Meniscal injury and repair: clinical status

Migration of a Meniscal Repair Implant Mimicking Meniscal Injury

Complications after arthroscopic meniscal suture repair have been reported. Migration of a meniscal repair implant mimicking meniscal injury is rare. A 28-year-old female had undergone Anterior Cruciate Ligament (ACL) reconstruction at another hospital 12 years ago . The remaining instability after ACL reconstruction resulted in medial meniscal damage, wear and narrowing in the posterior third. The H-fix that was used in the meniscal repair became detached, exposing the inside of the knee joint. Meniscal repair is a successful procedure in conjunction with ACL reconstruction. However, when knee instability after ACL reconstruction remains, the choice of meniscal repair implants may lead to potential complications even after long-term clinical follow-up.

Chondral Injury After Inside-Out Meniscal Suture Repair Using Meniscal Sutures

Chondral injury after arthroscopic meniscal suture repair is rare. We present a case of chondral injury due to the migration of suture after meniscal repair. The aberrant suture that remained temporarily at the medial tibiofemoral joint may have led to the chondral lesion of the femoral medial condyle and the tibial medial plateau at the weight-bearing portion.

The Role of Cells in Meniscal Guided Tissue Regeneration: A Proof of Concept Study in a Goat Model

OBJECTIVE

Successful repair of defects in the avascular zone of meniscus remains a challenge in orthopedics. This proof of concept study aimed to investigate a guided tissue regeneration approach for treatment of tears in meniscus avascular zone in a goat model.

DESIGN

Full-depth longitudinal tear was created in the avascular zone of the meniscus and sutured. In the two treatment groups, porcine collagen membrane was wrapped around the tear without (CM) or with injection of expanded autologous chondrocytes (CM+cells), whereas in the control group the tear remained only sutured. Gait recovery was evaluated during the entire follow-up period. On explantation at 3 and 6 months, macroscopic gross inspection assessed healing of tears, degradation of collagen membrane, potential signs of inflammation, and osteoarthritic changes. Microscopic histology scoring criteria were developed to evaluate healing of tears, the cellular response, and the inflammatory response.

RESULTS

Gait recovery suggested protective effect of collagen membrane and was supported by macroscopical evaluation where improved tear healing was noted in both treated groups. Histology scoring in CM compared to suture group revealed an increase in tear margins contact, newly formed connective tissue between margins, and cell formations surrounded with new matrix after 3 months yet not maintained after 6 months. In contrast, in the CM+cells group these features were observed after 3 and 6 months.

CONCLUSIONS

A transient, short-term guided tissue regeneration of avascular meniscal tears occurred upon application of collagen membrane, whereas addition of expanded autologous chondrocytes supported more sustainable longer term tear healing.

Repair of meniscal lesions using a scaffold-free tissue-engineered construct derived from allogenic synovial MSCs in a miniature swine model

The menisci of the knee are fibro-cartilaginous tissues and play important roles in the joint, and the loss of the meniscus predisposes the knee to degenerative changes. However, the menisci have limited healing potential due to the paucity of vascularity. The purpose of the present study was to test the feasibility of a scaffold-free tissue-engineered construct (TEC) derived from synovial mesenchymal stem cells (MSCs) to repair incurable meniscal lesions. Porcine synovial MSCs were cultured in monolayers at high density in the presence of ascorbic acid followed by the suspension culture to develop a three-dimensional cell/matrix construct (TEC). A 4-mm cylindrical defect was created bilaterally in the medial meniscus of skeletally mature miniature pigs. The defects were implanted with an allogenic TEC or were left empty. After 6 months, the TEC-treated defects were consistently repaired by a fibro-cartilaginous tissue with good tissue integration to the adjacent host meniscal tissue, while the untreated were either partially or not repaired. The ratio of Safranin O positive area within the central body of the meniscus adjacent to the original defect was significantly higher in the TEC-treated group than in the control group. Moreover, TEC treatment significantly reduced the size and severity of post-traumatic chondral lesions on the tibial plateau. These results suggest that the TEC could be a promising stem cell-based implant to repair meniscal lesions with preventive effects from meniscal body degeneration and the development of post-traumatic arthritis.

