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The meniscus plays a crucial role in the proper functioning of the knee joint, and when it becomes damaged, partial removal or replacement is necessary to restore proper function. Understanding the stress and deformation of the meniscus during various movements is essential for developing effective materials for meniscus repair. However, accurately estimating the contact mechanics of the knee joint can be challenging due to its complex shape and the dynamic changes it undergoes during movement. To address this issue, the open-source software SCONE can be used to establish a kinematics model that monitors the different states of the knee joint during human motion and obtains relevant gait kinematics data. To evaluate the stress and deformation of the meniscus during normal human movement, values of different states in the movement gait can be selected for finite element analysis (FEA) of the knee joint. This analysis enables researchers to assess changes in the meniscus. To evaluate meniscus damage, it is necessary to obtain changes in its mechanical behavior during abnormal movements. This information can serve as a reference for designing and optimizing the mechanical performance of materials used in meniscus repair and replacement.

Since the meniscus is an important stabilizing structure of the knee joint and has a significant role in load-bearing and shock absorption, so the complete structural and functional reconstructions of the teared menisci should be done not only after partial meniscectomy but also post total meniscectomy. So far, animal experiments and good clinical practice have showed that TMAT after total meniscectomy has partially solved the problem of structural and functional reconstructions after total meniscectomy. However, partial meniscectomy will also lead to accelerated knee degeneration, and its proportion is much higher than that of patients with total meniscectomy. Herein, the feasibility of PMAT after partial meniscectomy was investigated for the first time by using the 40% posterior horn meniscectomy model of the medial meniscus in Beagle dogs, and also for the first time, TMAT group and the total meniscectomy group were used as control groups. Compared with the TMAT, the transcriptomics evaluation, scanning electron microscope observation, histological regeneration and structure, biomechanical property, inflammation environment, and the knee function post PMAT were more similar to that of normal meniscus was first reported. This study provides a PMAT scheme with clinical translational value for the complete structural and functional reconstruction of the patients with partial meniscectomy and fills the gap in the field of teared meniscus therapy on the basis of quite well clinical applications of the meniscus repair and the TMAT., (© 2022 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Reduced knee weight-bearing from prescription or sedentary lifestyles are associated with cartilage degradation; effects on the meniscus are unclear. Rodents exposed to spaceflight or hind limb unloading (HLU) represent unique opportunities to evaluate this question. This study evaluated arthritic changes in the medial knee compartment that bears the highest loads across the knee after actual and simulated spaceflight, and recovery with subsequent full weight-bearing. Cartilage and meniscal degradation in mice were measured via microCT, histology, and proteomics and/or biochemically after: (1) ~ 35 days on the International Space Station (ISS); (2) 13-days aboard the Space Shuttle Atlantis; or (3) 30 days of HLU, followed by a 49-day weight-bearing readaptation with/without exercise. Cartilage degradation post-ISS and HLU occurred at similar spatial locations, the tibial-femoral cartilage-cartilage contact point, with meniscal volume decline. Cartilage and meniscal glycosaminoglycan content were decreased in unloaded mice, with elevated catabolic enzymes (e.g., matrix metalloproteinases), and elevated oxidative stress and catabolic molecular pathway responses in menisci. After the 13-day Shuttle flight, meniscal degradation was observed. During readaptation, recovery of cartilage volume and thickness occurred with exercise. Reduced weight-bearing from either spaceflight or HLU induced an arthritic phenotype in cartilage and menisci, and exercise promoted recovery.

The degeneration of radial tie fibres of the central meniscal layer, and thinning of its lamellar layer results in increased intensity signals on magnetic resonance imaging, making it difficult to differentiate from true meniscal tear. This study aimed to assess the rate of encountered MRI grades 1 and 2 intrasubstance meniscal changes, and to set guidelines to report these changes based on predicted clinical outcome. A systematic review approach was employed using search engines, libraries, and databases (Google Scholar, ERIC, PubMed, and Medline) to search for scholarly sources on meniscal lesions and their significance in MRI published between 1 January 2000 and 30 June 2019. It retrieved 2750 abstracts, out of which 2738 were excluded and 13 studies meeting inclusion criteria were meta-analysed. It found an association between intrasubstances meniscal changes and outcomes. It resulted that intrasubstance meniscal changes were preservable through the protective functioning of the meniscus. Other than weight gain, no other significant risk factor of developing true meniscal tears later in life was found. It is important to examine intrasubstance meniscal change when patients suffer from mechanical meniscal symptoms especially in old age.

