Healthy Meniscus Research Articles

Low-Field Magnetic Resonance Imaging for the Detection of Medial Meniscal Lesions in Cranial Cruciate-Deficient Stifle Joints in Dogs

Background: The aim of this study was to substantiate the ability of noninvasive low-field magnetic resonance imaging (lfMRI) to accurately depict meniscal lesions, thereby establishing lfMRI as a viable option for the diagnosis of meniscal pathology. Study Design: This was a prospective, controlled study. Materials and Methods: In each of 57 stifle joints, 5 predefined lfMRI sequences using a 0.25 T lfMRI were used. The scans were evaluated by an experienced surgeon (DECVS) and through external assessment by a radiologist (DECVDI). The patients were divided into two groups depending on their meniscal status after lfMRI. Dogs (Group 1; n = 33) without lfMRI evidence of medial meniscal pathology underwent TPLO, whereas concurrent craniomedial mini-arthrotomy was performed in patients with suspected meniscal lesions (Group 2; n = 24). Gait assessment was performed 6 weeks later and 6 months postoperatively. Results: Cohen’s kappa value of 0.8571 corresponds to a high level of agreement between the observers. A significant correlation was found between preoperative lameness severity and intraoperative meniscal damage (p < 0.04). The results showed a highly significant correlation between meniscal injuries on MRI and intraoperative findings (p < 0.0001). Conclusions: LfMRI appears to be a noninvasive, reliable imaging tool for the detection of medial meniscal lesions in cranial cruciate-deficient stifle joints, aiming to avoid (minimally) invasive diagnostics in healthy menisci.

Differences Between Traumatic and Degenerative Medial Meniscus Posterior Root Tears: A Systematic Review.

Intact meniscus roots are a prerequisite for normal meniscal function, including even distribution of compressive forces across the knee joint. An injury to the root disrupts the hoop strength of the meniscus and may lead to its extrusion and the development of osteoarthritis. A medial meniscus posterior root tear (MMPRT) is often thought to have a primary degenerative pathogenesis. However, there is mention of some cases of MMPRTs where the patients have a solely traumatic injury to a previously healthy meniscus. To describe a subpopulation of patients with traumatic MMPRT. Systematic review; Level of evidence, 5. The Web of Science database (www.webofscience.com) was queried using the Medical Subject Headings term "medial root tear." Articles were reviewed, and those evaluated for MMPRTs in a degenerative meniscus were excluded. A total of 25 articles describing cases of acute traumatic causes were included in this study. For these articles, the patient characteristics, injury mechanisms, and concomitant injuries evaluated were recorded and pooled. The search revealed 660 articles, and 25 were selected for inclusion. A total of 113 patients with a traumatic MMPRT were identified and included in this review. The study population had a mean age of 27.1 years and a high share of men (64%). Also, this review displays how most patients with traumatic MMPRTs also suffer concomitant injuries (68%). The findings in this review support our hypothesis that there is a unique subgroup with acute traumatic MMPRTs that have unique patient characteristics, injury mechanisms, and combined injuries, compared with previously published reviews on MMPRTs.

RNA-binding proteins potentially regulate the alternative splicing of apoptotic genes during knee osteoarthritis progression

BackgroundAlternative splicing (AS) is a principal mode of genetic regulation and one of the most widely used mechanisms to generate structurally and functionally distinct mRNA and protein variants. Dysregulation of AS may result in aberrant transcription and protein products, leading to the emergence of human diseases. Although considered important for regulating gene expression, genome-wide AS dysregulation, underlying mechanisms, and clinical relevance in knee osteoarthritis (OA) remain unelucidated. Therefore, in this study, we elucidated and validated AS events and their regulatory mechanisms during OA progression.ResultsIn this study, we identified differentially expressed genes between human OA and healthy meniscus samples. Among them, the OA-associated genes were primarily enriched in biological pathways such as extracellular matrix organization and ossification. The predominant OA-associated regulated AS (RAS) events were found to be involved in apoptosis during OA development. The expression of the apoptosis-related gene BCL2L13, XAF1, and NF2 were significantly different between OA and healthy meniscus samples. The construction of a covariation network of RNA-binding proteins (RBPs) and RAS genes revealed that differentially expressed RBP genes LAMA2 and CUL4B may regulate the apoptotic genes XAF1 and BCL2L13 to undergo AS events during OA progression. Finally, RT-qPCR revealed that CUL4B expression was significantly higher in OA meniscus samples than in normal controls and that the AS ratio of XAF1 was significantly different between control and OA samples; these findings were consistent with their expected expression and regulatory relationships.ConclusionsDifferentially expressed RBPs may regulate the AS of apoptotic genes during knee OA progression. XAF1 and its regulator, CUL4B, may serve as novel biomarkers and potential therapeutic targets for this disease.