Structured three-dimensional co-culture of mesenchymal stem cells with meniscus cells promotes meniscal phenotype without hypertrophy

Menisci play a crucial role in weight distribution, load bearing, shock absorption, lubrication, and nutrition of articular cartilage within the knee joint. Damage to the meniscus typically does not heal spontaneously due to its partial avascular nature. Partial or complete meniscectomy is a common clinical treatment of the defective meniscus. However, this procedure ultimately leads to osteoarthritis due to increased mechanical stress to the articular cartilage. Meniscus tissue engineering offers a promising solution for partial or complete meniscus deficiency. Mesenchymal stem cells (MSC) have the potential to differentiate into meniscal fibrochondrocyte as well as deliver trophic effects to the differentiated cells. This study tested the feasibility of using MSC co-cultured with mature meniscal cells (MC) for meniscus tissue engineering. Structured cell pellets were created using MC and MSC at varying ratios (100:0, 75:25, 50:50, 25:75, and 0:100) and cultured with or without transforming growth factor-beta 3 supplemented chondrogenic media for 21 days. The meniscal and hypertrophic gene expression, gross appearance and structure of the pellets, meniscus extracellular matrix (ECM), histology and immunohistochemistry of proteoglycan and collagen were evaluated. Co-culture of MC with MSC at 75:25 demonstrated highest levels of collagen type I and glycosaminoglycans (GAG) production, as well as the lowest levels of hypertrophic genes, such as COL10A1 and MMP13. All co-culture conditions showed better meniscus ECM production and hypertrophic inhibition as compared to MSC culture alone. The collagen fiber bundles observed in the co-cultures are important to produce heterogenic ECM structure of meniscus. In conclusion, co-culturing MC and MSC is a feasible and efficient approach to engineer meniscus tissue with enhanced ECM production without hypertrophy.

Arthroscopic partial medial meniscectomy

BACKGROUND/AIM

Meniscal injuries are common in professional or recreational sports as well as in daily activities, If meniscal lesions lead to physical impairment they usually require surgical treatment. Arthroscopic treatment of meniscal injuries is one of the most often performed orthopedic operative procedures.

METHODS

The study analyzed the results of arthroscopic partial medial meniscectomy in 213 patients in a 24-month period, from 2006, to 2008.

RESULTS

In our series of arthroscopically treated medial meniscus tears we noted 78 (36.62%) vertical complete bucket handle lesions, 19 (8.92%) vertical incomplete lesions, 18 (8.45%) longitudinal tears, 35 (16.43%) oblique tears, 18 (8.45%) complex degenerative lesions, 17 (7.98%) radial lesions and 28 (13.14%) horisontal lesions. Mean preoperative International Knee Documentation Committee (IKDC) score was 49.81%, 1 month after the arthroscopic partial medial meniscectomy the mean IKDC score was 84.08%, and 6 months after mean IKDC score was 90.36%. Six months after the procedure 197 (92.49%) of patients had good or excellent subjective postoperative clinical outcomes, while 14 (6.57%) patients subjectively did not notice a significant improvement after the intervention, and 2 (0.93%) patients had no subjective improvement after the partial medial meniscectomy at all.

CONCLUSION

Arthroscopic partial medial meniscetomy is minimally invasive diagnostic and therapeutic procedure and in well selected cases is a method of choice for treatment of medial meniscus injuries when repair techniques are not a viable option. It has small rate of complications, low morbidity and fast rehabilitation.

Magnetic Resonance Imaging Double Popliteus Tendon Sign: A Case Report

The double popliteus tendon sign is seen on sagittal magnetic resonance imaging (MRI) of the knee as a low-signal-intensity band parallel to the popliteus tendon at the level of the popliteus hiatus. It is the result of a displaced complex flap tear of the lateral meniscus. This type of displaced meniscal tear can be easily missed on MRI, unless the clinician is aware of its existence and significance and is familiar with its MRI appearance.

