Medial Meniscotibial Ligament Research Articles

The meniscotibial ligament does exist: An anatomic and histological description

PurposeTo describe the anatomical and histological characteristics of the human MTL (meniscotibial ligament) that keeps the meniscus stable and are rarely discussed. Study designDescriptive laboratory study. MethodsIn total, six fresh-frozen adult cadaver knees were dissected, and the dissection protocol were designed by two experienced anatomy professors. The anatomical morphology of MTL was observed. The main anatomical specimens included meniscus, tibial plateau, MTL. The osteotome was used to excise the portion of the tibial plateau, which could obtain the complex including partial meniscus, MTL, and a tibial fragment. A histopathologic study was performed by two experienced pathologists. ResultsMacroscopically, the MTL could be divided into two parts: medial meniscotibial ligament (MMTL)and lateral meniscotibial ligament (LMTL). The MMTL is distributed continuously, whereas the LMTL is discontinuous on the tibial plateau. The average length from the tibial attachment of the LMTL to the articular surface was 19 ± 1.0mm (mean ± SD). The average length from the tibial attachment of the MMTL to the articular surface was 10 ± 1.2 mm (mean ± SD). Microscopy of the MTL showed that the MTL is a ligamentous tissue, composed of a network of oriented collagenous fibers. ConclusionsIn all knees, the MTL was inserted on the outer edge of the meniscus, attaching to the tibia below the level of articular cartilage, which was key to maintaining the rotational stability of knee and the meniscus in the physiological position on the tibial plateau. Histological analysis of this ligament demonstrated that the MTL is a veritable ligamentous structure, which is made up of collagen type I–expressing fibroblasts. Clinical relevanceThis article contributes to the understanding of the anatomical and histological characteristics of the MTL. It is beneficial to promote the development of relevant surgical techniques for the MTL lesion.

Ginsenoside compound K alleviates osteoarthritis by inhibiting NLRP3‑mediated pyroptosis.

Ginsenoside compound K (GCK) has been previously reported to be a potent antiarthritic and bone-protective agent. Therefore, the present study aimed to explore the potential effects of GCK on osteoarthritis and its regulatory effects on the pyroptosis of chondrocytes. Primary mouse chondrocytes (PMCs) were used for in vitro analysis. ELISA assays revealed that compared with the untreated cells, TNF-α induced a significant increase in IL-6, MMP13, A disintegrin and metalloproteinase with thrombospondin motifs 5 and MMP3 expression but induced a significant decrease in aggrecan and collagen II expression. By contrast, GCK reversed the aforementioned alterations in a dose-dependent manner. Experimental osteoarthritis was subsequently induced in mice through transection of the medial meniscotibial ligament and medial collateral ligament in the right knee [destabilization of the medial meniscus (DMM) mice]. GCK was found to reduce cartilage degradation in vivo in DMM mice, which was assessed using the Osteoarthritis Research Society International (OARSI) score, collagen II and MMP13 expression. Cartilage degradation is associated with higher OARSI score, decreased collagen II and increased MMP13 expression. In PMCs, TNF-α treatment stimulated an increase in the expression of NLR family pyrin domain containing 3 (NLRP3), Gasdermin D-N terminal (GSDMD-NT), cleaved caspase-1 and mature IL-1β, markers that indicate the occurrence of pyroptosis. However, GCK treatment suppressed the increase of the aforementioned proteins in a dose-dependent manner. Immunohistochemistry staining of the knee joint tissue sections from the DMM mice confirmed that GCK attenuated the NLRP3 and GSDMD-NT expression that was induced by DMM surgery. In conclusion, the present study revealed that GCK can reduce cartilage degradation in an osteoarthritis model by inhibiting the NLRP3-inflammasome activation and subsequent pyroptosis.

Effects of risk factors on evoked pain patterns in rat models of experimental knee osteoarthritis.

Pain experiences in patients with knee osteoarthritis (OA) may be influenced differently by OA risk factors, reducing the translatability of preclinical research into the clinic. Our objective was to contrast evoked pain patterns after exposure to different OA risk factors including acute joint trauma, chronic instability, or obesity/metabolic syndrome using rat models of experimental knee OA. We tested longitudinal patterns of evoked pain behaviors (knee pressure pain threshold and hindpaw withdrawal threshold) in young male rats exposed to different OA-inducing risk factors including (1) nonsurgical joint trauma (impact-induced anterior cruciate ligament (ACL) rupture); (2) surgical joint destabilization (ACL + medial meniscotibial ligament transection); and (3) high fat/sucrose (HFS) diet-induced obesity. Histopathology for synovitis, cartilage damage, and subchondral bone morphology was performed. Pressure pain threshold was reduced (more pain) most, and earlier by joint trauma (Week 4-12) and HFS (Week 8-28) than by joint destabilization (Week 12). Hindpaw withdrawal threshold was reduced transiently after joint trauma (Week 4), with smaller and later reductions after joint destabilization (Week 12), but not with HFS. Synovial inflammation occurred at Week 4 after joint trauma and instability but only coincided with pain behaviors after joint trauma. Cartilage and bone histopathology were most severe after joint destabilization and least severe with HFS. The pattern, intensity, and timing of evoked pain behaviors varied due to OA risk factor exposure and were inconsistently associated with histopathological OA features. These findings may help to explain the challenges with translating preclinical OA pain research to multimorbid clinical OA contexts.