The normalcy index (NI) has been implemented by several studies as a simple index for quantitatively analyzing diffident gait abnormalities, such as children with cerebral palsy and idiopathic toe-walkers. However, whether the NI can be used in anterior cruciate ligament (ACL) deficiency with different types of meniscus injuries or not, has not been reported yet. In this study, 25 patients who combined different types of ACL and meniscus injuries were evaluated by the NI analysis. 12 healthy subjects were used to define the normal range of NI. The result showed that NI values of patients were significantly larger than the control group (P < 0.05). Meanwhile, the tendency of increasing NI values associated with increasing pathology were significant with only 5 subjects in the smallest group (Jonkheere-Terpsta test: P < 0.001). These results indicated that the NI was a concise yet effective tool to evaluate combined ACL and meniscus injury patients. Increasing severity degree of meniscus tears in ACL rupture patients is corresponded to increasing NI values. It also demonstrates that the proposed NI can be applied as a robustness factor to detect the discrepancy between healthy and patient subjects clinically, and has the potential in the quantitative evaluation of pre- or post-surgery and rehabilitation.

Background: The most commonly damaged structures of the knee are the anterior cruciate ligament (ACL), medial collateral ligament (MCL), and menisci. Given that these injuries present as either isolated or concomitant, it follows that these events are driven by specific mechanics versus coincidence. This study was designed to investigate the multiplanar mechanisms and determine the important biomechanical and demographic factors that contribute to classification of the injury outcome., Hypothesis: Linear discriminant analysis (LDA) would accurately classify each injury type generated by the mechanical impact simulator based on biomechanical input variables (ie, ligament strain and knee kinetics)., Study Design: Controlled laboratory study., Methods: In vivo kinetics and kinematics of 42 healthy, athletic participants were measured to determine stratification of injury risk (ie, low, medium, and high) in 3 degrees of knee forces/moments (knee abduction moment, anterior tibial shear, and internal tibial rotation). These stratified kinetic values were input into a cadaveric impact simulator to assess ligamentous strain and knee kinetics during a simulated landing task. Uniaxial and multiaxial load cells and implanted strain sensors were used to collect mechanical data for analysis. LDA was used to determine the ability to classify injury outcome by demographic and biomechanical input variables., Results: From LDA, a 5-factor model (Entropy R 2 = 0.26) demonstrated an area under the receiver operating characteristic curve (AUC) for all 5 injury outcomes (ACL, MCL, ACL+MCL, ACL+MCL+meniscus, ACL+meniscus) of 0.74 or higher, with "good" prediction for 4 of 5 injury classifications. A 10-factor model (Entropy R 2 = 0.66) improved the AUC to 0.86 or higher, with "excellent" prediction for 5 injury classifications. The 15-factor model (Entropy R 2 = 0.85), produced 94.1% accuracy with the AUC 0.98 or higher for all 5 injury classifications., Conclusion: Use of LDA accurately predicted the outcome of knee injury from kinetic data from cadaveric simulations with the use of a mechanical impact simulator at 25° of knee flexion. Thus, with clinically relevant kinetics, it is possible to determine clinical risk of injury and also the likely presentation of singular or concomitant knee injury., Clinical Relevance: LDA demonstrates that injury outcomes are largely characterized by specific mechanics that can distinguish ACL, MCL, and medial meniscal injury. Furthermore, as the mechanics of injury are better understood, improved interventional prehabilitation can be designed to reduce these injuries.