Electrospinning of photocrosslinked and degradable fibrous scaffolds

Electrospun fibrous scaffolds are being developed for the engineering of numerous tissues. Advantages of electrospun scaffolds include the similarity in fiber diameter to elements of the native extracellular matrix and the ability to align fibers within the scaffold to control and direct cellular interactions and matrix deposition. To further expand the range of properties available in fibrous scaffolds, we developed a process to electrospin photocrosslinkable macromers from a library of multifunctional poly(beta-amino ester)s. In this study, we utilized one macromer (A6) from this library for initial examination of fibrous scaffold formation. A carrier polymer [poly(ethylene oxide) (PEO)] was used for fiber formation because of limitations in electrospinning A6 alone. Various ratios of A6 and PEO were successfully electrospun and influenced the scaffold fiber diameter and appearance. When electrospun with a photoinitiator and exposed to light, the macromers crosslinked rapidly to high double bond conversions and fibrous scaffolds displayed higher elastic moduli compared to uncrosslinked scaffolds. When these fibers were deposited onto a rotating mandrel and crosslinked, organized fibrous scaffolds were obtained, which possessed higher moduli (approximately 4-fold) in the fiber direction than perpendicular to the fiber direction, as well as higher moduli (approximately 12-fold) than that of nonaligned crosslinked scaffolds. With exposure to water, a significant mass loss and a decrease in mechanical properties were observed, correlating to a rapid initial loss of PEO which reached an equilibrium after 7 days. Overall, these results present a process that allows for formation of fibrous scaffolds from a wide variety of possible photocrosslinkable macromers, increasing the diversity and range of properties achievable in fibrous scaffolds for tissue regeneration.

Meniscal gymnastics: common and uncommon locations of meniscal flip and flop

The majority of knee magnetic resonance imaging examinations are performed for meniscal evaluations. Displaced meniscal tears including free meniscal fragments are an important diagnosis as most of these tears are unstable and require surgical intervention. Magnetic resonance imaging can be an invaluable tool in the arthroscopic search for a free meniscal fragment. In addition to the commonly seen bucket-handle tears flipped into the intercondylar notch, it is important to be aware of less common locations where menisci may be displaced. First, we briefly summarize the basic meniscal anatomy and some of the more common tear patterns. We then investigate the broad range of meniscal migration.

Effects of dynamic compressive load on collagen-based scaffolds seeded with fibroblast-like synoviocytes

Synoviocytes have been speculated to play potential reparative and remodeling roles in vascular meniscal injuries. In addition, synoviocytes may mediate the transformation of intraarticularly placed collagen-based scaffolds into fibrocartilage through exposure to dynamic compressive loads. The objectives of this study were to assess the feasibility of using fibroblast-like synoviocytes (FLS) to engineer meniscal-like fibrocartilage and to better understand the mechanosensitivity of FLS by seeding them onto collagen scaffolds exposed to dynamic compressive loads. Canine FLS were seeded onto disks of four commercially available collagen-based scaffolds (Restore, Permacol, Cuff Patch, and Graff Jacket) and subjected either to one of two levels of intermittent dynamic compressive load or no load. The disks were harvested at 1 and 2 weeks and assessed for cell viability, retention, and infiltration, as well as extracellular matrix production. In general, loading regimens decreased cellularity, and nonloaded Restore grafts retained the most cells across time intervals. Spatial distribution of FLS was optimized in Restore grafts and was overall better in non-crosslinked collagen scaffolds (Restore and Graft Jacket) than cross-linked matrices. Collagen production was noted in association with penetrating FLS clusters in the Restore scaffolds only. The applied biomechanical stimulus did not appear to induce fibrochondrogenesis in any treatment group. These data suggest that Restore scaffolds may foster greater cell retention and infiltration when compared to other commercially available, collagen-based biomatrices.

Regeneration of whole meniscus using meniscal cells and polymer scaffolds in a rabbit total meniscectomy model

The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering method.