Silencing of IRF7 ameliorates osteoarthritis by inhibiting chondrocyte pyroptosis via targeting FGF21

Osteoarthritis (OA) is the most common joint disease which can lead to serious disability. Interferon regulatory factor 7 (IRF7) is a member of the interferon regulatory factor family. This study aimed to explore the function and potential mechanism of IRF7 in OA.Our results found that IRF7 was increased in LPS-stimulated C28/I2 chondrocytes and in OA mice established with medial menisco-tibial ligament (MMTL) transection. IRF7 silencing enhanced cell viability, reduced IL-18 and IL-1β levels and suppressed cell apoptosis. IRF7 knockdown decreased ROS and LDH levels, and inhibited pyroptosis in LPS-treated chondrocytes. IRF7 negatively regulated FGF21 expression. FGF21 overexpression alleviated pyroptosis in LPS-stimulated chondrocytes. Knockdown of IRF7 improved OA injury in mice. In conclusion, our study demonstrates that silencing of IRF7 alleviates OA by inhibiting chondrocyte pyroptosis via upregulation of FGF21.

Study of the nerve endings and mechanoreceptors of the medial meniscotibial ligament of the knee: A structural and distribution analysis

BackgroundThe aim of the present study is to describe the morphology and distribution of the nerve endings of the meniscotibial ligament (MTL) of the knee, in order to understand the interaction between the proprioceptive system and knee mechanics. MethodsTwenty medial MTLs were obtained from deceased organ donors. The ligaments were measured, weighed and cut. Sections (10 mm) were prepared on hematoxylin and eosin-stained slides for analysis of tissue integrity, and 50 mm sections were submitted to immunofluorescence with the protein gene product (PGP) 9.5 as primary antibody and Alexa Fluor 488 as secondary antibody, followed by microscopic analysis. ResultsThe medial MTL was identified in 100% of the dissections, with average length, width, thickness and weight of 7.07 ± 1.34 mm, 32.25 ± 3.09 mm, 3.53 ± 0.27 mm and 0.67 ± 0.13 g, respectively. The hematoxylin and eosin-stained histological sections exhibited typical ligament structure, with dense well-organized collagen fibers and vascular tissue. All the specimens analyzed contained type I (Ruffini) mechanoreceptors and free (type IV) nerve endings, varying from parallel to intertwined fibers. Nerve endings not classified with different irregular shapes were also found. Most type I mechanoreceptors were found close to the MTL insertions on the tibial plateau, while the free nerve endings were found adjacent to the capsule. ConclusionThe medial MTL showed a peripheral nerve structure, primarily type I and IV mechanoreceptors. These findings suggest that the medial MTL is important for proprioception and medial knee stabilization.

In vivo ligamentogenesis in embroidered poly(lactic-co-ε-caprolactone) / polylactic acid scaffolds functionalized by fluorination and hexamethylene diisocyanate cross-linked collagen foams

Although autografts represent the gold standard for anterior cruciate ligament (ACL) reconstruction, tissue-engineered ACLs provide a prospect to minimize donor site morbidity and limited graft availability. This study characterizes the ligamentogenesis in embroidered poly(L-lactide-co-ε-caprolactone) (P(LA-CL)) / polylactic acid (PLA) constructs using a dynamic nude mice xenograft model. (P(LA-CL))/PLA scaffolds remained either untreated (co) or were functionalized by gas fluorination (F), collagen foam cross-linked with hexamethylene diisocyanate (HMDI) (coll), or F combined with the foam (F + coll). Cell-free constructs or those seeded for 1 week with lapine ACL ligamentocytes were implanted into nude mice for 12 weeks. Following explantation, cell vitality and content, histo(patho)logy of scaffolds (including organs: liver, kidney, spleen), sulphated glycosaminoglycan (sGAG) contents and biomechanical properties were assessed.Scaffolds did not affect mice weight development and organs, indicating no organ toxicity. Moreover, scaffolds maintained their size and shape and reflected a high cell viability prior to and following implantation. Coll or F + coll scaffolds seeded with cells yielded superior macroscopic properties compared to the controls. Mild signs of inflammation (foreign-body giant cells and hyperemia) were limited to scaffolds without collagen. Microscopical score values and sGAG content did not differ significantly. Although remaining stable after explantation, elastic modulus, maximum force, tensile strength and strain at Fmax were significantly lower in explanted scaffolds compared to those before implantation, with no significant differences between scaffold subtypes, except for a higher maximum force in F + coll compared with F samples (in vivo). Scaffold functionalization with fluorinated collagen foam provides a promising approach for ACL tissue engineering.Graphical abstracta Lapine anterior cruciate ligament (LACL): red arrow, posterior cruciate ligament: yellow arrow. Medial anterior meniscotibial ligament: black arrow. b Explant culture to isolate LACL fibroblasts. c Scaffold variants: co: controls; F: functionalization by gas-phase fluorination; coll: collagen foam cross-linked with hexamethylene diisocyanate (HMDI). c1-2 Embroidery pattern of the scaffolds. d Scaffolds were seeded with LACL fibroblasts using a dynamical culturing approach as depicted. e Scaffolds were implanted subnuchally into nude mice, fixed at the nuchal ligament and sacrospinal muscle tendons. f Two weeks after implantation. g Summary of analyses performed. Scale bars 1 cm (b, d), 0.5 cm (c). (sketches drawn by G.S.-T. using Krita 4.1.7 [Krita foundation, The Netherlands]).