Objective: The composition of cervical-spine meniscoids may have clinical significance in neck-pain conditions, but the accuracy of assessment of meniscoid composition in vivo using magnetic resonance imaging has not been established. The aim of this study was to compare cervical-spine meniscoid composition by magnetic resonance imaging with histologic composition., Methods: Four embalmed cadaveric cervical spines (mean [standard deviation] age, 79.5 [3.7] years; 1 female, 3 male) underwent magnetic resonance imaging, allowing radiologic classification of lateral atlantoaxial- and zygapophyseal-joint (C2-3 to C6-7) meniscoids as either mostly fatty, mixed tissue, or mostly connective tissue. Subsequently, each joint was dissected and disarticulated to allow excision of meniscoids for histologic processing. Each meniscoid was sectioned sagittally, stained with hematoxylin and eosin, examined using light microscopy, and classified as adipose, fibroadipose, or fibrous in composition. Data were analyzed using the kappa statistic with linear weighting., Results: From dissection, 62 meniscoids were identified, excised, and processed; 46 of these 62 were visualized with magnetic resonance imaging. For single-rater identifying structures, agreement between assessment of meniscoid composition by magnetic resonance imaging and by microscopy was fair (κ = 0.24; 95% confidence interval, 0.02-0.46; P = .02)., Conclusion: Findings suggest that the accuracy of this method of magnetic resonance imaging assessment of cervical-spine meniscoid composition may be limited. This should be considered when planning or interpreting research investigating meniscoid composition using magnetic resonance imaging., (Copyright © 2020. Published by Elsevier Inc.)

Background: Knee pain is a common symptom in the community. There is a wide range of conditions that can cause pain. Identifying the type and severity of the condition is important for effective management. There are several guidelines for the appropriate imaging of patients presenting with knee pain. Presentation is generally divided into a post-traumatic group and those without known trauma (including arthritis)., Objective: The aim of this article is to discuss the approach to imaging of the knee with reference to Diagnostic Imaging Pathways and illustrate some of the conditions that may be encountered., Discussion: The initial workup is typically done in general practice to determine which patients require referral for specialist management and which patients can be cared for in the community. Most cases presented in this article are patients referred from primary care to a metropolitan radiology practice during a six-month period, and they represent examples of some of the more common pathologies.

BACKGROUND To better understand the process of osteoarthritic degenerative meniscal lesions (DMLs) formation, this study analyzed the dataset GSE52042 using bioinformatics methods to identify the pivotal genes and pathways related to osteoarthritic DMLs. MATERIAL AND METHODS The GSE52042 dataset, comprising diseased meniscus samples and healthier meniscus samples, was downloaded and the differentially-expressed genes (DEGs) were extracted. The reactome pathways assessment and functional analysis were performed using the "ClusterProfiler" package and "ReactomePA" package of Bioconductor. The protein-protein interaction network was constructed, followed by the extraction of hub genes and modules. RESULTS A set of 154 common DEGs, including 64 upregulated DEGs and 90 downregulated DEGs, were obtained. GO analysis suggested that the DEGs primarily participated in positive regulation of the mitotic cell cycle and extracellular matrix organization. Reactome pathway analysis showed that the DEGs were predominantly enriched in TP53, which regulates transcription of genes involved in G2 cell cycle arrest and extracellular matrix organization. The top 10 hub genes were TYMS, AURKA, CENPN, NUSAP1, CENPM, TPX2, CDK1, UBE2C, BIRC5, and CCNB1. The genes in the 2 modules were primarily associated with M Phase and keratan sulfate degradation. CONCLUSIONS A series of pivotal genes and reactome pathways were identified elucidate the molecular mechanisms involved in the formation of osteoarthritic DMLs and to discover potential therapeutic targets.