Mechanical and histological properties of native medial menisci compared to allograph medial menisci in the osteoarthritic knee.

This study was designed to provide information on how the menisci change over the course of osteoarthritis, particularly with regard to their mechanical properties. The aim was to determine the difference between healthy menisci (fresh frozen meniscal transplants) and menisci harvested during total knee arthroplasty. The latter allows the grading of age-related and osteoarthritic changes in the menisci on macroscopic and microscopic levels. A total of 10 menisci from arthritic knee joints (medial) harvested during total knee arthroplasty were used and compared with 10 medial fresh frozen meniscal transplants. The mechanical measurements were carried out on a Mach-1 testing machine using indentation testing to determine the instantaneous modulus and the thickness of the menisci. The specimens were then embedded in paraffin, sectioned on a microtome, and stained with hematoxylin-eosin and safranin-O. All measurements were divided into the anterior horn, pars intermedia, and posterior horn. There was no significant difference in the instantaneous modulus for the posterior horn in the fresh frozen menisci with 0.27 ± 0.1MPa compared to the arthritic menisci with 0.18 ± 0.03MPa. No significant difference could be determined for the meniscus thicknesses. There was a significant difference in the safranin-O staining. There were also significant differences in the Pauli score: the arthrosis menisci showed a sum score that was, on average, four times higher than the sum score of the fresh frozen menisci. In the present study, it could be shown very well that there are significant differences in the mechanical properties as well as in the macroscopic and histopathological scores, such as the Pauli score, between the fresh frozen meniscus allografts considered healthy and osteoarthritic menisci resulting from total knee arthroplasty. With a degradation score of 3 (Pauli), the instantaneous modulus was reduced by more than 50% compared to healthy controls. More importantly, however, the fresh frozen menisci only show a grade 2 when converting the sum values into grades, where a grade 2 indicates slight degeneration. This is interesting because fresh frozen meniscus transplants were always considered healthy in previous publications and should, therefore, actually have a grade 1.

Could a three-dimensional contralateral meniscus segmentation for allograft or scaffold sizing be possible? A prospective study.

Meniscal allografts and biodegradable meniscal implants are attractive surgical options for painful subtotal or total meniscectomies. In order to get the best results, these should be as similar as possible to the original meniscus in terms of shape, structure, and volume. Three-dimensional meniscus sizing could be an approach to improve the accuracy of meniscus matching. Therefore, the aims of this study were to perform a comparative morphological and volumetric analysis of the healthy meniscus based on manual tri-planar segmentation and to demonstrate that the menisci from the contralateral knee could be used as a reference in the sizing of a meniscal graft or a scaffold. Three-dimensional meniscal models were created based on 120 MRIs in 60 healthy subjects (bilateral knees). The differences between the pairs of menisci concerning the widths, thicknesses, lateromedial distances, anteroposterior distances, angles of coverage, and meniscal volumes were evaluated. T-Student tests were used to compare the quantitative numerical variables of the different groups. Pearson's linear regression was used to determine if correlations existed between demographic variables (age, gender, height, weight) and anatomical parameters. Statistical significance was set at p < 0.05. Comparing the 120 pairs of menisci of each subject, there was no statistically significant difference for all parameters studied for both the medial and lateral meniscus. When the measurements were stratified by gender, statistically significant differences were observed for all parameters except meniscal coverage angles. We observed that anteroposterior and lateromedial distances were positively correlated with height and body mass index both at the level of the medial meniscus (r = 0.68; r = 0.66; r = 0.65; and r = 0.63) and lateral (r = 0.68; r = 0.69; r = 0.61; and r = 0.60). Our study demonstrated that the intra-individual 3D shapes of the left and right menisci are very similar. Therefore, the contralateral side could be used as a template for the 3D sizing of meniscal allografts or meniscal implants.

Controllable Damping Magnetorheological Elastomer Meniscus.