6-Shogaol (enexasogoal) treatment improves experimental knee osteoarthritis exerting a pleiotropic effect over immune innate signalling responses in chondrocytes.

The pathogenesis of osteoarthritis implicates a low-grade inflammation associated to the innate immune system activation. Toll like receptor (TLR) stimulation triggers the release of inflammatory mediators, which aggravate osteoarthritis. We studied the preventive effect of 6-shogaol, a potential TLR4 inhibitor, on the treatment of experimental knee osteoarthritis. Osteoarthritis was induced in C57BL6 mice by surgical section of the medial meniscotibial ligament, which received 6-shogaol for eight weeks. Cartilage damage, inflammatory mediator presence and disease markers were assessed in joint tissues by immunohistochemistry. Computational modelling was used to predict binding modes of 6-shogaol into the TLR4/MD2 receptor and its permeability across cellular membranes. Employing LPS-stimulated chondrocytes and MAPK assay, we elucidated 6-shogaol action mechanisms. 6-Shogaol treatment prevented articular cartilage lesions, synovitis and the presence of pro-inflammatory mediators, and disease markers in osteoarthritis animals. Molecular modelling studies predicted 6-shogaol interaction with the TLR4/MD-2 heterodimer in an antagonist conformation through its binding into the MD-2 pocket. In cell culture, we confirmed that 6-shogaol reduced LPS-induced TLR4 inflammatory signalling pathways. Besides, MAPK assay demonstrated that 6-shogaol directly inhibits the ERK1/2 phosphorylation activity. 6-Shogaol evoked a preventive action on cartilage and synovial inflammation in osteoarthritis mice. 6-shogaol effect may take place not only by hindering the interaction between TLR4 ligands and the TLR4/MD-2 complex in chondrocytes, but also through inhibition of ERK phosphorylation, implying a pleiotropic effect on different mediators activated during osteoarthritis, which proposes it as an attractive drug for osteoarthritis treatments.

Destabilization of the Medial Meniscus and Cartilage Scratch Murine Model of Accelerated Osteoarthritis.

Osteoarthritis is the most prevalent musculoskeletal disease in people over 45, leading to an increasing economic and societal cost. Animal models are used to mimic many aspects of the disease. The present protocol describes the destabilization and cartilage scratch model (DCS) of post-traumatic osteoarthritis. Based on the widely used destabilization of the medial meniscus (DMM) model, DCS introduces three scratches on the cartilage surface. The current article highlights the steps to destabilize the knee by transecting the medial meniscotibial ligament followed by three intentional superficial scratches on the articular cartilage. The possible analysis methods by dynamic weight-bearing, microcomputed tomography, and histology are also demonstrated. While the DCS model is not recommended for studies that focus on the effect of osteoarthritis on the cartilage, it enables the study of osteoarthritis development in a shorter time window, with special focus on (1) osteophyte formation, (2) osteoarthritic and injury pain, and (3) the effect of cartilage damage in the whole joint.

Water-in-Water Emulsions, Ultralow Interfacial Tension, and Biolubrication

Water-in-Water Emulsions, Ultralow Interfacial Tension, and Biolubrication

Investigating the Chronology of Meniscus Root Tears: Do Medial Meniscus Posterior Root Tears Cause Extrusion or the Other Way Around?