Purpose: To evaluate the incidence and degree of shrinkage of transplanted fresh-frozen meniscal allografts in a long-term period of >8 years and to investigate whether the shrinkage of allograft progresses and is associated with inferior clinical and radiologic outcomes after meniscal allograft transplantation (MAT) in the long term., Methods: Twenty-two knees were reviewed in 20 patients (mean age, 31.41 ± 9.11 years) who underwent isolated lateral MAT. All patients were followed with magnetic resonance imaging (MRI) for at least 8 years (mean, 11.78 ± 3.10 years). The allograft widths of the anterior horn, mid-body, and posterior horn at 1 and >8 years postoperatively were measured by using MRI. To estimate the degree of shrinkage, the relative changes in widths during intervals were calculated. Patients were categorized into 4 groups according to shrinkage degree: minimal (<10%), mild (10%-25%), moderate (25%-50%), and severe (>50%). The joint space width was measured on the weightbearing radiographs to evaluate the radiologic outcome. The Lysholm score was used to evaluate the clinical outcome., Results: The relative change in the width of the anterior horn, mid-body, and posterior horn, compared with that 1 year postoperatively, was 82.7% (95% confidence interval 77.4%-87.5%), 75.9% (70.7%-81.0%), and 85.0% (81.4%-88.5%), respectively. The shrinkage degree was greater at the mid-body than at the anterior and posterior horns. About 70% of allografts showed ≥10% shrinkage of the posterior horn. Meniscal shrinkage did not show significant correlation with clinical and radiologic outcome., Conclusions: At long-term follow-up (>8 years), shrinkage of transplanted fresh-frozen meniscal allografts progressed at 1 year postoperative. On average, the shrinkage was mild and more prominent in the mid-body than in the anterior or posterior horn. In this study, it could not be concluded that the shrinkage of allografts was significantly associated with inferior clinical and radiologic outcomes in the long term., Level of Evidence: Level IV, therapeutic case series., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: Artificial meniscal implants can be used to replace a severely injured meniscus after meniscectomy and restore the normal functionality of a knee joint. The aim of this paper was to design porous meniscal implants and assess their biomechanical properties., Methods: Finite element simulations were conducted on eight different cases including intact healthy knees, knee joints with solid meniscal implants, and knee joints with meniscal implants with two types of triply periodic minimal surfaces. Compression stresses, shear stresses, and characteristics of stress concentrated areas were evaluated using an axial compressive load of 1150 N and an anterior load of 350 N., Results: Compared to the solid meniscal implant, the proposed porous meniscal implant produced lower levels of compression and shear stresses on the cartilage, which facilitated the cartilage to retain a semilunar characteristic similar to the natural meniscus. Moreover, both compression and shear stresses on the artificial cartilage were found to be sensitive to the pore properties of the meniscal implant. The meniscal implants with primitive surfaces (porosity: 41%) showed a better performance in disseminating stresses within the knee joint., Conclusion: The present commercial meniscal implant has the problem of equivalent biomechanical properties compared to natural menisci. The main advantage of the proposed porous structure is that it can be used to prevent excessive compression and shear stresses on the articular cartilages. This structure has advantages both in terms of mechanics and printability, which can be beneficial for future clinical applications.

Meniscus injuries are among the most common orthopedic injuries. Tears in the inner one-third of the meniscus heal poorly and present a significant clinical challenge. In this study, we hypothesized that progenitor cells from healthy human articular cartilage (chondroprogenitor cells [C-PCs]) may be more suitable than bone-marrow mesenchymal stem cells (BM-MSCs) to mediate bridging and reintegration of fibrocartilage tissue tears in meniscus. C-PCs were isolated from healthy human articular cartilage based on their expression of mesenchymal stem/progenitor marker activated leukocyte cell adhesion molecule (ALCAM) (CD166). Our findings revealed that healthy human C-PCs are CD166+, CD90+, CD54+, CD106- cells with multilineage differentiation potential, and elevated basal expression of chondrogenesis marker SOX-9. We show that, similar to BM-MSCs, C-PCs are responsive to the chemokine stromal cell-derived factor-1 (SDF-1) and they can successfully migrate to the area of meniscal tissue damage promoting collagen bridging across inner meniscal tears. In contrast to BM-MSCs, C-PCs maintained reduced expression of cellular hypertrophy marker collagen X in monolayer culture and in an explant organ culture model of meniscus repair. Treatment of C-PCs with SDF-1/CXCR4 pathway inhibitor AMD3100 disrupted cell localization to area of injury and prevented meniscus tissue bridging thereby indicating that the SDF-1/CXCR4 axis is an important mediator of this repair process. This study suggests that C-PCs from healthy human cartilage may potentially be a useful tool for fibrocartilage tissue repair/regeneration because they resist cellular hypertrophy and mobilize in response to chemokine signaling. Stem Cells 2019;37:102-114., (© 2018 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.)