The human healthy meniscus fulfills key biomechanical functions in the tibiofemoral (knee) joint. Meniscal injury leads to an increased risk for symptomatic osteoarthritis. In order to prevent osteoarthritis, many researchers have put efforts into developing new-type meniscal substitute materials. In this study, MRI data of the human knee joint is obtained by CT scanning, and a three-dimensional finite element model of the meniscus is established. Compressive forces of 400 N, 600 N, 800 N, and 1000 N are selected to complete the meniscus modeling and finite element simulation analysis of the meniscus by ANSYS; at the same time, the compressive force and compressive displacement of the magnetorheological elastomer are controlled by changing the current size. The results show that the compressive force and compressive displacement of the magnetorheological elastomer can be controlled by an electric current, so as to adapt to the required mechanical properties of the meniscus under external complex loads and provide a theoretical and experimental basis for clinical meniscus replacement.

Mechanical Unloading of Engineered Human Meniscus Models Under Simulated Microgravity: A Transcriptomic Study

Osteoarthritis (OA) primarily affects mechanical load-bearing joints, with the knee being the most common. The prevalence, burden and severity of knee osteoarthritis (KOA) are disproportionately higher in females, but hormonal differences alone do not explain the disproportionate incidence of KOA in females. Mechanical unloading by spaceflight microgravity has been implicated in OA development in cartilaginous tissues. However, the mechanisms and sex-dependent differences in OA-like development are not well explored. In this study, engineered meniscus constructs were generated from healthy human meniscus fibrochondrocytes (MFC) seeded onto type I collagen scaffolds and cultured under normal gravity and simulated microgravity conditions. We report the whole-genome sequences of constructs from 4 female and 4 male donors, along with the evaluation of their phenotypic characteristics. The collected data could be used as valuable resources to further explore the mechanism of KOA development in response to mechanical unloading, and to investigate the molecular basis of the observed sex differences in KOA.

Biomechanical effects of medial meniscus radial tears on the knee joint during gait: A concurrent finite element musculoskeletal framework investigation.

The biomechanical variation in the knee during walking that accompanies medial meniscal radial tears stemming from knee osteoarthritis (OA) has not been explored. This study introduced a finite element musculoskeletal model using concurrent lower limb musculoskeletal dynamics and knee joint finite element analysis in a single framework and expanded the models to include knees with medial meniscal radial tears and total medial meniscectomy. The radial tears involved three locations: anterior horn, midbody, and posterior horn with grades of 33%, 50%, and 83% of the meniscus width. The shear and hoop stresses of the tear meniscus and tibial cartilage contact load, accompanying tears, and postmeniscectomy were evaluated during the stance phase of the gait cycle using the models. In the 83% width midbody tear group, shear stress at the end of the tear was significantly greater than in the intact meniscus and other tear groups, and the maximum shear stress was increased by 310% compared to the intact meniscus. A medial meniscus radial tear has a much smaller effect on the tibial cartilage load (even though in the 83% width tear, the cartilage/total load ratio increased by only 9%). However, the contact force on the tibial cartilage with total postmeniscectomy was increased by 178.93% compared with a healthy intact meniscus, and the peak contact pressure after meniscectomy increased from 11.94 to 12.45 MPa to 17.64 and 13.76 MPa, at the maximum weight acceptance and push-off, respectively. Our study shows that radial tears with larger medial meniscus widths are prone to high stress concentrations at the end of the tears, leading to the potential risk of complete meniscal rupture. Furthermore, although the tears did not change the cartilage load distribution, they disrupted the circumferential stress-transmitting function of the meniscus, thus greatly increasing the likelihood of the onset of knee OA. The significant increase in the tibial cartilage load with total postmeniscectomy indicates a potential risk of OA flare-ups. This study contributes to a better understanding of meniscal tear-induced OA biomechanical changes during human activities and offers some potential directions for surgical guidance of meniscectomies and the prophylaxis and treatment of OA.