Objectives:Meniscus root tears are increasingly being recognized. Meniscus extrusion has previously been associated with medial root tears; however, the relationship between secondary meniscus restraints, such as the meniscotibial (MT) ligament, extrusion, and root tears has yet to be formally evaluated. The purpose of this study was to better understand the association between MT ligament competence, medial meniscus extrusion, and medial meniscus posterior root tears (MMPRT), as well as to determine the progression of meniscus extrusion over time.Methods:Serial MRI’s from our institution were reviewed for patients who showed evidence of medial meniscus extrusion and MMPRT on at least one of 2+ available MRI’s. All patients were symptomatic at the time of diagnosis. All MRI’s were analyzed independently by two board-certified musculoskeletal radiologists. MT ligament disruption, medial meniscus extrusion, and MMPRT presence was recorded for each MRI. The time between MRI’s, presence of insufficiency fractures, and Outerbridge classification for the medial femur and tibia were also evaluated.Results:27 knees in 26 patients were included in this study, with a total of 63 MRI’s analyzed (21 knees with 2 MRI’s, 3 with 3 MRI’s, and 3 with 4 MRI’s). All patients demonstrated clear medial meniscus extrusion and meniscotibial ligament disruption prior to the subsequent development of MMPRTs (p < 0.001). Mean extrusion at the time of initial MRI was 3.3 ± 1.1 mm, and increased significantly to 5.5 ± 1.8 mm at the time of first imaging with an identified MMPRT (p < 0.001). The average time between initial MRI and the first identification of MMPRT on a later MRI was 1.7 ± 1.6 years.Conclusions:In a sample of 27 symptomatic knees with serial MRI’s both before and after MMPRT diagnosis, all patients demonstrated MT ligament disruption and associated meniscus extrusion prior to the development of subsequent medial meniscus root tears. These findings suggest that MT ligament disruption and medial meniscus extrusion represent early and predisposing events contributing to MMPRT. Therefore, this provides a possible explanation of why meniscus extrusion is not corrected with medial meniscus root repair.

What Is the Relationship Between the Distal Semimembranosus Tendon and the Medial Meniscus? A Gross and Microscopic Analysis From the SANTI Study Group

Background: Some authors have suggested that the semimembranosus tendon is involved in the pathophysiology of ramp lesions. This led us to conduct a gross and microscopic analysis of the posterior horn of the medial meniscus and the structures inserted on it. Hypothesis: (1) The semimembranosus tendon has a tendinous branch inserting into the posterior horn of the medial meniscus, and (2) the meniscotibial ligament is inserted on the posteroinferior edge of the medial meniscus. Study Design: Descriptive laboratory study. Methods: In total, 14 fresh cadaveric knees were dissected. From each cadaveric donor, a stable anatomic specimen was harvested en bloc, including the medial femoral condyle, medial tibial plateau, whole medial meniscus, cruciate ligaments, joint capsule, and distal insertion of the semimembranosus tendon. The harvested blocks were cut along the sagittal plane to isolate the distal insertion of the semimembranosus tendon on the posterior joint capsule and the posterior horn of the medial meniscus in a single slice. Histological slides were made from these samples and analyzed under a microscope. Results: In all knees, gross examination revealed a direct branch of the semimembranosus and a tendinous capsular branch ending behind the posterior horn of the medial meniscus. This capsular branch protruded over the joint capsule, over the meniscotibial ligament below and the meniscocapsular ligament above, but never ended directly in the meniscal tissue. The capsular branch was 14.3 ± 4.4 mm long (mean ± SD). The direct tendon inserted 11 ± 2.8 mm below the articular surface of the tibial plateau. The meniscotibial ligament inserted on the posteroinferior edge of the medial meniscus, and the meniscocapsular ligament insertion was on its posterosuperior edge. Highly vascularized adipose tissue was found, delimited by the posterior horn of the medial meniscus, meniscotibial ligament, meniscocapsular ligament, and capsular branch of the semimembranosus tendon. Conclusion: In all knees, our study found a capsular branch of the semimembranosus tendon inserted behind the medial meniscus. The meniscotibial ligament was inserted on the posteroinferior edge of the medial meniscus. Histological analysis of this area revealed that this ligament inserted differently from the insertion previously described in the literature. Clinical Relevance: This laboratory study provides insight into the pathophysiology of ramp lesions frequently associated with anterior cruciate ligament injury. To restore anatomy, it is mandatory to reestablish meniscotibial ligament continuity in ramp repairs.

Refining surgical models of osteoarthritis in mice and rats alters pain phenotype but not joint pathology.