Grafting of tissue-engineered cartilage to joints with osteoarthritis has the potential to supersede arthroplasty as the standard of care. However, in order to support the development of functional tissue engineering methods, the subfailure biomechanics of the individual cartilage types that comprise joints must be determined. Current methods for analyzing tissues are based on imaging and are therefore unable to profile the strain dependence of mechanical behaviors within different cartilage types. Recently, an analysis technique based on Optical Fiber Polarimetric Elastography (OFPE) has overcome these challenges. OFPE has been used to characterize the different mechanical behaviors of a range of unprocessed biomaterials and tissues. In the present work, this technique is used to characterize the biomechanics of both articular cartilage and meniscal fibrocartilage within a porcine knee. OFPE testing of the tissue is conducted over a range of physiological loading and unloading values. These results demonstrate the distinctive mechanics of each cartilage type. Due to their different locations within the knee, each cartilage type exhibits distinctly unique biomechanical behavior. Based on the results of OFPE, we correlate the specific buckling, delamination, and bridging events to maxima and minima along the loading and unloading curves. This provides unprecedented detail with regard to the subfailure biomechanics. This information is integral to the design of the next generation of tissue-engineered constructs. Therefore, OFPE will be used across multiple disciplines to rapidly determine the mechanical behavior of tissue-engineered constructs to support functional tissue engineering efforts.

Partial meniscectomy for meniscus tears is one of the most common procedures performed by orthopaedic surgeons. Much research has been done to evaluate the biomechanical consequences and clinical outcomes from meniscus débridement. Biomechanically, as the portion of the meniscus that is removed increases, greater contact pressures are experienced by the cartilage, which leads to altered knee mechanics. The use of partial meniscectomy to manage degenerative meniscus tears in knees with mild preexisting arthritis and mechanical symptoms may be beneficial; however, its routine use in the degenerative knee over physical therapy alone is not supported. In younger populations, partial meniscectomy may provide equal long-term symptom relief, earlier return to play, and lower revision surgery rate compared with meniscal repair. Partial meniscectomy may result in earlier development of osteoarthritis. Treatment should be patient specific in a shared-decision making process with the patient after discussion about known outcomes.

The objectives of this study were to compare the ultrashort T2* relaxation time with the T2* relaxation time using the 3 dimensional (3D) cones sequence in 3 groups of patients with normal, degenerated, and torn knee menisci, and to demonstrate the additional effect of the ultrashort echo time (UTE) signal intensity.Following institutional review board approval, 42 knee magnetic resonance imaging (MRI) scans of 42 patients who presented with knee pain and underwent knee MRIs, with the 3D Cones of UTE sequence (minimum TEs: 32 μs) and a 3T MRI scanner (Discovery 750, GE Healthcare, Waukesha, WI), were analyzed. The enrolled patients were classified into 3 subgroups:normal meniscus on conventional MRI, with no positive meniscus-related physical examination in medical records;meniscal degeneration with signal changes on conventional MRI; andmeniscal tear.For the quantitative assessment, the mean values inside user-drawn regions of interest (ROIs) of the medial menisci were drawn on UTE T2* map and T2* map. For statistical analyses, 1-way analysis of variance (ANOVA) with post-hoc analysis using the Tukey HSD test was conducted to compare groups, and effect size was used to compare the discrimination power.The ultrashort T2* relaxation times were higher in patients with meniscal tear than in those with normal and degeneration groups (P <.05, respectively) whereas T2* relaxation times were not statistically significantly different. The ultrashort T2* relaxation times showed higher effect sizes than the T2* times between tear and normal/degeneration.The ultrashort T2* relaxation times showed better delineation of meniscal degeneration or tears than T2* relaxation times. The ultrashort T2* relaxation times could be more sensitive at differentiating between normal and pathologic meniscal conditions in patients.

Pressure distribution of the native ovine knee meniscus was compared to a medial meniscectomy and three treatment conditions including a suture reattachment of the native tissue, an allograft, and a novel thermoplastic elastomer hydrogel (TPE) construct. The objective of this study was to assess the efficacy of a novel TPE hydrogel construct at restoring joint pressure and distribution. Limbs were loaded in uniaxial compression at 45°, 60°, and 75° flexion and from 0 to 181 kg. The medial meniscectomy decreased contact area by approximately 50% and doubled the mean and maximum pressure reading for the medial hemijoint. No treatment condition tested within this study was able to fully restore medial joint contact area and pressures to the native condition. A decrease in lateral contact area and increase in pressures with the meniscectomy was also seen; and to some degree, all reattachment and replacement conditions including the novel TPE hydrogel replacement helped to restore lateral pressures. Although the TPE construct did not perform as well as hoped in the medial compartment, it performed as well as, if not better, than the other reattachment and replacement options in the lateral. Further work is necessary to determine the best anchoring and attachment methods.