Effects of Meniscus Longitudinal Tear on Knee Biomechanics Based on Cross-Ligament Conditions

Knee meniscuses are fibrous cartilages that are present to disperse friction in the knee joint between the tibia and femur bones. They work to disperse body weight and reduce friction while moving. Because the condyles of the femur and the tibia converge at one point (which changes as they bend and stretch), the meniscus expand the weight of the body.&#x0D; It is important to describe the mechanical behavior of the meniscus because of its significant role in bearing the load on the knee joint. Research shows Compressive stresses on the menisci have been shown to be a major factor in destructive joint injuries, including osteoarthritis. Anterior cruciate ligament tearcan also have a profound effect on the meniscus. Clinically, meniscus injury is common in patients with a tear cruciate ligament. The main purpose of this study is to determine the stress distribution diagram of internal and external menisci and to evaluate the comparison of healthy meniscus stress and meniscus tearwith the stability of the cruciate ligament and the instability of this ligament.&#x0D; The bone structure of a healthy joint was designed and analyzed in ANSYS program package, and the forces applied to the meniscus under the presence or absence of ACL ligament were evaluated.&#x0D; The results of biomechanical studies showed that tearof the meniscus and the anterior cruciate ligament play an important role in the stability of the meniscus. With the tearof the meniscus and ligament diagram, the distribution of stress and the amount of stress in the meniscus increases, which can be obtained by the interdependence of the meniscus and the surrounding ligaments for normal joint function.

Identification and diagnosis of meniscus tear by magnetic resonance imaging using a deep learning model.

ObjectiveMeniscus tear is a common problem in sports trauma, and its imaging diagnosis mainly relies on MRI. To improve the diagnostic accuracy and efficiency, a deep learning model was employed in this study and the identification efficiency was evaluated.MethodsStandard knee MRI images from 924 individual patients were used to complete the training, validation and testing processes. Mask regional convolutional neural network (R–CNN) was used to build the deep learning network structure, and ResNet50 was adopted to develop the backbone network. The deep learning model was trained and validated with a dataset containing 504 and 220 patients, respectively. Internal testing was performed based on a dataset of 200 patients, and 180 patients from 8 hospitals were regarded as an external dataset for model validation. Additionally, 40 patients who were diagnosed by the arthroscopic surgery were enrolled as the final test dataset.ResultsAfter training and validation, the deep learning model effectively recognized healthy and injured menisci. Average precision for the three types of menisci (healthy, torn and degenerated menisci) ranged from 68% to 80%. Diagnostic accuracy for healthy, torn and degenerated menisci was 87.50%, 86.96%, and 84.78%, respectively. Validation results from external dataset demonstrated that the accuracy of diagnosing torn and intact meniscus tear through 3.0T MRI images was higher than 80%, while the accuracy verified by arthroscopic surgery was 87.50%.ConclusionMask R–CNN effectively identified and diagnosed meniscal injuries, especially for tears that occurred in different parts of the meniscus. The recognition ability was admirable, and the diagnostic accuracy could be further improved with increased training sample size. Therefore, this deep learning model showed great potential in diagnosing meniscus injuries.Translational potential of this articleDeep learning model exerted unique effect in terms of reducing doctors’ workload and improving diagnostic accuracy. Injured and healthy menisci could be more accurately identified and classified based on training and learning datasets. This model could also distinguish torn from degenerated menisci, making it an effective tool for MRI-assisted diagnosis of meniscus injuries in clinical practice.

Micromechanical properties of the healthy canine medial meniscus

AimsKnowledge of the micromechanical characteristics of the menisci is required to better understand their role within the stifle joint, improve early diagnosis of meniscal lesions, and develop new treatment and/or replacement strategies. The aim of the study was to determine the mechanical properties of the healthy medial canine meniscus and to evaluate the effect of regional (caudal, central, and cranial) and circumference (axial and abaxial) locations on these properties. MethodsTo study the micromechanical properties of the medial menisci in healthy (Beagle) dogs, the influence of regional (caudal, central, and cranial) and circumference (axial and abaxial) locations were evaluated. Nanoindentation-relaxation tests were performed to characterize the local stiffness and the viscoelastic properties at each region and specific circumference. Linear interpolation onto the indentation points was performed to establish a map of the micromechanical property heterogeneities. ResultsThe results indicate that the cranial region was significantly stiffer and less viscous than the central and caudal regions. Within the central region the inner part (axial) was significantly stiffer than the periphery (abaxial). Within the caudal region the inner part was significantly less viscous than the periphery. ConclusionSignificant regional and radial variations were observed for both the stiffness and the viscoelastic properties. Moreover, a viscous behavior of the entire medial meniscus was observed (elastic fraction <0.5). These results deter the use of average elastic modulus to study the regional mechanical properties of healthy meniscus.