The relationship between osteoarthritis (OA) structural change and pain is complex. Surgical models of OA in rodents are often rapid in onset, limiting mechanistic utility and translational validity. We aimed to investigate the effect of refining surgical small rodent models of OA on both joint pathology and pain behaviour. Adult male C57BL/6 mice (n = 76, 10–11 weeks of age at time of surgery) underwent either traditional (transection of the medial meniscotibial ligament [MMTL]) or modified (MMTL left intact, transection of the coronary ligaments) DMM surgery, or sham surgery. Adult male Sprague Dawley rats (n = 76, weight 175-199g) underwent either modified meniscal transection (MMNX) surgery (transection of the medial meniscus whilst the medial collateral ligament is left intact) or sham surgery. Pain behaviours (weight bearing asymmetry [in mice and rats] and paw withdrawal thresholds [in rats]) were measured pre-surgery and weekly up to 16 weeks post-surgery. Post-mortem knee joints were scored for cartilage damage, synovitis, and osteophyte size. There was a significant increase in weight bearing asymmetry from 13 weeks following traditional, but not modified, DMM surgery when compared to sham operated mice. Both traditional and modified DMM surgery led to similar joint pathology. There was significant pain behaviour from 6 weeks following MMNX model compared to sham operated control rats. Synovitis was significant 4 weeks after MMNX surgery, whereas significant chondropathy was first evident 8 weeks post-surgery, compared to sham controls. Pain behaviour is not always present despite significant changes in medial tibial plateau cartilage damage and synovitis, reflecting the heterogeneity seen in human OA. The development of a slowly progressing surgical model of OA pain in the rat suggests that synovitis precedes pain behaviour and that chondropathy is evident later, providing the foundations for future mechanistic studies into the disease.

Surgical Treatment of Meniscal Extrusion: A Biomechanical Study on the Role of the Medial Meniscotibial Ligaments With Early Clinical Validation.

Background:Meniscal extrusion refers to meniscal displacement out of the joint space and over the tibial margin, altering knee mechanics and increasing the risk of osteoarthritis. The meniscotibial ligaments have been shown to have an important role in meniscal stability. However, it remains unclear whether an isolated lesion of the medial meniscotibial ligaments will result in meniscal extrusion and whether repairing the detached ligament will reduce extrusion.Hypothesis:A lesion of the medial meniscotibial ligament will result in meniscal extrusion, and repairing the joint capsule will eliminate the extrusion by returning the meniscus back to its original position.Study Design:Controlled laboratory study.Methods:Fresh-frozen human cadaveric knees (N = 6) were used for biomechanical testing. The test protocol involved 100 flexion-extension cycles. In full extension, meniscal extrusion was measured using ultrasound, in both an otherwise unloaded state and while subjected to a 10-N·m varus load. Each knee was tested in its native condition (baseline), after creating a detachment of the medial meniscotibial ligament, and finally with the joint capsule repaired using 3 knotless SutureTak anchors. We also performed a retrospective review of 15 patients who underwent meniscotibial ligament repair with a minimal follow-up of 5 weeks (mean, 14 weeks; range, 5-35 weeks).Results:During biomechanical testing, the mean absolute meniscal extrusion at baseline was 1.5 ± 0.6 mm. After creation of the meniscotibial ligament lesion, the mean absolute meniscal extrusion was significantly increased (3.4 ± 0.7 mm) (P < .001). After repair, the extrusion was reduced to 2.1 ± 0.4 mm (P < .001). Clinically, a reduction in absolute meniscal extrusion of approximately 48% was reached (1.2 ± 0.6 vs 2.4 ± 0.5 mm preoperatively; P < .001).Conclusion:This study indicates that the medial meniscotibial ligaments contribute to meniscal stability as lesions cause the meniscus to extrude and that repair of those ligaments can significantly reduce extrusion. Early clinical results using this meniscotibial ligament repair technique support our biomechanical findings, as a significant reduction in meniscal extrusion was achieved.Clinical Relevance:Our biomechanical findings suggest that repair of medial meniscotibial ligaments reduces meniscal extrusion and clinically may improve meniscal function, with the possible long-term benefit of reducing the risk for osteoarthritis.

Two‐Phase Change in Cartilage Metabolism Indicated by Serum Biomarkers at Onset of Posttraumatic Osteoarthritis in a Medial Meniscus Destabilization Rat Model