Growth factors and fibrochondrocytes in scaffolds

Four growth factors, transforming growth factor-beta1 (TGF-beta1), platelet-derived growth factor-AB (PDGF-AB), insulin-like growth factor I (IGF-I), and basic fibroblastic growth factor (bFGF), were tested at different concentrations for their effects on extracellular matrix (ECM) production in three-dimensional cultures of meniscal fibrochondrocytes. Cells from New Zealand white rabbits were seeded on poly-glycolic acid (PGA) scaffolds and were stimulated with growth factors for three weeks. (3)H-proline and (35)S-sulfate labels were used to measure uptake of collagen and glycosaminoglycan (GAG) components, respectively. Biochemical assays were performed to measure the total collagen, GAG, and DNA present in the scaffolds at the end of the study. TGF-beta1 (10 and 100 ng/ml) stimulated both (3)H-proline and (35)S-sulfate uptake, showing a dose-dependent response for both and a temporal response for (35)S-sulfate uptake. IGF-I (5 ng/ml) and bFGF (25 and 100 ng/ml) showed increases in (3)H-proline uptake by the third week of growth factor addition. PDGF-AB did not show notable increases in uptake. Because TGF-beta1 (10 and 100 ng/ml) had visibly denser scaffolds, as evidenced by gross microscopy, at 100x, and the strongest uptake responses to both (35)S-sulfate and (3)H-proline, it appears to be the most effective growth factor for use in scaffold-based approaches to tissue engineer the knee meniscus.

Fibrochondrogenesis of free intraarticular small intestinal submucosa scaffolds

Naturally occurring biomaterials, such as small intestine submucosa (SIS), are attractive as potential scaffolds for engineering various tissue types. The aim of this study was to determine whether acellular SIS scaffolds can support cell attachment and ingrowth in a diarthroadial joint without significant intraarticular hemorrhage. Disks of porcine SIS were arthoscopically implanted freely within a randomized knee joint of 21 dogs and harvested 1, 2, 3, and 6 weeks postoperatively. Harvested disks were assessed for gross and histologic appearance, cellular infiltration, and immunoreactivity of collagenase and collagen types I and II. Knee synovium and synovial fluid were also evaluated. All disks were thickened and opacified at harvest. Eleven disks (52%) had adhered to intraarticular tissues and cellular infiltration into the disks was positively correlated with tissue adherence. Further, tissue adherence was positively correlated with duration of intraarticular implantation. Five disks (24%) contained focal areas of homogeneous extracellular matrix. A trend toward more collagenase immunoreactivity was noted in the 3-week disks. Collagen type I was present in remaining SIS and extracellular matrix associated with infiltrated cells. Placed freely within a joint, acellular SIS disks underwent cellular and extracellular matrix modification resulting in fibrocartilage-like tissue. Utilization of SIS as a scaffold for intraarticular tissue-engineering applications is supported as cytoconductivity, appropriate residence time, and absence of untoward effects of implantation are desirable criteria for a tissue-engineering biomaterial.

Combined effects of growth factors and static mechanical compression on meniscus explant biosynthesis

OBJECTIVE

To compare the actions of fibroblast growth factor-basic (bFGF), insulin-like growth factor-I (IGF-I), platelet derived growth factor-AB (PDGF-AB), and transforming growth factor-beta 1 (TGF-beta1) on bovine meniscus tissue explants with and without static mechanical compression.

DESIGN

Meniscus tissue explants were cultured in a serum-free environment supplemented with an individual growth factor (1) over a range of concentrations for 4 days, (2) at a single concentration for 2-14 days, and (3) at a single concentration for 4 days coupled with graded levels of static compression. Explants were analyzed for accumulation of newly synthesized proteoglycan and total protein as measured by 35S-sulfate and 3H-proline incorporation, respectively.

RESULTS

Over the range of chosen concentrations, TGF-beta1 was the most potent stimulator of both protein and proteoglycan production, whereas bFGF was the least effective stimulator. Over a 2-week period for all four growth factors, the stimulation of proteoglycan production was sustained while there was no stimulation of protein production during this period. The superposition of static mechanical compression inhibited matrix production in the presence of each anabolic factor, with comparable inhibition relative to uncompressed controls for all factors.