Meniscal Treatment as a Predictor of Worse Articular Cartilage Damage on MRI at 2 Years After ACL Reconstruction: The MOON Nested Cohort

Background: Patients undergoing anterior cruciate ligament reconstruction (ACLR) are at an increased risk for posttraumatic osteoarthritis (PTOA). While we have previously shown that meniscal treatment with ACLR predicts more radiographic PTOA at 2 to 3 years postoperatively, there are a limited number of similar studies that have assessed cartilage directly with magnetic resonance imaging (MRI). Hypothesis: Meniscal repair or partial meniscectomy at the time of ACLR independently predicts more articular cartilage damage on 2- to 3-year postoperative MRI compared with a healthy meniscus or a stable untreated tear. Study Design: Cohort study; Level of evidence, 2. Methods: A consecutive series of patients undergoing ACLR from 1 site within the prospective, nested Multicenter Orthopaedic Outcomes Network (MOON) cohort underwent bilateral knee MRI at 2 to 3 years postoperatively. Patients were aged <36 years without previous knee injuries, were injured while playing sports, and had no history of concomitant ligament surgery or contralateral knee surgery. MRI scans were graded by a board-certified musculoskeletal radiologist using the modified MRI Osteoarthritis Knee Score (MOAKS). A proportional odds logistic regression model was built to predict a MOAKS-based cartilage damage score (CDS) relative to the contralateral control knee for each compartment as well as for the whole knee, pooled by meniscal treatment, while controlling for sex, age, body mass index, baseline Marx activity score, and baseline operative cartilage grade. For analysis, meniscal injuries surgically treated with partial meniscectomy or meniscal repair were grouped together. Results: The cohort included 60 patients (32 female; median age, 18.7 years). Concomitant meniscal treatment at the time of index ACLR was performed in 17 medial menisci (13 meniscal repair and 4 partial meniscectomy) and 27 lateral menisci (3 meniscal repair and 24 partial meniscectomy). Articular cartilage damage was worse in the ipsilateral reconstructed knee (P < .001). A meniscal injury requiring surgical treatment with ACLR predicted a worse CDS for medial meniscal treatment (medial compartment CDS: P = .005; whole joint CDS: P < .001) and lateral meniscal treatment (lateral compartment CDS: P = .038; whole joint CDS: P = .863). Other predictors of a worse relative CDS included age for the medial compartment (P < .001), surgically observed articular cartilage damage for the patellofemoral compartment (P = .048), and body mass index (P = .007) and age (P = .020) for the whole joint. Conclusion: A meniscal injury requiring surgical treatment with partial meniscectomy or meniscal repair at the time of ACLR predicted worse articular cartilage damage on MRI at 2 to 3 years after surgery. Further research is required to differentiate between the effects of partial meniscectomy and meniscal repair.

Visualization of meniscus with 3D axial reconstructions

PurposeTo visualize the meniscus of the knee joint in the axial plane and identify injuries that cannot be visualized using conventional sequences. MethodsTwo hundred and two subjects underwent an improvised 3-Dimensional Proton Density Fat Saturation (3D-PD FS) Magnetic Resonance (MR) sequence on their meniscus. The transverse images were reconstructed and examined. Fifty-three of the subjects had a healthy meniscus and their images were used as part of a qualitative evaluation to verify that all parts of the meniscus were properly visualized. The evaluation was based on a four-level scale indicating the visualization of meniscal parts. The same evaluation was also performed on the 149 subjects with meniscal pathologies. Another qualitative evaluation was performed on all subjects concerning five image characteristics based on a five-level scale. Finally, images from 20 patients with meniscal pathologies were compared with arthroscopic images visualizing meniscal tears. ResultsIn all subjects, all parts of the meniscus were clearly visualized. The axial reformats provided ideal imaging of the meniscus, yielding high total image quality, satisfactory smoothing and sharpening, fewer artifacts, and successful fat saturation. The findings of the MR images from the 20 subjects with meniscal pathologies, concerning the topography of meniscal tears coincided at 100% with their arthroscopic findings. ConclusionThe use of the improvised 3D-PD FS sequence provides the possibility of axial reconstruction with a better depiction of the meniscus. These images can accurately illustrate the range of the meniscus and any meniscal tears along with their exact location with high image quality.

Pilot imaging of ex vivo meniscus using phase-contrast enhanced synchrotron micro-tomography

Purpose: We aimed to investigate the feasibility of performing synchrotron radiation-based phase-contrast micro-tomography of ex vivo human meniscus. An advantage with the use of synchrotron light is that the high radiation and coherence enables fast imaging with high resolution. Additionally, the use of phase contrast has the benefit of achieving high contrast in soft tissues. Thus, in this pilot study, for the first time we obtained and analyzed high-resolution phase-contrast images with the purpose to visualize and describe collagen structures of the healthy meniscus.