PurposeOsteoarthritis (OA) is a chronic degeneration of articular cartilage from a deficit of supporting proteins. Surgical destabilization of the medial meniscus (DMM) experimentally leads to trauma‐induced knee OA in rats. Changes in cartilage function or joint remodeling associated with joint instability or disease may be reflected by changes in synthesis or degradation of extracellular matrix, assessed by measuring metabolites, serving as biomarkers, of cartilage synthesis/degradation. Aggrecan chondroitin sulfate 846 epitope (CS846) is associated with synthesis of cartilage ground substance and is elevated in patients with OA. Degradation of type I and II collagen is related to increased serum concentration of C‐terminus of 3/4 peptide, measured as C1,2C.MethodsFemale Lewis rats (n=40) were randomly assigned to DMM (n=20) or sham (n=20) surgery groups. Surgical intervention followed a 2‐week acclimation. The joint capsule was opened and the medial meniscotibial ligament was transected for DMM; no ligaments were cut for sham. Blood samples were collected by tail clipping 1 week prior (baseline) and 2‐weeks (acute phase, surgery effect) and 6‐weeks (late phase, OA effect) postsurgery. Clotted blood was centrifuged (3000 rpm, 30 minutes) and aliquots of serum stored (−80ºC) until analysis. CS846 and C1,2C were analyzed by enzyme‐linked immunosorbent assay kits.ResultsCS846 and C1,2C serum level changes were significant over time (mean [SD] ng/ml) in both groups, but the dynamics were different. CS846 was elevated 2‐weeks postsurgery (1334.7 [1786.6]) compared to baseline (417.8 [591], P=.012), but decreased 6‐weeks postsurgery (610 [1213.4], P=.066) in DMM. CS846 did not change from baseline to 2‐weeks or 6‐weeks postsurgery (P=.16 and .35) in sham. C1,2C decreased 2‐weeks postsurgery in DMM (4211 [1176], P&lt;.001) and sham (4580 [1238], P&lt;.001) compared to baseline (sham 6817 [1348], DMM 5918 [1211]), but the decrease was slightly less in DMM (P=.076). C1,2C continued to decrease between 2‐weeks and 6‐weeks postsurgery in sham (3447 [897], P&lt;.001), but not DMM (4111 [485], P=.360); the between‐groups difference was significant (P&lt;.001).ConclusionsBiomarker dynamics suggested a 2‐phase progression of OA in the posttraumatic model. During the acute phase (2 weeks after trauma), altered joint configuration resulted in increased pressure on articular cartilage causing destruction of ground substance, indicated by increased CS846. Surgical intervention caused collagen type I fiber damage in both groups. Wound healing caused products of collagen breakdown (C1,2C) to rapidly decrease in sham and to a lesser extent in DMM. In the late phase of OA (6 weeks after trauma), erosion of cartilage resulted in collagen type II breakdown, indicated by a lesser decrease in C1,2C in DMM than sham. Continued damage to articular cartilage in DMM caused C1,2C to remain relatively constant between 2‐weeks and 6‐weeks postsurgery. These data indicate that CS846, but not C1,2C, is more useful in the diagnosis of early stages of OA and that the opposite is true in the later phase.

CPII and C2C Biomarkers Favor Cartilage Degradation During Initial Progression of Osteoarthritis in Rats That Have Undergone Destabilization of the Medial Meniscus Surgery

PurposeMeniscal tears can be simulated in animal models using destabilization of the medial meniscus (DMM) surgery, which has been shown to lead to the progression of knee osteoarthritis (OA). Previous studies on DMM‐induced knees have noted damage to the articular cartilage as soon as 2 weeks post‐surgery. By 10 weeks, severe OA was observed in the DMM‐induced knees. While histological markers for OA have been established, no prior study has examined OA serum biomarker changes during the progression from trauma to cartilage degradation. Cartilage turnover can be assessed by measuring metabolites produced during synthesis and degradation of cartilage. These metabolites can serve as biomarkers for cartilage remodeling. Due to the abundance of type II collagen in articular cartilage, CPII and C2C serum biomarkers involved in the synthesis and degradation of type II collagen were selected for this study. Degradation of type II collagen results in increased levels of fragment epitopes (Col2‐3/4long mono), which can be measured as collagen type II cleavage product (C2C). Whereas, synthesis of type II collagen can be detected from circulating levels of procollagen IIC propeptide (CPII), the cleaved C‐terminal globular domain of the pre‐propeptide. Both CPII and C2C have been suggested as early indicators of cartilage injury. Thus, the focus of this study was to document changes in these biomarkers over 2 months in rats that have undergone DMM surgery.MethodsFemale Lewis rats (n=35) underwent a unilateral DMM surgery, in which the medial meniscotibial ligament was transected. Five rats were sacrificed weekly for 7 weeks. Blood from the tail of each rat was collected prior to DMM surgery and euthanasia, for a total of 2 blood samples per rat. Serum from each blood sample was analyzed for C2C and CPII using ELISA kits.ResultsPrior to surgery, C2C and CPII averaged 260 ± 12 ng/mL and 780 ± 47 ng/mL, respectively. Subsequent to DMM surgery, C2C and CPII levels increased to 356 ± 31 ng/mL and 2502 ± 807 ng/mL, respectively, resulting in a degradation‐synthesis ratio (C2C:CPII) of 0.142 during the first week. C2C:CPII increased to 0.462 at 2 weeks post‐surgery, and decreased to 0.093 after 3 weeks. C2C:CPII again increased 4 weeks post‐surgery to 0.393, where it plateaued throughout the remaining 3 weeks. By 7 weeks post‐surgery C2C:CPII was 0.323.ConclusionsThese results lead to the suggestion that collagen type II degradation increased within 2 weeks following the DMM surgery, and collagen type II synthesis was highest 3 weeks after the surgery. An explanation for this may be the physiological and biochemical need to compensate for articular cartilage deterioration after onset of trauma‐induced OA. As OA progressed throughout the remaining weeks (4–7), degradation of type II collagen increased relative to the rate of synthesis and remained above the pre‐surgery ratio. This indicates there is substantial articular cartilage degeneration and remodeling occurring within the first 4 weeks of DMM‐induced knee OA and may represent the optimal period for therapeutic intervention.