Meniscus injuries appear to be becoming increasingly common and pose a challenge for orthopedic surgeons. However, there is no curative approach for dealing with defects in the inner meniscus region due to its avascular nature. Numerous strategies have been applied to regenerate and repair meniscus defects and native tissue-based strategies have received much attention. Native tissue usually has good biocompatibility, excellent mechanical properties and a suitable microenvironment for cellular growth, adhesion, redifferentiation, extracellular matrix deposition and remodeling. Classically, native tissue-based strategies for meniscus repair and regeneration are divided into autogenous and heterogeneous tissue transplantation. Autogenous tissue transplantation is performed more widely than heterogeneous tissue transplantation because there is no immunological rejection and the success rates are higher. This review first discusses the native meniscus structure and function and then focuses on the use of the autogenous tissue for meniscus repair and regeneration. Finally, it summarizes the advantages and disadvantages of heterogeneous tissue transplantation. We hope that this review provides some suggestions for the future design of meniscus repair and regeneration strategies.

Meniscus injuries are extremely common with approximately one million patients undergoing surgical treatment annually in the U.S. alone. Upon injury, the outer zone of the meniscus can be repaired and expected to functionally heal but tears in the inner avascular region are unlikely to heal. To date, no regenerative therapy has been proven successful for consistently promoting healing in inner-zone meniscus tears. Here, we show that controlled applications of connective tissue growth factor (CTGF) and transforming growth factor beta 3 (TGFβ3) can induce seamless healing of avascular meniscus tears by inducing recruitment and step-wise differentiation of synovial mesenchymal stem/progenitor cells (syMSCs). A short-term release of CTGF, a selected chemotactic and profibrogenic cue, successfully recruited syMSCs into the incision site and formed an integrated fibrous matrix. Sustain-released TGFβ3 then led to a remodeling of the intermediate fibrous matrix into fibrocartilaginous matrix, fully integrating incised meniscal tissues with improved functional properties. Our data may represent a novel clinically relevant strategy to improve healing of avascular meniscus tears by recruiting endogenous stem/progenitor cells.

This study aimed to investigate the biomechanical properties of anterior cruciate ligament (ACL); tibial, femoral articular cartilage; and meniscus in knee joints receiving computer-aided or conventional ACL reconstruction. Three-dimensional (3D) knee joint finite element models were established for healthy volunteers (normal group) and patients receiving computer-aided surgery (CAS) or conventional (traditional surgery [TS]) ACL reconstruction. The stress and stress distribution on the ACL, tibial, femoral articular cartilage, and meniscus were examined after force was applied on the 3D knee joint finite element models. No significant differences were observed in the stress on ACL among normal group, CAS group, and TS group when a femoral backward force was loaded. However, when a vertical force of 350 N was loaded on the knee joints, TS group had significant higher stress on the articular cartilage and meniscus than the other two groups at any flexion angle of 0, 30, 60, and 90 degrees. However, no significant differences were observed between CAS group and normal group. In conclusion, computer-aided ACL reconstruction has advantages over conventional surgery approach in restoring the biomechanical properties of knee joints, thus reducing the risk of damage to the knee joint cartilage and meniscus after ACL reconstruction., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Chondral lesions are commonly encountered during arthroscopic partial meniscectomy (APM); however, it is unknown how these lesions affect postoperative outcomes., Purpose: The authors compared postoperative outcomes among patients with and without unstable chondral lesions 1 year after APM., Study Design: Cohort study; Level of evidence, 3., Methods: The authors conducted a secondary analysis of data from the ChAMP (Chondral Lesions and Meniscus Procedures) randomized controlled trial. They compared the following outcomes for patients with unstable chondral lesions that were left in situ and observed (CL-noDeb) versus patients without unstable chondral lesions (NoCL) at 1 year after APM: Western Ontario and McMaster Universities Osteoarthritis Index, Knee injury and Osteoarthritis Outcome Score, visual analog scale for pain, the Short Form Health Survey, range of motion, quadriceps circumference, and effusion. Multivariate linear regression was used to obtain mean differences (MDs) with corresponding 95% CIs adjusted for age, body mass index, and preoperative score (for postoperative scores)., Results: Compared with the CL-noDeb group, the NoCL group had greater improvement in Western Ontario and McMaster Universities Osteoarthritis Index for pain (MD, 7.9, 95% CI: 2.7-13.1), stiffness (MD, 9.1, 95% CI: 1.9-16.3), and physical function (MD, 4.6, 95% CI: 0.1-9.0) and Knee injury and Osteoarthritis Outcome Score for pain (MD, 8.4, 95% CI: 2.7-14.0), function in sport and recreation (MD, 11, 95% CI: 3.0-19.1), and quality of life (MD, 10.4, 95% CI: 2.3-18.5). The NoCL group was less likely than the CL-noDeb group to have an effusion ( P = .02) 1 year after surgery., Conclusion: Patients undergoing APM without unstable chondral lesions had better outcomes than patients with unstable chondral lesions.