3D-bioprinting ready-to-implant anisotropic menisci recapitulate healthy meniscus phenotype and prevent secondary joint degeneration.

Objectives: Disruption of anisotropic phenotypes of the meniscus would contribute to OA progression. Exploring phenotype changes of the anisotropic meniscus in joint degeneration would help understand the biologic interaction between the meniscus and OA, and further facilitate the therapeutic strategies of meniscus injury-related joint degeneration. Meanwhile, engineering biomimetic meniscal tissue mimicking the anisotropy of the healthy meniscus remains a challenge.Methods & Results: Meniscal disruption of phenotype anisotropy (PBV growth, cellular phenotype and ECM depositions) was confirmed in OA patient samples. To recapitulate healthy meniscus phenotypes, 3D-bioprinted anisotropic TCM meniscus constructs with PBV growth and regional differential cell and ECM depositions were generated. Transplanted 3D-bioprinted meniscus into rabbit knees recapitulated phenotypes of native healthy meniscus and conferred long-term protection against secondary joint degeneration.Conclusion: 3D-bioprinted TCM meniscus not only restored the anisotropy of native healthy meniscus with PBV infiltration and better shape retention, but better maintained joint function and prevented secondary joint degeneration, which provided a new strategy for the clinical treatment of meniscus injury-related joint degenerative diseases.

Trajectory of patient-reported outcomes over 5 years in young and old patients undergoing meniscal surgery

Purpose: Patients undergoing arthroscopic surgery for a meniscal tear have a high risk of developing knee osteoarthritis (OA). Meniscal tears among younger patients are often due to acute trauma to an otherwise healthy meniscus, whereas tears in the middle-aged and older population often occur in an already degenerated meniscus. Thus, the trajectory of patient-reported symptoms and the route towards symptomatic OA may differ between these patients. In this study, we examined and compared the trajectory of knee-related patient-reported outcomes over 5 years, as a proxy for symptomatic OA development, between patients aged 40 years or younger and over 40 years undergoing surgery for a meniscal tear.

Use of magnetic resonance imaging to determine laterality of meniscal size in healthy volunteers.

IntroductionThe menisci are responsible for several functions. They are shock absorbers during dynamic loading on the knee and provide a broader surface area on which to distribute stress evenly to the tibia and femur. These functions allow for smoother movement and greater stability of the knee joint. Meniscal injury can be a great impediment to the function of the knee. Therefore, in the case of meniscal injury, our main concern is the relief of patient symptoms, followed by consequent restoration of meniscal function to the greatest of our ability.To prevent the long terms effects of a meniscectomy, meniscal allograft transplantation (MAT) was developed. The potential of using the size of the contralateral healthy menisci, to determine the size of the menisci to be replaced, will be discussed.MethodsKnee MRIs done on healthy patients in the past 5 years were reviewed. Magnetic Resonance Imaging was performed using a 3-T scanner. Each individual was examined with knee joints in full extension. Measurements were performed two separate times, two weeks apart. A mean of three measurements was made during each session to reduce error.Thirty-eight normal bilateral knee joints MRIs remained (16 males, 22 females). Participants were sampled from the institutional Picture Archiving and Communication System (PACS). Age, gender, and the medial meniscal and lateral meniscal size of both knees were recorded. The laterality of the menisci was compared between both knees in each patient.ResultsA total of 38 patients were included in this study, with a mean age of 37.39 (±9.50) years. They were 16 (42.1%) men and 22 (57.9%) women. We didn’t find any significant difference in the mid-coronal section between left and right knees meniscal measurements. None of the measurements were significantly different between men and women. There was no significant difference in the medial mid-sagittal section or lateral mid-sagittal section between left and right knee meniscal measurements.ConclusionThe results obtained in this study may support the use of MRI of the bilateral knee to obtain an appropriately sized allograft.

Single-cell RNA-seq analysis identifies meniscus progenitors and reveals the progression of meniscus degeneration

ObjectivesThe heterogeneity of meniscus cells and the mechanism of meniscus degeneration is not well understood. Here, single-cell RNA sequencing (scRNA-seq) was used to identify various meniscus cell subsets and investigate...