TNF alpha-stimulated gene 6 (TSG6) is chondroprotective in vivo but overexpression cannot compensate for loss of FGF2

Purpose: TNF alpha stimulated gene 6 (TSG6) is expressed in response to tissue injury and has purported tissue-protective and anti-inflammatory effects. High levels of TSG6 have been detected in the synovial fluid of patients with OA and following acute knee injury. Our published work shows that TSG6 is regulated after joint destabilisation in mice, in a highly mechanosensitive and fibroblast growth factor 2 (FGF2)-dependent fashion. As FGF2-/- mice develop accelerated OA, and injury-induced FGF2-dependent genes such as Timp1 and inhibin were downregulated in TSG-6-/- mouse joints, we speculated that the chondroprotective role of FGF2 may be mediated through TSG6. We asked whether overexpressing TSG-6 could reduce the severity of OA in wild type or FGF2-/- mice. Methods: OA was induced by cutting the medial menisco-tibial ligament (DMM) in 10-12 week old male and female TSG6-/-, TSG6tg, FGF2-/- mice with their respective controls (C57BL/6 and Balb/c), and male FGF2-/-;TSG6tg+/+ or FGF2-/-;TSG6tg-/- mice. Focal cartilage injury was also performed in male and female TSG6tg mice. 8 and 12 weeks post-surgery, joints were sectioned and the severity of cartilage degradation was assessed according to a modified OARSI score. FGF2 levels were measured in cartilage injury conditioned medium from FGF2-/-, Balb/c, TSG-6tg+/+, TSG-6tg-/+, TSG-6tg-/- hips by V-PLEX bFGF kit from Meso Scale Discovery (MSD, Rockville, MD). Results: Accelerated OA was seen in TSG6-/- male mice at 12 but not 8 weeks post DMM compared with wild type (C57BL/6). A reciprocal improvement in OA scores was seen in male TSG6Tg mice 12 weeks after DMM. FGF2−/− mice developed accelerated OA post DMM as shown previously, but overexpression of TSG6 (FGF2-/-;TSG6tg+/+) was unable to overcome this. There was no significant difference observed in cartilage repair scores 8 weeks after focal cartilage injury in male or female TSG-6tg mice compared with wild type (Balb/c). Secreted FGF2 in cartilage injury conditioned medium was not influenced by genotype indicating that the bioavailability of FGF2 is not determined by TSG-6. Conclusions: TSG-6 is weakly chondroprotective in murine OA. Despite being strongly FGF2 dependent in vivo, TSG6 overexpression does not protect FGF2-/- mice from accelerated OA. The chondroprotective role of FGF2 cannot be explained by FGF2-dependent regulation of TSG6.

Role of vasoactive intestinal peptide in the progression of osteoarthritis through bone sclerosis and angiogenesis in subchondral bone

ObjectiveOsteoarthritis (OA) is a progressive joint disorder, with abnormal remodeling of subchondral bone linked to the disruption of cartilage metabolism. Nerves also play an important role in bone remodeling in OA progression, and vasoactive intestinal peptide (VIP), one of the neuropeptides, plays an important role in bone metabolism. The aim of this study was to analyze the expression pattern of VIP in subchondral bone, and its potential as a therapeutic target for OA progression. DesignThe pattern of VIP expression in the human tibia was histologically evaluated. The effect of VIP on angiogenesis was investigated using human umbilical vein endothelial cells (HUVECs). Knee OA was induced by the resection of the medial meniscotibial ligament in C57BL/6 mice. A VIP receptor antagonist was intraperitoneally administered postoperatively, and therapeutic effects were analyzed at 4 and 8 weeks. ResultsVIP expression in the subchondral bone increased as OA progressed in human tibia. VIP was also expressed in the vascular channels into the cartilage layer. The total length and branch points were significantly increased, due to the VIP receptor agonist in HUVECs. In OA mice, the VIP receptor antagonist could prevent cartilage degeneration and subchondral bone sclerosis. The Osteoarthritis Research Society International score in the VIP receptor antagonist group was significantly lower than in the control group. ConclusionVIP is involved in the progression of OA through its effect on subchondral bone sclerosis and angiogenesis. Inhibition of VIP signaling has the potential to be a therapeutic target to prevent OA progression.