Activation of transforming growth factor-β (TGF-β) signaling has been used to enhance healing of meniscal degeneration in several models. However, the exact role and molecular mechanism of TGF-β signaling in meniscus maintenance and degeneration are still not understood due to the absence of in vivo evidence. In this study, we found that the expression of activin receptor-like kinases 5 (ALK5) in the meniscus was decreased with the progression of age and/or osteoarthritis induced meniscal degeneration. Col2α1 positive cells were found to be specifically distributed in the superficial and inner zones of the anterior horn, as well as the inner zone of the posterior horn in mice, indicating that Col2α1-CreER T2 mice can be a used for studying gene function in menisci. Furthermore, we deleted Alk5 in Col2α1 positive cells in meniscus by administering tamoxifen. Alterations in the menisci structure were evaluated histologically. The expression levels of genes and proteins associated with meniscus homeostasis and TGF-β signaling were analyzed by quantitative real-time PCR analysis (qRT-PCR) and immunohistochemistry (IHC). Our results revealed severe and progressive meniscal degeneration phenotype in 3- and 6-month-old Alk5 cKO mice compared with Cre-negative control, including aberrantly increased hypertrophic meniscal cells, severe fibrillation, and structure disruption of meniscus. qRT-PCR and IHC results showed that disruption of anabolic and catabolic homeostasis of chondrocytes may contribute to the meniscal degeneration phenotype observed in Alk5 cKO mice. Thus, TGF-β/ALK5 signaling plays a chondro-protective role in menisci homeostasis, in part, by inhibiting matrix degradation and maintaining extracellular matrix proteins levels in meniscal tissues., (© 2018 Wiley Periodicals, Inc.)

Background: Contralateral anterior cruciate ligament (CACL) injury after recovery from a first-time ACL rupture occurs at a high rate in young females; however, little is known about the risk factors associated with bilateral ACL trauma., Hypothesis: The geometric characteristics of the contralateral knee at the time of the initial ACL injury are associated with risk of suffering a CACL injury in these female athletes., Study Design: Case-control study; Level of evidence, 3., Methods: Sixty-two female athletes who suffered their first noncontact ACL injury while participating in sports at the high school or college level were identified, and geometry of the femoral notch, ACL, tibial spines, tibial subchondral bone, articular cartilage surfaces, and menisci of the contralateral, uninjured, knee was characterized in 3 dimensions. We were unable to contact 7 subjects and followed the remaining 55 until either a CACL injury or an ACL graft injury occurred or, if they were not injured, until the date of last contact (mean, 34 months after their first ACL injury). Cox regression was used to identify risk factors for CACL injury., Results: Ten (18.2%) females suffered a CACL injury. Decreases of 1 SD in femoral intercondylar notch width (measured at its outlet and anterior attachment of the ACL) were associated with increases in the risk of suffering a CACL injury (hazard ratio = 1.88 and 2.05, respectively). Likewise, 1 SD decreases in medial-lateral width of the lateral tibial spine, height of the medial tibial spine, and thickness of the articular cartilage located at the posterior region of the medial tibial compartment were associated with 3.59-, 1.75-, and 2.15-fold increases in the risk of CACL injury, respectively., Conclusion: After ACL injury, subsequent injury to the CACL is influenced by geometry of the structures that surround the ACL (the femoral notch and tibial spines). This information can be used to identify individuals at increased risk for CACL trauma, who might benefit from targeted risk-reduction interventions.