Point-of-Care Procedure for Enhancement of Meniscal Healing in a Goat Model Utilizing Infrapatellar Fat Pad–Derived Stromal Vascular Fraction Cells Seeded in Photocrosslinkable Hydrogel

Background: Large radial tears of the meniscus involving the avascular region can compromise meniscal function and result in poor healing and subsequent osteochondral degeneration. Augmentation of surgical repairs with adipose-derived stromal vascular fraction (SVF), which contains mesenchymal stromal cells, may improve meniscal healing and preserve function (ie, chondroprotection). Purposes: (1) To develop a goat model of a radial meniscal tear with resulting osteoarthritis and (2) to explore the efficacy of a 1-step procedure utilizing infrapatellar fat pad–derived SVF cells seeded in a photocrosslinkable hydrogel to enhance meniscal healing and mitigate osteochondral degeneration. Study Design: Controlled laboratory study. Methods: A full-thickness radial tear spanning 90% of the medial meniscal width was made at the junction of the anterior and middle bodies of the goat stifle joint. Tears received 1 of 3 interventions (n = 4 per group): untreated, repair, or repair augmented with photocrosslinkable methacrylated gelatin hydrogel containing 2.0 × 106 SVF cells/mL and 2.0 µg/mL of transforming growth factor β3. The contralateral (left) joint served as a healthy control. At 6 months, meniscal healing and joint health were evaluated by magnetic resonance imaging (MRI) and assessed by histological and macroscopic scoring. The Whole-Organ Magnetic Resonance Imaging Score and the presence of a residual tear, as evaluated with T2 MRI sequences, were determined by a single blinded orthopaedic surgeon. Results: When compared with tears left untreated or repaired with suture alone, augmented repairs demonstrated increased tissue formation in the meniscal tear site, as seen on MRI and macroscopically. Likewise, the neotissue of augmented repairs possessed a histological appearance more similar, although still inferior, to healthy meniscus. Osteochondral degeneration in the medial compartment, as evaluated by the Whole-Organ Magnetic Resonance Imaging Score and Inoue (macroscopic) scale, revealed increased degeneration in the untreated and repair groups, which was mitigated in the augmented repair group. Histological evaluation with a modified Mankin score showed a similar trend. In all measures of osteochondral degeneration, the augmented repair group did not differ significantly from the uninjured control. Conclusion: A radial tear spanning 90% of the medial meniscal width in a goat stifle joint showed poor healing potential and resulted in osteochondral degeneration by 6 months, even if suture repair was performed. Augmentation of the repair with a photocrosslinkable hydrogel containing transforming growth factor β3 and SVF cells, isolated intraoperatively by rapid enzymatic digestion, improved meniscal healing and mitigated osteoarthritic changes. Clinical Relevance: Repair augmentation with an SVF cell–seeded hydrogel may support successful repair of meniscal tears previously considered irreparable.

Contralateral MRI scan can be used reliably for three-dimensional meniscus sizing — Retrospective analysis of 160 healthy menisci

BackgroundMeniscus allograft transplantation is a valuable surgical option for post-meniscectomy syndrome. For best results, the selected allograft should be as similar as possible to the original meniscus. Three-dimensional meniscus sizing could be a new approach to improve the accuracy of meniscus matching. The contralateral anatomy might therefore be a suitable reconstruction template. The purpose of this study was to compare the three-dimensional shape of the right and left menisci by bi-planar segmentation of magnetic resonance imaging (MRI) scans. MethodsThree-dimensional surface models of healthy menisci were created based on 40 bilateral MRI scans. Manual segmentation was performed on the MRI data in sagittal and coronal planes. For side-to-side comparison, each left meniscus model was mirrored and then superimposed to its corresponding right meniscus model. Differences between the meniscus pairs were assessed by width, length, height and surface distances. Inter-reader reliability, as well as accuracy of bi-planar segmentation was assessed by two different readers. ResultsThe meniscus pairs were not significantly different in terms of width, length and height (P = at least 0.138). Side difference of mean surface distances was 0.76 mm (±0.13 standard deviation (SD)) for medial and 0.78 mm (±0.15 SD) for lateral menisci. Inter-reader reliability was good to excellent (0.828–0.987). ConclusionThe three-dimensional shapes of the left and right menisci are very similar. Therefore, the contralateral meniscus can be used as a template for three-dimensional meniscus allograft sizing. Three-dimensional meniscus segmentation and sizing can be performed accurately by combination of sagittal and coronal planes.