² = 0.33–0.35). uC2C prediction was better for females than for males (R² = 0.42 vs. 0.22 by TF-OA). The best predictive model for uC2C level (R² = 0.75) included three OA features: macroscopic cartilage lesions, TF Ophs, and PF-JSN.

uC2C as an integrative marker of kOA is associated with cartilage degradation and Oph formation in the PF- and TF-joints. Increased uC2C concentration could be used as an early diagnostic marker for kOA in clinical studies.