Dense connective tissue injuries have limited repair, due to the paucity of cells at the wound site. We hypothesize that decreasing the density of the local extracellular matrix (ECM) in conjunction with releasing chemoattractive signals increases cellularity and tissue formation after injury. Using the knee meniscus as a model system, we query interstitial cell migration in the context of migratory barriers using a novel tissue Boyden chamber and show that a gradient of platelet-derived growth factor-AB (PDGF-AB) expedites migration through native tissue. To implement these signals in situ, we develop nanofibrous scaffolds with distinct fiber fractions that sequentially release active collagenase (to increase ECM porosity) and PDGF-AB (to attract endogenous cells) in a localized and coordinated manner. We show that, when placed into a meniscal defect, the controlled release of collagenase and PDGF-AB increases cellularity at the interface and within the scaffold, as well as integration with the surrounding tissue.

Background: Temporomandibular joint dysfunction is often related to excessive load in the stomatognathic system., Objectives: The objective of the model tests, using numeric calculations, was to assess the articular disc loads in the temporomandibular joints after prosthetic and pharmacological treatment of functional disorders of the masticatory organ., Material and Methods: The study involved 10 patients, aged 21-48 years, of both sexes, randomly selected from a group of 120 patients treated with relaxation occlusal splints (60 patients, group I) and intramuscular injection of botulinum toxin type A (60 patients, group II), suffering from temporomandibular joint dysfunction with the dominant muscle component. In all subjects, a specialized functional examination was carried out. Treatment groups: occlusal splint therapy (group I) and intramuscular injection of botulinum toxin type A (group II). An assessment of the loads of 4 disc zones of the temporomandibular joints was carried out based on the results of clinical studies (phase I of the study), and numeric model tests (phase II). In the representatives of the study groups (5 patients in each group), measurements of occlusal forces and an evaluation of tension of the masseter and temporalis muscle were performed., Results: The results of the average load values for all evaluated zones of the right and left articular disc differ in a statistically significant way in favor of group II, with the exception of the external mid part of the discs. In the case of the anterior of the right disc, the load was lower in patients belonging to group I than in those obtained in group II., Conclusions: Botulinum toxin type A significantly reduces the loads within the temporomandibular joints, generated by masseter muscle hypertonia.

The meniscal cartilages in the knee function to improve congruity of the medial and lateral femoro-tibial joints and play critical roles in load distribution and joint stability. Meniscal tears of various configurations are one of the most common conditions of the knee and are associated with an increased risk of developing osteoarthritis (OA). While this risk has been largely attributed to loss of the biomechanical functions of the menisci, there is accumulating evidence suggesting that other aspects of meniscal biology may play a role in determining the long-term consequences of meniscal damage for joint health. In this narrative review, we examine the existing literature and present some new data implicating synthesis and secretion of enzymes and other pro-catabolic mediators by injured and degenerate menisci, contributing to the pathological change in other knee joint tissues in OA.

The aim of this study was to quantify how abnormal dynamic tibiofemoral surface alignment affects the load bearing function of menisci in vivo. Using a sheep model of ACL deficiency, we tested the hypothesis that increased in vivo meniscal loads correlate with greater tibiofemoral surface alignment abnormality. Stifle kinematics were recorded using a bone-mounted instrumented spatial linkage in four sheep before, and at four and twenty weeks (w) after ACL transection. A parallel robotic manipulator was used to quantify stifle kinetics by reproducing each animal׳s in vivo kinematics and measuring tissue loads during gait. Meniscal resultant loads were estimated from the change in joint reaction force after sequentially removing load-bearing tissues. Tibiofemoral subchondral surfaces were then traced and modeled using thin plate splines. Proximity disturbance is a surface interaction measure used to quantify dynamic tibiofemoral surface alignment abnormality. ACL transection increased meniscal loads by 30-145% at 20w post-ACL transection, whereas the degree of dynamic tibiofemoral subchondral surface alignment varied between sheep. Positive and significant correlations between increased meniscal loads and proximity disturbance values >10mm were observed (R 2 =0.04-0.57; p≤0.05). Our results suggest that the proximity disturbance measure reflects abnormal meniscal loads following ACL injury; however given the range of R 2 values, perturbations in dynamic tibiofemoral subchondral surface alignment do not explain abnormal joint kinetics entirely, and point to the presence of other dynamic compensatory mechanisms that may have a significant bearing on in vivo joint function and long-term joint health., (Copyright © 2016 Elsevier Ltd. All rights reserved.)