Traumatic Injury of Medial Meniscotibial Ligament – Diagnostics and Conservative Treatment

The paper aims to present diagnostic methods and options of conservative treatment of traumatic injuries of medial meniscotibial ligament (MTL). Ca. 75% of all sport-related injuries pertains to the lower extremity; among those, knee damage the second most frequent, after ankle damage. The anteromedial part is where knee pain occurs most frequently. Knee injuries often lead to damage to ligament structures, including medial meniscotibial ligament, which is rarely reported in the literature. Those ligaments may be damaged when the knee is subject to forces leading to valgity and rotation of the femur, internally, and of the tibia, externally. Damage may be caused in an isolated manner, through overloads and combined microdamage. Medial meniscotibial ligaments are formed by a fibrous layer of the articular capsule and are a part of the deep medial collateral ligament. They run from the medial meniscus to the proximal part of the tibia. An MTL examination consists of three parts: medical interview, physical examination and additional examinations. Due to the structure of MTL, its diagnostics must be expanded by an examination of the anterior cruciate ligament (ACL), medial collateral ligament (MCL) and the medial meniscus. Treatment in the acute condition is carried out according to the PRICE (Protection, Rest, Ice, Compression, Elevation) rules. In the subacute and chronic condition, therapy may be expanded for instance by manual therapy methods, functional training, physical therapy and kinesiology taping.

Accelerated post traumatic osteoarthritis in a dual injury murine model

Joint injury involving destabilisation of the joint and damage to the articular cartilage (e.g., sports-related injury) can result in accelerated post-traumatic osteoarthritis (PTOA). Destabilised medial meniscotibial ligament (DMM) surgery is one of the most commonly used murine models and whilst it recapitulates Osteoarthritis (OA) pathology, it does not necessarily result in multi-tissue injury, as occurs in PTOA. We hypothesised that simultaneous cartilage damage and joint destabilisation would accelerate the onset of OA pathology. OA was induced in C57BL/6 mice via (a) DMM, (b) microblade scratches of articular cartilage (CS) or (c) combined DMM and cartilage scratch (DCS). Mice were culled 7, 14 and 28 days post-surgery. Microcomputed tomography (μCT) and histology were used to monitor bone changes and inflammation. Dynamic weight bearing, an indirect measure of pain, was assessed on day 14. Osteophytogenesis analysis via μCT revealed that osteophytes were present in all groups at days 7 and 14 post-surgery. However, in DCS, osteophytes were visually larger and more numerous when compared with DMM and cartilage scratch (CS). Histological assessment of cartilage at day 14 and 28, revealed significantly greater damage in DCS compared with DMM and CS. Furthermore, a significant increase in synovitis was observed in DCS. Finally, at day 14 osteophyte numbers correlated with changes in dynamic weight bearing. Joint destabilisation when combined with simultaneous cartilage injury accelerates joint deterioration, as seen in PTOA. Thus, DCS provides a novel and robust model for investigating multiple pathological hallmarks, including osteophytogenesis, cartilage damage, synovitis and OA-related pain.

Chondrocyte specific expression of CCN2 does not modify osteoarthritis development in mice

Purpose: CCN2 is a matricellular protein which has been shown to be heavily involved in several complex biological processes including angiogenesis, fibrosis, and chondrogenesis. CCN2 is known to be expressed in both healthy and osteoarthritic cartilage, and involved in the production of the major cartilage matrix proteins; aggrecan and collagen type II. CCN2 null mice have been reported to exhibit a range of skeletal dysmorphisms, highlighting the importance of CCN2 in regulating matrix formation and turnover. The aim of this study was to determine the function of CCN2 in chondrocytes postnatally, in models of trauma-induced osteoarthritis (OA). Methods: Three double transgenic mouse models were generated; two inducible CCN2 knockout (KO) lines and one inducible CCN2 overexpressing (O/E) line. Both CCN2 KO lines contained Aggrecan CreERT2 enhancers which enabled the deletion of CCN2 from different populations of chondrocytes, whilst the O/E line contained an UbcCCN2-IRES-LacZ transgene enabling CCN2 O/E in all chondrocytes. CCN2 deletion and overexpression was induced following tamoxifen treatment in males aged 8 weeks. OA was induced either through surgical injury (transection of the medial meniscus and medial menisco-tibial ligament), or non-invasively by applying a controlled loading regimen to the tibio-femoral joint at 10 weeks of age. Knee joints were harvested and fixed, scanned with μCT, and processed for histology. Sections were stained with Toluidine Blue and scored for articular cartilage degeneration using the OARSI grading system. Results: In the surgical model of OA, cartilage degeneration was most severe on the medial side of the joint, however no significant differences were observed between lesion severity in wildtype (WT) and KO at any of the time-points analysed (2, 4, and, 8 weeks post-surgery). In the non-invasive model of OA lesion severity was most severe on the lateral femur in both the KO and O/E lines. As with the surgical model, no differences in lesion severity were observed between WT / KO and WT / O/E when analysed 6 weeks post-loading. μCT analysis of trabecular bone BV/TV and joint space in both models showed no effect of CCN2 KO and O/E between WT and experimental animals. Conclusions: CCN2 did not appear to play a protective role in the development of OA irrespective of whether the damage was induced surgically or non-invasively. The progression and severity of OA in both models, at all time-points, suggests the expression of CCN2 specifically in chondrocytes is not enough to protect articular cartilage from the degeneration associated with trauma-induced OA.