CONCLUSIONS

The growth factors chosen exhibited an anabolic effect on the meniscus tissue explants, encouraging matrix production and deposition. The addition of static mechanical compression produced comparable relative inhibition of matrix production for each growth factor, suggesting that static compression and growth factors may modulate meniscal fibrochondrocyte biosynthesis via distinct pathways.

"All-inside" meniscal repair devices: an experimental study in the goat model

BACKGROUND

Although the use of "all-inside" absorbable meniscal repair devices has become popular, numerous complications have been reported. The authors applied their well-established goat model to evaluate three "all-inside" meniscal repair devices.

METHODS

A "tear" was created in the medial meniscus of both knees in 26 goats. The animals were randomized into four groups, and the meniscus was treated as follows: (A) meniscal repair with Mitek Fastner, (B) meniscal repair with BioStinger, (C) meniscal repair with Mitek Clearfix Screw, and (D) no repair. All animals were sacrificed at 6 months postoperatively, and all specimens were carefully evaluated and results recorded and compared with historical results of meniscal repair with suture in this same animal model.

RESULTS

Meniscal repair results with all three all-inside devices studied were inferior to suture repair. Chondral injury was present in 75% to 100% of repairs with all-inside devices and none of the control specimens.

DISCUSSION

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CONCLUSION

Although new all-inside meniscal repair devices are relatively quick and easy, results may not be as good as with traditional suture techniques. The high rate of chondral injury associated with these devices in the goat model is worrisome for chondral damage in humans, especially in patients with smaller or tighter knees.

Chondral injury and synovitis after arthroscopic meniscal repair using an outside-in mulberry knot suture technique

Arthroscopic meniscal repair has a relatively low incidence of complications. We describe a novel complication of outside-in Mulberry knot repair of the medial meniscus, namely, aseptic synovitis and chondral injury. The presence of synovitis was diagnosed clinically and by multiple arthrocenteses and confirmed, along with a chondral lesion, by repeat arthroscopy. After subtotal meniscectomy, the synovitis subsided clinically.

MR imaging of the meniscus

It should be the goal of any radiologist who interprets MRI examinations of the knee to be able not only to recognize normal meniscal anatomy and accurately diagnose meniscal pathology, but also to develop a better grasp of the surgical implications of the imaging findings. By thinking more like an arthroscopist, one can provide a more clinically relevant report, and by doing so, add value to the work-up of a patient who presents with a potential meniscal tear.

Evaluation of small-intestinal submucosa implants for repair of meniscal defects in dogs

OBJECTIVE

To assess the effects of porcine small intestinal submucosa (SIS) implants on the healing of meniscal lesions in dogs.

ANIMALS

16 adult Greyhounds of both sexes.

PROCEDURE

Unilateral osteotomy was performed at time 0 to disrupt the medial collateral ligament attachment, and two (1 cranial and 1 caudal) 4-mm circular defects were created in the avascular portion of the medial meniscus. One defect was filled with an SIS graft, and the other defect remained empty (control). Three months later, the identical procedure was performed on the contralateral limb. Three months after the second surgery, dogs were euthanatized, and meniscal tissue specimens from both stifle joints were collected for gross, histologic, biomechanical, and biochemical evaluations.

RESULTS

Regenerative tissue was evident in 4 (2 SIS-implanted and 2 control) of 16 defects examined histologically. In 3 defects, this thin bridge of tissue was composed of immature haphazardly arranged fibrous connective tissue with a relatively uniform distribution of fibroblasts. Aggregate modulus, Poisson ratio, permeability, and shear modulus were not significantly different between control and SIS-implanted defects either 3 or 6 months after surgery. Hydroxyproline content also did not differ between SIS-implanted and control defects at 3 or 6 months.

CONCLUSIONS AND CLINICAL RELEVANCE

Implantation of porcine SIS into experimentally induced meniscal lesions in dogs did not promote tissue regeneration.